Seroprevalence of hepatitis A virus infection among schoolchildren and adolescents in Kaduna, Nigeria.

Background: Hepatitis A is an infectious viral disease, caused by hepatitis A virus (HAV), endemic in many developing countries. A recent review of the global prevalence of HAV infection and susceptibility by the WHO had few data on the seroprevalence of HAV in Nigeria. This study was designed to determine the seroprevalence of HAV among schoolchildren and adolescents in Kaduna State and to identify factors associated with seropositivity.

Methods: Questionnaires were administered to 403 participants aged 2-19 years, and blood samples were collected during April-July 2009 and screened for anti-HAV IgG using an anti-HAV IgG enzyme immunoassay kit. χ(2) and Fisher's exact tests were used to identify variables associated with the presence of anti-HAV IgG.

Results: The mean ± SD age of the study population was 11.7 ± 3.2 years. Of the 403 serum samples, 29 were positive for HAV, giving an overall seroprevalence of 7.2% (95% CI 4.9-10.2%) among the study population. Seropositivity with respect to age ranged from 4.6% (10/218; 95% CI 2.2-8.3%) in the 11-15 years age group to 30% (3/10; 95% CI 6.7-65.3%) in the ≤5 years age group. Anti-HAV seropositivity was associated with sewage disposal methods and parents' educational level (p < 0.05).

Conclusion: This study shows that the majority of the study population lacked natural immunity (anti-HAV IgG). This low HAV exposure may be attributed to improvements in sanitary conditions and socioeconomic status. Further research involving an older population in different parts of the country is required to determine the current epidemiological pattern of HAV.