Malaria High-Risk Populations in Namibia

This study aims to determine the effectiveness, cost-effectiveness, acceptability, and feasibility of targeted delivery of a package of malaria interventions for improving effective coverage and reducing Plasmodium falciparum malaria transmission among malaria high-risk populations in Northern Namibia. Previous research identified cattle herders and agricultural workers as populations at higher risk of infection. The investigators hypothesize that targeted delivery of interventions will lead improve coverage in these groups and lead to a reduction in P. falciparum transmission.

This study is the second phase of work in Zambezi and Ohangwena Regions, Namibia, building off a formative phase of work that characterized the risk behaviors migratory patterns, health-seeking behaviors, intervention strategies and social networks of agricultural workers and cattle herders, who are previously identified malaria high-risk populations (HRPs). This phase of the study now aims to determine the effectiveness, cost-effectiveness, acceptability, and feasibility of targeted delivery of a package of malaria interventions for improving effective coverage and reducing Plasmodium falciparum malaria transmission in these regions among these populations.

The study will specifically assess the coverage and impact of interventions delivered at worksites to HRPs, including presumptive treatment administered alongside vector control interventions (indoor residual spraying \[IRS\], long-lasting insecticidal nets \[LLINs\], and topical repellents). The effectiveness of these interventions will be compared against areas with no study interventions (standard of care) over the course of implementation (November 2019 - May 2020). Primary outcomes will include the coverage of each intervention at worksites over the study period and PCR-based P. falciparum prevalence measured at endline. Following a baseline cross-sectional survey in November/December 2019, the interventions will consist of 2 rounds of presumptive treatment spaced at least one month apart between January and March, and delivery of vector control interventions at worksites and key access points with support from employers, with the primary evaluation to be conducted through an endline cross-sectional survey in April/May 2020. Secondary outcomes around effectiveness will be assessed through incident case data providing measures of incidence in HRP and non-HRP populations, odds of infection associated with each intervention in cases compared to controls and entomological data collection. In addition, operational and feasibility outcomes will be assessed through qualitative data collection, population size estimation of HRP groups and a global positioning system (GPS) logger study.

Eligibility Criteria:
Inclusion Criteria: HRP study populations (all)

* Study participants include those in the 8 selected health facility catchment areas within Zambezi and Ohangwena Regions.
* Identify primary occupation as a agricultural worker or cattle herder
* Zambezi Region: Have slept or worked outside at a farm or cattle post in the past 7 days or will do over the next 3 weeks (sleeping outside, working outside ploughing or guarding crops/cattle, or sleeping in any type of structure located at a farm or cattle post site)
* Ohangwena Region: Report overnight travel to Angola for grazing cattle during the malaria transmission season (November to May) Be willing and able to provide consent (ie mentally fit)

Inclusion Criteria: Presumptive AL treatment

* In addition to the above, subjects must report travel outside of Namibia within the past 60 days to be eligible to receive AL.

Inclusion Criteria: Enhanced vector control

* In addition to the above, participants must not sleep in a structure sprayed with insecticide to be eligible to receive an LLIN or sprayed tent/tarp.

Inclusion Criteria: Focus group discussions and key informant interviews

* Meet eligibility criteria as a member of an HRP, health facility staff or health extension worker involved in the diagnosis and treatment of HRP populations.
* Individuals must be 18 years and older and willing and able to provide consent to be included in the GPS logger, focus group discussions or key informant interviews

Exclusion Criteria:

* Per national guidelines in Namibia, presumptive treatment with AL will not be given to women who are pregnant in the first trimester, individuals weighing less than 5kg, those with a known AL allergy or suspected severe malaria.
* Individuals under the age of 18 will be excluded from the GPS logger study, focus group discussions and key informant interviews.