Metapneumovirus is new cause of respiratory ills. (Causes Severe Lower Respiratory Infection).

SAN DIEGO -- Human metapneumovirus, a newly recognized pathogen, can cause severe lower respiratory tract infections in adults as well as children, researchers said at the annual Inter-science Conference on Antimicrobial Agents and Chemotherapy.

Two Canadian teams conducted retrospective studies of this new paramyxovirus. Human metapneumovirus (MPV) was discovered in 2001 in 28 children with respiratory tract infection in the Netherlands, where further studies found that all children under age 5 years had antibodies indicating exposure to MPV.

In the current studies, MPV was found mainly in the very old and very young, but all age groups were affected. Pediatric symptoms can mimic respiratory syncytial virus (RSV) infection.

No simple test for diagnosing MPV in outpatients exists yet. The researchers performed polymerase chain reaction assays on nasopharyngeal or throat swabs from inpatients and outpatients with respiratory tract infections who tested negative for influenza, parainfluenza, and adenovirus.

In one study of samples from 126 Canadian patients with unexplained respiratory symptoms from the 2001-2002 flu season, 22% had MPV: 17 were outpatients and 11 were inpatients. That's double the 11% rate of MPV infection found in children in the Netherlands, said Dr. E.L. Chan of the Saskatchewan Regional Laboratory, Regina.

MPV was equally distributed between males and females, but patients aged 60 years and older were more likely to be women. Patients ranged in age from 1 month to 94 years. Nearly all patients with MPV had fever, most had cough, and half had flulike symptoms and a sore throat. Up to one-third of inpatients had bronchitis, Dr. Chan said.

Dr. Gilles Pelletier and associates at Laval University, Quebec City, detected 28 samples containing MPV from hospitalized patients with ...