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Updated: Jan 9, 2026
Standard Membrane Feeding Assay for the Detection of Plasmodium falciparum Infection in Anopheles Mosquito Vectors
Published on: May 12, 2022
Malaria outbreak facilitated by increased vector-breeding sites from erosion control pits sustained by intermittent
Gloria Bahizi1,2, Fred Monje3, Daniel Kadobera3,4
1Uganda Public Health Fellowship Programme, Ministry of Health, P.O. Box 7272, Kampala, Uganda. gbahizi@musph.ac.ug.
Background:
In June 2019, the Uganda Ministry of Health, through routine surveillance data analysis, was notified of an increase in malaria cases in Mbale District, which exceeded the outbreak action thresholds. This investigation was conducted to assess the magnitude of the outbreak, identify transmission risk factors, and recommend evidence-based control measures.
Methods:
A confirmed case was defined as a positive malaria result using a malaria rapid diagnostic test or microscopy from 1 January 2019 to 30 June 2019 in a resident or visitor of Bumbobi or Nyondo Sub-County, Mbale District. Medical records were reviewed to develop a line list for descriptive epidemiology. Using a case-control study, exposures were compared between 150 case-persons and 150 asymptomatic controls matched by age and village. Environmental and entomological assessments on vector dynamics were further conducted.
Results:
Eight thousand eight hundred twenty-seven case-patients (attack rate [AR] = 33%) were identified. Females (AR = 36%) were more affected than males (AR = 27%). The 5-18-year age group (AR = 2.6%) was most affected. The epidemic curve showed a steady increase in malaria cases in March, peaking 4 weeks after the last peak of rainfall. In the matched pair case-control analysis, 95% (143/150) of case-patients and 49% (73/150) of controls had soil erosion control pits that held stagnant water near their homes for several days following rainfall (OR = 18, 95% CI 7.0-50); 31% (47/150) of case-patients and 72% (108/150) of controls wore long-sleeve clothes during evening hours (OR = 0.19, 95% CI 0.08-0.3); 69% (104/150) of case-patients and 92% (138/150) of controls slept under a bed net (OR = 0.17, 95% CI 0.07-0.38). Active breeding sites were found near and within homesteads with Anopheles gambiae as the predominant vector.
Conclusion:
Increased vector breeding sites due to erosion control pits as a soil conservation practice sustained by the intermittent rainfall, likely caused this outbreak. Draining pits immediately after the rains and increasing coverage for bed nets were recommended.
