A serologic study of California serogroup Bunyaviruses in Sri Lanka

A seroepidemiologic study of California (CAL) serogroup viruses (genus bunyavirus, family Bunyaviridae) was carried out on 952 human and 1,834 animal sera collected from different ecological zones of Sri Lanka (latitudes 5-10° N, longitudes 79-82° E). The sera were screened for neutralizing antibody to Lumbo (LUM), snowshoe hare (SSH), and trivittatus (TVT) viruses by plaque neutralization tests on Vero cells. Of 2,786 sera screened, 262 (9.5%) had antibody to one or more viruses Twenty-two sera, selected to represent different species of origin and reaction profiles, were titrated against nine CAL viruses: LUM, SSH, TVT, Tahyna (TAH), California encephalitis (CE), La Crosse (LAC), Inkoo (INK), Melao (MEL), and Guaroa (GRO). Results suggested that there were multiple CAL viruses active in Sri Lanka, one or more of them closely related to LUMBO and SSH viruses, and another related to MELAO virus. These viruses were active in both the wet and dry zones of the country, and infected humans as well as a range of domestic livestock.link_to_subscribed_fulltex

Japanese encephalitis in Sri-Lanka: Comparison of vector and virus ecology in different agro-climatic areas

The ecology of Japanese encephalitis (JE) in different agro-climatological areas of Sri Lanka was studied in relation to the abundance of mosquito vectors, infection in domestic livestock, and human infection and disease. There was an inverse correlation between altitude and the abundance of potential JE vectors, as well as JE seroprevalence in domestic livestock and in man. Little or no JE infection was documented above 1200 m elevation. JE seroprevalences in cattle and goats were better predictors of human infection risk than was porcine seroprevalence. In areas with asynchronous porcine infection occurring over many months, high overall JE seroprevalence in pigs was found with little evidence of human infection. Porcine JE infection occurring in synchronous bursts associated with monsoonal rains was correlated with significant bovine, ovine and human seroprevalence in 2 low elevation study areas, Anuradhapura (dry zone) and Ragama (wet zone), with epidemic human JE in the former area and endemic disease in the latter.link_to_subscribed_fulltex

Viruses isolated from mosquitoes collected in Sri Lanka

Attempts to isolate viruses from 178,181 unengorged female mosquitoes collected from different ecologic areas of Sri Lanka yielded 31 isolates: 17 of Japanese encephalitis (JE) virus, nine of Getah virus, three of a Batai- related bunyavirus, and two of Arkonam virus. Culex tritaeniorhynchus and Mansonia uniformis mosquitoes were found to carry JE virus in a dry zone nonepidemic area, and Cx. pseudovishnui was found to carry it in a wet zone nonepidemic area. Japanese encephalitis virus was isolated from Cx. tritaeniorhynchus, Cx. gelidus, Cx. fuscocephala, and Cx. whitmorei during a human epidemic in the dry zone. Getah virus was isolated from Cx. tritaeniorhynchus, Cx. gelidus, and Cx. fuscocephala collected in the vicinity of swine. Isolations of Getah, Arkunam, and Batai-related viruses from Sri Lanka are reported for the first time.link_to_subscribed_fulltex