DESCRIPTIVE ANALYSIS OF ACUTE FLACCID PARALYSIS (AFP) SURVEILLANCE DATA, SIERRA LEONE, 2018 TO 2022.

Abstract

Background: In 2020, Sierra Leone confirmed an outbreak of circulating Vaccine Derived Poliovirus type 2. However, information on the country’s performance on AFP surveillance indicators is limited. We aimed to describe incidence of AFP and assess the AFP surveillance performance in Sierra Leone using the World Health Organization (WHO) performance indicators.

Methods: We conducted a descriptive analysis of the national AFP surveillance data, for 2018-2022. Data were extracted from the national AFP surveillance database and analyzed using Epi Info 7. Key AFP surveillance performance indicators reviewed include non-polio AFP rate (WHO target: ≥2/100,000), case notification within 7 days of symptom onset (Target: ≥80%), case investigation within 48 hrs. after notification (≥80%), stool condition and adequacy (≥80%). We compared the system’s performance on those indicators and compared them with WHO targets.

Results: There were 668 cases of AFP reported, of which 55% (368/668) were males and 78% (521/668) were under 5 years of age. Of the total cases, 2% (15/668) were confirmed as cVDPV with zero WPV. The average annual non-polio AFP rate was 4 per 100,000 <15-year populations. The Proportion of cases notified ≤7 days of symptom onset was 70% (468/668), and cases investigated ≤48 hours was 90% (601/668). Though stool condition was 90% (601/668) good, the adequacy was 77% (450/585) and only 7% (41/585) arrived at the national laboratory within 3 days after collection. Majority of the cases, 91% (609/668), including confirmed cVDPV2, had received three or more doses of oral poliovirus vaccine (OPV).

Conclusion: The performance of the AFP surveillance system in Sierra Leone surpassed WHO indicators for annualized non-polio AFP rate, case investigation, and stool condition but failed to achieve the minimal target for stool adequacy, case notification, and sample transportation indicating the likelihood of missing a case. We recommend that the Ministry of Health strengthen the sample referral system.

Keywords: Acute flaccid paralysis, data, surveillance, Sierra Leone, poliovirus