Malaria Elimination Pilot Study in Military Forces in Cambodia

Antimalarial drug resistance has reached critical levels on the Thai-Cambodian border. Many have begun advocating for concerted malaria elimination efforts in Cambodia. However, there is currently no consensus on how malaria elimination is to be achieved with the tools available.

In this study, the investigators will conduct operational research with the Royal Cambodian Armed Forces (RCAF) and National Malaria Center (CNM) to quantify the relative effectiveness of the two major interventional approaches - monthly malaria prophylaxis (MMP) or focused screening and treatment (FSAT) - in a head to-head comparison. In addition, the investigators will quantify the relative contribution of a recently advocated vector intervention for military personnel - the insecticide treated uniform (ITU) - in addition to other vector control measures currently employed by the RCAF. The investigators will employ the same permethrin insecticide self-application kits currently used by the US military. The investigators will estimate the cost effectiveness of each approach and attempt to define the best way forward for malaria elimination efforts in a critically important malaria reservoir in military population (and their dependents) who reside on the Thai-Cambodian border. The aim of the study is not only to conduct research to better define the best way forward in malaria elimination efforts in the high risk military populations, but to also build capacity within the RCAF to support and lead future elimination efforts in the most difficult-to-reach mobile populations.

This is a cluster-randomized, open label interventional study to determine the feasibility of achieving significant reduction in malaria cases in military encampments on the Thai-Cambodian border. The study will compare the effectiveness, safety, and tolerability of monthly malaria prophylaxis (MMP) to monthly focused screening and treatment (FSAT). This study will thus investigate the effectiveness of two potential interventions for malaria elimination. Subjects in the monthly malaria prophylaxis (MMP) arm will receive a standard 3-day treatment course of dihydroartemisinin-piperaquine on months 1, 2 and 3 and weekly low-dose primaquine (22.5mg for 12 weeks). Volunteers in the focused screening and treatment (FSAT) arm will be screened monthly and then treated for malaria following national treatment guidelines. For G6PD-deficient volunteers in the FSAT arm, primaquine will be administered weekly (45mg for 8 weeks) as radical curative and/or presumptive anti-relapse therapy. For G6PD normal volunteers with vivax infection, primaquine will be administered daily (15mg for 14 days). All FSAT volunteers with confirmed P. falciparum infection will receive a single, low dose (15mg) Primaquine as a P. falciparum transmission-blocking agent. The incremental benefit of an insecticide treated uniform (ITU) will also be assessed as a single-blind sham-controlled intervention in addition to personal protective measures currently employed by the RCAF. Volunteers will be followed monthly for a total of 6 months, to determine the proportion remaining malaria-free on day 180 following enrollment.

Eligibility Criteria:
Inclusion Criteria:

1. Military volunteers aged 18-65 years of age plus their dependents \> 2 years of age, eligible for care at an RCAF facility, or otherwise eligible Cambodian civilians at risk for contracting malaria who live within the designated geographical areas
2. Able to give informed consent/assent
3. Resides in the selected study areas, and available for monthly follow-up for 6 month study duration
4. Agrees not to seek outside medical care for febrile illness unless referred by study team
5. Authorized by local commander to participate in the study if on active duty

Exclusion Criteria:

1. Allergic reaction or contraindication to dihydroartemisinin-piperaquine or primaquine or artesunate+mefloquine
2. Pregnant or lactating female, or female of childbearing age, up to 50 years of age or otherwise individually assessed for childbearing potential, who does not agree to use an acceptable form of contraception during the study
3. Judged by the investigator to be otherwise unsuitable for study participation