Spatiotemporal and clinical characterisation of acute flaccid paralysis in Uganda, 2016-2023

Uganda, in line with global efforts to eradicate polio by 2026, conducts surveillance for acute flaccid paralysis (AFP) among children <15 years to enable the timely detection of poliovirus. We analysed national AFP surveillance data to characterise case demographics, spatiotemporal patterns and clinical outcomes, and to evaluate surveillance performance and progress towards eradication.

We conducted a retrospective descriptive analysis of routine AFP surveillance data from 2016 to 2023. Variables included timeliness indicators, non-polio AFP (NPAFP) rates, stool adequacy and demographic, clinical, vaccination and laboratory characteristics. Trends were assessed using the Mann-Kendall test, and spatial patterns were illustrated using choropleth maps.

A total of 6409 AFP cases were reported, of which 5837 (91.1%) were confirmed as true AFP. The median age was 3 years (IQR: 1-7), with most cases occurring in children <5 years (59.3%) and males (57.8%). Timeliness indicators showed that 63% of cases were notified within 7 days, 93.4% were investigated within 48 hours and 76.5% of stool specimens were shipped within 3 days. Stool adequacy was 88.6% and 99.8% of samples arrived in good condition. The NPAFP rate averaged 3.4/100 000, meeting the ≥3.0 target in 5 of 8 years. Clinically, 90% of cases were community-identified; 91% had fever at onset, 86% showed rapid progression within 3 days and 80% had asymmetrical paralysis. Among cases with vaccination history, 77% had received ≥3 oral polio vaccine doses and 3% were unvaccinated. Of 6405 samples tested, 2% were classified as suspected poliovirus and 0.1% as mixed non-polio enterovirus and poliovirus. Among 823 followed-up cases, 30% had residual paralysis, 1% had died and 0.6% were lost to follow-up. District-level performance was variable and suboptimal, with averages of 63.4% districts achieving the NPAFP rate target, 74.8% stool adequacy and 49% both core indicators.

Uganda's AFP surveillance system remains largely robust, though improvements in timeliness, regional equity and follow-up are needed to sustain progress towards polio eradication.