Seroprevalence of hepatitis A virus and varicella zoster antibodies in a Javanese community (Yogyakarta, Indonesia).

Hepatitis A virus (HAV) cause an acute inflammation of the liver. Varicella-zoster virus (VZV) cause chickenpox (varicella) and herpes zoster. Effective vaccines against hepatitis A and varicella are available for children, adolescents and adults. In order to implement an appropriate vaccination policy, a baseline to assess the potential benefits and sections of the population who would benefit most are required. We investigated seroprevalence of hepatitis A virus and varicella zoster antibodies in a Javanese community. A total of 1,103 subjects were studied. The 600 subjects aged 4 to 9 years were sampled between 23 October and 2 November, 1995. The other subjects were sampled between 12 October and 1 November, 1996. The overall prevalence of anti-HAV in cohort was 28.7%. Anti-HAV seroprevalence rates were below 30% until the age of 15 and below 40% until the age of 25. The anti-varicella seroprevalence showed only in two thirds of seropositive population at the age of 15. The results of the study have implications for vaccination strategies for both hepatitis A and varicella zoster.

Comparative sensitivity of laboratory methods to diagnose dengue virus infections at Husada Hospital, Jakarta.

Several methods are available for diagnosis of dengue virus infections including a new commercially available dengue blot IgG assay. We conducted a study to compare the sensitivity of the dengue blot with the conventional diagnostic methods. Serum samples from suspected dengue patients were collected for virus isolation and the following serological assays: the hemagglutination-inhibition assay, an IgM/IgG enzyme-linked immunosorbent assay, and the dengue blot. When suspected dengue samples were tested by all methods, viral isolation detected the fewest dengue infections (10.5%), while the IgM/IgG ELISA was the most successful (46.3%) in diagnosing dengue infections. In a specific comparison between the IgM/IgG ELISA and the dengue blot, the dengue blot had an overall sensitivity of 48.8%, with a specificity of 88.7%. When patients were classified by their serological response, the dengue blot had a sensitivity of only 1.7% in those patients with a primary or recent dengue infection, however in secondary infections, the sensitivity of the dengue blot improved to 93.5%. Testing convalescent samples from patients with primary infections, only slightly changed the sensitivity of the dengue blot. The diagnosis of dengue is needed rapidly by clinicians to insure prompt treatment of patients. The dengue blot provides a rapid and easily performed assay, especially sensitive in secondary dengue infections which are most common in hospitalized cases in Asia.

Correlation of population indices of female Culex tritaeniorhynchus with Japanese encephalitis viral activity in Kapuk, Indonesia.

Nineteen consecutive monthly light trap collections of mosquitoes were made between October 1978 and April 1980 in Kapuk, Indonesia. Kapuk is a small suburb of Jakarta where pigs are raised in close proximity to rice paddies which are breeding sites for Culex tritaeniorhynchus. Japanese encephalitis (JE) virus is believed to be endemic and has been recovered from mosquitoes and pigs in the area on several occasions. A total of 18,435 female Cx. tritaeniorhynchus were allocated to 359 pools of approximately 50 per pool. Virus isolations were attempted in both Vero and BHK-21 cells and agents producing cytopathic effect were identified in a micro-neutralization test. Nineteen strains of JE were recovered from the 359 pools of Cx. tritaeniorhynchus tested. The light trap index of female Cx. tritaeniorhynchus (X) and the relative frequency of pools positive for JE (Y) for each month of the study were plotted and correlation coefficients (r) calculated after transforming the mosquito population data logarithmically and the relative frequencies of isolation by arcsine square root. The close fit of the data (p less than 0.001) to an inverse linear model (1/y = a + b log10X) suggests a close dependence of JE viral activity on the population dynamics of Cx. tritaeniorhynchus. Three additional strains of JE were recovered from other Culex spp. at the same study site. One strain each was isolated from individual pools of Cx. gelidus, Cx. vishnui and Cx. fuscocephala. Cx. tritaeniorhynchus was more frequently infected with JE than the other species tested.

Comparative sensitivity of mosquito inoculation and mammalian cell culture for isolation of some arboviruses in Indonesia.

The sensitivity of parenteral inoculation of colony reared male Aedes aegypti and mammalian cell cultures for isolation of Japanese encephalitis virus and dengue virus were compared. The mosquito inoculation technique proved to be more sensitive for the isolation of dengue virus from the sera of febrile patients than did the mammalian cell cultures (Vero and BHK21) employed in these studies. Mosquito inoculation proved to be no more sensitive that the mammalian system for the isolation of Japanese encephalitis virus from field caught female mosquitoes.