Background. Southern Province, Zambia has experienced a dramatic decline in Plasmodium falciparum malaria transmission in the past decade and is targeted for elimination. Zambia's National Malaria Elimination Program recommends reactive case detection (RCD) within 140 m of index households to enhance surveillance and eliminate remaining transmission foci. Methods. To evaluate whether RCD captures local transmission, we genotyped 26 microsatellites from 106 samples collected from index (n = 27) and secondary (n = 79) cases detected through RCD in the Macha Hospital catchment area between January 2015 and April 2016. Results. Participants from the same RCD event harbored more genetically related parasites than those from different RCD events, suggesting that RCD captures, at least in part, infections related through local transmission. Related parasites clustered in space and time, up to at least 250 m from index households. Spatial analysis identifed a putative focal transmission hotspot. Conclusions. Te current RCD strategy detects focal transmission events, although programmatic guidelines to screen within 140 m of index households may fail to capture all secondary cases. Tis study highlights the utility of parasite genetic data in assessing programmatic interventions, and similar approaches may be useful to malaria elimination programs seeking to tailor intervention strategies to the underlying transmission epidemiology.
Bibliographical noteFunding Information:
Financial support. This research was financially supported by the National Institutes of Health (5T32AI007417 to J.C.P. as a trainee on the Molecular and Cellular Basis of Infectious Diseases Training Grant in the Department of Molecular Microbiology and Immunology at the Johns Hopkins Bloomberg School of Public Health and 5U19AI089680 to the Southern and Central African International Centers of Excellence in Malaria Research). This work was supported by the Bloomberg Philanthropies. G.C. received a postdoctoral fellowship award from the Johns Hopkins Malaria Research Institute. A. W. is funded by a Career Award at the Scientific Interface by the Burroughs Wellcome Fund. B. G. is a Chan Zuckerberg Biohub investigator.
© 2018 The Author(s).
- Molecular epidemiology
- Reactive case detection