Saturday, June 30, 2018

Indiana Reports H3N2v Infection In Fairgoer


As we discussed almost a month ago, The `Other' Novel Flu Threat We'll Be Watching This Summer, the summer and fall are typically the times of the year when we see scattered reports of human swine variant flu infection, which  are often linked to visiting animal exhibits at state or country fairs.   

The CDC describes Swine Variant viruses in their Key Facts FAQ.
What is a variant influenza virus?
When an influenza virus that normally circulates in swine (but not people) is detected in a person, it is called a “variant influenza virus.” For example, if a swine origin influenza A H3N2 virus is detected in a person, that virus will be called an “H3N2 variant” virus or “H3N2v” virus.
Most (but not all) swine variant infections are mild or moderate, and are clinically indistinguishable from regular seasonal influenza. Which is why it is believed many swine variant infections go undetected (see CID Journal: Estimates Of Human Infection From H3N2v (Jul 2011-Apr 2012).

Overnight numerous Indiana media outlets have carried reports of that state's first swine variant case since 2013, when 4 cases were reported.  The previous year, 2012, Indiana saw the largest outbreak on record (n=138). 
These reports, as you'll see, carry very little specific information.  While we are told the exposure was linked to attendance at a county fair, we aren't told when or in what county that exposure occurred.
This from Tribune-Star.
Officials warn of flu; 1 Hoosier confirmed case after exposure to pigs
Tribune-Star staff report

The state department said its seen one recent, confirmed case of a resident developing influenza after exposure to pigs.

This is the first human case of H3N2 variant influenza reported in Indiana since 2013 and the first human case in the U.S. this year, according to the Centers for Disease Control and Prevention, which confirmed the test results Friday.

H3N2 variant influenza is most commonly associated with contact with pigs. The Indiana resident became ill after being exposed to pigs during a county fair that has since ended. The resident is recovering.

The affected county health department has been notified and is collaborating on the investigation. No additional details about the patient or the fair will be released at this time in order to maintain the patient’s privacy, the state agencies said in a news release.
        (Continue . . . )

The decision not to release the name of the county fair where exposure occurred is a bit unusual, and could prove problematic, should more cases turn up.
Despite concerns over `patient privacy', other states have released basic information, like the location and likely time frame of the exposure (see Maryland DOH: 20 Presumptive Positive & Confirmed H3N2v Cases), to help facilitate surveillance and reporting.
While I suspect it's not what the organizers of agricultural exhibits want to hear, last August's  EID Journal: Transmission Of Swine H3N2 To Humans At Agricultural Exhibits - Michigan & Ohio 2016 examined the risks of novel flu transmission at these types of venues, including from healthy-looking pigs. 
Of particular interest, while widespread illness in pigs was only rarely reported, surveillance revealed an average prevalence of influenza A in fair pigs of 77.5%. The authors cautioned that this suggests `that subclinical influenza A infections in pigs remain a threat to public health (3).'
Despite the current low risk of infection, there are some things you should consider doing to reduce your chances of getting sick, particularly if you are at `high risk' of flu complications.  This from the CDC.
CDC Recommendations For People At High Risk:
  • If you are at high risk of serious flu complications and are going to a fair where pigs will be present, avoid pigs and swine barns at the fair. This includes children younger than 5 years, people 65 years and older, pregnant women, and people with certain long-term health conditions (like asthma, diabetes, heart disease, weakened immune systems, and neurological or neurodevelopmental conditions).
If you are not at high risk, take these precautions:
  • Don’t take food or drink into pig areas; don’t eat, drink or put anything in your mouth in pig areas.
  • Don’t take toys, pacifiers, cups, baby bottles, strollers, or similar items into pig areas.
  • Wash your hands often with soap and running water before and after exposure to pigs. If soap and water are not available, use an alcohol-based hand rub.
  • Avoid close contact with pigs that look or act ill.
  • Take protective measures if you must come in contact with pigs that are known or suspected to be sick. This includes wearing personal protective equipment like protective clothing, gloves and masks that cover your mouth and nose when contact is required.
  • To further reduce the risk of infection, minimize contact with pigs in the pig barn and arenas.
That said, swine variant flu infection remains a relatively minor public health threat in the United States. But flu viruses are constantly changing, and so that could change. The CDC's Risk Assessment on H3N2v and other swine variant viruses reads:

CDC Assessment
Sporadic infections and even localized outbreaks among people with variant influenza viruses may occur. All influenza viruses have the capacity to change and it's possible that variant viruses may change such that they infect people easily and spread easily from person-to-person. The Centers for Disease Control and Prevention (CDC) continues to monitor closely for variant influenza virus infections and will report cases of H3N2v and other variant influenza viruses weekly in FluView and on the case count tables on this website

H3N2 Variant:[A/Indiana/08/11] is among the 16 novel viruses currently being  tracked by the CDC's IRAT (Influenza Risk Assessment Tool) Rankings.
The summary average risk score for the virus to achieve sustained human-to-human transmission was in the moderate risk category (less than 6). The summary average risk score for the virus to significantly impact public health if it were to achieve sustained human-to-human transmission was in the low-moderate risk category (less than 5).
For more information on swine variant viruses, and how to protect yourself when in contact with farm animals, the CDC provides the following guides.

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