Factors contributing to outbreaks of wild poliovirus type 1 infection involving persons aged ≥15 years in the Democratic Republic of the Congo, 2010-2011, informed by a pre-outbreak poliovirus immunity assessment.

BACKGROUND: The Democratic Republic of the Congo (DRC) experienced atypical outbreaks of wild poliovirus type 1 (WPV1) infection during 2010-2011 in that they affected persons aged ≥15 years in 4 (Bandundu, Bas Congo, Kasaï Occidental, and Kinshasa provinces) of the 6 provinces with outbreaks. METHODS: Analyses of cases of WPV1 infection with onset during 2010-2011 by province, age, polio vaccination status, and sex were conducted. The prevalence of antibodies to poliovirus (PV) types 1, 2, and 3 was assessed in sera collected before the outbreaks from women attending antenatal clinics in 3 of the 4 above-mentioned provinces. RESULTS: Of 193 cases of WPV1 infection during 2010-2011, 32 (17%) occurred in individuals aged ≥15 years. Of these 32 cases, 31 (97%) occurred in individuals aged 16-29 years; 9 (28%) were notified in Bandundu, 17 (53%) were notified in Kinshasa, and 22 (69%) had an unknown polio vaccination status. In the seroprevalence assessment, PV type 1 and 3 seroprevalence was lower among women aged 15-29 years in Bandundu and Kinshasa, compared with those in Kasaï Occidental. Seropositivity to PVs was associated with increasing age, more pregnancies, and a younger age at first pregnancy. CONCLUSIONS: This spatiotemporal analysis strongly suggests that the 2010-2011 outbreaks of WPV1 infection affecting young adults were caused by a PV type 1 immunity gap in Kinshasa and Bandundu due to insufficient exposure to PV type 1 through natural infection or vaccination. Poliovirus immunity gaps in this age group likely persist in DRC.

Correlates of syphilis seropositivity and risk for syphilis-associated adverse pregnancy outcomes among women attending antenatal care clinics in the Democratic Republic of Congo.

Screening and treatment for syphilis among pregnant women is the primary means of prevention of congenital syphilis. Sentinel surveillance for syphilis can inform these prevention efforts. We reviewed antenatal syphilis screening results to assess trends and to identify correlates of seropositivity among women attending antenatal care clinics in the Democratic Republic of Congo during 2011. Syphilis seropositivity among the 17,669 women attending the antenatal care clinics during 2011 was 4.2% (range 0.4%-16.9%). Syphilis seropositivity was significantly higher among women attending rural clinics (5.0%) as compared to urban clinics (3.0%) and those tested in antenatal care clinics in the provinces of Equateur (7.6%) and Orientale (7.7%) as compared to other provinces (p < 0.001). Based on the antenatal care syphilis seroprevalence and national pregnancy estimates, we estimate that approximately 128,591 pregnant women countrywide would have tested seropositive for syphilis during 2011. Over 85,000 adverse pregnancy outcomes would have resulted from these maternal infections, assuming prenatal syphilis diagnosis and treatment were not available. The prevalence of syphilis was highest in rural areas, but exceeded 1% in every area, indicating a need to assure screening and treatment throughout Democratic Republic of Congo. These sentinel surveillance estimates can be used to guide national congenital syphilis prevention efforts.