Residual risk of mother-to-child transmission of hepatitis B virus infection despite timely birth-dose vaccination in Cameroon (ANRS 12303): a single-centre, longitudinal observational study.

BACKGROUND: In sub-Saharan Africa, administration of hepatitis B virus (HBV) birth-dose vaccines remains suboptimal. Evidence is scarce on whether African countries should focus on increasing vaccine coverage or developing strategies incorporating additional measures, such as peripartum antiviral prophylaxis to pregnant women at high risk. To better inform decision makers, we estimated the residual risk of mother-to-child transmission despite HBV birth-dose vaccine in Cameroon. METHODS: We did a single-centre, longitudinal observational study. Pregnant women were systematically screened for HBV surface antigen (HBsAg) at Tokombéré District Hospital (Tokombéré district, Cameroon). Children born to HBsAg-positive mothers in 2009-16 who received the HBV birth-dose vaccine and three subsequent doses of pentavalent vaccine at 6, 10, and 14 weeks were followed up prospectively in 2015-17. In children, capillary blood was obtained for HBsAg rapid test and dried blood spots to quantify HBV DNA concentrations. Venous blood was also collected from HBsAg-positive children. Mother-to-child transmission was confirmed by whole-genome sequencing. FINDINGS: Between Jan 31, 2009, and Dec 31, 2016, 22 243 (66·8%) of 33 309 pregnant women accepted antenatal HBV screening, of whom 3901 (17·5%) were HBsAg positive. 2004 (51·4%) of 3901 children who were born to HBsAg-positive mothers received the HBV birth-dose vaccine, of whom 1800 (89·8%) also completed the three-dose pentavalent vaccine. In total, the current analysis included 607 children who had a follow-up serosurvey. The prevalence of HBsAg was 5·6% in children who received the birth-dose vaccine in less than 24 h, 7·0% in those who received it 24-47 h after birth, and 16·7% in those who received it 48-96 h after birth (ptrend=0·083). 35 (89·7%) of 39 infected children were born to mothers positive for HBV e antigen with high HBV DNA of 5·3 log10 IU/mL or more. Whole-genome sequencing of HBV in infected mother-child pairs confirmed high identity proportions of 99·97-100%. INTERPRETATION: We documented a substantial risk of mother-to-child transmission despite timely administration of the HBV birth-dose vaccine within 24 h after birth. To reach WHO's elimination targets, peripartum antiviral prophylaxis might be required in parts of Africa, in addition to increasing coverage of the HBV birth-dose vaccine. FUNDING: Agence nationale de recherches sur le sida et les hépatites virales (ANRS).

High endemicity and low molecular diversity of hepatitis B virus infections in pregnant women in a rural district of North Cameroon.

BACKGROUND: A program, supported by the GEMHEP (Groupe d'étude Moléculaire des Hépatites), was established in 2007 in the sanitary district of Tokombéré, to prevent perinatal transmission of hepatitis B virus (HBV). It comprises screening for HBV surface antigen (HBsAg) in all pregnant women and vaccinating the newborn if tests are positive. METHODS/PRINCIPAL FINDINGS: 1276 women were enrolled in the study after providing informed consent. Demographic data and blood samples were available for 1267 of the enrolled patients. HBsAg was determined locally using a rapid test (Vikia HBsAg, Biomerieux). Tests for HBV and HDV virological markers (HBeAg, anti-HDV antibodies (Ab), HBV-DNA, HDV-RNA, HBV and HDV genotypes) were performed on the confirmed HBsAg-positive samples in the virology unit of the Angers University Hospital (France). HBsAg was found in 259 of the 1267 pregnant women (20.4%) between January 2009 and April 2010, of whom 59 were HBeAg-positive (22.7%) with high levels of HBV-DNA. Anti-HDV Ab were found in 19 (7.3%) of the HBsAg-positive women. The prevalence rates of HBsAg and HDV were not age-dependent whereas HBeAg carriers were statistically younger than non carriers. Basal core promoter (BCP) and precore (PC) mutations and genotypes were determined by sequencing. Of 120 amplified sequences, 119 belonged to HBV genotype E (HBV/E) and the 9 HDV strains belonged to HDV clade 1. In the PC region, 83/228 patients (36.4%) harbored a G1896A mutant or mixed phenotype virus. In the BCP region, the double mutation A1762T/G1764A and the G1757A substitution were detected respectively in 26/228 patients (11.4%) and 189/228 patients (82.8%). CONCLUSIONS: Our results confirm the high prevalence and low molecular diversity of HBV in Far Northern Cameroon; more than 20% of the infected women were highly viremic, suggesting a high rate of HBV perinatal transmission and supporting the WHO recommendation to vaccinate at birth against hepatitis B.

Epidemiologic pattern of meningococcal meningitis in northern Cameroon in 2007-2010: contribution of PCR-enhanced surveillance.

OBJECTIVES: Monitoring acute bacterial meningitis in northern Cameroon. METHODS: Health professionals collected cerebrospinal fluid (CSF) specimens from patients presenting with clinical symptoms of meningitis. Specimens were tested using gram stain, latex agglutination test, and culture. A PCR assay completed the diagnostic testing. Multilocus sequence typing (MLST) was performed on some Neisseria meningitidis (Nm) isolates. RESULTS: From 2007 through 2010, of the 1429 CSF specimens tested, 292 (20·4%) were positive, either for Nm (205), Streptococcus pneumoniae (Sp) (57), or Haemophilus influenzae (Hi) (30). From 2007 through 2009, the serogroup W135 represented 98·8% of 164 case isolates. Until 2008, most serogroup W135 isolates presented the sequence-type ST-2881 usually associated with sporadic cases. Since 2009, the ST-11 (an epidemic-associated clone) became predominant, although no epidemic occurred. Serogroup A ST-7 was observed in 2010 and caused a localized epidemic. Using the detection PCR on turbid CSF, a 2·7-fold increase in cases with etiologic diagnosis was obtained, compared to culture. All tested meningococcal isolates (42) were susceptible to ampicillin, chloramphenicol, and cefotaxim. CONCLUSIONS: Resurgence of serogroup A and recent increase in ST-11 among serogroup W135 isolates were worrying when considered with the epidemic wave of serogroup A meningitis, which affected neighboring countries and the serogroup W135 epidemic in Niger in 2009-2010.