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Malaria in Post-earthquake Haiti
Abstract & Commentary
By Lin H. Chen, MD
Dr. Chen is Assistant Clinical Professor, Harvard Medical School Director, Travel Medicine Center, Mt. Auburn Hospital, Cambridge, MA.
Dr. Chen reports no financial relationships relevant to this field of study.
Synopsis: Malaria cases have occurred in U.S. residents who traveled to Haiti post-earthquake, including emergency responders and a traveler. Some resulted in severe illnesses. Individuals traveling to Haiti should use personal protection measures and take a recommended malaria chemoprophylaxis.
Source: CDC. Malaria acquired in Haiti 2010. MMWR 2010;59(8):217-219.
A 7.0 magnitude earthquake struck Haiti on Jan. 12, 2010, with an epicenter 10 miles west of Port-au-Prince, the capital. Approximately 200,000 fatalities occurred, and 500,000 people were left homeless. From Jan. 12 to Feb. 25, 11 laboratory-confirmed cases of Plasmodium falciparum malaria acquired in Haiti were reported to the CDC. Among the patients were seven United States residents who were emergency responders, three Haitian residents, and one American traveler. Six of the seven emergency responders were U.S. military personnel, and four had uncomplicated malaria treated in Haiti. The other two were moderate to serious cases that required transfer to the United States for intensive care, including one who developed acute respiratory distress syndrome necessitating intubation and mechanical ventilation.
Chemoprophylaxis would have been recommended for the seven emergency responders and the American traveler. However, six of the eight did not comply with the recommended chemoprophylaxis, including the two who required hospitalization. The three Haitian residents with malaria who traveled to the United States included a Haitian adoptee.
The current Haitian government estimates of fatalities and displaced persons are 217,366 and 511,405, respectively.1 Because of the massive collapse of buildings and resulting lack of housing, most emergency responders to Haiti have slept in tents or other temporary structures. The main vector of malaria in Haiti, Anopheles albimanus, like other Anopheles species mosquitoes, is active at night. Therefore, sleeping outdoors at night, or staying in a shelter that does not keep out mosquitoes, increases an individual's chance of mosquito bites.
Haiti, with a population of 9,876,401, reported 36,774 cases of outpatient malaria cases to the World Health Organization in 2008: 6 cases of P. vivax, and the remaining cases were P. falciparum.2 A study of 274 Haitian refugees arriving by boat in Jamaica in 2004 identified, by microscopy, P. falciparum (30 isolates), P. vivax (13 isolates), P. malariae (1 isolates), and unidentified Plasmodium species (31 isolates).3 When additional testing was performed using the polymerase chain reaction, 15 samples were positive for P. malariae, including 7 that were also positive for P. falciparum; PCR did not identify any P. vivax.3
The rainy season in Haiti occurs from May through October and is associated with peak malaria transmission from November to January and a lesser peak in May-June.4 A population-based PCR survey in the Artibonite Valley of Haiti estimated a prevalence of 3.1% for P. falciparum infection during the high transmission season in 2006.4
Approximately 1300-1500 cases of malaria occurring in the United State are reported to the CDC annually. In 2007, 1505 cases were reported, of which 34 cases were acquired in Haiti. Among the reported cases attributed to Haiti, 29 isolates were Plasmodium falciparum, 1 isolate was P. vivax, and 4 were unknown species.5 Among the 34 reported cases, 23 were in U.S. residents (civilians, not military personnel or foreign residents). P. falciparum, the primary species associated with severe malaria, is the predominant species that causes malaria in Haiti.
Occasionally, cases of malaria co-infection with other pathogens have been reported, such as malaria and dengue. One case of P. falciparum, Clostridium perfringens, and Candida spp. co-infection occurred in a German traveler to Haiti, which led to the demise of the patient.6
The currently recommended regimens for malaria chemoprophylaxis for U.S. travelers to Haiti are either chloroquine, mefloquine, atovaquone-proguanil, or doxycycline.7,8 Although the P. falciparum parasites are still considered sensitive to chloroquine, which is one of the regimens recommended for chemoprophylaxis, concern is rising about the potential development of resistance. In 2006 and 2007, amplification of the P. falciparum chloroquine resistance transporter (pfcrt) gene on blood samples that had been positive by microscopy or PCR for P. falciparum detected several samples that possessed the chroloquine-resistant haplotype.9
A medical surveillance of the U.S. Joint Task Force, which served in Haiti during the spring of 2004, found only one case of malaria during the 17,938 person-weeks deployment.10 However, any cases reported after return to the United States would not have been included in the report. Despite the routine guidance in the military to take doxycycline for malaria chemoprophylaxis in addition to using repellent and insecticide-treated uniforms and nets, several emergency responders from the military adhered poorly to prevention.
In summary, malaria cases have occurred in emergency responders to post-earthquake Haiti. P. falciparum is the predominant species, and rare cases of P. malariae and P. vivax have been identified. Individuals planning to travel to Haiti, whether for earthquake relief or to visit family and friends or other activities, should understand the status of their accommodations. For malaria prevention, travelers should sleep in tents or under mosquito nets to reduce nighttime mosquito exposure, apply repellent appropriately, and use a recommended chemoprophylaxis.