Evaluating the Role of Chloroquine for Malaria Elimination
Status:
Completed
Trial end date:
2015-06-01
Target enrollment:
Participant gender:
Summary
One of the proposed ideas for malaria elimination includes the use of drugs to interrupt
malaria transmission by exhausting the human reservoir of infection. Theoretically, mass
treatment of an entire population with a very effective and rapid-acting drug (for instance
an ACT), followed by the administration of an effective prophylactic regime during a minimum
of four weeks, so as to outlast the typical development period of Plasmodium parasites in
Anopheline mosquitoes, could achieve the same objective. In this respect, chloroquine (CQ)
would be an appropriate candidate. This drug exhibits two conditions that make it attractive
for elimination campaigns: 1) It has been demonstrated to have an excellent safety profile,
allowing for its use in all age groups including pregnant women and children; and 2) Its
relatively long elimination half life (t1/2=1-2 months) can provide a long post-treatment
prophylactic effect. Recent evidence suggests that CQ sensitivity may be returning in places
where discontinuation has reduced the drug pressure to the parasite populations. In countries
such as Malawi, P. falciparum seems to have regained full sensitivity to CQ, and molecular
markers of antiCQ resistance have nearly disappeared. While this does not support the
reintroduction of CQ as first line therapy, it does suggest that, if proven sensitive in a
given area, it could play a prophylactic role in malaria elimination strategies when used in
combination with other drugs or tools. Thus, we intend to evaluate the potential role of
chloroquine in preventing infections during elimination campaigns by performing a randomized,
single-blind, placebo-controlled trial in asymptomatic Mozambican adults.
Choosing asymptomatic parasitaemic adult males from a malaria-endemic area as our study
population introduces limited risks when administering a drug with an uncertain efficacy (47%
efficacious in 2001-2002). In malaria-endemic areas, this age group has a remarkably low risk
of developing severe disease (irrespective of clinical symptoms), and it is foreseeable that
parasitemia may be well tolerated, and in certain cases, spontaneously cleared from the
individual's blood as a result of the immune system. In the unlikely event of any clinical
symptomatology appearing throughout the follow-up, individuals will be examined by a study
clinician and treated immediately with the country's first-line malaria treatment
(artemether-lumefantrine, Coartem ®).