Malaria Transmission at The Zimbabwe–Mozambique Border: An Observational Study of Parasitemia by Travel History and Household Location

Ellen Ferriss Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland;

Search for other papers by Ellen Ferriss in
Current site
Google Scholar
PubMed
Close
,
Sungano Mharakurwa Africa University, Mutare, Zimbabwe;

Search for other papers by Sungano Mharakurwa in
Current site
Google Scholar
PubMed
Close
,
Shungu Munyati Biomedical Research and Training Institute, Harare, Zimbabwe;

Search for other papers by Shungu Munyati in
Current site
Google Scholar
PubMed
Close
,
Lovemore Gwanzura Biomedical Research and Training Institute, Harare, Zimbabwe;
University of Zimbabwe, Harare, Zimbabwe;

Search for other papers by Lovemore Gwanzura in
Current site
Google Scholar
PubMed
Close
,
Marisa A. Hast Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland;

Search for other papers by Marisa A. Hast in
Current site
Google Scholar
PubMed
Close
,
Lawrence H. Moulton Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland;
Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland;

Search for other papers by Lawrence H. Moulton in
Current site
Google Scholar
PubMed
Close
,
Amy Wesolowski Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland;

Search for other papers by Amy Wesolowski in
Current site
Google Scholar
PubMed
Close
, and
William J. Moss Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland;
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland;
W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland

Search for other papers by William J. Moss in
Current site
Google Scholar
PubMed
Close
for the Southern and Central Africa International Centers of Excellence for Malaria Research

Cross-border human population movement contributes to malaria transmission in border regions, impeding national elimination. However, its impact in low-to-moderate transmission settings is not well characterized. This community-based study in Mutasa District, Zimbabwe, estimated the association of parasite prevalence with self-reported overnight travel to Mozambique and household distance to the border from 2012–2020. A fully adjusted Poisson regression model with robust variance estimation was fit using active surveillance data. The population attributable fraction of parasite prevalence from overnight travel was also estimated. The relative risk of testing positive for malaria by rapid diagnostic test declined 14% (prevalence ratio [PR] = 0.86, 95% CI = 0.81–0.92) per kilometer from the border up to 12 km away. Travel to Mozambique was associated with a 157% increased risk (PR = 2.57, 95% CI = 1.38–4.78), although only 5.8% of cases were attributable to overnight travel (95% CI = −1.1% to 12.7%), reflecting infrequent overnight trips (1.3% of visits). This study suggests that transmission in eastern Zimbabwe is driven by increasingly conducive social or environmental conditions approaching the border and low levels of importation from overnight travel. Although day trips to Mozambique during peak biting hours were not assessed, the contribution of such trips to ongoing transmission may be significant. Future malaria control efforts should prioritize high coverage of existing interventions and continued support for community health workers and health facilities at the border, which provide free case management.

Author Notes

Financial support: This research was supported by funding from the National Institutes of Health awarded to the Southern and Central Africa International Centers of Excellence for Malaria Research (U19AI089680), the Johns Hopkins Malaria Research Institute, and Bloomberg Philanthropies.

Authors’ addresses: Sungano Mharakurwa, Africa University, Mutare, Zimbabwe, E-mail: mharakurwas@africau.edu. Shungu Munyati, Biomedical Research and Training Institute, Harare, Zimbabwe, E-mail: smunyati@brti.co.zw. Lovemore Gwanzura, University of Zimbabwe, Harare, Zimbabwe, and Biomedical Research and Training Institute, Harare, Zimbabwe, E-mail: gwanzura@mweb.co.zw. Marisa A. Hast, Amy Wesolowski, and William J. Moss, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, E-mails: marisahast@gmail.com, awesolo2@jhu.edu, and wmoss1@jhu.edu. Lawrence H. Moulton, La Minerve, Quebec, Canada, E-mail: lmoulto1@jhu.edu.

Address correspondence to Ellen Ferriss, Department of International Health, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205. E-mail: elferriss@gmail.com
Save