California Group Arboviruses in Florida and Report of a New Strain, Keystone Virus: Epidemiologic and Virological Observations in the Tampa Bay Area

Abstract

The 1963-65 ecologic studies for arboviruses in the Tampa Bay area by the Encephalitis Research Center, Florida State Board of Health, show that the California encephalitis group arboviruses are the most commonly recovered viral agents from mosquitoes. Of 27, 035 Aedes mosquitoes tested in 790 pools during Jan. 1963 to Dec. 1964, 41 pools were positive. The trivitatus-like strain was recovered most frequently and predominantly from A. infirmatus. A newly identified strain, named the Keystone, was obtained from A. atlanticus tormentor. Human disease related to California viruses by serologic tests is uncommon; 2 patients with viral symptoms of the central nervous system were identified in 618 tested. Human infection without history of central-nervous-system disease was found in 1-6% of the general population. Human serums should be extracted with kaolin rather than acetone to detect specific inhibitor to BFS-283 [prototype] antigen. The lower vertebrate source of the California encephalitis group arboviruses in Florida remains unknown. Extremely low rates of hemagglutination-inhlbition antibody were found in mammals. Preliminary serum neutralization tests suggest that most of these are nonspecific. The year-round recovery of the virus from mosquitoes, however, suggests'' its continual presence in a common host.