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

A systematic review of the epidemiology of hepatitis A in Africa

BACKGROUND

Hepatitis A, caused by the hepatitis A virus (HAV), is a vaccine preventable disease. In Low and Middle-Income Countries (LMICs), poor hygiene and sanitation conditions are the main risk factors contributing to HAV infection. There have been, however, notable improvements in hygiene and sanitation conditions in many LMICs. As a result, there are studies showing a possible transition of some LMICs from high to intermediate HAV endemicity. The World Health Organization (WHO) recommends that countries should routinely collect, analyse and review local factors (including disease burden) to guide the development of hepatitis A vaccination programs. Up-to-date information on hepatitis A burden is, therefore, critical in aiding the development of country-specific recommendations on hepatitis A vaccination.

METHODS

We conducted a systematic review to present an up-to-date, comprehensive synthesis of hepatitis A epidemiological data in Africa.

RESULTS

The main results of this review include: 1) the reported HAV seroprevalence data suggests that Africa, as a whole, should not be considered as a high HAV endemic region; 2) the IgM anti-HAV seroprevalence data showed similar risk of acute hepatitis A infection among all age-groups; 3) South Africa could be experiencing a possible transition from high to intermediate HAV endemicity. The results of this review should be interpreted with caution as the reported data represents research work with significant sociocultural, economic and environmental diversity from 13 out of 54 African countries.

CONCLUSIONS

Our findings show that priority should be given to collecting HAV seroprevalence data and re-assessing the current hepatitis A control strategies in Africa to prevent future disease outbreaks.

Hepatitis A seroprevalence in public school children in Campos dos Goytacazes, Rio de Janeiro State, Brazil, prior to the introduction of the hepatitis A universal childhood vaccination

This cross-sectional study was carried out between August 2011 and July 2012 in the city of Campos dos Goytacazes in Rio de Janeiro State, Brazil. Dried blood spot samples were collected on filter paper from 919 individuals between the ages of 1 and 19 and were tested for antibodies against the hepatitis A virus (anti-HAV). The total prevalence was 20.7%, while 94.7% of children under the age of 5 were found to be susceptible to HAV infection. The prevalence of anti-HAV increased with age, reaching 33.3% among individuals aged between 15 and 19, thereby indicating that this municipality has a low level of endemicity for hepatitis A. Age, non-white skin color, accustomed to swimming in the river and more than five people living at home were the factors that were associated with an increase in the chance of a positive anti-HAV result. Mother's education level (secondary or tertiary) was considered a protective factor for HAV infection. The data obtained showed that a large proportion of the children from Campos dos Goytacazes were at risk of HAV infection, which should be minimized with the introduction of the vaccination program against hepatitis A that was launched in the municipality in 2011.

Hepatitis A virus in West Africa: Is an epidemiological transition beginning?

Background:

Studies of hepatitis A virus (HAV) seroprevalence in sub-Saharan Africa have generally found very high anti-HAV IgG seroprevalence rates, but economic development and improved drinking water access may be contributing to decreasing incidence.

Materials and Methods:

This review evaluates all 19 articles that have been published on HAV epidemiology in West Africa.

Results:

Nearly all studies conducted before 1990 found that the majority of preschool-aged children had already developed immunity due to prior infection. However, several recent studies have observed that the age at midpoint of population immunity in some urban populations has shifted to school-aged children.

Conclusion:

There is preliminary evidence that some West-African countries are beginning the transition towards lower hepatitis A endemicity levels. Additional studies of child seroprevalence rates in diverse parts of West Africa are required in order to clarify the extent to which an early transition may be occurring.