Friday, August 26, 2016

CDC FluView: 7 More H3N2v Cases (4 Michigan, 3 Ohio) In Week 33


For the second week in a row the CDC's Weekly FluView is reporting 7 new H3N2v cases linked to swine exposures at county fair agricultural exhibits in Michigan and Ohio.   Swine variant viruses include H1N1v, H1N2v, and (most commonly) H3N2v.

This brings the August total to 18  H3N2v cases, and 2016's swine variant total to 22 cases (3 H1N1v cases & 1 additional H3N2v). 

Most years, we see fewer than 10 cases, although in 2012 we saw a multi-state outbreak with more than 300 confirmed infections, nearly all linked to county and state fairs (see EID Journal: H3N2v Swine To Human Transmission At Agricultural Fairs – 2012).

Due to their (often) unremarkable presentation, and limited laboratory testing, cases likely occur more often than we know (see CID Journal: Estimates Of Human Infection From H3N2v (Jul 2011-Apr 2012).

Here is today's announcement, after which I'll return with a bit more.
Novel Influenza A Viruses:

Seven human infections with novel influenza A viruses were reported by two states (Michigan [4] and Ohio [3]) during week 33. All seven persons were infected with influenza A (H3N2) variant (H3N2v) viruses and reported exposure to swine in fair settings during the week preceding illness onset. To date, a total of 18 (Michigan [12] and Ohio [6]) human infections with H3N2v viruses have been identified during 2016, all reported during the month of August. One of the 18 persons were hospitalized as a result of H3N2v illness. No deaths have occurred. All variant virus infections have been associated with swine exposure in fair settings. No human-to-human transmission has been identified. Public health and agriculture officials are investigating the extent of disease among humans and swine, and additional cases may be identified as the investigation continues.

Early identification and investigation of human infections with novel influenza A viruses are critical to ensure timely risk assessment and so that appropriate public health measures can be taken. Additional information on influenza in swine, variant influenza infection in humans, and strategies to interact safely with swine can be found at

We’ve not seen sustained or efficient spread of these swine flu viruses in humans - but like all flu viruses - swine variant viruses are capable of evolving, reassorting, and adapting to their hosts.
People who raise, or work with pigs are probably at greatest risk of infection, but County and State Fair animal exhibits also provide opportunities for these viruses to jump to humans.

The CDC offers the following advice to the public. 

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.

And for more on swine and swine variant influenza, you may wish to revisit some of these blogs:

Front. Microbiol.: A Novel H1N2 Reassorted Influenza Virus In Chinese Pigs 

Sci Rpts: Transmission & Pathogenicity Of Novel Swine Flu Reassortant Viruses
JID: Evolutionary Dynamics Of Influenza A Viruses In US Exhibition Swine 

Live Markets & Novel Flu Risks In The United States