A serological survey of arboviral diseases among the human population of the Andaman and Nicobar Islands, India.

In an attempt to determine the prevalence of certain arthropod-borne viruses of public health importance amongst the human population of the Andaman and Nicobar Islands of India, 2,401 sera were collected from six major localities. The sera were analysed by the hemagglutination inhibition (HI) and neutralization (N) tests, using Chikungunya (CHIK), Japanese encephalitis (JE), West Nile (WN), dengue (DEN-2), Langat (TP-21) and Kyasanur Forest disease (KFD) viral antigens. The highest prevalence of HI antibodies was detected against KFD virus (22.4%), followed by Langat (20.2%), JE (5.9%), DEN-2 (3.1%), CHIK (2.9%) and WN (0.8%) viruses. Cross-reactions to the viral antigens were also noted. The results of N tests indicated a high prevalence of DEN-2 (25.4%) virus, followed by Langat (17.5%), CHIK (15.3%), KFD (12%), JE (2.19%) and WN (1.8%). These results are discussed in relation to important epidemiological parameters like age, sex and geographical location. To our knowledge, this is the first report of an extensive serosurvey of arthropod-borne viruses on these islands.

Prevalence of West Nile virus infection in India.

During the course of the virological investigation of cases of suspected viral fevers carried out at the National Institute of Virology (NIV), Pune, India, evidence of recent infection with West Nile (WN) virus was detected in 88 cases. Fever, general aches, headache, nausea and vomiting were the principal clinical features in 92% (81/88) of the cases; there were seven cases of encephalitis, in which WN virus-specific IgM class antibodies were detected in CSF samples. These cases of encephalitis were from Japanese encephalitis (JE) nonendemic areas, like Maharashtra and Rajasthan, as well as from JE endemic areas, like Goa and Orissa. Interestingly, neutralizing antibodies predominantly to WN virus were detected in CSF samples by the 50% cytopathic effect inhibition method; the titers ranged from 5 to 375. Cases of WN virus infection associated with both encephalitis and classic features have been reported for the first time in recent years in India. Reports of unique urban West Nile virus encephalitis epidemics in New York, Romania, and Algeria in recent years have signaled the emergence of neurological infection due to West Nile virus as a novel public health threat. This study is important because it records evidence of WN virus infection in India.

An outbreak of dengue fever in rural areas of northern India.

During the past few decades, epidemics of dengue fever are causing concern in several South-East Asian countries including India. The rural areas of Hissar district of Haryana state, situated about 170 km North-West of Delhi, experienced an outbreak of febrile illness during July-August 1996. A total of 13 villages in eight affected primary health centres reported fever cases. The clinical, epidemiological and entomological findings indicated that the present episode was due to dengue fever. The aetiological agent of the current outbreak, the DEN-2 virus, was isolated from 12 acute-phase sera specimens. Though, in the recent past outbreaks have been reported from the rural areas of southern and western India, the present episode is the first outbreak being reported from the rural areas of northern India. The increasing frequency of dengue fever outbreaks in rural areas of various Indian states reflects the changing life style of the rural population as a result of urbanization process and calls for a suitable prevention and control policy based on strengthened surveillance, appropriate health education to the community coupled with proper training of health personnel.

HIV seroprevalence & awareness about AIDS among pregnant women in rural areas of Pune district, Maharashtra, India.

The present unlinked anonymous study was done among sexually active rural women to assess the extent of spread of HIV and its awareness. Peripheral blood samples were collected on filter paper strips from 1251 pregnant women residing in villages in three Primary Health Centres in Pune district of Maharashtra. Elutes were tested for HIV antibodies in two different ELISA systems. Awareness on HIV/AIDS was assessed using a structured questionnaire. Fifteen (1.2%) samples were detected to be HIV seropositive. HIV seroprevalence was significantly higher among villages situated close to highways (P < 0.025). Majority (> 95%) of the participating women were housewives. Although 70 per cent were aware of the existence of AIDS, only 33 per cent knew about all the main modes of HIV transmission. Their main sources of information on AIDS were health camps, health workers (70%) and television (45%). Awareness was associated with higher level of literacy (P < 0.001). Many women had misconceptions about the modes of spread of HIV. Greater emphasis needs to be placed on instituting long-term and sustainable strategies to create awareness among young couples with an emphasis on involvement of health workers in rural areas.

Japanese encephalitis in Sangli district, Maharashtra.

During the months June to December, 1997, 52 cases of suspected viral encephalitis were admitted at the Government Hospital, Sangli. These cases were from the congested areas of Sangli and the adjoining villages. All age groups and both genders were affected. IgM antibodies to Japanese encephalitis (JE) virus were detected in the sera of five of the 52 cases. Perhaps JE virus has established itself in a new locality in Maharashtra and could cause serious public health problems.

A retrospective serological survey of humans in India for Wanowrie virus.

Wanowrie virus (WAN) is an ungrouped arbovirus having morphogenetic characters in common with Bunyavirus. It was isolated for the first time from ticks, Hyalomma marginatum isacci (6700 strain) and subsequently from a human case (68923 strain). In the absence of any reports on the prevalence of this virus amongst humans in India, 600 human sera were tested in the Complement Fixation (CF) test against both the strains of WAN virus. One hundred human sera were randomly selected from six different states, viz Jammu and Kashmir, Rajasthan, Orissa, Maharashtra, Karnataka and Tamil Nadu. CF antibodies were detected in 77 sera (12.8%) against the 6700 antigen while 91 sera (15.1%) possessed antibodies against the 68923 antigen; 60 sera were found to be reactive against both the antigens, with almost identical titres. There was no statistical difference in the distribution of CF reactive sera with respect to age, gender and geographic locations. All the CF reactive sera were found to be negative when tested in the neutralization test against the respective virus strains. The CF antibodies detected in these sera may have been produced during exposure to an antigenically closely related virus yet to be identified.

Putative chikungunya virus-specific receptor proteins on the midgut brush border membrane of Aedes aegypti mosquito.

Two proteins (putative receptors) of 60 and 38 kDa, for chikungunya (CHIK) virus were detected in the brush border membrane fraction (BBMF) of the normal population of Aedes aegypti mosquitoes. Mosquitoes were infected orally with CHIK virus and infectivity checked by testing the head squashes. BBMF was prepared from proved positive and negative mosquitoes. The receptor proteins were found to be present in both the proved genotypes. However, dot-b'ot assays showed that the CHIK virus binding activity of BBMF/mg protein was noticeably low in the proved negative mosquitoes as compared to the positives. BBMF from the larvae of the normal populations also showed the presence of the receptor proteins, binding to CHIK virus. Receptor proteins from larvae as well as the adults were found glycosylated. CHIK virus receptor proteins of 24, 45, 58, 60 and 62 kDa were also seen in the membrane fraction of the C6/36 cells.

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.

The 1993 epidemic of dengue fever in Mangalore, Karnataka state, India.

An epidemic of febrile illness with hemorrhagic manifestations occurred in certain parts of Mangalore city, Karnataka state, India, from the last week of July 1993. The epidemic reached its peak by mid-August and then started declining. Sporadic cases, however, continued to occur till early December. About 200 cases were reported covering all age groups and both sexes. The cases presented with pyrexia, myalgia, arthralgia and headache. Palatal petechiae, magenta colored tongue with central coating, maculopapular rash and facial flush were observed as classical signs. The tourniquet test was positive in 12% of the cases. Hemorrhage was observed in the form of epistaxis (2 cases), subconjunctival hemorrhage (2 cases) or purpura (3 cases). There were no deaths which were attributable to the epidemic. Five strains of dengue (DEN-2) virus were recovered from the acute-phase sera. Dengue virus-specific IgM type of antibodies were detected in 29/116 (25%) sera. Breeding of Aedes aegypti was observed in some of the areas where cases had occurred. No virus was isolated from any of the field-caught Ae. aegypti mosquitos.