Outbreaks of H3N2 in Iowa, 11 other states

Two small outbreaks of influenza A/H3N2 in Iowa and cases of H3N2 in 11 other states have caused the Centers for Disease Control and Prevention to urge healthcare providers to be vigilant.

The CDC released a health advisory on August 4 that reported an increase in the incidents of H3N2 in late June and July, according to CIDRAP News. While noting that localized influenza outbreaks occur every summer, the CDC said clinicians should consider the flu as a possible diagnosis when patients demonstrate acute respiratory illness, including pneumonia.

The outbreaks in Iowa occurred in two non-contiguous counties. In the first incidence, four out of 13 members of a college sports team became ill. In the second, nine of 12 children and one parent became ill at a daycare center.

None of the patients had recently travelled and there were no known epidemiological links between the two outbreaks, according to the CDC. The Iowa Department of Public Health, however, issued a July 30 epidemiological update stating that the two outbreaks have connections to travel outside Iowa.

The CDC report said that, on the basis of hemagglutinin gene sequencing of four isolates so far, the viruses are expected to be similar to the A/Perth/16/2009-like H3N2 viruses, which are included in the 2010 seasonal vaccine. Since the strain has yet to circulate widely in the United States, last year’s vaccine would offer scant protection.

In addition to the H3N2 cases, a number of people have recently tested positive for the 2009 H1N1 and influenza B viruses.