Chloroquine-Resistant Malaria in Travelers Returning from Haiti after 2010 Earthquake

Myriam Gharbi

, Dylan R. Pillai, Rachel Lau, Véronique Hubert, Krishna Khairnar, Alexandre Existe, Eric Kendjo, Sabina Dahlström, Philippe J. Guérin, Jacques Le Bras, and members of the French National Reference Center for Imported Malaria Study

Author affiliations: Université Paris-Descartes, Paris, France (M. Gharbi, J. Le Bras); École des Hautes Études en Santé Publique, Rennes, France (M. Gharbi, P.J. Guérin); Worldwide Antimalarial Resistance Network, Paris (M. Gharbi, S. Dahlström, J. Le Bras); Public Health Ontario, Toronto, Ontario, Canada (D.R. Pillai, R. Lau, K. Khairnar); University of Calgary; Calgary, Alberta, Canada (D.R. Pillai); Hospital Bichat-Claude Bernard, Paris (V. Hubert, J. Le Bras); Laboratoire National de Santé Publique, Port-au-Prince, Haiti (A. Existe); Centre National de Référence Paludisme, Paris (V. Hubert, E. Kendjo, J. La Bras); Hospital Pitié-Salpétrière, Paris (E. Kendjo); Université Pierre et Marie-Curie-Paris VI, Paris (E. Kendjo); Worldwide Antimalarial Resistance Network, Oxford, UK (P.J. Guérin); Centre for Tropical Medicine, Oxford (P.J. Guérin); University of Oxford, Oxford, UK (P.J. Guérin); and Institut National de la Santé et de la Recherche Médicale, Paris (P.J. Guérin)

Abstract

We investigated chloroquine sensitivity to Plasmodium falciparum in travelers returning to France and Canada from Haiti during a 23-year period. Two of 19 isolates obtained after the 2010 earthquake showed mixed pfcrt 76K+T genotype and high 50% inhibitory concentration. Physicians treating malaria acquired in Haiti should be aware of possible chloroquine resistance.

In Haiti (2011 population ≈9.7 million), malaria is endemic. Approximately 30,000 malaria infections are confirmed annually among ≈200,000 estimated malaria cases, mainly Plasmodium falciparum infections (1). On January 12, 2010, a 7.0 magnitude earthquake struck Haiti near Port-au-Prince, leaving much of the population homeless.

The main malaria vector in Haiti, Anopheles albimanus mosquitoes, which mostly bite outdoors during November–January, placed evacuees at high risk for infection (2,3). Severe flooding after hurricane Tomas in November 2010 probably compounded the problem by facilitating parasite reservoirs and mosquito breeding (4). Some studies suggest that these events might have increased malaria transmission in Haiti. Two observational surveys, 1 performed by a mobile medical team during March–April 2010 (5) and 1 during November 2010–February 2011 in a primary care clinic in Leogane (6), reported a high proportion of malaria infection among persons with fever (20.3% and 46.9%, respectively) compared with reports from a population-based survey in 2006 (14.2%) (2). The US National Malaria Surveillance System reported a 3-fold increase in malaria among travelers returning from Haiti in 2010 (170 cases) compared with 2009 (58 cases) (7).

Chloroquine associated with primaquine since 2009, is the recommended first-line treatment for uncomplicated malaria. In vitro and molecular surveillance data collected during the past 2 decades suggest continued P. falciparum sensitivity to chloroquine (3,8,9). However, a 2006–2007 study in Artibonite Valley, Haiti, showed the chloroquine resistance–associated Pfcrt76T genotype in ≈6% (5/79) of P. falciparum isolates, although clinical data were lacking (10). Subsequently, the Haitian Ministry of Health acknowledged that routine chloroquine efficacy surveillance should be reinforced (11). We investigated the chloroquine sensitivity of P. falciparum parasites isolated from travelers recently returned from Haiti to Canada and France by using genotypic and phenotypic methods.