Performance and impact of contact tracing in the Sudan virus outbreak in Uganda, September 2022-January 2023.

BACKGROUND: Contact tracing (CT) is critical for ebolavirus outbreak response. Ideally, all new cases after the index case should be previously-known contacts (PKC) before their onset, and spend minimal time ill in the community. We assessed the impact of CT during the 2022 Sudan Virus Disease (SVD) outbreak in Uganda. METHODS: We collated anonymized data from the SVD case and contacts database to obtain and analyze data on CT performance indicators, comparing confirmed cases that were PKC and were not PKC (NPKC) before onset. We assessed the effect of being PKC on the number of people infected using Poisson regression. RESULTS: There were 3844 contacts of 142 confirmed cases (mean: 22 contacts/case). Forty-seven (33%) confirmed cases were PKC. PKCs had fewer median days from onset to isolation (4 vs 6; P<0.007) and laboratory confirmation (4 vs 7; P<0.001) than NPKC. Being a PKC vs NPKC reduced risk of transmitting infection by 84% (IRR=0.16, 95% CI 0.08-0.32). CONCLUSION: Contact identification was sub-optimal during the outbreak. However, CT reduced the time SVD cases spent in the community before isolation and the number of persons infected in Uganda. Approaches to improve contact tracing, especially contact listing, may improve control in future outbreaks.

Investigation of human tungiasis cases, Sheema District, Uganda, November 2021-February 2022.

Introduction: no formal surveillance system exists in Uganda for jiggers (tungiasis); however, outbreaks are frequently reported in the media. On 27th January 2022, a news alert reported a jiggers' outbreak in Sheema District, Southwestern Uganda. We investigated to establish the magnitude of the problem and identify possible exposures associated with infestation to inform control measures. Methods: we defined a confirmed case as visible Tunga penetrans (T. penetrans) in the skin of a resident of any of 6 villages in Bwayegamba Parish, Sheema District, in February 2022. A suspected case was self-reported T. penetrans infestation during the three months preceding the interview. We visited all households in the 3 most affected villages in Bwayegamba Parish to identify cases and conducted interviews to identify possible exposures. We described cases by person, place, and time. We assessed socioeconomic status, household construction, mitigation measures against jiggers, and observed participants and their environments for hygiene. We conducted 2 case-control studies. One compared case-households (with ≥1 case) with control-households (without any cases). The second compared individual cases (suspected and confirmed) to neighbourhood controls. Results: among 278 households, we identified 60 case-patients, among whom 34 (57%) were male. Kiyungu West was the most affected village (attack rate=31/1,000). Cases had higher odds of being male (ORMH=2.3, 95% CI=1.3-4.0), <20 years of age (ORMH=2.0, 95%CI=1.1-3.6), unmarried (ORMH=2.97, 95% CI=1.7-5.2), unemployed (ORMH=3.28, 95% CI=1.8-5.8), and having poor personal hygiene (ORMH=3.73, 95% CI=2.0-7.4) than controls. In the household case-control study, case-households had higher odds of having dirty or littered compounds (ORMH=2.3, 95% CI=1.2-4.6) and lower odds of practicing mitigation measures against jiggers (ORMH=0.33, 95% CI=0.1-0.8) than control-households. Conclusion: males, unemployed persons, and those with poor personal or household hygiene had increased odds of tungiasis in this outbreak. Multi-sectoral, tailored interventions that improve standards of living could reduce risk of tungiasis in this area. Adding tungiasis to national surveillance reporting tools could facilitate early identification of future outbreaks.

Ownership and use of long-lasting insecticidal nets three months after a mass distribution campaign in Uganda, 2021.

BACKGROUND: Uganda conducted its third mass long-lasting insecticidal net (LLIN) distribution campaign in 2021. The target of the campaign was to ensure that 100% of households own at least one LLIN per two persons and to achieve 85% use of distributed LLINs. LLIN ownership, use and associated factors were assessed 3 months after the campaign. METHODS: A cross-sectional household survey was conducted in 14 districts from 13 to 30 April, 2021. Households were selected using multistage sampling. Each was asked about LLIN ownership, use, duration since received to the time of interview, and the presence of LLINs was visually verified. Outcomes were having at least one LLIN per two household members, and individual LLIN use. Modified Poisson regression was used to assess associations between exposures and outcomes. RESULTS: In total, 5529 households with 27,585 residents and 15,426 LLINs were included in the analysis. Overall, 95% of households owned ≥ 1 LLIN, 92% of the households owned ≥ 1 LLIN < 3 months old, 64% of households owned ≥ 1 LLIN per two persons in the household. Eighty-seven per cent could sleep under an LLIN if every LLIN in the household were used by two people, but only 69% slept under an LLIN the night before the survey. Factors associated with LLIN ownership included believing that LLINs are protective against malaria (aPR = 1.13; 95% CI 1.04-1.24). Reported use of mosquito repellents was negatively associated with ownership of LLINs (aPR = 0.96; 95% CI 0.95-0.98). The prevalence of LLIN use was 9% higher among persons who had LLINs 3-12 months old (aPR = 1.09; 95% CI 1.06-1.11) and 10% higher among those who had LLINs 13-24 months old (aPR = 1.10; 95% CI 1.06-1.14) than those who had LLINs < 3 months old. Of 3,859 LLINs identified in the households but not used for sleeping the previous night, 3250 (84%) were < 3 months old. Among these 3250, 41% were not used because owners were using old LLINs; 16% were not used because of lack of space for hanging them; 11% were not used because of fear of chemicals in the net; 5% were not used because of dislike of the smell of the nets; and, 27% were not used for other reasons. CONCLUSION: The substantial difference between the population that had access to LLINs and the population that slept under LLINs indicates that the National Malaria Control Programme (NMCP) may need to focus on addressing the main drivers or barriers to LLIN use. NMCP and/or other stakeholders could consider designing and conducting targeted behaviour change communication during subsequent mass distribution of LLINs after the mass distribution campaign to counter misconceptions about new LLINs.

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

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.