ABSTRACT
Japanese encephalitis (JE) and rabies are 2 viral encephalitis that are of public health importance in India. JE is a zoonosis with the primary cycle occurring in arthropods (mosquito vectors) and vertebrate animals (primarily the pig), man being only an incidental 'dead end' host. Out-breaks have been seen in most parts of India except the north west. The disease presents with a prodromal stage, an acute encephalitic stage with coma, convulsions and variable deficits and a convalescent stage. Diagnosis can be made by viral isolation from CSF or brain, or serologic tests such as haemagglutination inhibition test and IgM antibody capture ELISA in CSF and blood. There is no specific treatment. Mortality ranges from 20-50% and almost half the survivors have sequelae. The most effective control measure besides control of mosquitos is vaccination. A killed mouse brain vaccine is being prepared in India and is safe and effective but expensive. Rabies is a highly fatal encephalomyelitis primarily occurring in urban dogs and wild animals especially canines. It is endemic in India and affects an estimated 3 per 100,000 persons annually. The patient initially may display bizarre combative behaviour. The disease can be effectively prevented by post exposure vaccination. The nervous tissue vaccine is no longer recommended because of unacceptable neurotoxicity. Three cell culture vaccines are presently available with about equal efficacy.
Subject(s)
Animals , Brain/pathology , Diagnosis, Differential , Dogs , Encephalitis Viruses, Japanese/isolation & purification , Encephalitis, Japanese/diagnosis , Humans , Mosquito Control , Rabies/diagnosis , Rabies virus/isolation & purificationSubject(s)
Adolescent , Age Distribution , Child , Child, Preschool , Developing Countries , Encephalitis Viruses, Japanese/isolation & purification , Encephalitis, Arbovirus/epidemiology , Female , Heat Stroke/complications , Humans , Incidence , India/epidemiology , Infant , Male , Risk Factors , SeasonsABSTRACT
Comparative evaluation of enzyme-linked immunosorbent assay (ELISA) and bioassay (virus isolation in Toxorhynchites splendens larvae and identification by immunofluorescence test using virus specific monoclonal antibody) was carried out in order to define a suitable strategy for monitoring Japanese encephalitis virus infection in field mosquitos. A total of 8,850 adult female mosquitos in 177 pools (Culex tritaeniorhynchus 91, Cx. vishnui 59 and Cx. fuscocephala 27) collected from an endemic area of Tamil Nadu were examined by both the techniques. In ELISA, 9 pools which had optical densities (OD) equal to the mean of normal infected pools plus > or = 4 standard deviations (SD) mean considered positive and all of them were virus positive by the bioassay also. Sixty-five pools had OD = Mean + 2-3 SD and 103 pools had OD = Mean + < 2 SD of normal pools. From these groups, 12 (18.5%) and 8 (7.8%) pools respectively were found to be virus positive by the bioassay. In total 29 (16%) pools were positive by the bioassay as against 9 (5%) by ELISA. This study demonstrated that the bioassay is sensitive for estimation of true positives and ELISA is a rapid screening system. A protocol has now been developed for surveillance in which field pools are first screened by ELISA and only those with OD = Mean + > or 2 SD are assayed in Toxorhynchites. By excluding a large majority of pools with low OD (Mean + < 2 SD), which are likely to yield to only a small percentage of true positives, the cost, time and labor involved are greatly reduced.(ABSTRACT TRUNCATED AT 250 WORDS)