Indian Pediatrics 2000;37: 149-152
Community studies on prevalence of HBsAg in two urban populations of southern india
Jagvir Singh, Rajesh Bhatia, Shashi Khare, S.K. Patnaik*, Shyamal Biswas**, Sohan Lal** D.C. Jain and Jotna Sokhey
From the National Institute of Communicable Diseases, 22 Shamnath
Marg, Delhi 110 054, India;
*National Institute of Communicable Diseases, Regional Filaria Training and Research
Center, Weavers Colony, Rajahmundry 533 105, Andhra Pradesh, India; and **National Institute
of Communicable Diseases, Plague Surveillance Unit, 8 Bellary Road, Bangalore 560 003,
Manuscript received: July 19, 1999; Initial review completed: August 6, 1999; Revision accepted: August 24, 1999.
Objective: To find out prevalence of HBsAg in general population, especially in under-five children. Setting: Bangalore and Rajahmundry towns in southern India. Methods: Localities were chosen as the sampling units in each town. About 10-20 households were randomly selected from each locality. Only the youngest but apparently healthy person present in the household was interviewed for age, sex and history of jaundice any time in life. Mothers were interviewed to collect data for children below 15 years of age. Blood samples were collected from these persons on filter paper strips (18-mm diameter disc, Whatman filter paper No. 3) by finger prick method. The samples were tested for HBsAg by Micro ELISA (Ortho-Clinical Diagnostics). Results: Overall, 3.3% (95% CI, 2.0-4.5) of 737 persons in Rajahmundry and 4.2% (95% CI, 2.8-5.5) of 816 persons in Bangalore were found carriers of HBsAg. Age-specific or sex specific carrier rates were similar in Rajahmundry as well as in Bangalore. Most of the carriers (96%) denied having jaundice ever in life. Conclusions: The results from this community based study are in agreement with the historical data from hospital based studies that about 3-5% of persons may be carriers of HBsAg and that the pool of chronic carriers of hepatitis B virus in India is built up in childhood and is then maintained in older children and adults. The results highlight the need of completing hepatitis B immunization during the infancy.
Key words: Chronic hepatitis B carriers, HBsAg carriers, Filter-paper method.
A large number of studies on antenatal mothers and voluntary blood donors have found that about 3-5% of adults may be chronic carriers of HBsAg in India (NICD unpublished review on prevalence of HBsAg in India). In contrast, only a few studies have estimated the prevalence of HBsAg in non-institutional healthy persons (Table I)(1-8).
Table I__Historical Data on Prevalence of HBsAg in Non-Institutional Healthy Persons in India.
*Data presented during meetings on Viral Hepatitis Surveillance Programme, NICD, Delhi.
RPHA = Reversed passive hemagglutination; IEOP = Immunoelectro-osmophoresis;
CIEP = Counter immuno electrophoresis;
RIA = Radio-immunoassay;
ELISA = Enzyme linked immunosorbent assay.
Moreover, these studies were plagued with the problem of sampling, and not all of them used the most sensitive tests for detection of HBsAg. Nevertheless, HBsAg prevalence rates were significantly higher in areas where tribal population was sampled. Keeping in view that community data on prevalence of HBsAg that are critical to define immunization strategies against hepatitis B virus infection are scarce, we planned the present study in urban population of Rajahmundry and Bangalore towns in south India. The results are presented in this report.
Subject and Methods
In 1997-98, a multi-centric study was carried out by the National Institute of Communicable Diseases (NICD), Delhi in Rajahmundry and Bangalore towns to understand the epidemio-logy of viral hepatitis in community settings. Localities were chosen as the sampling units in each town, and all the population in selected localities were surveyed. More than 70,000 population was surveyed in each town. The paramedics went from house to house to enquire about the cases of jaundice. Data on age and sex of all the family members were also collected and entered in the registers. These registers were used as sampling frame for the present study. About 10-20 households were selected from each locality for the present study. Only the youngest but apparently healthy person present in the household was included. Thus, there was a positive bias for selection of younger children. All the selected subjects were interviewed for their age, sex and history of jaundice any time in life. Mothers were interviewed to collect data for children below 15 years of age. Blood samples were collected from all the selected persons on filter paper strips (18 mm diameter disc, Whatman filter paper No. 3) by finger prick method. Informed oral consent was obtained from all the subjects/mothers before collecting the samples. The samples were dried in the air and stored in a plastic bag at room temperature. All the samples were transported to the laboratories of NICD at Delhi at room temperature but stored at-20° C till tested for HBsAg.
Filter paper discs soaked with blood were cut and put in half test tube containing 0.5 ml of phosphate buffer saline. They were left at room temperature for one hour. After that, discs were removed by squeezer and forceps and squeezed on the side wall of the test tube to eluate as much serum as possible. From one disc, about 0.2 ml of eluate was obtained which was tested for HBsAg by standard procedure using Micro ELISA test kit (Ortho-Clinical Diagnostic System, Johnson and Johnson Ltd., Mumbai). Samples tested positive for HBsAg were repeated before labeling them positive for HBsAg.
Overall, 3.3% (95% CI, 2.0-4.5) of 737 persons in Rajahmundry and 4.2% (95% CI, 2.8-5.5) of 816 persons in Bangalore were found positive for HBsAg (Table II). Age-specific or sex-specific HBsAg carrier rates were similar in Rajahmundry as well as in Bangalore (p>0.05). About 96% (23/24) of the carriers in Rajahmundry denied having jaundice any time in the life. A 9-year-old child had jaundice at the age of 2 years. Such histories were not collected in Bangalore.
Table II__Age and Sex Specific HBsAg Carrier Rates in Urban Rajahmundry and Bangalore
HBsAg carrier rate of 3.3% (95% CI, 2.0-4.5) and 4.2% (95% CI, 2.8-5.5) in the general population of Rajahmundry and Bangalore respectively indicated that hepatitis B virus infection is widespread in these areas. The results are also in agreement with a large number of hospital based studies on antenatal mothers and voluntary blood donors that about 3-5% of adults from different parts of the country may be carriers of HBsAg. About 3.4% (15/444) of healthy adults (15 years and above) in the present study were positive for HBsAg.
Most of the carriers (23/24 = 96%) in Rajahmundry denied any history of jaundice in the past; the presence of jaundice in the only person may or may not be due to hepatitis B. Thus the results support the previous observa-tions that most of the persons become HBsAg carriers after asymptomatic infection or after a mild disease which do not produce clinical jaundice(9).
Although the need of introducing the hepatitis B vaccine under the immunization programme is well recognized, timing of the first dose remains to be decided. If the perinatal transmission contributes a significant proportion of infections, the first dose of vaccine should be given as soon after birth as poosible. When the transmission is mainly horizontal, the first dose of hepatitis B vaccine may be given later with other vaccines, for example, with the first dose of DPT vaccine(10). Unfortunately, our data were not helpful in making such decision because not many newborns were available for testing of HBsAg. Nevertheless, the data indicated that the pool of chronic carriers of hepatitis B virus is built up in the childhood or may be even during infancy - 6.3% (1/16) of infants in Rajahmundry and 7.3% (2/41) in Bangalore were found carriers of HBsAg. The results thus highlight the importance of completing hepatitis B immunization during the infancy itself.
Finally, the blood samples were collected on filter papers. It has been found a suitable method for detecting HBsAg carriers and most anti-HBs positive individuals, but not anti-HBc positive individuals(11). We also found in a small study in the laboratory that this technique is suitable for detecting HBsAg carriers (data not shown). We believe that community studies to find the prevalence of HBsAg in general population were not carried out in India earlier because the healthy individuals, especially children, do not agree to provide blood samples by vene-puncture. Collection of blood samples on filter paper may provide a convenient and suitable method for future community based studies in India.
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