Lack of Evidence for Chloroquine-Resistant Plasmodium falciparum Malaria, Leogane, Haiti

Ami Neuberger, Kathleen Zhong, Kevin C Kain, and Eli Schwartz

Author affiliations: Rambam Medical Center, Haifa, Israel (A. Neuberger); University of Toronto, Toronto, Ontario, Canada (K. Zhong, K.C Kain); Sheba Medical Center, Tel Hashomer, Israel (E. Schwartz); and Tel Aviv University, Tel Aviv, Israel (E. Schwartz)

Abstract

Plasmodium falciparum malaria in Haiti is considered chloroquine susceptible, even though the pfcrt haplotypes associated with chloroquine resistance were recently detected. We found no chloroquine treatment failure among 49 patients with falciparum malaria who had parasites carrying pfcrt haplotypes. Continued vigilance is needed to detect the emergence of chloroquine resistance.

Plasmodium falciparum malaria, which has been eliminated from most of the Caribbean islands, is endemic to the island of Hispaniola (1–3) and is especially prevalent in Haiti. Epidemiologic data from Haiti are scarce, but malaria is probably endemic to most areas situated at altitudes <300 m. The town of Leogane, situated in Ouest Province 30 km west of Port-au-Prince, is no exception, and we have reported a high incidence of malaria among febrile patients during the peak malaria transmission season of November 2010–March 2011 (1).
In sharp contrast to the situation in most other malarial regions in the world, P. falciparum parasites in Haiti remain susceptible to chloroquine (4,5). To the best of our knowledge, clinical failure of chloroquine for prophylaxis or treatment of P. falciparum malaria has not been reported, and the Centers for Disease Control and Prevention recommends chloroquine as a first-line option for the treatment and prophylaxis of malaria in Haiti (6).
All studies reporting universal chloroquine susceptibility of P. falciparum parasites in Haiti were performed before the 1990s (4,5). However, a recent report from the Artibonite Valley north of Port-au-Prince documented that the P. falciparum chloroquine resistance transporter (pfcrt) haplotypes were detected in 5 (6%) of 79 blood samples from Haitians with blood smears positive for P. falciparum parasites (7). Although this report did not include clinical data, did not document clinical chloroquine treatment failure, and reported the detection of haplotypes associated with chloroquine resistance in a minority of all tested samples, the emergence of chloroquine resistance would be of great concern. Because epidemiologic data from Haiti are scarce, at best, and because the malaria surveillance system operating in the country is inadequate, undetected cases of chloroquine-resistant malaria might exist. We aimed to search for chloroquine-resistant cases either clinically or by detecting pfcrt haplotypes in P. falciparum isolates in Leogane, Haiti.