Prevalence of the antibody to influenza C virus in a northern Luzon Highland Village, Philippines.

A total of 101 serum samples were collected from the persons (1 to 85 years of age) living in a Philippine mountain village where the contact with other communities has largely been restricted. These sera were tested for the presence of antibody to influenza C virus with hemagglutination-inhibition and radioimmuno-precipitation tests. The results showed that all the subjects, including the persons who had never been outside the village, contained the antibody to the surface glycoprotein of the virus, and that the age of acquisition of the antibody was significantly lower in this village than in any of the previously studied communities. Thus it appeared that infection with influenza C virus was prevalent even in this small mountain village, presumably with a higher incidence than in the larger, industrialized communities.