HIV-Infected or -Exposed Children Exhibit Lower Immunogenicity to Hepatitis B Vaccine in Yaoundé, Cameroon: An Appeal for Revised Policies in Tropical Settings?

BACKGROUND: Since 2005, anti-hepatitis B virus (anti-HBV) vaccine is part of the Expanded Program on Immunization (EPI) for infants born in Cameroon, with 99% anti-HBV coverage. In a context of generalized HIV epidemiology, we assessed paediatric anti-HBV vaccine response according to HIV status, feeding option and age in a tropical context. METHODOLOGY: Prospective, observational and cross-sectional study conducted among 82 children (27 [IQR: 9-47] months, min-max: 6-59), after complete anti-HBV vaccination (Zilbrix Hepta: 10µg AgHBs) at the Essos Health Centre in Yaounde, Cameroon, classified as group-A: HIV unexposed (28), group-B: HIV-exposed/uninfected (29), group-C: HIV-infected (25). Quantitative anti-HBs ELISA was interpreted as "no", "low-" or "protective-response" with <1, 1-10, or ≥10 IU/L respectively; with p-value<0.05 considered significant. RESULTS: Children were all HBV-unexposed (AcHBc-negative) and uninfected (HBsAg-negative). Response to anti-HBV vaccine was 80.49% (66/82), with only 45.12% (37/82) developed a protective-response (≥10IU/L). According to HIV status, 60.71% (17/28) developed a protective-response in group-A, vs. 51.72% (15/29) and 20% (5/25) in group-B and group-C respectively, Odds Ratio (OR): 2.627 [CI95% 0.933-7.500], p = 0.041. According to feeding option during first six months of life, 47.67% (21/45) developed a protective-response on exclusive breastfeeding vs. 43.24% (16/37) on mixed or formula feeding, OR: 1.148 [CI95% 0.437-3.026], p = 0.757. According to age, protective-response decreased significantly as children grow older: 58.33% (28/48) <24 months vs. 26.47% (9/34) ≥24 months, OR: 3.889 [CI95% 1.362-11.356], p = 0.004; and specifically 67.65% (23/34) ≤6 months vs. 0%, (0/5) 33-41 months, p = 0.008. CONCLUSIONS: Anti-HBV vaccine provides low rate of protection (<50%) among children in general, and particularly if HIV-exposed, infected and/or older children. Implementing policies for early vaccination, specific immunization algorithm for HIV-exposed/infected children, and monitoring vaccine response would ensure effective protection in tropical settings, pending extensive/confirmatory investigations.

[Current status of schistosomiasis in Santchou health area, (Santchou Health District, Cameroon western region)]. / Situation actuelle de la schistosomiase dans l'aire de santé de Santchou, (District de santé de Santchou, Région de l'Ouest-Cameroun).

INTRODUCTION: Schistosomiasis, the second endemic parasitic infection in the world, is a parasitosis caused by trematodes from the genus Schistosoma. Our study aims to assess the prevalence of different species of schistosomes (Schistosoma mansoni, haematobium and intercalatum) among schoolchildren and to identify risk factors, clinical signs of schistosomiasis, and schistosomiasis intermediate host snails in stagnant water. METHODS: We conducted a cross sectional study over a three months period. The study consisted of sociodemographic and clinical data recording, collection of stool samples and urine, molluscan research and treatment of positive students for other helminths. Laboratory tests were performed at the Medical Research Institute and the study of Medicinal Plants in Yaounde where stool samples and urine were examined using KATO KATZ and centrifugation technique respectively, and shellfish species were determined by a malacologist. RESULTS: A total of 400 students aged between 8-16 years, 223 (55.7%) girls and 177 (44.3%) boys attending 4 elementary school were enrolled in the study. The social survey revealed that 154 students out of 400 (or 38.5%) were in contact with the river water at least once a week, 58% from around noon. All students had at least one symptom of schistosomiasis although nonspecific and dominated by abdominal pain in 72% of cases (n = 288 of 400). Biologically, no schistosomiasis eggs were detected. Cercaria releasing rate was negative in the 100 watery species found. CONCLUSION: The Santchou health area is not an active outbreak of schistosomiasis, but remains a risk area because of rice cultivation and stagnant water. The intensification of health education campaigns among the general population would delay the onset of this infection in the locality.

Hepatitis B infection awareness, vaccine perceptions and uptake, and serological profile of a group of health care workers in Yaoundé, Cameroon.

BACKGROUND: Cameroon is one of the countries in Africa with the highest burden of Hepatitis B infection. Health care workers are known to be at risk of occupational exposure to blood and other infectious bodily fluids. The aim of this study was to assess the profile of serological markers of hepatitis B virus (HBV) infection, knowledge and perceptions regarding HBV infection among health care workers in a health area in Yaoundé. METHODS: A cross-sectional study was conducted in the Mvog-Ada Health Area of the Djoungolo Health District from March 1 to November 31, 2014. All consenting health care workers were included in the study. Serological markers of HBV (HBs Ag, Hbe Ag, anti-HBs Ab, anti-HBe Ab, anti-HBc Ab) were qualitatively tested using Biotech®(OneHBV-5 parameter rapid test website) in each participant and the anti-HBs antibodies were quantified by ELISA (Biorex) among those who were positive with the qualitative test. Chi square test or its equivalents were used to compare qualitative variables and a p-value less than or equal to 0.05 was considered significant. RESULT: A total of 100 participants were retained for the study out of 163 in the health area giving a response rate of 61.34 %; the mean age was 30.5 (SD 6.8) years and 71 % of participants were women. Forty seven percent (47 %) of workers had good level of knowledge of HBV infection. The men were 3.20 times (95 % CI: 1.02-9.19, p = 0.04) more likely to have a good level of knowledge than women. Participants with a university study level were more (95 % CI: 3.17-25, p < 0.0001) likely to have a good level of knowledge than those with a high school study level. Ninety-six percent of participants thought that they were at a greater risk of becoming infected with HBV than the general population, 93 % felt that the vaccine should be compulsory and all (100 %) were willing to recommend it to others. However, only 19 % had received at least one dose of the vaccine. The proportion of HBs Ag was 11 %. The different serological profiles with regard to HBV infection were naive subjects (62 %), chronic carriers (11 %), vaccinated (19 %) and subjects naturally immunized (8 %). Three out of the 19 participants who received at least one dose of the vaccine, only 9 (47.4 %) of whom had titers ≥100 IU/l indicating a good response to vaccination. Among those who received three doses of the vaccine (n = 12, 63 %), 2 (16, 66 %) had poor response to vaccination (HBs Ab titers < 100 IU/l). CONCLUSION: The prevalence of HBs Ag among health care workers in the Mvog-Ada Health Area is high (11 %). These workers are at high risk of HBV infection because of very low vaccine uptake and poor post-exposure practices. Their knowledge of HBV infection is non-optimal.

Co-infections of malaria and geohelminthiasis in two rural communities of Nkassomo and Vian in the Mfou health district, Cameroon.

BACKGROUND: Human co-infection with malaria and helmimths is ubiquitous throughout Africa. Nevertheless, its public health significance on malaria severity remains poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: To contribute to a better understanding of epidemiology and control of this co-infection in Cameroon, a cross-sectional study was carried out to assess the prevalence of concomitant intestinal geohelminthiasis and malaria, and to evaluate its association with malaria and anaemia in Nkassomo and Vian. Finger prick blood specimens from a total of 263 participants aged 1-95 years were collected for malaria microscopy, assessment of haemoglobin levels, and molecular identification of Plasmodium species by PCR. Fresh stool specimens were also collected for the identification and quantification of geohelminths by the Kato-Katz method. The prevalence of malaria, geohelminths, and co-infections were 77.2%, 28.6%, and 22.1%, respectively. Plasmodium falciparum was the only malaria parasite species identified with mean parasite density of 111 (40; 18,800) parasites/µl of blood. The geohelminths found were Ascaris lumbricoides (21.6%) and Trichuris trichiura (10.8%), with mean parasite densities of 243 (24; 3,552) and 36 (24; 96) eggs/gram of faeces, respectively. Co-infections of A. lumbricoides and P. falciparum were the most frequent and correlated positively. While no significant difference was observed on the prevalences of single and co-infections between the two localities, there was a significant difference in the density of A. lumbricoides infection between the two localities. The overall prevalence of anaemia was 42%, with individuals co-infected with T. trichiura and P. falciparum (60%) being the most at risk. While the prevalence of malaria and anaemia were inversely related to age, children aged 5-14 years were more susceptible to geohelminthiasis and their co-infections with malaria. CONCLUSION/SIGNIFICANCE: Co-existence of geohelminths and malaria parasites in Nkassomo and Vian enhances the occurrence of co-infections, and consequently, increases the risk for anaemia.

Factors associated to bed net use in Cameroon: a retrospective study in Mfou health district in the Centre Region.

INTRODUCTION: Insecticide treated net remains a tool of choice for malaria prevention in Cameroon. However, data suggests that its use by the population, especially vulnerable groups remains low. Moreover, there is a paucity of information about factors influencing its use. We sought out to identify factors associated with net use in Mfou health district, prior to distribution of long lasting insecticides treated nets (LLINs) in households. METHODS: A two-stage cluster random sampling was conducted in 4 health areas with an average of 13 villages each. A total of 541 households were selected and heads interviewed using a structured household questionnaire. Data collected were entered into a database and multivariate logistic regression analyses of the association between net use and explanatory factors were performed using SPSS. RESULTS: Net possession and use were respectively, 59.7 and 42.6%; thus, 2 out of 5 people who spent the previous night in households, slept under a net. Factors associated with net use included: net density≥0.5 (OR=8.88, 95% CI: 6.24-12.64), age≥5 years (OR=0.37, 95%CI: 0.28-0.47), secondary education (OR=1.41, 95% CI: 1.11-1.80) compared to primary/no education, parent status (OR=3.32, 95% CI: 2.31-4.76), house construction (OR=1.37, 95% CI: 1.10-1.71) and environment characteristics (OR=1.46, 95% CI: 1.18-1.80). CONCLUSION: These data suggest that a universal coverage with one LLIN for two people should be achieved in households. Then, malaria health education should be conducted to re-enforce net use among school-aged children and adolescents, as well as older household members. Moreover, management of environment and improvement in houses construction are necessary.