Seroepidemiological survey of hospital-associated populations in Colombo, Sri Lanka.

Almost 1,500 sera from hospital-associated groups in Colombo, Sri Lanka were tested for antibodies against melioidosis, scrub typhus, influenza, and group B arboviruses. A low prevalence of antibodies was found against meliodosis and scrub typhus. Crude prevalence rates of more than 50% were encountered for antibodies against A influenza, and there was no apparent difference in rates when these were analysed according to age, sex, or ethnic background. Influenza B antibodies were more prevalent in older individuals. Antibodies against group B arboviruses were found in all groups tested, and were significantly more prevalent in older Tamils, who has estimated attack rates of more than 5% per year.