Human metapneumovirus infection shows biennial seasonality

By Reuters Staff

NEW YORK (Reuters Health) - Human metapneumovirus (HMPV) circulation follows a biennial pattern of alternating early and late seasons, new research indicates.

And HMPV seasons always came after respiratory syncytial virus (RSV) seasons, Dr. Amber Haynes of the Centers for Disease Control and Prevention in Atlanta and colleagues found.

The findings, published online April 4 in Pediatrics, are based on 2008-2014 data from the National Respiratory and Enteric Virus Surveillance System.

HMPV, first described in 2001, causes upper and lower respiratory tract infections, especially among children younger than 5 years old, older people, and immunocompromised patients, Dr. Haynes and colleagues explain. Symptoms of HMPV infection are "clinically indistinguishable" from RSV and influenza, they add, although prevention options and populations for each virus vary.

"Describing HMPV circulation in the United States in the context of RSV and influenza may help clinicians to prioritize diagnostic testing, identify an etiologic agent, manage patients clinically, and choose appropriate prevention strategies," they write.

Dr. Haynes and her team defined "season" as consecutive weeks of 3% or more positivity for HMPV, and 10% or more positivity for RSV and influenza. Overall, among the 33,583 specimens reported, 3.6% were positive for HMPV, 15.3% for RSV, and 18.2% for flu.

Each virus had similar season durations of 21 to 22 weeks each, with sequential onset of RSV, influenza, and HMPV. HMPV had a biennial pattern, with alternating early and late seasons, while RSV and influenza did not.

"Our findings suggest that RSV onset occurs the earliest during the fall/winter respiratory virus season, followed by influenza and then HMPV," the researchers write. "To distinguish HMPV from other circulating viruses, health professionals should consider HMPV testing during the respiratory season, especially when HMPV is the predominant virus circulating."

Dr. Haynes was unavailable for comment.

The authors reported no external funding or disclosures.

SOURCE: http://bit.ly/203CdNs

Pediatrics 2016.

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