The Centers for Disease Control and Prevention has confirmed three mildly ill children with viruses similar to the swine-origin influenza A (H3N2) viruses identified in three other states. These viruses contain the “matrix (M) gene segment” from the 2009 “Swine Flu” pandemic known as H1N1 virus.

This combination of genes was first identified in a person in July. There have been several more infections with this virus, bringing the total number of human infections to 10 (Indiana 2, Pennsylvania 3, Maine 2, and Iowa 3). All 10 patients have recovered and the majority of cases had relatively mild symptoms, although 3 patients were hospitalized.

This new occurrence of the virus is being described as a “novel strain” and as yet does not appear to be causing significant illness or spreading at any great rate, which was the fear in 2009. Iowa has increased its monitoring of any influenza type illnesses.

Unfortunately these new viruses are different enough from human influenza A (H3N2) viruses, so that the seasonal vaccine is not expected to provide much protection among adults and no protection to children. However, laboratory tests so far show the viruses are susceptible to the antiviral drugs oseltamivir (Tamiflu®) and zanamivir (Relenza®). CDC recommends these drugs for treatment of seasonal and these swine-origin influenza viruses.

Prior to the three cases in Iowa, most human infections with this virus were associated with exposure to some form or other of pig farming. In Iowa, however, no swine exposure has been pinpointed.

So far scientists think that unsustained human-to-human transmission may have occurred. The viruses have been detected in swine in several states in the United States. Transmission can only occur from live animals and the CDC states that swine influenza viruses do not spread through contact with pork or pork products. Eating properly handled and cooked pork is safe.

As part of routine preparedness measures to counter possible pandemic threats posed by novel influenza viruses in the event that they gain the ability to spread easily from person-to-person, CDC has developed a candidate vaccine virus and provided it to manufacturers. These cases will be officially reported in the MMWR and FluView.

The CDC also recommends that doctors and healthcare professionals remain vigilant and where they suspect novel influenza viruses might be acting to submit nose and throat swabs for testing.

Written by Rupert Shepherd