Achieving High Poliovirus Antibody Seroprevalence in Areas at Risk of Vaccine-Derived Poliovirus Transmission-Niger Experience.

BACKGROUND: Outbreaks of vaccine-derived poliovirus type 2 (VDPV2) continue to expand across Africa. We conducted a serological survey of polio antibodies in high-polio risk areas of Niger to assess risk of poliovirus outbreaks. METHODS: Children between 1 and 5 years of age were enrolled from structures randomly selected using satellite imaging enumeration in Diffa Province, Niger, in July 2019. After obtaining informed consent, dried blood spot cards were collected. Neutralizing antibodies against 3 poliovirus serotypes were detected using microneutralization assay at the Centers for Disease Control and Prevention. RESULTS: We obtained analyzable data from 309/322 (95.9%) enrolled children. Seroprevalence of polio antibodies was 290/309 (93.9%), 272/309 (88.0%), and 254/309 (82.2%) for serotypes 1, 2, and 3, respectively. For serotypes 1 and 2, the seroprevalence did not significantly change with age (P = .09 and P = .44, respectively); for serotype 3, it increased with age (from 65% in 1-2-year-olds to 91.1% in 4-5-year olds; P < .001). We did not identify any risk factors for type 2 seronegativity. CONCLUSIONS: With type 2 seroprevalence close to 90%, the risk of emergence of new cVDPV2 outbreaks in Niger is low; however, the risk of cVDPV2 importations from neighboring countries leading to local transmission persists. Niger should maintain its outbreak response readiness capacity and further strengthen its routine immunization.

Bacterial meningitis in Niger: an analysis of national surveillance data, 2003-2015.

INTRODUCTION: Bacterial meningitis (BM) is one of the most severe infectious disease in Niger republic. To best describe the trends of BM disease, meningitis surveillance data from the Centre de Recherche Medicale et Sanitaire (CERMES) and the Direction of Surveillance and Response to Epidemics (DSRE) were reviewed and analyzed. METHODS: Data on number of notified cases of BM and on pathogens were analyzed during 2003-2015. Excel 2013 was used for trend analysis on the etiology of BM prevalence and incidence. RESULTS: A total of 10051 cerebrospinal fluid (CSF) samples collected were confirmed by laboratory methods. The main etiologies of meningitis detected were N. meningitidis (82.1%), S. pneumonia (12.1%) and H. influenza (3.4%). N. meningitidis mostly affected children in the age groups of 5-9 years (32.9%) and 10-14 years (24.9%) with respective mean incidence of 14.9 and 11.3. The percentage estimate of N. meningitidis serogroup A (NmA) meningitis fell to 0% in 2015 while during the same year that of N. meningitidis serogroup C (NmC) and N. meningitidis serogroup W (NmW) reached 82.9% and 17% respectively. CONCLUSION: Overall, the epidemiological trends of the BM in Niger were dynamic. The emergence of NmC strains suggests that there may be an urgent need for serogroup C containing vaccines in Niger in the coming years.