Published Date: 2012-09-08 19:45:20
Subject: PRO/AH/EDR> Influenza (83): USA (MN) A(H1N2)v human infection
Archive Number: 20120908.1286721
INFLUENZA (83): UNITED STATES OF AMERICA (MINNESOTA) A(H1N2)V HUMAN INFECTION
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Fri 7 Sep 2012
Source: CDC Seasonal Influenza
H1N2 Variant Virus Detected in Minnesota
The Minnesota Department of Health has reported detection of 3 infections with an influenza an A(H1N2) variant ("H1N2v") virus with the pandemic M gene from the 2009 H1N1 virus. These cases were reportedly associated with prolonged contact with pigs at a fair. H1N2 viruses normally circulate in pigs, not people, but rare human infections with this virus have been detected in the past. This virus is different from the H3N2v virus that, as of today, is reported to have caused 296 human infections across 10 U.S. states since July 2012. These additional human infections underscore the fact that swine influenza viruses can spread to people after close contact with infected pigs, and support the importance of ongoing surveillance for both human and swine influenza viruses.
According to the state of Minnesota, each of the 3 people infected with the H1N2v virus had exhibited pig(s) or spent prolonged time with pig(s) at the Minnesota State Fair. Two of the 3 people had underlying health conditions that placed them at high risk of serious flu complications; one of the 2 people with high risk factors was hospitalized, highlighting again the importance of the CDC recommendation that people with high risk factors avoid close contact with pigs and pig arenas at fairs this season. All 3 people have recovered from their illnesses.
People who are at high risk of serious flu complications include children younger than 5 years, people 65 years and older, pregnant women, and people with certain long-term health conditions (like asthma and other lung disease, diabetes, heart disease, weakened immune systems, and neurological or neurodevelopmental conditions). A full list of high risk factors is available on the CDC seasonal flu site.
In addition to avoiding pigs and pig arenas at fairs this year, as always, people with high risk conditions who develop flu-like symptoms should seek prompt medical attention. The H1N2v virus should be susceptible to both currently recommended influenza antiviral drugs [oseltamivir (Tamiflu) and zanamivir (Relenza)].
CDC has confirmed the Minnesota samples as H1N2v viruses. Sequencing of the viruses indicates these H1N2 variant viruses are very similar to those found in humans previously; with the exception of the addition of the pandemic M gene. This is the 1st time this virus has included the M gene from the 2009 H1N1 pandemic virus when isolated from a person. Genetic analysis shows that the hemagglutinin (H) of this virus is similar to human seasonal influenza viruses that circulated in people as recently as 2007, so there would likely be protective immunity against this particular virus in the human population.
The University of Minnesota Veterinary Diagnostic Lab also isolated an H1N2 virus from swine sampled at the Minnesota State Fair. Sequencing at National Veterinary Services Laboratories in Ames, Iowa, confirmed that it matches the human isolates
Date: Fri 7 Sep 2012
Source: CIDRAP News [abridged & edited]
Flu parallels: Swine-origin H1N2 has gene from 2009 H1N1
Swine-origin H1N2 virus found in 3 Minnesotans last week carries the matrix gene from the 2009 H1N1 pandemic virus, marking the 1st time such a virus has been found in humans, according to state and federal health officials.
The variant H1N2 (H1N2v) virus is different from the swine-origin H3N2v strain that has cropped up in nearly 300 people within the past year. But the 2 are alike in that both picked up the pandemic virus's matrix gene.
The number of H3N2v cases has now risen to 297, an increase of 7 since a week ago, according to the Centers for Disease Control and Prevention's (CDC's) new count, posted today. Nearly all the cases have been in people who were exposed to pigs, most of them at agricultural fairs this summer. Only one death, that of an Ohio woman who had other medical conditions, has been linked to the virus, but there have been 16 hospitalizations.
No ongoing human-to-human transmission of either H3N2v or H1N2v viruses has been reported, but the CDC has said that the H1N1 matrix gene might increase the transmissibility of H3N2v and that a few instances of likely human-to-human spread of that virus have been found. In reporting the H1N2v cases in a statement today, the CDC said the population probably has some immunity to it because of past exposure to seasonal H1N1 flu viruses.
The 3 confirmed H1N2v cases reported in Minnesota last week were all in people who were exposed to pigs at the State Fair. The Minnesota Department of Health (MDH) said today that a 4th case has since been reported and is awaiting confirmation by the CDC. MDH spokesman Buddy Ferguson said the "presumptive positive" case is a teenage boy from outside the Twin Cities area who exhibited pigs at the State Fair from 23 to 26 Aug 2012 and got sick on 28 Aug . Ferguson said he didn't know of any connection between the teenager and the other 3 cases.
Although H1N2v is new in humans, the US Department of Agriculture's swine flu surveillance program has detected very similar H1N2 viruses with the 2009 H1N1 matrix gene in pigs in Minnesota and some other states since early 2010, the CDC reported. In reporting the cases last week, the MDH said 2 sick pigs at the State Fair tested positive for H1N2. Ferguson reported that the virus in the pigs was also found to contain the 2009 H1N1 matrix gene.
The H1N2v cases demonstrate once again that swine flu viruses can spread to people, and they point up the importance of the CDC recommendation that people at risk for serious flu complications should avoid close contact with pigs and pig barns at fairs this season, the agency said. Those at risk include children under age 5, people over 65, pregnant women, and people who have long-term health problems such as asthma, other lung diseases, diabetes, heart disease, weakened immunity, and neurologic or neurodevelopmental conditions.
Although the recent H1N2v cases are the 1st known to contain the 2009 H1N1 matrix gene, a few other H1N2v cases have been reported in recent years. One case was reported in a Minnesota child in December 2011. Another case was reported in 2007 in an 18-month-old Michigan child who had been in a swine barn. Both of those patients recovered. In 2002 the CDC reported that a total of 11 human H1N2 cases had been detected in Wisconsin, Texas, and Nevada the previous year.
[Byline: Robert Roos]
ProMED-mail Rapporteur Mary Marshall
[CDC has confirmed the isolation of H1N2v viruses in Minnesota from 3 people have close contact with pigs. Sequencing of the viruses indicates these H1N2 variant (H1N1v) viruses are very similar to those found in humans previously; with the exception of the addition of the pandemic M gene. This is the 1st time this virus has included the M gene from the 2009 H1N1 pandemic virus when isolated from a person. Previously H3N2 swine viruses, incorporating the matrix protein gene of the HiN1 2009 pandemic virus, have been isolated in several states including Minnesota. Genetic analysis of the H1N2v virus shows that the hemagglutinin (H) of this virus is similar to human seasonal influenza viruses that circulated in people as recently as 2007, so there would likely be protective immunity against this particular virus in the human population. No sustained person-to-person transmission of either the H1N2v and H2N2v viruses has been observed. The H1N2v cases demonstrate that swine influenza viruses can spread to people, and these occurrences reinforce the importance of the CDC recommendation that people at risk for complications induced by influenza virus infection should avoid close contact with pigs and pig barns at fairs this season. - Mod.CP
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