We've had 3 pretty quiet weeks on the swine variant flu front since the September 1st announcement of the 20th case of 2017 (see FluView Week 34: 1 Novel H1N2v Flu Infection Reported In Ohio). This morning, however, we are learning of 7 additional swine variant (H3N2v) infections in Maryland linked to the Charles County Fair.
This press release from the Maryland Department of Health, released late yesterday.
None of those who attended Charles County event is seriously ill with H3N2v
Baltimore, MD (September 20, 2017) – The Maryland Department of Health has presumptively identified the influenza virus strain H3N2v (variant flu) in seven Maryland residents who had close contact with pigs at the Charles County Fair. None of the infected individuals has developed serious illness or been hospitalized.
Influenza is an infection caused by the influenza virus which can affect people and other animals, including pigs and birds. Symptoms for the H3N2v strain are the same as seasonal flu and include fever and respiratory symptoms, such as sore throat and cough. Historically, there is limited human to human transmission from this strain of variant flu. The treatment recommendations for this strain of influenza are the same as for seasonal flu.
Health officials recommend that people with influenza-like illness contact their healthcare provider and inform them if they have had pig contact within the past seven days. Providers are advised to contact their local health departments if they suspect variant flu in their patients to coordinate appropriate testing with their local health department. The Charles County Health Department can be reached at 301-609-6900 ext. 6025 and the St. Mary’s County Health Department can be reached at 301-475-4330.
Twenty other cases of variant flu have been detected in other states this year. Of those, 18 were also the virus strain H3N2v. Illnesses associated with these variant flu infections have been mostly mild with symptoms similar to those of seasonal flu. In 2012, 13 individuals developed influenza after direct contact with sick pigs at the Queen Anne’s County fair in Maryland.
Certain people are at higher risk for complications of influenza, including children under five, the elderly, pregnant women, and those with chronic heart, lung, liver, kidney and neurologic conditions or immunosuppression. The spread of influenza, including the possible spread of H3N2v, between humans can be prevented by:
Avoiding close contact with sick people;
The spread of influenza between pigs and humans can be prevented by:
- Limiting contact with others as much as possible if you are sick to keep from infecting them and staying home from work or school if you are sick until you are fever free for 24 hours without fever reducing medicines;
- Covering your nose and mouth with a tissue when you cough or sneeze and dispose of the tissue immediately after use;
- Washing your hands often with soap and water or alcohol-based hand rub if soap and water are not available;
- Avoiding touching your eyes, nose and mouth;
- Cleaning and disinfecting surfaces and objects that may be contaminated with germs like the flu; and
- Getting the seasonal influenza vaccine when it becomes available. Although it is not effective against H3N2v, it is protective against other common strains of influenza.
- Washing your hands frequently with soap and running water before and after exposure to pigs;
- Never eating, drinking or putting things in your mouth in pig areas;
- Considering avoiding exposure to pigs and swine barns this summer, especially if sick pigs have been identified and if you are high risk of complications from influenza;
- Watching your pig for signs of illness and calling a veterinarian if you suspect they might be sick;
- Avoiding close contact with pigs that look or act ill; and
- Avoiding contact with pigs if you are experiencing flu-like symptoms.
Additional information from the Centers for Disease Control and Prevention regarding Swine Influenza/Variant Influenza Viruses is available here.
Due to concerns over additional possible transmission, Maryland's Secretary of Agriculture has issued an order closing the swine venues at two upcoming county fairs.
Last month, in EID Journal: Transmission Of Swine H3N2 To Humans At Agricultural Exhibits - Michigan & Ohio 2016, we looked at the risks of novel flu transmission in these types of venues, including from healthy-looking pigs.
Most years fewer than a dozen `swine variant' infections are reported in the United States, mostly involving farm or livestock workers. Most are mild, but it is likely that many others go undiagnosed.A far cry from 2012, when 10 states reported more than 300 confirmed cases (see H3N2v Update: CDC Reports 52 New Cases, Limited H2H Transmission) - assuming these 27 cases are confirmed by the CDC - would make 2017 the 2nd busiest swine variant year on record.
With state and county fair season continuing over the summer and into fall, it would not be unexpected to see additional, scattered reports of swine variant infection.While rarely as severe as avian flu in humans, swine influenza viruses nevertheless are considered to have some pandemic potential. The CDC's IRAT (Influenza Risk Assessment Tool) Rankings monitors and characterizes 14 different novel flu viruses, and has this assessment on H3N2v.
Swine-origin flu viruses do not normally infect humans. However, sporadic human infections with swine-origin influenza viruses have occurred. When this happens, these viruses are called “variant viruses.” Influenza A H3N2 variant viruses (also known as “H3N2v” viruses) with the matrix (M) gene from the 2009 H1N1 pandemic virus were first detected in people in July 2011. The viruses were first identified in U.S. pigs in 2010. In 2011, 12 cases of H3N2v infection were detected in the United States. In 2012, 309 cases of H3N2v infection across 12 states were detected. The latest risk assessment for this virus was conducted in December 2012 and incorporated data regarding population immunity that was lacking a year earlier.
Summary: 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 some recent blogs on Swine variant influenza, and why the CDC closely monitors these infrequent human infections, you may wish to revisit:
Ohio: Henry County Fair Closes Pig Barn Over H1N2 Swine Flu
Second Ohio County Fair Closes Hog Barn Over Swine Flu
A Reminder About The `Other' Novel Flu Threat
MMWR: Investigation Into H3N2v Outbreak In Ohio & Michigan - Summer 2016