Avian Flu Diary: Arkansas Reports Two H1N1v Infections

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The most common swine flu viruses are H1N1, H1N2, H3N1, H3N2, and H2N3. These viruses, when they jump to humans, are called variant viruses (e.g. H3N2v, H1N2v, H1N1v). While the public health risk posed by these variant flu viruses appears low right now, emerging flu viruses can abruptly change, and so the CDC keeps a close watch on these variant flu strains.

So far – out of nearly 370 cases reported since 2005 - most illnesses have been moderate-to-mild, few patients have required hospitalization, and only 1 death has been attributed to these variant viruses.

Over the past several years, H3N2v has – by far – been the most commonly reported variant strain reported in the United States, making up more than 90% of the reported cases. This summer, we’ve seen 18 H3N2v cases reported, from Indiana, Illinois, and Michigan. Since 2005, H1N2v is the least common (n=5), while H1N1v had accounted for 14 cases.

Today, from the Arkansas Department of Health, we learn of two new H1N1v cases.

Friday, Sep 13, 2013

Swine Flu Variant in Arkansas

Little Rock -- Two people in Arkansas have been infected with a strain of influenza (flu) known as H1N1(v) after contact with swine (pigs). These cases have been confirmed by the Centers for Disease Control and Prevention (CDC).

“A few times a year an animal variant of the influenza virus is identified in humans” said Dr. Dirk Haselow, State Epidemiologist. “Viruses of this type typically cause only mild illness in those affected and, in contrast to seasonal flu, are not easily transmitted from person to person” added Haselow. ADH has carefully monitored the patient contacts for several days without evidence of any human to human spread. Both patients identified to date have recovered fully.

When an influenza virus that normally circulates in swine is detected in a person, it is called a variant influenza virus and is labeled with a ‘v’. Influenza viruses such as H1N1(v) and other related variants are not unusual in swine and can be directly transmitted from swine to people and from people to swine. When humans are in close proximity to live swine, such as in barns and livestock exhibits at fairs, movement of these viruses can occur back and forth between humans and animals.

“We are not currently aware of any additional human influenza cases caused by H1N1(v) and do not anticipate making any new public health recommendations regarding human exposure to swine. However, we will continue to assess the situation and conduct aggressive surveillance for additional influenza cases” Haselow emphasized.

Influenza has not been shown to be transmitted by eating properly handled and prepared pork or other products derived from pigs.

"ADH has been carefully following all suspected cases of influenza. We have also worked closely with our veterinary colleagues and the Arkansas Livestock and Poultry Commission to remain informed about potential infections in swine. It is because of this careful surveillance that these cases have come to our attention,” said Haselow.

Case investigations have indicated that the illnesses resulting from H1N1(v) infection have been similar to seasonal influenza. Symptoms include fever, muscle aches, decreased energy, coughing, runny nose, and sore throat. Contact your health care provider if you are experiencing flu-like symptoms and inform the doctor if you have had contact with swine.

To prevent the spread of other infections you can get from animals, the following precautions are recommended:

Wash your hands often with soap and running water. Particularly after contact with animals. If soap and water are not available, use an alcohol-based hand rub.

Never eat, drink or put things in your mouth in areas where animals are present, and don’t take food or drink into areas where animals are housed.

Never take toys, pacifiers, spill-proof cups, baby bottles, strollers or similar items into areas with animals.

Avoid close contact with animals that look or act ill.

Children younger than 5 years, people 65 years and older, pregnant women, and people with certain chronic medical conditions (like asthma, diabetes, heart disease, weakened immune and nervous systems) are at higher risk for serious complications of infections. These people should consider avoiding exposure to pigs and other animals at petting zoos and barns during fair season.

Although it is likely (see CID Journal: Estimates Of Human Infection From H3N2v (Jul 2011-Apr 2012)) that the number of confirmed cases (this year, and in previous years) under-represents the total number of variant flu infections that occur each year - for now, the threat to the public from these swine variant viruses appears low.

The CDC, in a statement on June 28th of 2013, offered this assessment on H3N2v:

CDC will continue to watch this virus closely to make sure there are no changes in the epidemiology of related human infections. That means watching for any changes in the severity of illness caused by infection with this virus and any signs that the virus is becoming more adept at spreading from person-to-person. Like all influenza viruses, it’s possible that mutations could occur that would allow this virus to become more severe or to spread more easily between people.

The risk of this virus triggering a full-blown pandemic is considered relatively low, however, because serology studies have suggested that significant numbers of adults have some existing immunity against this virus. Children younger than about 10 years old, however, have little to no immunity against H3N2v virus. Given this, a more likely scenario if H3N2v were to become more transmissible among people would be localized outbreaks in pockets of the population that do not have immunity against this virus, for example, in day care or school settings.