TRANSACTIONS OFTHE ROYAL Soctsru UF TROPICAL ME?HCINE ANU HYGIENE (1995) 89,481-483 481 Epidemiological aspects of hepatitis B and D virus infection in the northern region of Amazonas, Brazil Margarita Arboleda’, Mgrcia C. Castilhoz, Josh C.F. Fonseca2, Bernardino C. Albuquerque2, Rbmulo C. Saboia2 and Clara F.T. Yoshida3 ‘Seruiciu Sectional de Salud de Antioquia, Institutu Colombiano de Medicina Tropical, Medellin, Colombia; ‘Institute de Medicina Tropical de Manaus, Amazonas, Brazil; 3Departmento de Virologia, Instituto Oswaido Cw, FIOCRUZ, &azil Abstract The State of Amazonas in the Brazilian Amazon region is an area of high prevalence of hepatitis B and D virus (HBV and HDV) infection. The aim of this study was to identify epidemiological patterns and risk fac- tors of HBV and HI )V infections in Barcelos. in the basin of the Negro river. A random samDle(798 in all1 of the total population in the urban area and in 2 rural villages was s&eyed. A standardizedqu&tionna& was used and blood samples were tested by enzyme-linked immunosorbent assay: 163% had hepatitis B surface antigen, 12.9% had anti-hepatitis B surface antibody and 21.4% had anti-hepatitis B core antigen, The overall prevalence of HBV infection was 24.6%. Anti-hepatitis D was present in 5 subjects, all of them non-natives, and hepatitis B e antigen in 2. A positive association between history of dental treatment with an unqualified dental surgeon was found (P<O.O5). These results suggest a low prevalence of HVB and HDV infection, in contrast with other parts of the Amazon area. Keywords: hepatitis B, hepatitis D, prevalence, epidemiology, Brazil Introduction Hepatitis B virus (HBV) infection is a public health problem, mainly in develo ing countries, where approxi- mately 90% of the 300 ml1 Ion hepatitis B surface antigen -P (HBsA ) carriers live (MAYNARD, 1990). Hepatitis D virus (fI DV) infection is a particular problem in those with chronic HBV infection and in countries with highly endemic HBV (RIZZETTO et al., 1991). In South America high rates of HBV and HDV infec- tion have been reported in Venezuela (HADLER et al., 1984; TORRES & MONDOLFI, 1991), Colombia (BUI- TRAGO et al., 1986; ARBOLEDA et al., 1987), Peru (MEN- DEZ et al., 1989) and Brazil (BENSABATH et al., 1987a; 1987b; FONSECA et al., 1988). In Bra&, the State of Amazonas has one of the highest rates of HBV infection in the world, affecting mainly children less than 10 years old (BENSABATH et al., 1987a; FONSECA et al., 1988), and HDV infection is common among chronic carriers of HBsAg (24%), acute hepatitis B cases (29%) and fulminant hepatitis cases (74%), as ob- served in the Boca do Acre municipality (BENSABATH et al., 1987b). The aim of this study was to determinate the pre- valence and epidemiology of HBV and HDV infection in Barcelos, Amazonas, which had not then begun an NBV vaccination programme. Study area Barcelos is located on the right bank of the Negro river, in the north of the State of Amazonas, Brazil, 40 m above sea level with an average annual temperature of 265°C The region has an area of 121 760 km* and the population is estimated to be 11 026, 36.5% of whom live in the urban centre; health conditions are precarious and there is a lack of public services. Approximately 70% of the population are native to the region and 30% from other parts of Amazonas Stateand elsewherein Brazil. Materials and Methods We selected 142 families in the urban area (18% of the total urban opulation) and 21 in the rural zone by syste- matic samp mg, glvmg a total of 798 subjects (407 males p . . and 391 females) with a mean age of 26.5 years, ranging from 3 months to 86 years. Blood samples were drawn from each individual after previous consent, and a ques- tionnaire was administered concerning risk factors (injec- tions, dental treatment, surgery, blood transfusion, tatt- ooing, ear piercing, sharing razor blades, beds and Address for correspondence: Dra Margarita Arboleda,Instituto Colombiano de MedicinaTropical, Hospital General de Medel- lin 4” p&o, Ka 48N” 32-102, Medellin, Colombia. personal objects, skin lesions, sexual activity, and house- hold characteristics). The following serological markers were tested for: hep- atitis B surface antigen (HEsAg), anti-HBs, and anti-he- patitis B core antigen (anti-HBc). The HBsAg positive subjects were subtyped (GASPAR 8r YOSHIDA, 1987) and tested for hepatitis B e antigen (HBeAg), anti-HBc im- munoglobulin M (IgM) and HBV deoxyribonucleic acid (DNA). All HBV reactive subjects were tested for anti- hepatitis D (anti-HD). The serological tests were done with enzyme-linked imrnunosorbent assay (ELISA) kits from Biomanguinhos-FIOCRUZ and from Abbott Labora- tories. Sampleswhich were reactive for HBsAg were con- firmed with Organon Teknika@ kits and HBV DNA was tested for by molecular hybridization (dot-blot) accord- ing to SCOTTO et 01. (19X3), modified by using biotiny- lated probes. Standard epidemiological methods of analysis for cross-sectional data were ap lied, using software pack- ages including SPSS and PI-Info, relative risks, P E values and 95% confidence intervals (95% Cl). Results The overall prevalence of HBV infection in the popu- lation was 24.6% (196/798), HBsAg l-63% (13/798), Anti-H& 12.8% (102/798‘1. and anti-HBc IaC 21.4% (1711798).There was no dgference in the epiaemiologi- cal pattern of HBV infection between the urban centre and the rural area. There was no observed sex difference in overall HBV infection rate, but anti-HBs titres were more common among women (15.3% vs. 10.3%; P<O*OS). There was a clear trend for HBV infection rates to increase with age (Table 1; ~2 for trend= 117.5, P<0~0001). The prevalence of HBsAg was higher in males (8113) than in females, but this difference was not statistically significant. HBeAg was present in 2 HBsAg positive sub- jects, one probably in the acute infection period; HBV Table 1. Serological prevalence of hepatitis B virus infection in tie north of Amazonas, Brazil Age No. Number of positive subjects (years) examined HBsAg Anti-FIBS Anti-H& Total 108 0 i-1 7 (6.5%) 1 (0.9%) 7 (6.5%) 289 2 (0.7%) 15 (5.2%) 16 (55%) 22 (76%) 15-24 1.24 1 (0%) 17 (13.7%) 21 (16.9%) 24 (19.4%) 25-34 77 2 (2.6%) 13 (16.9%) 19 124.7%) 23 (29.9%) 3544 45-54 2 9 (17.3%) 33 (63.5%) 34 (65,4%) 55-64 265 :t 0 (-) 13 (34~2%) 28 (73.7%) 28 (73.7%) 3 (8.8%) 8 (23.5%) 20 (58.8%) 24 (70.6%) Total 798 13 (1.6%) 102 (12,8%) 171 (21,4%) 1% (24.6%)