The Centers for Disease Control has issued a notice that the first cases for 2013 of H3N2 variant virus infection (a.k.a. swine flu) have been reported. The H3N2 variant virus, or “H3N2v,” is a non-human influenza virus that usually affects swine but which has no infected human beings.
The new outbreak has caused concern among some vacationers in the US since a normal summer past-time may actually serve to spread the fatal disease. There were four cases of swine flu reported by the state government of Indiana that have been associated with attendance at agricultural fairs: a classic American institution. Pigs at the fair were reported to have tested positive for H3N2 infection. Given the incidence of the multi-state outbreak of 2012, the report from Indiana “may foreshadow a number of such outbreaks this summer based on what happened last summer,” according to the CDC. In 2012, there were 309 reported H3N2v cases, including 16 hospitalizations and one death. A genetic sequencing conducted by CDC on one of the Indiana samples has confirmed that the H3N2v virus in Indiana is 99% similar to the H3N2v viruses detected in 2012.
The spread of the swine-borne illness seems consistent with the 2012 summer outbreak when most of the cases reported exposure to pigs, especially at agricultural fairs. So far, none of the people affected in Indiana cases were hospitalized and there were no deaths.
According to the CDC, H3N2v symptoms include fever, sore throat, cough and body aches. Though no sustained human-to-human spread of the virus has been detected, sporadic limited spread of this virus has occurred in the past.
Agricultural fairs are a summer tradition throughout the US annually. Many of them have swine barns, where farmers and proud youngsters show off their pigs and win prizes. Pigs arrive from a number of different places and then come into contact with each other and people. The fairs, then, magnify the risk of spread of influenza viruses between pigs and people.
The spread of the flu infection from swine to humans is believed to occur mostly through droplets ejected by coughing and sneezing pigs. Swine may be infected, however, even if they show no signs of illness. They can still spread the flue to people. The elderly, pregnant women, young children, and people suffering from asthma, diabetes, heart disease, or compromised immune systems are especially at risk.
The CDC is that persons at high risk for the flu should avoid pigs and swine barns at fairs this summer. This same advice was circulated in 2012. According to the CDC, most of the 16 people who were hospitalized and the one person who died last summer from H3N2v infection had one or more underlying medical conditions.
The CDC warned, however, that the flu is a danger to everyone. it’s also important to note that flu can be dangerous for anyone, including healthy people. CDC has recommendations for the public on what steps they can take to help protect against H3N2v or other swine influenza infections if they do attend an agricultural fair where swine are present. Here are some recommendations being circulated to healthcare professionals:
• If you are high risk for influenza complications, avoid exposure to pigs and
• Wash your hands thoroughly with soap and running water before and after
• Avoid eating or drinking in animal areas.
• Avoid close contact with animals that look or act ill.
Please note: influenza viruses have not been shown to be transmissible to people through eating properly handled and prepared pork or other products derived from pigs.
While there is work being done to devise a vaccine, no vaccine is currently available for H3N2v. The 2012-2013 and 2013-2014 seasonal flu vaccines are not formulated to provide protection against H3N2v, but are formulated to protect against seasonal flu viruses that circulate widely each season. However, the same influenza antiviral drugs used to treat seasonal flu can treat H3N2v. Currently, the recommended drugs – oseltamivir and zanamivir - are available by prescription only. Early treatment works better and is especially important for people with a high risk condition.
CDI says will monitor the virus and any changes that would affect its spread. “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,” said a CDC report. Mutations in the virus may make it more severe and spread more easily within the human population. According to the CDC, “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.”
If the virus should mutate, localized outbreaks in pockets of non-immune people may emerge. Children younger than about 10 years of age, noted the CDC, have very little immunity against the H3N2v virus. This means that if that if H3N2v were to become more transmissible, day care facilities and schools would be especially vulnerable and also become centers of contagion.
Recommendations for health professionals
The CDC provided the following advice for public health officials and healthcare providers:
• Clinicians who suspect influenza in persons with recent exposure to swine should obtain a nasopharyngeal swab or aspirate from the patient, place the swab or aspirate in viral transport medium, and contact their state or local health department to arrange transport and request a timely diagnosis at a state public health laboratory.
• Commercially available rapid influenza diagnostic tests (RIDTs) may not detect H3N2v virus in respiratory specimens. Therefore, a negative rapid influenza diagnostic test result does not exclude infection with H3N2v or any influenza virus. In addition, a positive test result for influenza A cannot confirm H3N2v virus infection, because these tests cannot distinguish between influenza A virus subtypes (i.e., they do not differentiate between other human influenza A viruses and H3N2v virus). Therefore, respiratory specimens should be collected and sent for sub-type specific real-time polymerase chain reaction (RT-PCR) testing at a state public health laboratory.
• Enhanced surveillance for influenza during agricultural fair season is recommended to facilitate timely detection and investigation of H3N2v
cases. Recommendations for influenza surveillance and testing can be found here
• Clinicians should consider antiviral treatment with oral oseltamivir
or inhaled zanamivir
in patients with suspected or confirmed H3N2v
virus infection. Antiviral treatment is most effective when started as soon as possible after influenza illness onset. For more information on antiviral treatment for H3N2v
virus infections, visit the CDC website here: http://www.cdc.gov/flu/swineflu/h3n2v-treatment.htm