TY - JOUR
T1 - Resurgence of malaria in Uganda despite sustained indoor residual spraying and repeated long lasting insecticidal net distributions
AU - Epstein, Adrienne
AU - Maiteki-Sebuguzi, Catherine
AU - Namuganga, Jane Frances
AU - Nankabirwa, Joaniter I.
AU - Gonahasa, Samuel
AU - Opigo, Jimmy
AU - Staedke, Sarah
AU - Rutazaana, Damian
AU - Arinaitwe, Emmanuel
AU - Kamya, Moses R.
AU - Bhatt, Samir
AU - Rodríguez-Barraquer, Isabel
AU - Greenhouse, Bryan
AU - Donnelly, Martin
AU - Dorsey, Grant
PY - 2022/9/7
Y1 - 2022/9/7
N2 - Five years of sustained indoor residual spraying (IRS) of insecticide from 2014 to 2019, first using a carbamate followed by an organophosphate, was associated with a marked reduction in the incidence of malaria in five districts of Uganda. We assessed changes in malaria incidence over an additional 21 months, corresponding to a change in IRS formulationsusing clothianidin with and without deltamethrin. Using enhanced health facility surveillance data, our objectives were to 1) estimate the impact of IRS on monthly malaria case counts at five surveillance sites over a 6.75 year period, and 2) compare monthly case counts at five facilities receiving IRS to ten facilities in neighboring districts not receiving IRS. For bothobjectives, we specified mixed effects negative binomial regression models with random intercepts for surveillance site adjusting for rainfall, season, care-seeking, and malaria diagnostic. Following the implementation of IRS, cases were 84% lower in years 4–5 (adjustedincidence rate ratio [aIRR] = 0.16, 95% CI 0.12–0.22), 43% lower in year 6 (aIRR = 0.57, 95% CI 0.44–0.74), and 39% higher in the first 9 months of year 7 (aIRR = 1.39, 95% CI 0.97–1.97) compared to pre-IRS levels. Cases were 67% lower in IRS sites than non-IRS sites in year 6 (aIRR = 0.33, 95% CI 0.17–0.63) but 38% higher in the first 9 months of year 7 (aIRR = 1.38, 95% CI 0.90–2.11). We observed a resurgence in malaria to pre-IRS levelsdespite sustained IRS. The timing of this resurgence corresponded to a change of active ingredient. Further research is needed to determine causality.
AB - Five years of sustained indoor residual spraying (IRS) of insecticide from 2014 to 2019, first using a carbamate followed by an organophosphate, was associated with a marked reduction in the incidence of malaria in five districts of Uganda. We assessed changes in malaria incidence over an additional 21 months, corresponding to a change in IRS formulationsusing clothianidin with and without deltamethrin. Using enhanced health facility surveillance data, our objectives were to 1) estimate the impact of IRS on monthly malaria case counts at five surveillance sites over a 6.75 year period, and 2) compare monthly case counts at five facilities receiving IRS to ten facilities in neighboring districts not receiving IRS. For bothobjectives, we specified mixed effects negative binomial regression models with random intercepts for surveillance site adjusting for rainfall, season, care-seeking, and malaria diagnostic. Following the implementation of IRS, cases were 84% lower in years 4–5 (adjustedincidence rate ratio [aIRR] = 0.16, 95% CI 0.12–0.22), 43% lower in year 6 (aIRR = 0.57, 95% CI 0.44–0.74), and 39% higher in the first 9 months of year 7 (aIRR = 1.39, 95% CI 0.97–1.97) compared to pre-IRS levels. Cases were 67% lower in IRS sites than non-IRS sites in year 6 (aIRR = 0.33, 95% CI 0.17–0.63) but 38% higher in the first 9 months of year 7 (aIRR = 1.38, 95% CI 0.90–2.11). We observed a resurgence in malaria to pre-IRS levelsdespite sustained IRS. The timing of this resurgence corresponded to a change of active ingredient. Further research is needed to determine causality.
U2 - 10.1371/journal.pgph.0000676
DO - 10.1371/journal.pgph.0000676
M3 - Article
SN - 2767-3375
VL - 2
SP - e0000676
JO - PLOS Global Public Health
JF - PLOS Global Public Health
IS - 9 September
M1 - e0000676
ER -
