Infectious Disease News With Views
Archive - 2012
New SARS-Like Corona Virus Can Infect Many Mammalian Cell Types
11Dec12 Updated: 12Dec12
A new report by an international group of investigators (led by a team from Eramus MC in The Netherlands) , and out in the open-access journal mBio, has uncovered yet another surprise about the new SARS-like corona virus, named hCoV-EMC, that emerged earlier this year in the Middle East. Just last month, some of the same investigators published a genomic characterization of hCoV-EMC, finding the novel virus most closely related to coronaviruses from bats, but nonetheless a “cousin” of the SARS virus, which was responsible for the 2002/2003 outbreak of severe respiratory infections that killed some 800 individuals around the world.
Coronaviruses are enveloped single-stranded positive-sense RNA viruses that can infect a wide variety of animals and birds, including bats (a natural reservoir for the SARS virus), birds, cats, dogs, pigs, and humans. Coronaviruses cause respiratory, neurological, or enteric disease of unpredictable severity in the infected species. For example, up until the SARS outbreak, only 2 coronaviruses were known that infected humans, typically causing only mild respiratory disease. Even today, there are now only a half dozen coronaviruses known to infect humans. So the appearance of hCoV-EMC, with its 9 confirmed cases, 5 associated deaths, and relatedness to SARS, warrants a wary eye.
There are common clinical manifestations with SARS and hCoV-EMC (pneumonia and kidney involvement) so the present study began by asking if the two viruses shared a host receptor molecule. Host receptor molecules enable viral entry into host cells, define the tropism of the virus, and influence the pathology of the ensuing disease. SARS virus utilizes the host protein angiotensin-converting enzyme 2 (ACE2) for viral entry. In humans, ACE2 is found only on respiratory cells deep within the lungs thereby contributing to ensuing disease severity but also limiting human-to-human transmission (healthcare workers were the largest population displaying secondary infections, as appears to be the case so far with hCoV-EMC). But the experimental data presented in this paper led the authors to conclude that ACE2 is not a receptor for hCoV-EMC. And, while the SARS virus can infect and replicate only in human cells (due to host adaptation) bearing ACE2 , hCoV-EMC can do so in human, pig, and bat cells, though the identity of the actual receptor has yet to be established.
The authors conclude that these observations suggest “… a low barrier against cross-host transmission” for hCoV-EMC. Such a suggestion has important implications for public health (the future course of the disease and interventions to contain the virus) and the complexity of the virus’ biology. Interestingly, it is thought that all human coronaviruses originated in bats [see this article, for example] with “most recent common ancestors” dating back 200-900 years ago. So the cross-species infectivity of hCoV-EMC may constitute a zoonotic “time machine”, driving viral evolution in a multi-zoonotic environment.
Flu Activity Ramps Up Across US and Canada
A host of news stories have appeared in the past few days sharing a common theme: since Thanksgiving there has been a dramatic increase in the incidence of influenza A cases in an ever increasing slice of the U.S. and even into Canada. States in the south and southeast have had perhaps the greatest spike in flu cases, especially TC, LA, AL, MS, and TN but also SC (with “hundreds of cases”) , and VA (at least one school closed). But other states from CO to NY have also reported large increases and at least one Canadian province (ON) has reported recent spikes in influenza including two deaths. Three have reportedly died already in Idaho and just today influenza is reported as widespread in RI, suggesting the virus has begun moving quickly up the East coast and into the Midwest this week.
Oneida county in upstate New York alone now has nearly 1000 confirmed cases of influenza. The county had only 329 confirmed cases all last season (2011-2012). CT, AK, and AR also have significant flu activity.
Much of the influenza data available (and it is still early) suggests influenza A/H3N2 is the major culprit, but this may change as more recent subtyping data becomes available. Interestingly, some regions are reporting fairly mild cases while other regions note severe disease. The current vaccine should protect against H3N2 but how well awaits more subtyping and sequencing data. The CDC is advising everyone who has not received this year’s flu vaccine to get one quickly.
WHO Issues Global Alert & Response (GAR) on Novel Corona Virus
01Dec12 Updated: 03Dec12
The WHO has issued a Global Alert & Response (GAR) on the novel corona virus (nCoV) first reported earlier this year and carefully followed for its potential similarity to the SARS virus. New confirmed cases of nCoV infection have now been identified in Jordan, in an ICU ward in Zarqa, Jordan in April of 2012. These new cases increase the official number of laboratory confirmed cases of severe acute respiratory illness (SARI) due to infection with the nCoV to 9, with 5 fatalities. The geographical distribution of nCoV infections has also increased from the original reports in Saudi Arabia [five cases (including 3 deaths)] and Qatar [two cases] to the new cases (both fatal and one in a health care worker) in Jordan.
West Nile Virus Outbreak -Update
Today's release of the latest data from the CDC shows that the decelleration of new reported cases of WNV in the US continues. So far this year, at total of 5,245 confirmed cases of WNV have been reported in the U.S. with 236 deaths. This new number represents a week-over-week increase of 38 cases (a 0.7% week-over-week increase; down from 1.5% in the week-over-week count one week ago) and 2 new fatalities. The U.S. is still on track for the second worst year for the disease on record.
Intense Local Outbreaks Portend Upcoming Flu Season?
New reports have emerged of notable influenza outbreaks in New York, Georgia, and Idaho. In Oneida County, New York, 94 confirmed cases of influenza A have been reported in the past week according to the County's Interim Director of the Health Department . In contrast, no cases of influenza were reported in the County last year until late December. A report out of South West Georgia indicates that one ER facility has seen a notable uptick in ER visits (~25% increase in volume) due to influenza, with 40 patients testing positive for influenza (mainly influenza A) this past Wednesday alone. And yet another news article cites Idaho Department of Health and Welfare officials reporting "early" cases of influenza in SW Idaho, especially among school age children and residents of long-term care facilities. An additional report out of Georgia suggests that even persons previously vaccinated this season against influenza are appearing in the ER with influenza.
FDA Panel Backs GSK's H5N1 Flu Vaccine
A report appearing in Internal Medicine News notes that "... the FDA’s Vaccines and Related Biological Products Advisory Committee voted 14-0 that the influenza A (H5N1) Virus Monovalent Vaccine should be approved based on the safety and immune responses to the vaccine in clinical studies." The vaccine candidate, Q-Pan H5N1, was developed by GSK under contract to the U.S. government and, if eventually approved, will be made and deposited into the "...U.S. Strategic National Stockpile and owned by the U.S. government, which would control the distribution and use of the vaccine in the case of a pandemic. GSK has no plans to market the vaccine."
Q-Pan H5N1 vaccine has been already licensed in 30 countries and is currently under review in Canada.
Malaria Vaccine Trial Results a Mixed Bag
The initial reports are out this week on the much anticipated RTS,S/AS01 malarial vaccine that has been under study in infants in seven African countries (see the following news items: Story 1, Story 2, & Story 3; also see the scientific report on the clinical study in the New England Journal of Medicine). On the positive side, some protection was conveyed to vaccine recipients but, on the somewhat disappointing side, the protective effect is small.
Malaria is a major health burden, especially in Africa. As noted on the WHO web site, "According to the World Malaria Report 2011, there were about 216 million cases of malaria and an estimated 655,000 deaths in 2010. Malaria mortality rates have fallen by more than 25% globally since 2000, and by 33% in the WHO African Region. Most deaths occur among children living in Africa where a child dies every minute from malaria."
A cohort of over 6500 infants received either the experimental malaria vaccine at 6-12 weeks of age or a bacterial meningitis vaccine (with the size of the group receiving the malaria vaccine be 2X the "control" vaccine group. All the infants were kept under nets at night (a protective action itself) such that just 2.3% of infants in the "control" group suffered a malarial infection while 1.5% of infants in the test group had a malarial infection, reduction of infection rate of 33%. This is a smaller protective effect than observed in another study last year with the same vaccine in children 5-17 months where a 50% protective effect was observed. Interestingly, infants in the malaria vaccine test group had an incidence of meningitis 2X the "control group.
Developing a vaccine to a parasitic disease is not easy. And despite the smaller protective effect observed in the present study, it is already clear that use of this new vaccine could save tens of thousands of lives and substantially reduce the incidence of a major health burden in Africa.
Two Firms Join Hands on Universal Flu Vaccine
MonoSol Rx has joined forces with BiondVax to develop an oral delivery system for the latter's universal flu vaccine, M-001, according to a report today in Fierce Vaccines. Specifically, MonoSol Rx will use its proprietary drug delivery technology, PharmaFilm, for oral administration of M-001. PharmaFilm employs a quick-dissolving film placed on the tongue. Best of all, "... the technology is small and likely stable at room temperature, meaning influenza vaccines could be sent in the mail. "
A 3rd Vaccination for Mumps Outbreaks?
The recent, major outbreak of Mumps in the Northeast in 2009-2010 was brought under control, at least in part, by the administration of a 3rd dose of MMR vaccine, according to an article out today in MedPage Today. The outbreak, which eventually sickened over 3500 individuals, "... was traced to a twice-vaccinated 11-year-old boy who developed mumps on June 28, 2009, while at a camp in Sullivan County, N.Y., with approximately 400 Orthodox Jewish boys." In one effected community in NY, the CDC investigators found that "...The overall attack rate for all students in grades 6 through 12 fell from 4.93% in the prevaccination period to 0.13% after vaccination (P<0.001)."
This report echoes a similar, on-going story on the bacterial pathogen front involving the duration of efficacy of acellular pertussis vaccines (see below).
West Nile Virus Outbreak -Update
Today's release of the latest data from the CDC shows that the decelleration of new reported cases of WNV in the US continues. So far this year, at total of 4,891 confirmed cases of WNV have been reported in the U.S. with 223 deaths. This new number represents a week-over-week increase of 166 cases (a 3.4% week-over-week increase; down from 7% in the week-over-week count two weeks ago) and 4 new fatalities. The U.S. is still on track for the second worst year for the disease on record.
A new report out yesterday in Emerging Infectious Diseases has found a 3-year cycle to the 2,274 WNV infections in Texas over the period 2002-2011, where two thirds of the cases involved neuroinvasive disease and 6% of which were fatal. The 2012 levels of infection in Texas are right in line with this cycle. WNV is now endemic in Texas and infection risk was found to be highest in regions where the Culex tarsalis mosquitoes are the predominant mosquito species.
New Study: Prevalence of Global Drug Resistant-TB "Worrying"
An article appearing in Medwire News cites the results of a new study appearing in The Lancet [Lancet 2012; 380:1406–1417] from investigators at the CDC. The report shows that "...prevalence of resistance to second-line therapy among individuals with multi-drug resistant (MDR) tuberculosis is high...". A total of over 1200 adult TB patients from eight countries around the world took part in the study. According to the article, "A total of 1278 adult tuberculosis patients treated between January 2005 and December 2008 from Estonia, Latvia, Peru, Philippines, Russia, South Africa, South Korea, and Thailand were included in the analysis.
In all, 43.7% showed resistance to at least one second-line drug, 20.0% to at least one second-line injectable drug, and 12.9% to at least one fluoroquinolone, report the authors. The rate of extensively MDR tuberculosis was 6.7% across the eight countries."
High Dose Vitamin Therapy No Help with HIV
A news item out yesterday in MedPage Today reports on a randomized, controlled clinical study out of Africa showing high dose vitamin therapy has no apparent utility for HIV patients when compared to standard dose vitamin supplementation.
"High-dose daily multivitamins started at the initiation of highly-active antiretroviral treatment (HAART) had no impact on AIDS-related mortality (4% versus 4%, RR 1.14, 95% CI 0.82 to 1.58) or on disease progression compared with a standard multivitamin providing only the daily recommended amounts, Sheila Isanaka, ScD, of Harvard School of Public Health, and colleagues found." Other parameters such as CD4 T cell counts and viral load levels were also unaffected.
Previous studies have suggested a possible beneficial role for high-dose vitamin supplementation for HIV patients (please see this link for a review) but these studies often used placebo as the comparator arm instead of the recommended daily allowance of vitamins employed in this study. The study authors did note that some parients receiving high-dose vitamins did show elevated levels of alanine aminotransferase, suggesting possible hepatotoxicity. The study was published in the Journal of the American Medical Association.
West Nile Virus Outbreak -Update
The latest data from the CDC, released today, indicates that the surge of WNV infections in the U.S. has begun to slow. So far this year, at total of 4,249 confirmed cases of WNV have been reported in the U.S. with 168 deaths. This new number represents a week-over-week increase of 280 cases (a 7% increase) and 5 fatalities, the smallest weekly increments since the summer outbreak began. But, as widely reported last week by Reuters, the CDC believes that the U.S. is still on track for the second worst year for the disease on record.
An Unexpected Surprise in This Past Summer's Flu Activity
This week's Morbidity and Mortality Weekly Report (MMWR) from the CDC has an interesting summary of influenza activity in the U.S. since May of this year. "During May 20–September 22, 2012,† U.S. WHO and NREVSS collaborating laboratories tested 42,562 respiratory specimens for influenza viruses." This is above the top end range of summer samples typically seen. In the preceding six years (excluding 2009, the year of the H1N1 pandemic), the range of respiratory specimens submitted for testing ranged between 20,652 and 39,523, with an average of 29,728. What is interesting is that typically the number of influenza positive samples found is 1.3% of submitted samples, on average 375 positives. This past summer, the number of positives was 7% [2,986]. That would seem to be quite a jump.
Overall, 50% of this past summer's positive flu tests were for influenza B and the other half for influenza A. Flu B dominated test results from May until mid-July while flu A donated thereafter. All of this higher-than-usual summer flu activity comes on the heels of an influenza season that was very mild, a non-event.
Influenza is stunningly unpredictable,always full of surprises, and these past summer months were no exception. There are also other events that have occurred in recent months that are unusual. Flu B was not a major player in last flu season's confirmed cases in the U.S., though it was elsewhere. More intruigingly, this past summer saw the unusual coincident occurrence of 3 novel swine-origin triple reassortant viruses (H3N2v, H1N1v, and H1N2v) infecting humans.These unusual events are perhaps fleeting glimpses of the complex machinations that create new influenza "surprises".
H3N2v: A Reprieve But With Increasing Discordance
The latest weekly update from the CDC, for the week ending Sept 29th and released Oct. 5th, shows that the variant swine flu virus, H3N2v, has taken a break, with the number of confirmed cases in the U.S. remaining at 306. To date, sixteen H3N2v-associated hospitalizations and one H3N2v-associated death have been reported to the CDC. “Cumulative totals by state since July 12 are: Hawaii , Illinois , Indiana , Maryland , Michigan , Minnesota , Ohio , Pennsylvania , West Virginia , and Wisconsin .” The total number of swine variant influenza infections in humans now stands at 310: “…As a result of enhanced surveillance activities for H3N2v, one infection with an influenza A (H1N1) variant (H1N1v) virus and three infections with influenza A (H1N2) variant (H1N2v) virus have been detected since July 2012.” Overall, the same report also noted “…6.3% of all deaths reported through the 122-Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 6.5% for week 39.”
The CDC weekly update continues to stipulate that “The vast majority of cases have occurred after prolonged swine exposure, though instances of likely human-to-human transmission have been identified. At this time no ongoing human-to-human transmission has been identified.” But in seeming contradiction to this statement, the genomic sequences of H3N2v viruses obtained over the past year or so from both pigs and humans show increasing discordance, as highlighted in a Commentary today from Recombinomics. “Although all released human sequences from 2011 and 2012 cases have an H1N1pdm09 M gene, the first 10 cases from 2011 have an N2 lineage that traces back to H1N2v swine. In contrast, the last 2 cases in 2011 and 89/91 human H3N2v sequences from 2012 have an easily distinguished N2, which is from an H3N2v swine lineage.” This switch in the N2 lineage of human isolates has not been seen in swine H3N2v. This discordance was recently extended when the USDA released the sequences of additional, more recent, swine isolates, though the story becomes a little more complex as sequences from human isolates have just recently begun to appear in pigs not at fairs. “This large discordance between human and swine H3N2v lineages suggest the lineage in most 2012 human cases is evolving in humans, and is rarely found in swine not at agricultural fair venues, although the recent swine cases identified in Indiana and Ohio may signal an entry into the swine population which increase frequencies in subsequent USDA samples acquired through its voluntary surveillance system.” The fact that the symptoms associated with human H3N2v infection are so similar to infection by “typical” seasonal H3N2 and thus escape special notice, likely increases the chance for distinct viral evolution in humans.
West Nile Virus Outbreak -Update
Reuters is reporting that the latest statistics from the CDC show that "... The outbreak of West Nile virus that has hit Texas and other states remains on pace to make 2012 the second-worst year on record for the disease in the United States, with another 424 cases and 16 deaths reported last week....". That would bring the year to date totals in the US to 3,969 confirmed cases and 163 fatalities. As in previous weeks, a little more than half of all reported cases are of the more severe neuroinvasive type of WNV infection, although striking regional differences are evident in the fraction of cases that are more severe. To date, eight states (TX, MS, MI, SD, LA, OK, IL, and CA) account for roughly 70% of all confirmed cases.
Swine Flu H1N1v Confirmed in Ontario Has the H1N1p M Gene
A report at the end of last week confirmed earlier suspicions that the swine H1N1v sample out of Ontario does indeed contain the M gene from the 2009 H1N1p strain of influenza A. There have been two recent cases of human infection by triple reassortant swine H1N1v in the US: in Wisconsin (December 2011) and Missouri (reported September 2012). Both have the M gene from the 2009 H1N1p strain of influenza A. Indeed, all variant swine viruses currently circulating in North America and infecting humans contain the M gene from 2009 H1N1p. Sequencing of the Ontatio H1N1v HA gene showed 98.8% homology to the Missouri virus, 96% homology to the Wisconsin virus, and 92% homology to 2009 H1N1p virus. The U.S. H1N1v viruses are related antigenically to the 2009 H1N1p strain, influenza A/California/7/2009, which is a component of the currently available influenza vaccine.
Worrisome New Coronavirus Gets a Name or Two
According to a report out in Medpage Today, the novel coronavirus causing so much worry, globally but notably in the UK, due to its potential similarity to SARS CoV [severe acute respiratory syndrome coronavirus; see below] viirus, now has a name: London1_novel CoV2012. Catchy, no? As noted in a Commentary from Recombinomics last week, "The Ron Fouchier Viroscience lab at the Erasmus Medical Centef has released the complete sequence (30118 BP) of an isolate, Human betacoronavirus 2c EMC/2012, from the recent fatal case (60M) from Saudi Arabia (at Genbank)." So, two names may be at play already. Also, note that there is, as yet, no viral isolate from the 2nd infected patient.
More importantly, it is clear from the available sequencing data that this new coronavirus emerged from group 2c [prevalent in bats]. As also noted by Recombinomics, "...The group 2c coronaviruses are distinct for the human SARS CoV, which maps to group 2b. However, coronavirus rapidly evolve via homologous recombination and portions of genes show regions of identity
o[r] high homology with coronavirus segments from other species or phylogenetic groups." A phylogenetic tree of coronavirus groups and the new 2c strain can be found at the UK's Health Protection Agency website. Also note that the fatal index case and the 2nd Qatar case viral strains are very similar, but not identical, at the genetic level.
The Medpage Today article also points out that many unanswered questions remain about this new CoV, including how long it takes from infection to symptom onset and if infection can occur without symptoms. So we watch and wait.
A 2nd EEE Fatality in MA
The Boston Globe is reporting the second death this year due to infection with the Eastern Equine Encephalitis (EEE) virus. The total number of confirmed EEE cases this year has climbed to 7. This victim, a 63-year-woman from Amesbury, died Saturday, according to the The Daily News of Newburyport, of complications from EEE. State Heath officials also reported that the number of confirmed infections from West Nile virus (WNV) has increased to 19, including one fatality.
An Echo of SARS: A New Coronavirus in the UK
A report out today in Medpage Today describes a new human infection in the UK by a coronavirus, the same type of virus that led to the SARS [severe acute respiratory syndrome] outbreak of 2002-2003. It is only the second known case concerning this new coronavirus; the only other case was in a man in Saudi Arabia several months ago who subsequently died. The viral sequences from the two patients are 99.5% identical.
West Nile Virus Outbreak -Update
CBS News is reporting that the CDC has released data showing the number of cases of WNV infection in the US has continued to increase to a year-to-date total of 3,142, with 134 fatalities. This represents an increase in confirmed cases of 19% over the past week. As in previous reports this year, a little over half (51.9%) of the reported cases are of the neuroinvasive type. A large fraction of the cases have occurred in TX (40% of reported cases), LA (4.7%), MS (5.5%), MI (5.1%), SD (5.0%), CA (4.0%) and OK (4.4%). Over 50 cases have been reported in IL, ND, MN, NE, NY, CO, and OH. Given the incubation of infection, there is hope that the rate of new cases will now slow as different regions head towards their first hard freeze of autumn.
Hantavirus Warnings Extended
Warnings to nearly a quarter million visitors to Yosemite National Park have been issued by the National Park Service after a 9th case of the disease emerged, according to a report on Medscape, citing a story by Reuters. All but one of those with confirmed infections at Yosemite are believed to have contracted the virus in Curry Village, while one stayed in the park's back country. With an incubation time of as much as six weeks or more, additional cases are possible.
Hantaviruses are RNA viruses of the Bunyaviridae family. According to the A.D.A.M. Medical Encyclopedia listing on PubMed, "...Hantavirus is a serious infection that gets worse quickly. Lung failure can occur and may lead to death. Even with aggressive treatment, more than half of people who have this disease in their lungs die." The virus is carried by rodents, notably deer mice, which remain asymptomatic but shed the virus in urine and feces. The early symptoms of hantavirus disease are similar to the flu (chills, fever, & muscle aches). Infected individuals may begin to feel better briefly, but within 1-2 days, it becomes hard to breathe. The condition of the patient degenerates quickly with symptoms such as dry cough, general malaise, headache with nausea and vomiting, as well as shortness of breath.
Update on Dengue Infections in Puerto Rico
The latest report out of Puerto Rico finds the total number of confirmed cases of dengue, a mosquito-borne virus like WNV and EEE, this year has reached 1221 with 3 deaths. Thousands of cases of dengue have been reported elsewhere in the Americas, especially in the Yucatan, Honduras, and El Salvador.
Flu Season Arrives Early
On a teleconference to mark the beginning of National Infleunza Vaccination Week, the CDC announced that the flu season has commenced in earnest a bit early this year – by about a month - according to an article by Todd Neale, out on MedPage Today. For the the week ending Nov. 24th, the percentage of visits to the doctor attributed to influenza-like illness -- fever, cough, sore throat, or a combination -- was 2.2%, which matches the national baseline. A total of five states (AL, LA, MS, TN, and TX) have reported high flu activity while GA and MO have reported moderate activity.
"This is the earliest regular flu season we've had in nearly a decade, since the 2003-2004 flu season," CDC director Thomas Frieden, MD, MPH, said during the call with reporters, according to the MedPage Today article. Just as in the 2003-2004 season, influenza A(H3N2) is the predominant strain circulating so far this year. Historically, the early presence of A(H3N2) portends a more severe flu season with poorer outcomes for the very young and very old.
Pertussis in U.K. Explodes to Level 10 Times Last Disease Peak
The U.K.'s Health Protection Agency has announced that the number of pertussis cases in England and Wales has sky rocketed to over 7,700 cases this year, according to a report by Kristen Hallam in Bloomberg News. "The number of cases in October reached 1,614, bringing the total for the year to 7,728 including 13 infant deaths, the agency said today in an e-mailed statement. Almost 800 cases were reported in 2008, according to the HPA. More than 80 percent of the 2012 cases are in people age 15 and older."
Pertussis is a disease that, prior to the introduction of a vaccine in the 1940's, infected some 200,000 each year in the US and caused about 9,000 deaths annually. In more recent times, about 10,000-25,000 cases reported each year in the U.S. But, according to the CDC, "pertussis is naturally cyclic in nature, with peaks in disease every 3-5 years. But for the past 20-30 years, we've seen the peaks getting higher and overall case counts going up. There are several reasons that help explain why we're seeing more cases as of late. These include: increased awareness, improved diagnostic tests, better reporting, more circulation of the bacteria, and waning immunity." However, a 10-fold jump in peak intensity of infection is startling and the root causes behind this jump require definition.
Pertussis: Waning Effectiveness of the DTaP Vaccine Over Time
An update to to news item that appeared here back in September. New data from a pertussis outbreak in CA back in 2010 further confirms the association between increased pertussis in children and young adults and an increased span of time since administration of the last (5th) acellular pertussis vaccine (DTaP) booster shot, suggesting DTaP loses its efficacy as time wanes from the last booster a child receives.
In a study apprearing in the Journal of the American Medical Association, the authors found that: "Among children in 15 California counties, children with pertussis, compared with controls, had lower odds of having received the 5-dose DTaP series; as time since last DTaP dose increased, the odds increased, which is consistent with a progressive decrease in estimated vaccine effectiveness each year after the final dose of pertussis vaccine."
California experienced its largest pertussis epidemic in more than 60 years during 2010. It was noted that many 7- to 10-year-old were affected despite high vaccine (DTaP) coverage. The authors arrived at their conclusions after performing a retrospective, case controlled study (n= 2698) that calculated "...odds ratios (ORs) for the association between pertussis and receipt of the 5-dose DTaP series and (2) ORs for the association between pertussis and time since completion .... of the 5-dose DTaP series. "
As noted in the accompanying editorial in JAMA, data that can establsh the duration of efficacy of the acellular pertussis vaccine is coming soon. But in the meantime, this (and other) correlative studies help spark a discussion of future directions for pertussis vaccines and their pediatric deployment.
Zoonotic Aerosol Transmission of Ebola?
An news story by Matt McGrath appearing online from the BBC reports that "....Canadian scientists have shown that the deadliest form of the ebola virus, Ebola Zaire, could be transmitted by air between species." Specifically, the investigators have shown that the virus can be "...transmitted from pigs to monkeys without any direct contact between them." Respiratory droplets are believed to the mode of transmission. That said, one of the study investigators, Dr. Gary Kobinger at the Public Health Agency of Canada, was quick to point out that this does NOT mean that Ebola is a true airborne respiratory virus like influenza. Interestingly, aerosol transmission was NOT observed between comparably separated macques.
This study was published against a backdrop of a fresh outbreak of Ebola in Uganda that has killed at least two (and follows a Ugandan outbreak in July that killed 17) and mounting evidence that pigs serve as a natural host for the virus.
The Ebola virus causes severe viral haemorrhagic fever (VHF) outbreaks in humans with case fatality rates of up to 90%. If pigs do play a role in viral zoonosis that leads to human infection, they could also provide a point for viral control and containment.
West Nile Virus Outbreak -Update
Today's release of the latest data from the CDC shows that the decelleration of new reported cases of WNV in the US continues. So far this year, at total of 5,128 confirmed cases of WNV have been reported in the U.S. with 229 deaths. This new number represents a week-over-week increase of 74 cases (a 1.4% week-over-week increase; down from 3.2% in the week-over-week count one week ago) and 1 new fatality. The U.S. is still on track for the second worst year for the disease on record.
News with Views
West Nile Virus Outbreak -Update: Has the Virus Mutated?
08Nov12 -- Updated 09Nov12
Today's release of the latest data from the CDC shows that the decelleration of new reported cases of WNV in the US continues, although only modestly. So far this year, at total of 5,054 confirmed cases of WNV have been reported in the U.S. with 228 deaths. This new number represents a week-over-week increase of 163 cases (a 3.2% week-over-week increase; down from 3.4% in the week-over-week count one week ago) and 5 new fatalities. The U.S. is still on track for the second worst year for the disease on record.
A new article by Brian Vastag in the Washington Post appeared today (Nov. 9th), entitled "Hints of a more virulent, mutating West Nile virus emerge". The article cites antecdotal information from several physicians that suggests that "...The virus, in some cases, is attacking the brain more aggressively than in the past, raising the specter that it may have mutated into a nastier form." While the CDC has stated that it has seen no evidence of altered patterns of brain damage, physicians contacted by the Washington Post have observed an enhanced level of neurovirulence as well as altered patterns of brain damage. The latter view is further supported by "... a Texas virologist whose laboratory has found signs of genetic changes in virus collected from the Houston area."
This would not be the first time the virus underwent a significant change since its introduction into the U.S. in 1999. In 2002, the founder NY99 strain was being displaced by a new gentoype, W02, which eventually displaced NY99 in North America. In 2003, another new regional strain was identified (WN03) which eventually expanded in North America.
FDA Panel Gives Nod to Anthrax Drug: The 2nd Ab to Be Approved for an ID?
An article appearing in MedPage Today reports that "An FDA panel has unanimously voted in favor of approving the monoclonal antibody raxibacumab for treating inhalational anthrax, just 3 years after the agency denied approval of the same drug." In its previous denial, the FDA panel expressed doubt that the mAb had any added benefit over the antibiotic levofloxacin alone.
To address these concerns, the drug's sponsor, Human Genome Sciences, conducted additional preclinical and clinical studies and re-submitted its application under the FDA's "animal rule." HGS used a rabbit model of inhalation antrax infection. Speficially, the " researchers administered the drugs 84 hours after exposure to anthrax in a new efficacy study. While only 76 of 180 rabbits (42%) survived until the 84-hour mark, 82% receiving raxibacumab and levofloxacin survived 28 days, compared with 65% with levofloxacin alone."
If approved later this year, raxibacumab will become only the second monoclonal antibody approved for an infectious disease indication.
Incidence of 2009 H1N1p Infection in U.S. Population in 2009
An article published yesterday in PLoS One showed that, by the end of 2009, nearly 20% of the U.S. population was infected by the pandemic influenza A strain, 2009 pH1N1, including about half of all school-age children. The investigators used serological tools to assess the cumulative incidence of the virus throughout 2009, starting with its appearance in the U.S. in April. "After adjusting for baseline cross-reactive antibody, pandemic vaccination coverage and the sensitivity/specificity of the HI assay, we estimate that 20.2% (95%CI: 10.1–28.3%) of the population was infected with A(H1N1)pdm09 by December 2009, including 53.3% (95%CI: 39.0–67.1%) of children aged 5–17 years."
This is a startling level of penetration by the virus into the pediatric population over an 8 month time period and raises new questions about the utility of a pandemic vaccine that began distribution in October of 2009.
West Nile Virus Outbreak -Update
Today's release of the latest data from the CDC indicates that the surge of WNV infections in the U.S. continues, but at a somewhat lower rate. So far this year, at total of 4,531 confirmed cases of WNV have been reported in the U.S. with 183 deaths. This new number represents a week-over-week increase of 282 cases (a 6.6% week-over-week increase; down from 7% in the previous week-over-week count) and 15 new fatalities. The U.S. is still on track for the second worst year for the disease on record.
Early Influenza B Outbreak in Loredo, TX?
A report out yesterday states that Laredo Texas is experiencing an early outbreak of influenza B, with an incidence 6 times higher than last year. This report states that the Texas Department of State Health Services has confirmed the outbreak, a contention denied by the TDSHS today. Rather, it seems the "outbreak" was detected by a new early surveillance system.
For the week ending Oct. 6th (week 40), the CDC is reporting 48% of all confirmed influenza samples as influenza B, while 64% are flu B in HHS region 6 (which contains TX). Influenza B levels (again as a % of confirmed samples) are even higher in the southeast and upper mid-west (HHS regions 4 and 5) though they are very low in the West and the mid-Atlantic states (HHS regions 3, 6,9,and 10).
The 2012-2013 flu season is just commencing in North America. Influenza A was the dominant viral type during last year's mild flu season in the U.S. (see this link) comprising 86% of all cases [and influenza B accounting for the remaining 14%]. But influenza B was much more prominent in the flu season just ended in southern latitudes, especially in certain regions in countries such as Australia. It will be interesting to see if and where influenza B dominates the upcoming season in northern latitudes.
A Dengue Fever Epidemic in Puerto Rico
Writing for MedPage Today, Michael Smith reports today that Puerto Rico has declared a dengue fever epidemic as the number of reported cases climbed to 342 for the week ending Sept. 15th. This is an increase of 247 cases over the preceding week. Puerto Rico’s Health Secretary, Dr. Lorenzo Feliciano, said in a statement Monday that the number of reported dengue fever cases has been above the epidemic threshold for two weeks in a row. The Health Secretary also noted that more than half half of the reported cases had laboratory confirmation. So far this year, there have been 4,816 suspected cases in Puerto Rico, 21 cases of dengue hemorrhagic fever, and six deaths.
After 3 Years, A New-Found Hemorrhagic Fever Virus?
An international effort has, after roughly 3 years of work, tentatively identified a new hemorrhagic fever virus from one of three patients in the Democratic Republic of Congo. Reporting in ScienceNow, Jon Cohen writes that the investigators did not actually isolate the new rhabdovirus, but rather assembled bits of viral RNA by deep sequencing of a sample of a convalescing patient's blood. However, it is still not certain that the Bas-Congo virus is etiological agent of disease. The investigators work was just published in the journal PLoS Pathogens.
The epidemiological odyssey began in late May/early June 2009 with an outbreak of acute hemorrhagic fever in three people from the village of Mangala. The first two patients, teenagers, exhibited symptoms of hemorrhagic fever and died shortly thereafter. But a third individual, a health care worker, survived. When initial efforts to identify the culprit virus from among known hemorrhagic viruses (e.g. Ebola virus, Marburg virus, Lassa fever, Rift Valley fever, and dengue) proved negative, the search drew in Eric Delwart at the Blood Systems Research Institute in San Francisco. Delwart's group randomly amplified genetic material by PCR and analysis of the products clearly indicated a rhabdovirus. But little else could be gleened until the amplified samples were sent to Charles Chiu, head of a viral discovery center at the University of California, San Francisco for deep sequencing.
A 3rd EEE Fatality in MA
The Boston Globe is reporting the third death this year due to infection with the Eastern Equine Encephalitis (EEE) virus. The total number of confirmed EEE cases this year is 7. Last year, there were a total of 2 confirmed cases of EEE in the state and 1 fatality.
Vitamin D Ineffective for Respiratory Tract Infections
An article appearing in Medscape Infectious Disease describes the results of a randomized, placebo-controlled trial which shows that "...adding vitamin D supplements to your diet with will not prevent upper respiratory tract infections (URTIs) or hasten your recovery from them". The results of the clinical trial will be published online October 3 in the Journal of the American Medical Association.
This is the first definitive clinical trial to determine whether vitamin D therapy reduces rates of upper respiratory tract infections in adults. The results stand in contrast to a variety of observational studies, as well as basic research, that indicated a possible benefit from Vitamin D against respiratory infections in humans.
More on the Deadly New Coronavirus
Medscape Infectious Disease is carrying an interesting article from Reuters on the efforts at the UK's HPA labs in pursuit of the London1_novel CoV2012 virus.
Hantavirus Warnings Extended
The U.S. has experienced an outbreak of hantavirus infection in Yosemite National Park this year, with 9 confirmed cases to date. One of the little mysteries surrounding this outbreak is that only park visitors, and not park employees, have been infected. As noted today in Medscape Infectious Disease, Public Health officials will commence screening park employees this week, collecting blood samples and distributing questionnaires, looking for clues behind this curious observation. It is hoped that insights gained will be useful in curtailing new infections in Yosemite and elsewhere.
The Novel Swine Flu H1N1v Confirmed in Ontario
The first confirmed case of human infection with the variant swine flu H1N1v in Canada has been reported. Dr. Arlene King, Ontario's Chief Medical Officer of Health, says the man is being treated in a hospital in southwestern Ontario. Prior to this announcement, two other reports of H1N1v infection in humans had been reported, both from the US. As noted in a Commentary on the Recombinomics web site, ".... [T]he genetic relationship between this [Ontario] isolate and the 2012 US isolate, A/Missouri/12/2012, is unclear, as is the presence of an H1N1pdm09 M gene." This Commentary also notes that ".....The Ontario cases creates an unprecedented situation involving three variant sub-clades (in addition to H1N1pdm09) co-circulation in North America."
Rediscovering a Potent Antibiotic for TB
An old antibiotic may have new life as a potent treatment for TB, including multidrug resistant TB according to an article out today in The Scientist. A group of Swiss investigators found that the antibiotic pyridomycin, reportedly produced by the bacteria Streptomyces pyridomyceticus and Dactylosporangium fulvum inthe 1950's exhibited broad anti-mycobacterial activity, includning against TB.
As described in the article, pyridomycin and isoniazid, a component of the current first-line treatments for TB, have intertwined histories and biochemistry. Both were discovered about the same time but subsequent interest focused on isoniazid while pyridomycin was consigned to the historical dust bin. Both compounds target a protein called inhA, but isoniazid is a pro-drug activated the enzyme KatG before it can bind to inhA while pyridomycin binds inhA directly.
The differences in method-of-action may be all important since a large majority of drug resistant mutations against isoniazid are found in the KatG gene. Indeed, pyridomycin showed excellent antibacterial activity against drug-resistant strains of TB. In addition, pyridomycin showed excellent broad spectrum antibacerial activity, unlike isoniazid which is active only against TB, including ".... in leprosy or Buruli ulcer or atypical mycobacterial infections that can occur in cystic fibrosis patients.”
Additional preclinical testing is still necessary prior to clinical evaluation.
A 5th Eastern Equine Encephalitis Virus Infection in Humans in MA
The Boston Globe is reporting a 5th case of human infection with Eastern Equine Encephalitis virus. The Massachusetts Department of Public Health has announced that the infected individual, a man in his 70's, is currently hospitalized. The Department also said that a man in his 40s from Greater Boston has been diagnosed with West Nile virus, the 15th such case this year. So far this year, there has been single fatlities each for EEE and WNV in the state.
Most Sore Throats Due to Viral, Not Bacterial, Infections
New guidelines from the Infectious Diseases Society of America, as reported on Medscape state that "...The majority of throat infections are viral and should not be treated with antibiotics...". The guidelines "are aimed at limiting the antimicrobial treatment of viral infections and correctly identifying and treating cases of group A streptococcal pharyngitis ("strep throat"). Penicillin and amoxicillin are the drugs of choice for treating streptococcal infections".
CDC Update on Novel Swine Flu Variants Infecting Humans
As reported by CIDRAP, the CDC has announced that the number of confirmed H3N2v cases in the US this year has now reached 305, up 9 cases over the previous week. Interestingly, two other variant swine influenza infection cases were noted (H1N1v in Missouri [only the 2nd such reported case] and H1N2v in Minnesota) both of which, like H3N2v, contain the M gene from the 2009 H1N1p virus. While 12 other H1N1v cases have been reported to the CDC since 2005, none of these contain the 2009 H1N1p M gene. And while CDC's numbers show 3 H1N2v infections this year [all with the 2009 H1N1p M gene], the Minnesota Department of Health has just increased the number to 4.
Of the 305 H3N2v confirmed cases, there have been 16 H3N2v-related hospitalizations (HR = 5.2%) and 1 death (CFR = 0.3%). Roughly one third (102) of all H3N2v cases are from Ohio. The CDC reiterated its views that a few instances of likely human-to-human transmission of H3N2v have occurred but no ongoing human transmission, a view hotly contested by others. Indeed, Recombinomics has noted the "discordance" between swine and human H3N2v sequences from confirmed cases in each species, with only 2 of the 138 deposited sequences from infected swine during 2012 showing correspondence to the 2012 human sequences.
Pertussis: Waning Effectiveness of the DTaP Vaccine Over Time
An article has appeared online at the New England Journal of Medicine describing a study of the persistence of immune protection to pertussis in children after receiving their standard 5th immunization with the DTaP vaccine. Children typically receive a total of 5 immunizations with the DTaP vaccine, completing the regimen by 7 years of age. As discussed, below, there have been increasing concerns about the effectiveness of the DTaP vaccine in the face of a rising incidence of pertussis in the US, especially in teens. The present study found that, after the fifth dose, "...the odds of acquiring pertussis increased by an average of 42% per year."
New Study on H1N2v in Ferrets Provides Insight Into Origins of a Zoonotic Pathogen
A new paper has been published in The Proceeding of the National Academy of Sciences from an international team of scientists studying a H1N2 strain of swine influenza capable of killing ferrets and spreading among them by respiratory droplets. The investigators were seeking "...to assess the pathogenicity and transmissibility of predominant Korean triple-reassortant swine (TRSw) H1N2 and H3N2 influenza viruses genetically related to North American strains. Although most of the TRSw viruses were moderately pathogenic, one [A/Swine/Korea/1204/2009; Sw/1204 (H1N2)] was virulent in ferrets, causing death within 10 d of inoculation, and was efficiently transmitted to naive contact ferrets via respiratory droplets." Interestingly, "...the Sw/1204 virus acquired mutations in hemagglutinin (HA) (Asp-225-Gly) and neuraminidase (NA) (Ser-315-Asn) proteins during the single ferret passage. The contact-Sw/1204 virus became more virulent in mice, replicated efficiently in vitro, extensively infected human lung tissues ex vivo, and maintained its ability to replicate and transmit in swine."
The latter virus, isolated in Korea, is similar to H1N2v viruses circulating the the US and responsible for 4 confirmed cases of human infection in MN this year.
This study underscores the continuing threat of swine flu to humans amid a wave of swine-origin flu cases in the US. And this study also illustrates how rapid the adaptation can be for novel triple-reassorted swine viruses to infect humans .
A 4th Eastern Equine Encephalitis Virus Infection in Humans in MA
The Boston Globe is reporting that the Massachusetts Department of Health is confirming a 4th case of human infection with Eastern Equine Encephalitis virus. The infected individual, a man in his 60's, is currently hospitalized. The Department of Health also confirmed a 14th case of West Nile virus infection in the state.
Anti-Bacterial Activity of Two Vitamins
Check out the Inflammation News with Views page for two reports on potential anti-bacterial activity for two well known vitamins: D and nicotinamide (B3). Vitamin D actually has a prior history as an anti-TB agent (and other respiratory pathogens) while nicotinamide has now been shown to possess anti-Staphylococcus aureus activity in vivo.
West Nile Virus Outbreak -Update
The CDC announced today that the number of cases of WNV infection in the US has continued to increase to a year-to-date total of 2636, with 118 fatalities. As in previous reports this year, a little over half (53.6%) of the reported cases are of the neuroinvasive type. A large fraction of the cases have occurred in TX (40% of reported cases), LA (5.6%), and OK (4.9%), but triple digit case reports are also observed in MI, MS, and SD. Over 50 cases have been reported in IL, CA, ND, MN, and OH.
A 3rd Eastern Equine Encephalitis Virus Infection in Humans in MA
The third confirmed case of human infection with EEE in Massachusetts was reported today. A young girl (under 18) from the Athol area has been hospitalized and the town has moved to close all parks and playgrounds from dusk to dawn as well as to suspend all evening sports activities.
The presence of EEE in populations of mosquitoes that bite humans is of some concern since human infection with EEE exhibits approximately 33% mortality and significant brain damage in most survivors (link).
Pediatric Flu Vaccine Guidelines for 2012-2013 Season
A report on Medscape has described new guidance and recommendations from the American Academy of Pediatrics regarding this upcoming season's influenza vaccination campaign. As in the past few years, the 2012-2013 vaccine contains A/California/7/2009 (H1N1)–like antigen. But the 2012- 2013 vaccine also contains A/Victoria/361/2011 (H3N2)–like antigen and B/Wisconsin/1/2010–like antigen [a Yamagata strain]. In contrast, last year's 2011-2012 vaccine contained A/Perth/16/2009 (H3N2)–like antigen and B/Brisbane/60/2008-like antigens. This is the first change to flu vaccine composition in 4 years.
West Nile Virus Outbreak -Update
The latest data from the CDC shows that the number of cases of WNV infection in the US has continued to increase to a year-to-date total of 2280. As in previous reports this year, a little over half of the reported cases are of the neuroinvasive type. Over 87 deaths have now been reported this year in the US. A large fraction of the cases have occurred in TX, LA, and OK, but additional regional clustering of cases are evident in the Northeast, the Dakotas, and CA.
Swine H3N2v Claims Its First Human Victim
A 71-year old woman from Ohio is the first reported fatality from the novel swine influenza strain, H3N2v, according to the CDC. As of today, the CDC says there have been 289 confirmed cases of swine flu this year and that two states, Ohio with 101 cases and Indiana with 138 cases, have been hit the hardest.
West Nile Virus Outbreak -Update
The CDC has announced that, through today, a total of 1590 cases of WNV have been reported in the US with 66 deaths. Over half of the cases  were of the neuroinvasive type. Today's tally is an increase of over 400 cases in just the last week. At this rate, the US is on course for the largest yearly case count since the disease was first reported in the U.S. in 1999.
West Nile Virus Outbreak Expands
The CDC has announced that, through today, a total of 1118 cases of WNV have been reported with 41 deaths. Over half of the cases were of the neuroinvasive type and nearly half of all cases alone were in Texas. Today's tally is an increase of over 400 cases in just the last week. At this rate, the US is on course for the largest yearly case count since the disease was first reported in the U.S.
New Case of Equine Encephalitis Virus Along the East Coast.
Eastern equine encephalitis (EEE) is one of the most severe mosquito-transmitted diseases in the United States with approximately 33% mortality and significant brain damage in most survivors (link). Fortunately, it is usually rare in humans.
This year, the occurance of EEE virus in the mosquito population along the eastern seaboard appears high. In the Boston area, the population of mosquitos infected with EEE is at a three decade high, according to a story in the Boston Globe. So far, only a single case of EEE in humans has been reported in the region and two nationally.
H3N8, NE Seals, and the Rapid Evolution of a New Pandemic Strain?
Influenza is a zoonotic disease, that is, it can pass from one animal species to another. Birds serve as a zoonotic reservoir for all of the human pandemic strains (as do pigs), such as the 1918 H1N1p virus that caused the great "Spanish Flu" pandemic at the start of the 20th century. While some avian flu strains have difficulty evolving their genomes to acquire the ability to jump species and readily transmit in a new host (for example, H5N1, at least so far), others become quite adept and can thus portend a possible new human pathogen. Hence, it is always a matter of biomedical interest when a new viral strain emerges that has acquired the ability to jump from birds to mammals and kill significant numbers of the new host species.
The identification (download paper here) of a new and highly virulent virus responsible for the death of some 162 baby seals on the shores of New England last fall has raised eyebrows ( WebLink 1, WebLink 2, WebLink 3). Infected seals had severe pneumonia and skin lesions, and most of them were less than 6 months old. The seals had died from the flu.
The culprit strain, H3N8, is an influenza virus well known to infect wild birds but only occasionally mammals. For example, a H3N8 virus that caused flu in horses appeared in the U.S. in the early 1960s and subsequently spread from horses to dogs, causing a flu outbreak among racing greyhounds in 2004. That strain of H3N8 now spreads easily among dogs, though without severe disease.
The H3N8 strain that precipitated the baby seal deaths was contracted from birds and presents a worrisome set of mutations# that enabled the virus to:
• spread to mammals, or at least from seal to seal;
• infect the seals' airways, destroying lung tissue or opening the door to fatal secondary infections;
• become more virulent; and
• acquire mutations that are frequently, though not exclusively, regarded as prerequisites for pandemic spread in humans. For example, the new viral strain has gained to agglutinate erythrocytes bearing either SAα-2,3 or the SAα-2,6 host receptor. Many of these mutations are present in circulating H5N1 strains.
As summarized by the investigators:
“...Together, the adaptations observed in A/harbor seal/Massachusetts/1/11 suggest that it may be able to persist within the seal population and evolve into a new clade within the H3N8 group, as happened with the canine and equine viruses. An additional concern is the potential zoonotic threat that this virus poses, as it has already acquired mutations in both PB2 and HA that are often, though perhaps not exclusively, regarded as prerequisites for pandemic spread....”
Sanofi's Dengue Vaccine Let Down
Sanofi SA has announced the results of a Phase IIb trial in Thailand for its heterotypic dengue vaccine (see the articles at Fierce Vaccines or from Reuters). The most advanced among the current crop of candidate dengue vaccines, the trial showed only a 30% overall efficacy against dengue type 2 (there are 4 broad types of dengue virus and Sanofi is seeking a vaccine that is effective against all 4), far short of the desired 70% efficacy goal. With a third of the world's population at-risk for dengue every year and 100 million new infections each year, the need for an effective vaccine is pressing.
A 2nd Eastern Equine Encephalitis Virus Infection in Humans in MA
The second reported case, this one fatal, of human infection of EEE was reported today by the Massachusetts Department of Public Health, as was a second case in horses. As a result, the EEE threat level has been raised to "critical" or "high" in a number of communities in central Massachusetts. Thus far this year, the number of reported cases of EEE in humans has matched the number observed in 2011. As a result, enhanced spraying for mosquitos is occurring in Massachusetts, including suburban communities around Boston.
Cases of Swine H3N2v Increase: H2H Transmission?
A total of 276 confirmed casses of swine influenza H3N2v have occurred in humans since July. And now, CDC says that three of the cases are indeed examples of human-to-human [H2H] transmission. This latter point has been the topic of some dispute [see 13Aug12 News with Views, below; till now, the CDC has stated that most cases occur due to human contact with swine].
Human H3N2v cases happen primarily in children who display symptoms similar to its distant cousin, seasonal H3N2 [sH3N2]. This makes field identification of H3N2v difficult, as does the sometimes lack of syptoms in infected pigs. There is currently no approved vaccine for H3N2v.
2 More Deaths in Quebec City Outbreak of Legionellosis
The Quebec public health authority has announced that 2 more people have died and 2 others were infected with Legionnaires' disease. To date, 104 people have contracted the disease in Quebec City since 31 Jul 2012 and 8 people have died from complications related to the illness.
Equine Encephalitis Virus Moves West of Boston
The Boston Globe reports today that mosquitoes carrying Eastern equine encephalitis [EEE] virus and that are capable of biting humans have recently moved from the south of Boston to the Western suburbs. "In July, EEE was found in bird-biting mosquitoes in Sudbury, Westborough, and Shrewsbury. But it was not until this month that EEE was identified in mammal-biting mosquitoes in Reading and, most recently, in Westborough."
EEE is frequently found with West Nile virus (WNV) in infected mosquito populations and mosquitoes carrying WNV have already been found in a number of northwestern Boston suburbs including Arlington, Framingham, Newton, Sudbury, Wayland, and Westford.
The presence of EEE in populations of mosquitoes that bite humans is of some concern since human infection with EEE exhibits approximately 33% mortality and significant brain damage in most survivors (link).
Pertussis: Return of an Old Foe
The August 15 edition of the New England Journal of Medicine contains a Perspective by Dr. John Cherry [UCLA] on what may be the largest outbreak of pertussis in the US in nearly 50 years. The article is worth a careful read.
Pertussis (aka "whooping cough" or "100-day cough") is a common, highly transmissive respiratory infection caused by Bordetella pertussis (also known as the Bordet-Gengou bacillus). B. pertussis infects only humans and the bacteria is spread person-to-person through respiratory droplets. There is no long-lasting immunity to the pathogen from either natural infection or from vaccination. Pertussis can cause serious and sometimes life-threatening complications in infants and young children; teens and adults can also experience complications, but less frequently than infants.
Pertussis is an old infectious nemesis with a history dating back to the 1500's. As noted by Dr. Cherry elsewhere, "The toll of pertussis before vaccines was staggering. For example, from 1926 to 1930, there were 36,013 pertussis-related deaths in the United States. The average death rates from 1940 to 1948 per 100,000 population per year were 64 in children less than 1 year old, 6.4 in those 1–4 years of age, and 0.2 in those 5–14 years of age." It is important to note that "...Today symptomatic adolescents and adults are the major source of infection in unvaccinated children." Globally, pertussis remains a significant cause of childhood mortality. The WHO estimates that, in 2008, nearly 200,000 died worldwide from pertussis, this in the midst of a global vaccination campaign that was estimated to have averted about 687 000 deaths that same year.
In the NEJM Perspective, Dr. Cherry summarizes 3 major factors behind today's increased prevalence of pertussis in the US:
1. Better awareness and better [PCR-based] testing
2. Failure of the "acellular" DTaP vaccine with "waning immunity" after the fifth dose
3. Genetic changes in the circulating strains of Bordetella pertussis
What then to do? Well, besides putting in the effort to improve the current DTaP vaccine, Dr. Cherry also suggests making better use of the vaccines we currently do have, for example by increasing vaccination rates for expectant mothers or by moving administration of the 3-dose primary vaccination series to start at birth and be completed by 3-5 months of age. This latter strategy was employed, using the cellular DTP vaccine, in the 1950's and 1960's when the greatest reductions in prevalence of whooping cough were achieved in the US. This observation is of interest given the presumed lack of immune system development of new-born infants. And, finally, the "re-emergence" of pertussis in the US reminds us of the constant struggle required to keep even once-beaten infectious foes at bay.
Cases of Swine H3N2v Spike in Humans in the US: H2H Transmission?
A new influenza virus, 2012 H3N2v, capable of infecting humans, has emerged this year, a process likely facilitated by (among other things) the large number of state fairs that occur in late summer. H3N2v is swine virus composed of genes from other swine viruses as well as the 2009 H1N1p virus. A total of 10 cases of human infection were confirmed last year, but human activity of the virus has jumped dramatically this year. Between July 12th and August 9th of this year, a total of 153 cases of H3N2v were reported. The cases were mainly in Indiana, but also were reported for patients as far away as Hawaii.
The H3N2v cases occur predominantly in children. Of the 153 reported cases, demographic data is available for 138 cases. Of these 138, 128 were pediatric and 10 were in adults. The median age of all patients is seven years. To date, only two patients have been hospitalized and no case fatalities have been reported. Overall, the couse and severity of H3N2v cases appears similar to human seasonal H3N2 [H3N2s], except for the case demographics. A comparable course and severity for H3N2v and H3N2s could lead to difficulties in estimating the actual incidence of H3N2v.
As noted by Recombinomics, a genetic difference between the H3N2v strain in cases from last year and those from this summer is the presence of a new NA gene. The NA gene in last year's H3N2v cases was derived from circulating swine H1N2 viruses while the NA in this year's cases is found circulating in swine H3N2 viruses.
Case files associated with H3N2v show ready swine-to-swine [S2S] and swine-to -human [S2H] transmission. At a minimum, they also show at least limited human-to-human [H2H] transmission. More realistically, H3N2v H2H transmission may be greater than this minimum, as has been argued well by Recombinomics.
Pandemic concerns around H3N2v center on either:
1. Continued zoonotic exchange leading to an enhanced virulence/pathogenicity; or
2. Recombination events involving H3N2v with viruses in the avian reservoir, leading to new viral strains via antigenic shift.
The percolation of a swine viruses such as H3N2v through the human population echoes episodic outbreaks of swine H1N1 cases in the years leading up to the 1918 pandemic.
West Nile Virus Epidemic in Texas
Dallas County, Texas, has declared a public health emergency after at least 9 deaths due to West Nile virus [WNV] infection have been reported (see the story at CNN.com). So far this year, the U.S. has seen over 690 reported cases of WNV, the largest number of cases since 2004. For the latest statistics from the CDC, please go the this LINK. Recent news reports (story_1, story_2, story_3) indicate that the number of fatalities continues to rise, exceeding 15 as of today.
According to the CDC,West Nile virus is transmitted to people by infected mosquitoes. Most individuals infected with WNV develop only mild symptoms (fever, headache, body aches, skin rash or swollen lymph glands ) but neuroinvasion by the virus results in a more severe, even fatal, disease (encephalitis or meningitis).
Since it first appeared in the U.S. in 1999, over 30,000 serious cases have been reported, nearly a third of these alone in 2003. In the U.S., most people are infected from June through September, with the number of new infections typically peaking in mid-August. More extensive online information on WNV can be obtained at the at the NIH and the CDC.
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