INFLUENZA (59): USA (NEW ENGLAND) H3N8, SEALS
A ProMED-mail post
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International Society for Infectious Diseases <http://www.isid.org>
Date: Tue 31 Jul 2012
Source: Medical Express [edited]
New avian flu virus jumps from birds to mammals
A novel avian influenza virus has acquired the ability to infect aquatic mammals and was responsible for an outbreak of fatal pneumonia that recently struck harbor seals in New England, according to scientists at the Center for Infection and Immunity (CII) at Columbia University's Mailman School of Public Health, the National Oceanic and Atmospheric Association, New England Aquarium, USGS National Wildlife Health Center, SeaWorld and EcoHealth Alliance.
Wildlife officials 1st became concerned in September 2011, when seals with severe pneumonia and skin lesions suddenly appeared along the coastline from southern Maine to northern Massachusetts. Most were infants (less than 6 months), and a total of 162 dead or moribund seals were recovered over the next 3 months. Pathogen screening was conducted in a subset of afflicted seals, using sensitive diagnostic tools developed at the CII, and a new strain of avian H3N8 influenza virus was identified as a culprit.
"When initial tests revealed an avian influenza virus, we asked the obvious question: how did this virus jump from birds to seals?" says Simon Anthony, D.Phil, postdoctoral research scientist at the CII and the lead author of the study. Based on full genome sequencing and phylogenetic analysis, seal H3N8 descended from an avian strain that has been circulating in North American waterfowl since 2002, which implies recent transmission from wild birds to seals.
Accordingly, seal H3N8 has acquired the ability to bind sialic acid receptors that are commonly found in the mammalian respiratory tract.
Mutations in the HA and PB2 genes -- required for cell entry and replication, respectively -- suggest enhanced virulence and transmission in mammals, but these putative attributes require further investigation. Given these findings along with the long history of the spread of avian influenza to humans -- most notably H1N1 and H5N1 -- seal H3N8 could pose a threat to public health.
"Our findings reinforce the importance of wildlife surveillance in predicting and preventing pandemics, says W. Ian Lipkin, director of the Center for Infection and Immunity and John Snow Professor of Epidemiology, at the Mailman School of Public Health. "HIV/AIDS, SARS, West Nile, Nipah and influenza are all examples of emerging infectious diseases that originated in animals. Any outbreak of disease in domestic animals or wildlife, while an immediate threat to wildlife conservation, must also be considered potentially hazardous to humans."
ProMED-mail from HealthMap Alerts
[The text refers to research published in mBio (<http://mbio.asm.org/content/3/4/e00166-12>).
In nature, influenza A viruses circulate in aquatic birds causing negligible pathogenicity. They are classified according to subtypes that are a combination of more than 15 possible HA (hamaglutinin) and
9 possible NA (neuraminidase). All H3N8 viruses belong to the same subtype, but this does not necessarily mean they are the same virus.
These viruses have the ability to use all known mechanisms of evolution (insertion-deletion, substitution, recombination, reassortment), thus they are capable of transforming into new agents which might infect other hosts or increment their pathogenicity.
The concern for public health is well founded. Catastrophic influenza pandemics such as the Spanish flu (1918, 50 million deaths), the Asian flu (1957, 2 million deaths) and the Hong Kong flu (1968, 1 million
deaths) had avian sources.
In the past (1979-1983), influenza A virus was isolated from seals died from pneumonia in New England. The interactive HealthMap/ProMED map for New England is available at: <http://healthmap.org/r/1xMA>. - Mod.PMB]
Die-off, seal, dolphin - USA: New England, update 20120209.1037523
Die-off, seal - USA (03): New England, influenza 20111221.3648 Die-off, harbor seals - USA (02): New England, influenza
Die-off, harbor seals - USA: northeast, influenza susp. 20111106.3301 Die-off, seal - USA: New England, RFI 20111027.3203] .................................................sb/pmb/ejp/dk/ll
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