Decline in Vaccine-Type Streptococcus pneumoniae Serotypes Following Pneumococcal Conjugate Vaccine Introduction in Madagascar.

BACKGROUND: The 10-valent conjugate vaccine (PCV10) was introduced into the Extended Program on Immunization in Madagascar. We assessed the impact of PCV10 on the targeted pneumococcal serotypes among children < 5 years of age at Centre Hospitalier Universitaire Mère Enfant Tsaralalàna. METHOD: Between 2012 and December 2018, cerebrospinal fluid (CSF) samples were collected and tested for S. pneumoniae by culture, and antigen tests. The Sentinel Site Laboratory (SSL) referred available CSF samples to the Regional Reference Laboratory (RRL) for real-time polymerase chain reaction confirmatory testing and serotyping. RESULTS: In total, 3616 CSF specimens were collected. The SSL referred 2716 to the RRL; 125 were positive for S. pneumoniae. At the RRL, 115 samples that tested positive for S. pneumoniae were serotyped; PCV10 serotypes accounted for 20%. Compared to the pre-PCV period, the proportion of S. pneumoniae detected declined from 22% to 6.6%, (P < .05), the proportion of PCV10 serotypes as the cause of pneumococcal meningitis cases declined by 26% following vaccine introduction. CONCLUSIONS: In our findings, PCV10 introduction resulted in a decline of meningitis caused by S. pneumoniae and PCV10 vaccine serotypes.

Epidemiology of rubella infection in Cameroon: a 7-year experience of measles and rubella case-based surveillance, 2008-2014.

OBJECTIVE: The aim of this study was to estimate the proportion of rubella disease in a measles case-based surveillance in Cameroon prior to rubella vaccine introduction into the national immunisation programme. DESIGN: This was a cross-sectional study for rubella infection in Cameroon for the period 2008 to 2014. SETTING: Patients suspected with measles from the 10 regions of Cameroon were recruited according to the WHO measles case definition and were tested for rubella IgM antibodies accompanied with the case report/investigation forms. PARTICIPANTS: All persons with rash and fever within 14 days of onset of rash according to the standard WHO African Regional Office (WHO/AFRO) case definition for a suspected measles case. OUTCOME MEASURES: Descriptive analyses and simple logistic regressions were performed. OR were estimated. RESULTS: A total of 9907 serum samples from people with fever and rash were received in the laboratory from 2008 to 2014. A total of 7489 (75.59%) measles-negative samples were tested for rubella; 699 (9.3%) were positive for rubella IgM antibodies. Logistic regression analysis was done using IgM antibodies detection as the outcome variable. Age, sex and setting were explanatory variables. Logistic regression analysis revealed that, comparing the proportion of rubella IgM seropositivity status by age, the association to a positive rubella IgM increased with age from 1 to 4 years (OR 7.11; 95% CI 4.35 to 12.41; p<0.0001), through 5 to 9 years (OR 13.07; 95% CI 7.93 to 22.93; p<0.001), to 10 to 14 years of age (OR 13.86; 95% CI 8.06 to 25.12; p<0.001). Persons aged ≥15 years were also more likely to have rubella infection than children under one (OR 3.69; 95% CI 1.85 to 7.48; p=0.0001). There were also significant associations with sex, with males being less associated to a positive rubella serology than females (OR 1.33; 95% CI 1.14 to 1.56; p=0.0001). No statistically significant difference in proportion of rubella cases was observed between urban and rural populations (OR 1.11; 95% CI 0.94 to 1.31; p=0.208). CONCLUSIONS: This study reveals that rubella virus circulates in Cameroon, with important number of cases in children under 15 years. This finding supports the planned introduction of rubella-containing vaccines into the Expanded Program on Immunization.

Circulating vaccine-derived polioviruses in the Extreme North region of Cameroon.

BACKGROUND: The World Health Organization (WHO) poliovirus eradication program includes careful surveillance of acute-flaccid paralysis (AFP) and mass and routine immunization with oral polio vaccine (OPV). In populations with low vaccine coverage, the live-attenuated Sabin strains, OPV types 1, 2 and 3, can evolve into virulent vaccine-derived polioviruses (VDPVs) and circulate in the community. Until recently, circulating VDPVs (cVDPVs) had not been reported in Cameroon despite the fact that VDPV2 outbreaks have occurred in nearby countries. OBJECTIVES: This study aimed to characterize virus isolates from four AFP patients infected with cVDPV2 in the Extreme North region of Cameroon in 2013. STUDY DESIGN: The complete VP1 region of the four VDPV strains was sequenced and the relationships with cVDPVs from neighboring countries were investigated. RESULTS: All four patients were infected by cVDPV2 strains showing 1.2-2.0% nucleotide difference compared to the reference Sabin 2 VP1 sequence. Phylogenetic analysis indicated that the VDPV strains were genetically linked to cVDPV2 lineages of the recent Chad cVDPV2 outbreak. CONCLUSIONS: The circulation of pathogenic VDPVs suggests that there are localized immunization gaps in some districts like Makary, Mada and Kolofata in Cameroon. To avoid poliomyelitis outbreaks in Cameroon, especially in the districts close to neighboring countries with ongoing cVDPV outbreaks, high polio vaccine coverage is essential.