Tracking Acute Flaccid Paralysis in Niger: A Half-Decade Epidemiological Portrait (2016-2021)

Abstract

Abstract Background: The global incidence of wild poliovirus cases has dramatically declined, with fewer than 350,000 cases in over 125 endemic countries. Despite progress, Niger experienced vaccine-derived poliovirus outbreaks in 2018, highlighting the importance of maintaining Acute Flaccid Paralysis (AFP) surveillance as a tool for polio eradication. This analysis aims to comprehensively assess AFP surveillance trends, patterns, and challenges in Niger, offering insights for public health initiatives in conflict-affected contexts. Methods: Nationwide AFP surveillance data spanning 2016 to 2021 were analyzed. Data included demographic information, vaccination status, clinical history, circulating vaccine-derived polioviruses (cVDPV), AFP cases, stool specimens, and non-polio enteroviruses (NPEV). Study findings were presented through tables, graphs, and maps. Results: A total of 4,134 AFP cases under 15 years old were included, with a Sex Ratio of 1.3. Most cases (79.85%) were aged 1 to 4 years, and 79.44% received three or more doses of oral polio vaccine (OPV). Fever onset (90.13%), asymmetric paralysis (80.33%), and a 3-day progression (80.48%) were common. Wild poliovirus type 2 was found in 33 cases, predominantly in Zinder province. The annualized non-polio AFP rate per 100,000 population <15 years fluctuated, with the lowest at 2.5 in 2016 and highest at 8.7 in 2018 (mean 5.93). Surveillance indicators, including faecal specimen collection, follow-up exams, NPEV detection, and timely laboratory results, performed well. However, stool specimen quality was suboptimal (69% in 2016), and stool transportation times exceeded 7 days. Five districts reported less than 80% stool adequacy. Conclusion: This study underscores the importance of continued AFP surveillance in Niger, with room for improvement in stool specimen quality and transportation times. Enhancing these aspects can improve public health efforts conflict-affected areas and contribute to polio eradication in the region.