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In 1989, the prevalence of antibody to cytomegalovirus (CMV) was determined by the ELISA method in serum samples from 198 apparently healthy children 4-14 years old in Kumba City (Cameroon). Children were randomly recruited from six primary schools located in different districts of the city. The overall prevalence was 94.0%, increasing from 88.5% in 4-6 years old to 98% in subjects 11-14 years old. A slight male predominance was observed (96.2% versus 92.4%), which was not statistically significant. Family size and father's occupation were not associated with anti-CMV prevalence. These findings demonstrate a virtually total exposure to CMV infection by late childhood in Cameroon. However, the undesirable consequences of congenitally acquired CMV infection are rare, because nearly 100% of the women are seropositive by the time they reach childbearing age.

Hepatitis C Virus (HCV) is the principal agent of non-A, non-B hepatitis and its spread in the community is not well defined. We evaluated the prevalence of anti-HCV (ortho ELISA System) in 696 children (4-14 years) in Kumba, Cameroon. Children were selected by systematic random sampling in six primary schools. A seroprevalence of 14.5% (101 children) was found which increased steadily with age. No significant differences were observed with respect to sex or to family size. There was a highly significant association both with parents' social class, the lowest class presenting a 2.2-fold risk factor, and with area of residence, suburban children showing a significantly higher prevalence (P less than 0.01). These results suggest that Cameroon is endemic for HCV infection, that children are infected at an early age and that infection increases with age. We can therefore hypothesize that transmission of HCV infection in this population is from child to child. Furthermore, the infection seems to be influenced by social factors but not by demographic ones.

In January 1989, the prevalence of antibodies to hepatitis A virus (anti-HAV) was determined by ELISA in 702 apparently healthy children 5-14 years old in Kumba City, Cameroon. Children were recruited from those attending six different primary schools, representative of the socio-demographic characteristics of the inhabitants, using a systematic random sampling. The overall IgG anti-HAV prevalence was 96.9%, reaching 100% by the age of 11 years. In primary school beginners the prevalence was very high, 94.0%, contrary to what has been observed in developed countries. The anti-HAV prevalence was not associated with family size, but was related to parent's occupation, children from the lower class having a 5.9 fold risk (C.I. = 1.9-18.3) of past exposure to HAV. These results suggest a persistently high prevalence of anti-HAV in children despite improving hygienic conditions. The spread of HAV in this population may be the result of domestic water and/or food contamination.

A pilot survey conducted in Cameroon comprising 702 children of primary school age revealed that 58.5% of the children were positive for at least one HBV marker. An overall HBsAg prevalence of 19.9% was observed. Both any HBV marker and HBsAg prevalences increased with age (P less than 0.01). Of the HBsAg-positive subjects, 28.4% were positive for HBV-DNA; none was positive for anti-HDV. There was no significant difference among sexes for either any HBV marker or for HBsAg prevalence. However, a significant difference by sex was found in the percentage ratio HBsAg+/and any marker + (41.0% in males against 28.2% in females; P less than 0.05). No significant difference with respect to the father's occupation and family size was observed. When the zone of location of school was taken into consideration it was observed that suburban school children had a higher prevalence of any HBV marker as compared to central town school children (73.9% vs. 56.6%; P less than 0.001). These results place Cameroon among countries of high endemicity for HBV. The results also indicate an early acquisition of infection, a high infectivity, and probably continuous infection even in the primary school ages.

In 1989, the prevalence of IgG antibodies to pertussis toxin (PT) in a sample of 367 unvaccinated apparently healthy children 5-14 years old was estimated by ELISA in Kumba City (Cameroon). Children were recruited using a systematic random sampling from six primary schools located in different districts of the city. The sample was representative of the various socioeconomic classes. The overall prevalence was 75%; it increased from 62% in 5 year old children to 81% in children 12-14 years old (P less than 0.01). IgG antibody prevalence was positively related to the family size. Children belonging to households of nine or more members had a 2.2-fold risk (C.I. 95 per cent = 1.1-4.6) of previous exposure to B. pertussis infection. No association was found with the father's occupation (O.R. = 1). These findings demonstrate a great impact of pertussis infection in Cameroon, with a nearly total exposure by late childhood.

A sero-epidemiological survey was carried out in Cameroon in January 1989 on a sample of 702 children of primary school age. A high HBV endemicity level was observed: 60.3% of the sera were positive to any HBV marker, 23.2% (163 sera) were HBsAg-positive. HBV-DNA positivity was observed in 38/163 (23.3%), thus showing a high level of infectivity among these carriers. Seventy-seven HBsAg-positive sera were tested for HBeAg/anti-HBe: 20 (26%) were HBeAg-positive 31 (40%) anti-HBe-positive, and 26 (34%) were negative for both. All sera were anti-HD-negative. Twenty-five per cent of HBeAg-positive sera were HBV-DNA-negative. This finding could be explained by a delayed HBeAg/anti-HBe seroconversion phase with fluctuant HBV-DNA. Only one case of HBV-DNA-positive anti-HBe-positive serum was observed. This study showed that HBV-DNA prevalence was significantly higher in boys (31.8%) than in girls (14.1%) (p less than 0.02). This difference was not observed for any HBV marker. We therefore conclude that in boys a prolonged HBV replicative phase might explain the observed high chronicity rate.