Incidence of neutralizing antibodies to Chandipura virus in domestic animals from Karimnagar and Warangal Districts of Andhra Pradesh, India.

In order to determine the possible role of domestic animals in the outbreak of acute encephalitis associated with Chandipura virus (CPV) among children in Andhra Pradesh in 2003, a serological survey of domestic animals was carried out during the epidemic in July 2003. Out of 180 animal sera from highly affected areas of the Karimnagar and Warangal districts of Andhra Pradesh 33 (18.3%) had virus neutralizing (VN) antibodies to CPV. The positive animals consisted of pigs (30.6%), buffalos (17.9%), cattle (14.3%), goats (9.3%) and sheep (7.7%). Isolation of CPV and detection of CPV antibodies in patients with encephalitis reported earlier and the evidence of antibodies to CPV in domestic animals shown here suggest that CPV circulates in this region and should be considered an emerging virus of public health importance.

Investigation of buffalopox outbreaks in Maharashtra State during 1992-1996.

During 1992-96, outbreaks of buffalopox zoonosis were reported from different villages in Jalgaon, Dhule and Beed districts of Maharashtra State. In humans, pox lesions were observed on the hands whereas in affected buffaloes and cows the lesions were noticed mainly on the teats and udder. Twenty two virus strains were isolated from the skin scabs collected from infected humans and milch animals. Neutralizing antibodies were detected not only in the sera of affected humans but also in their contacts. Detection of antibodies in young individuals from endemic area, who were neither vaccinated for smallpox nor had any contact with buffaloes or history of any poxvirus disease, is suggestive of occurrence of subclinical infection. A few children who had no contact with infected animals also showed clinical manifestations with disseminated lesions on the face, arm and buttocks, and thus suspected to have acquired infection through their infected parents or other family members indicating a possible man to man transmission. Therefore, in the light of discontinuation of smallpox vaccination, buffalopox outbreaks need to be monitored carefully as this may emerge as a serious zoonotic disease in India.

Two-way cross-protection between West Nile and Japanese encephalitis viruses in bonnet macaques.

Cross-protection between Japanese encephalitis (JE) and West Nile (WN) viruses was tested in bonnet macaques (Macaca radiata) immunized either with JE virus (JEV) or WN virus (WNV). JEV immunized monkeys were challenged by intranasal (i.n.) route with WNV and vice versa. Four control unimmunized monkeys were similarly infected either with WNV or JEV. Two of three control monkeys infected with WNV, developed paralysis followed by death. Virus was recovered from the central nervous system (CNS) of the both dead control monkeys and the histopathological examination of CNS revealed changes suggestive of viral encephalitis. The control monkey infected with JEV developed encephalitis and the virus was recovered from the blood and CNS. All the 3 JEV-immunized monkeys withstood WNV challenge, whereas only 2 of the 5 WNV immunized monkeys withstood the challenge with JEV. Out of 3 WNV-immunized monkeys surviving challenge with JEV, 2 revealed symptoms suggestive of mild encephalitis followed by complete recovery. The third monkey died on the 60th day post-infection (p.i.) without any symptoms and virus was recovered only from the olfactory lobe. These studies indicate that the immunization with JEV protects the bonnet macaques against WNV, whereas the WNV immunization only reduces the severity of the disease due to JEV.

Susceptibility of four species of mosquitoes to Chandipura virus and its detection by immunofluorescence.

Susceptibility of Culex tritaeniorhynchus, Cx. Bitaeniorhynchus, Cx. quinquefasciatus, and Aedes aegypti to Chandipura (CHP) virus was compared after parental inoculation of the mosquitoes. Virus detection was done by indirect immunofluorescence (IF). CHP antigen in head squashes of all the four species was seen at 24 hr post infection (p.i.). The mosquitoes supported the virus growth and transmission by bite to 2 days old suckling Swiss albino mice. Ae. aegypti which was found the most susceptible mosquito species for CHP virus can be used as a substitute for laboratory mice.