Epidemiological studies on feline leukaemia virus infection. I. A serological survey in urban cats.

A survey of the incidence of feline leukaemia virus (FeLV) infection in cats in a large urban area was made by studying the prevalence of antibodies to feline leukaemia virus-associated cell membrane antigens. Two serological tests were used, immunofluorescence and a mixed immunoglobulin rosette technique. The overall incidence of cats with antibodies was 40%, contrasting with 6% in the surrounding rural area. Only 6% of urban kittens were positive while 50% of adults had antibodies. The incidence in adults rose from 29% at 5-6 months to 74% in cats over 3 years. Stray cats had an incidence twice as high as that of domestic pets. These results support and extend earlier findings that FeLV infection is common and is horizontally transmitted.