Minnesota Reports Swine H1N2v Flu

 

 

# 6530

 

File this under - `Once you start looking, no telling what you’ll find’.

 

Enhanced surveillance for H3N2v flu cases associated with contact with pigs by Minnesota’s Department of Health has turned up 1 confirmed, and 2 probable human cases of H1N2v influenza.

 

The H1N2 virus is one of three flu strains that commonly circulate in swine (H1N1, H3N2, & H1N2).

 

H1N2 is assumed to be a reassortment between the H1N1 and H3N2 virus. It has on rare occasions been detected in humans. 

 

Credit CDC

 

Minnesota reported a human infection with A/H1N2 in December of 2011, and it was said to be similar to an H1N1 virus (A/New Caledonia /20/99-like) that circulated as recently as 2007. 

 

Michigan reported an H1N2 human infection in 2007. 

 

As has been pointed out in this blog before, we honestly don’t know how often these novel swine (or avian)origin flu viruses jump to humans. Given the limits of testing and surveillance, it is probably more common than the numbers suggest.

 

Heightened surveillance around the country for the H3N2v virus may very well tell us a good deal about other variant viruses that we know can occasionally show up in the human population.

 

 

Here is the Press release from the MDH.

 

 

News Release
August 31, 2012
 

Three human cases of influenza linked to swine exposure at State Fair

Strain is different from the one that prompted current surveillance and prevention efforts

Three people are believed to have developed a strain of influenza known as variant H1N2 (H1N2v) after exhibiting pigs or spending time in the swine barn at the Minnesota State Fair.

 

One of the three cases has been confirmed by CDC. Test results for the other two are pending.

 

The H1N2v strain is different from the H3N2v strain that has prompted stepped up surveillance and prevention efforts nationwide, after causing 289 reported cases of illness and one death since the beginning of the year.

 

Officials at the Minnesota Department of Health (MDH) say they are not currently aware of any additional human influenza cases caused by H1N2v, and they do not anticipate changing their current public health recommendations regarding human exposure to swine.

 

They emphasized, however, that they will continue to assess the situation and conduct aggressive surveillance for additional influenza cases.

 

Current recommendations include asking individuals at high risk for severe influenza to avoid swine contact at exhibitions, fairs, live markets and other venues, including the swine barn at the State Fair. High risk individuals include children under five years of age, pregnant women, people 65 years of age or older and those with chronic medical conditions.

 

"For the past two weeks, we have been looking very hard for cases of influenza in people who have been exposed to swine," said Richard Danila, Deputy State Epidemiologist. "We have also worked closely with our veterinary colleagues to remain informed about potential infections in swine at the Fair. It is because of this careful surveillance that these cases have come to our attention.

 

"Right now, we don’t have any basis for changing our recommendations to the public," Danila said.

 

The illness has been confirmed in a teenage girl who was exhibiting pigs at the fair and became ill on Aug. 26. The other two cases occurred in an elementary-school-aged boy who became ill on Aug. 27 after spending all day in the swine barn on Aug. 24, and a woman in her late seventies who became ill on Aug. 26 after spending a prolonged period of time in the swine barn and at the swine show in the Exhibit Hall on Aug 24.

 

Both the boy and the older woman had underlying health conditions, and were treated with antiviral drugs. The woman was hospitalized, but has now been released. All three patients have recovered or are recovering.

 

The teenager was tested for influenza after she reported illness to nursing staff at the Fair. The other cases were reported to MDH by health care providers. Health care providers have been asked to report cases of influenza-like illness in people who report that they have had contact with swine. Swine exhibitors have been asked to report it if they experience symptoms of influenza.

 

Fair officials have also been monitoring swine for possible symptoms of illness, so they can be tested. Two pigs at the swine exhibit were found to be infected with the same H1N2 virus earlier this week, and were both isolated from contact with other pigs. Infection with H1N2 is not considered unusual in pigs.

-MDH-

 

 

For more on the H1N2 virus, you may wish to revisit:

Hong Kong Swine Influenza Surveillance

CDC: Variant Influenza Strains

CDC Confirms 2 More Novel Flu Infections

If You’ve Seen One Triple Reassortant Swine Flu Virus . . .

»» Read More

CDC Confirms 2 More Novel Flu Infections

 

H3N2 influenza virions –CDC PHIL

# 6001

 

 

The CDC announced today the detection of two new novel flu isolates; one in West Virginia (trH3N2) and another in Minnesota (A/H1N2).

 

The West Virginia virus isolate is described today by the CDC as being:

 

A novel influenza A (H3N2) virus with genes from swine, human, and avian lineages with the M gene from the 2009 H1N1 virus that was first identified in August 2011. Ten prior human infections with this virus in four other states have been confirmed.

 

This virus is distantly related to an H3N2 virus that circulated 20+ years ago, which may explain why those born after 1990 have made up vast majority of cases detected so far.

 

Earlier posts on those cases include:

 

Branswell On The New trH3N2 Flu Virus

CIDRAP: New Details In The trH3N2 Story

ECDC Risk Assessment On trH3N2 Cases In North America

CDC Update On Iowa trH3N2 Cases

 

The Minnesota isolate is an H1N2 virus that has been known to circulate in swine for some time, and is said to be similar to an H1N1 virus (A/New Caledonia /20/99-like) that circulated as recently as 2007.

In neither case did these patients have recent known contact with swine, and so these reports imply that low level human-to-human transmission may have taken place.

 

First stop, a notice in today’s (otherwise quiet) FluView week 48 Report, followed by some choice excerpts from the latest Have You Heard? statement from the CDC.

 

http://www.cdc.gov/flu/weekly/

Novel Influenza A Viruses:

Two human infections with novel influenza A viruses were detected in children from two states (Minnesota and West Virginia). One patient was infected with a novel influenza A (H1N2) virus and one patient was infected with a novel influenza A (H3N2) virus. Both patients have recovered from their illnesses. While both viruses are known to circulate in U.S. swine, there was no close contact with pigs reported preceding illness onset in either case. Both states have been investigating case contacts and sources of exposure, however, no additional confirmed cases have been detected at this time. Additional information on these cases can be found in the CDC Have You Heard posting.

 

CDC is required to report all cases of human infection with novel influenza viruses – including swine influenza viruses -- to the World Health Organization (WHO) as part of the International Health Regulations (IHR). Domestically, CDC reports these cases in this report and on its website. Early identification and investigation of human infections with novel influenza A viruses is critical to evaluate the extent of the outbreak and possible human-to-human transmission. Additional information on influenza in pigs and swine-origin influenza infection in humans can be found at http://www.cdc.gov/flu/swineflu/.

 

Below are some excerpts from today’s announcement (bolding & reparagraphing mine). Follow the link to read it in its entirety.

 

 

CDC confirms two human infections with novel influenza viruses

December 9, 2011 -- CDC has confirmed two cases of human infection with two different novel influenza A viruses in different states. Both patients have fully recovered. While the viruses infecting both patients have been found in U.S. swine and some of the prior human infections with these viruses have been associated with direct or close swine contact, there are no reports of direct or close contact with swine prior to illness onset in either of these cases. Laboratory testing at CDC has confirmed that both novel viruses are susceptible to the antiviral medications oseltamivir (Tamiflu®) and zanamivir (Relenza®).

<SNIP Narrative on 2 New Cases> 

 

Detection of Swine Influenza Infections in Humans

Human infections with novel influenza A viruses normally found in swine are rare events. Recently, however, the frequency of such detections has increased.

 

This could be occurring for a number of reasons, including one or more of the following factors:

 

First, laboratory methods for testing for these viruses in the United States were improved following the 2009 H1N1 pandemic. These improvements may be resulting in viruses being identified now that would have gone undetected previously.

 

Second, this could be due to increased surveillance in the United States for influenza at this time of year. CDC has requested that states analyze, and then send, their first influenza virus specimens of the season for seasonal influenza surveillance purposes. This practice, coupled with very low levels of seasonal flu activity at this time, could mean that sporadic novel influenza infections are more likely to be tested.

 

Third, it is possible that the increased frequency of detection of novel influenza viruses with swine origins identified by CDC represents a true increase in the number of such cases, possibly occurring from exposure to infected swine  or through subsequent, limited human-to-human transmission.

 

(Continue . . .)

 

 

While the CDC and public health officials are obviously taking these novel virus detections seriously, and are ramping up surveillance to track their spread, it is too soon to know whether any of these new flu strains will take hold in the human population.

 

As I wrote in Pseudo Pandemics And Viral Interlopers it is certainly possible for new strains of influenza to appear and circulate among humans, without sparking a pandemic.

 

Influenza is notoriously unpredictable.

 

For now, we are in a watchful waiting mode; looking for signs that one of these novel viruses is getting better adapted to human physiology.

 

In the meantime, maintaining good flu hygiene this winter (washing/sanitizing your hands, covering coughs & sneezes, staying home when sick), and getting your seasonal flu shot, remain the best strategies to avoid getting sick during this flu season.

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