The results of this study indicate a high prevalence of HBV infection among pregnant women in Cameroon. To the best of our knowledge, this is the first study carried out among pregnant women in an urban setting in Cameroon. Earlier studies had reported an HBsAg prevalence of 5.4% among pregnant women in a rural setting in Cameroon [10
]. In a previous study in a general population of Cameroon, about 9.6% of the 272 individuals tested were HBsAg-positive [11
]. Another study on city school children reported a high HBsAg prevalence of 19.9% among the 702 school children tested [12
]. This high prevalence in children could be due in part to mother-to-child transmission and also could be due to horizontal transmissions between school children [13
]. The high prevalence of HBsAg observed in this study among pregnant women could be an indication that pregnant women serve as a very important reservoir to fuel the HBV epidemic in the general population. However, previous studies indicate that in areas of high HBV prevalence (i.e. ≥ 8%) like Cameroon, transmission is said to be predominantly during childhood [14
In our survey, HBsAg positivity rate was similar in HIV-positive (9%) and negative pregnant women (7%). Similar results have been obtained in Côte d'Ivoire [16
] a sub-Saharan African country just like Cameroon. This high prevalence among HIV-positive and HIV-negative pregnant women suggests that HBsAg screening should be included as part of prenatal testing in Cameroon. The role of sexual transmission could also be postulated in this population of pregnant women in conformity to what has been previously reported in Tanzania [17
Hepatitis B 'e' status and viral load are factors associated with the frequency of vertical transmission. Despite the fact that similar and high prevalence of HBsAg was observed in this study, no HBeAg reactive sample was detected in this study population. HBeAg reactive women are known to have a high viral load and to transmit HBV to their children. The rate of maternofetal infection in East Asia, particularly China, was estimated to be about 88% [18
], compared with 8% or less observed in the studies conducted in sub-Saharan Africa [19
]. This difference was largely attributed to the natural history of HBV infection in South-East Asia where infected individuals carry HBeAg and high viral load in age groups that include most women of gestational age [23
]. Conversely, in sub-Saharan Africa, seroconversion to anti-HBe occurs before age 15 or 16, with the consequence that most women of gestational age carry anti-HBe [25
]. Since perinatal transmission of HBV is mostly effective when the mother is HBeAg-positive, this form of transmission could play a negligible role in HBV transmission in Cameroon. Despite the fact that this study did not test for mother-to-child transmission of HBV we could conjecture that horizontal transmissions could be the most common mechanism of HBV infection in Cameroon, as reported in some sub-Saharan African countries [20
]. Before the integration of HBsAg screening into the routine package of biological analyses carried out during pregnancy, we presuppose that our results are in line and could be considered as a justification of the current immunization program. The present Cameroon vaccination program against HBV consists of vaccination of all newborn at 6 weeks, efforts should therefore be directed at making available these vaccines to all children in Cameroon from 6 weeks old.
We are considering a follow-up of these findings on a larger scale where more pregnant women would be screened with the principal aim of determining the real proportion of HBeAg positive pregnant women and the ensuing mother to child transmission rates of HBV in Cameroon.