Trends of key surveillance performance indicators of acute flaccid paralysis: a descriptive analysis, Uganda, 2015-2020

Abstract

Background: Polio is disease caused by poliovirus which can in turn cause irreversible paralytic disease, presenting as Acute Flaccid Paralysis (AFP). A sensitive AFP surveillance system, in which all reported AFP cases are evaluated, first to determine if they are true AFP cases or not, is key for tracking polio eradication. True AFP cases are then later categorized as polio AFP or non-polio AFP (NPAFP) cases. Sensitivity is defined by meeting an annual NPAFP rate/100,000 population < 15 years of ≥ 4/100,000, and an annual stool adequacy (SA) rate of ≥ 80%. We describe Uganda's AFP surveillance performance between 2015-2020, based on the WHO-recommended indicators, including; NPAFP and stool adequacy rate.

Methods: We performed a descriptive analysis of national AFP surveillance data, 2015-2020 obtained from ministry of health. We evaluated proportion of reported AFP cases that were true AFP, and changes in NPAFP and stool adequacy (SA) rate over the study period. We evaluated the trends in achieving the targeted NPAFP and SA rates from 2015-2020. We used QGIS to illustrate patterns in NPAFP and SA rates across districts and subregions.

Results: Among 3,605 AFP cases reported and investigated countrywide from 2015-2020, 3,475 (96%) were true AFP cases. All the true AFP cases were non-polio related. District reporting was near-complete (97-100% each year). Overall, the mean NPAFP rate declined from 3.1/100,000 in 2015 to 2.1/100,000 in 2020. Less than 40% of districts met the NPAFP target rate in all years. The proportion of districts achieving the NPAFP target rate of ≥ 4/100,000 significantly declined from 35% in 2015 to 20% in 2020. The mean annual SA rate nationally was 88% from 2015-2020. Only 66% of districts achieved the SA target rate of ≥ 80% in the study period. The proportion of districts with SA rate ≥ 80% significantly increased from 68 to 80% between 2015 and 2020.

Conclusion: Most districts reported AFP cases. However, there was a decline in the NPAFP rate from 2015-2020 and few districts achieved the target rate. The suboptimal AFP surveillance system performance leaves the country at risk of missing ongoing poliovirus transmission. We recommend health worker training on active AFP searches, intensified supportive supervision, increase the number of environmental surveillance sentinel sites to boost AFP surveillance in the country, and periodic review meetings with districts to assess AFP surveillance performance.

Keywords: AFP; Eradication; Polio; Surveillance; Uganda.

Fig. 1

Trends of non-polio AFP performance rate during evaluation of AFP surveillance in Uganda, 2015–2020

Fig. 2

Distribution of Non-polio AFP rate per 100,000 children < 15 years of age by districts, Uganda, 2015–2020

Fig. 3

Trend of stool adequacy performance rate during evaluation of AFP surveillance in Uganda, 2015–2020

Fig. 4

Percentage of districts that achieved the minimum stool adequacy performance rate (of ≥ 80%) in Uganda, 2015–2020

Fig. 5

Distribution of stool adequacy rate performance by districts during evaluation of AFP surveillance, Uganda, 2015–2020