Nearly two weeks ago, on August 5th, Michigan's DOH Announced 2 H3N2v Cases Connected To Muskegon County Fair. Since then we've seen two additional cases reported in Ohio, also linked to a local fair, and reports of sick pigs in at several Michigan and Ohio fairgrounds.
Overnight the State of Michigan released the following statement indicating that 6 more people have tested positive for the swine variant (H3N2v) flu virus, and all are linked to swine exposure at fairs in Cass, Ingham, and Muskegon counties.
First the statement, then I'll be back with a bit more.
Contact: Jennifer Eisner 517-241-2112 For Immediate Release: August 19, 2016
LANSING, Mich. – The Michigan Departments of Health and Human Services and Agriculture and Rural Development today announced that there have been eight human cases of influenza A variant viruses reported in Michigan. They have tested positive for influenza A H3N2 variant (H3N2v) and one person has been hospitalized and since released. All of the confirmed cases had exposure to swine at county fairs in Muskegon, Cass, and Ingham counties during July and August where sick pigs had also been identified.
MDHHS and MDARD are working closely with local health departments, the healthcare community, and fairs to protect swine exhibitors and the public and identify any additional cases.
Fair exhibitors and animal caretakers should be following proper biosecurity processes such as regular handwashing with soap and water, disinfecting wash areas at least once each day and making sure it has time to dry thoroughly after being disinfected. Additionally, weight scales and sorting boards should also be disinfected. Use a 10 percent bleach/water mixture in combination with a detergent (dish or laundry soap) to increase effectiveness.
In 2012, there were six H3N2v cases in Michigan and in 2013 two cases were confirmed. Human infection is thought to happen when an infected pig cough or sneezes and droplets with influenza virus land in someone’s nose or mouth, or are inhaled. There also is some evidence that the virus might spread by someone touching something that has virus on it and then touching their mouth or nose.
Symptoms of H3N2v infection in people are usually mild and similar to those of seasonal flu viruses, but as with seasonal flu, complications can lead to hospitalization and death. Symptoms include fever and respiratory symptoms, such as cough and runny nose, as well as body aches, nausea, vomiting, or diarrhea. Some populations are at higher risk of developing complications if they get influenza, including children younger than five years of age, people 65 years of age 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.
The incubation period (the time it takes from exposure to illness) for this influenza is typically similar to seasonal influenza at about two days, but may be up to 10 days. Currently, there is no vaccine for H3N2v and the seasonal flu vaccine will not protect against H3N2v. Antiviral drugs are effective in treating H3N2v virus infections. Early treatment works best and may be especially important for people with a high risk condition.
Below are some steps that you can take to protect yourself and prevent the spread of any illness:
While it does not protect against H3N2v, MDHHS recommends annual season influenza vaccination for everyone six months of age and older to reduce the risk of infection from other influenza viruses.
- Anyone who is at high risk of serious flu complications and planning to attend a fair should avoid pigs and swine barns
- Do not eat or drink in livestock barns or show rings
- Don’t take toys, pacifiers, cups, baby bottles, strollers, or similar items into pig areas
- Avoid contact with pigs if you have flu-like symptoms. Wait seven days after your illness started or until you have been without fever for 24 hours without the use of fever-reducing medications, whichever is longer
- Avoid close contact with sick people
- Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it
- Wash your hands often with soap and water. If soap and water are not available, use an alcohol-based hand rub
- Avoid touching your eyes, nose and mouth. Germs spread this way
- If you are sick, stay home from work or school until your illness is over
For more information about H3N2v, visit www.cdc.gov/flu/swineflu/h3n2v-basics.htm
Individual infections with H3N2v tend to produce mild or moderate illness, and community transmission (at least so far) appears to have been limited - albeit probably greater than the numbers we've seen reported.
In 2013, a review (see Outbreak of Variant Influenza A (H3N2v) Virus in the United States) of 2012's major outbreak (300+ cases) conducted by CDC and local Health department researchers, found the vast majority appear to have contracted the virus from direct exposure to infected pigs, while only about 5% appeared to be the result of H-2-H transmission.
In contrast, another study published in 2013 (see CID Journal: Estimates Of Human Infection From H3N2v (Jul 2011-Apr 2012)- estimated that during a time when only 13 cases were reported by the CDC - that the actual number of infections was likely 200 times (or more) higher.
Results. We estimate that the median multiplier for children was 200 (90% range, 115–369) and for adults was 255 (90% range, 152–479) and that 2055 (90% range, 1187–3800) illnesses from H3N2v virus infections may have occurred from August 2011 to April 2012, suggesting that the new virus was more widespread than previously thought.
Since relatively few who get flu symptoms are ever tested for variant influenza, the real number infected (and the estimates) are impossible to verify, and both should be taken with a large grain of salt.
We've looked at this same ambiguity (and extended estimated range) of human infections with other novel viruses in the past, including H7N9 in China and H5N1 in Egypt.
In any event, the number of swine variant cases reported in the past two weeks has now reached 10, and it seems likely we'll be hearing more about H3N2 in the weeks to come.