Age-specific seroprevalence of hepatitis A in Antananarivo (Madagascar).

BACKGROUND: Hepatitis A virus (HAV) is an enteric, viral, infectious disease endemic in many developing countries such as Madagascar. Infection is often subclinical or asymptomatic in children; however, symptomatic acute infections become more common with increasing age. In some developing countries, improvements in living conditions have led to changes in the epidemiological pattern of HAV infection. There are very few reports on the prevalence of HAV in Madagascar. This study was to determine the seroprevalence of hepatitis A virus antibodies in relation to age in the city of Antananarivo, Madagascar. METHODS: Serum samples collected in 2004 during a cross-sectional survey of individuals aged between two and 24 years from Antananarivo were tested for anti-HAV antibody using a commercial enzyme immunoassay kit. Subjects were investigated using a standardized social and medical history questionnaire. RESULTS: 926 subjects were enrolled including 406 males and 520 females. There were 251 children under 10 years old and 675 subjects between 10 and 24 years old. Of the 926 serum samples tested, 854 (92.2%) were positive for anti-HAV antibodies. The number of seropositive samples was similar for males and females. The overall seroprevalence was 83.7% (210/251) for children under 10 years old and 95.5% (644/675) for subjects aged between 10 and 24 years (p < 0.001). CONCLUSION: Despite improvements in sanitary conditions and hygiene over the last few years, the prevalence of HAV in Antananarivo is high. Only children under five years old remain susceptible to HAV infection. Immunization against HAV is not needed at the present time in the Madagascan population, but should be recommended for travellers.

Evaluation of the performance of four rapid tests for detection of hepatitis B surface antigen in Antananarivo, Madagascar.

Four rapid immunochromatographic assays--Determine HBsAg, Virucheck HBsAg, Cypress HBsAg Dipstick and Hexagon HBsAg--for human hepatitis B surface antigen (HBsAg) detection in human serum were evaluated. A collection of reference serum samples (91 HBsAg positive and 109 HBsAg negative) stored at -80 degrees C was used. Sensitivity and positive predictive value (PPV) exceeded 95%, and specificity and negative predictive value (NPV) exceeded 96% for all tests. The Determine HBsAg test performed best in this study, with a sensitivity of 97.8%, a specificity and PPV of 100%, a NPV of 98.2% and an accuracy rate of 99.0%. However, the differences between the tests were not significant. Other factors should therefore also be taken into account by the Ministry of Health in its decision to recommend a particular test: price, availability, delivery time and feasibility of whole-blood testing. The Determine test appears to be the most suitable for Madagascar, based on all these criteria. The use of this test, despite its lower sensitivity, could prevent blood-borne transmission of hepatitis B virus (HBV) in areas with limited resources.