Malaria Among U.S. Embassy Personnel -- Kampala, Uganda, 1992

The treatment and prevention of malaria in Africa has become a challenging and complex problem because of increasing drug resistance. Although the risk of acquiring malaria for U.S. citizens and their dependents stationed overseas generally has been low, this risk varies substantially and unpredictably. During May 1992, the Office of Medical Services, Department of State (OMS/DOS), and CDC were notified of an increased number of malaria cases among official U.S. personnel stationed in Kampala, Uganda. A review of the health records from the Embassy Health Unit (EHU) in Kampala indicated that 27 cases of malaria were diagnosed in official personnel from March through June 1992 compared with two cases during the same period in 1991. EHU, OMS/DOS, and CDC conducted an investigation to confirm all reported malaria cases and identify potential risk factors for malaria among U.S. Embassy personnel. This report summarizes the results of the investigation.

Malaria blood smears from 25 of the 27 reported case-patients were available for review by OMS/DOS and CDC. A case of malaria was confirmed if the slide was positive for Plasmodium sp. Of the 25 persons, 17 were slide-confirmed as having malaria.

A questionnaire was distributed to all persons served by the EHU to obtain information about residence, activities, use of malaria chemoprophylaxis, and use of personal protection measures (i.e., using bednets and insect repellents, having window and door screens, and wearing long sleeves and pants in the evening). Of the 157 persons eligible for the survey, 128 (82%) responded.

Risk for malaria was not associated with sex or location of residence in Kampala. Although the risk for malaria was higher among children aged less than or equal to 15 years (6/32 {19%}) than among persons greater than 15 years (11/94 {12%}), this difference was not significant (relative risk {RR}=1.6; 95% confidence interval {CI}=0.6-4.0). Eighty-two percent of the cases occurred among persons who had been living in Kampala for 1-5 years, compared with those living there less than 1 year. Travel outside of the Kampala area to more rural settings was not associated with increased risk for malaria.

Four malaria chemoprophylaxis regimens were used by persons who participated in the survey: mefloquine, chloroquine and proguanil, chloroquine alone, and proguanil alone. In addition, 23 (18%) persons who responded were not using any malaria chemoprophylaxis. The risk for malaria was significantly lower among persons using either mefloquine or chloroquine and proguanil (8/88 {9%}) than among persons using the other regimens or no prophylaxis (9/37 {24%}) (RR=0.4; 95% CI=0.2-0.9). Twelve persons not using prophylaxis reported side effects or fear of possible side effects as a reason.

The risk for malaria was lower among persons who reported using bednets all or most of the time (2/27 {7%}) than among persons who sometimes or rarely used bednets (15/99 {15%}) (RR=0.5; 95% CI=0.1-2.0). The risk for malaria was also lower among persons who consistently used insect repellent in the evening (0/16), compared with those who rarely used repellent (17/110 {15%}) (RR=0; upper 95% confidence limit=1.2). Risk for malaria was not associated with failure to have window or door screens or wear long sleeves or pants in the evening.

As a result of this investigation, EHU staff reviewed with all personnel the need to use and comply with the recommended malaria chemoprophylaxis regimens. EHU staff also emphasized the need to use personal protection measures and made plans to obtain insecticide-impregnated bednets and to provide window and door screens for all personnel.

Reported by: U.S. Embassy Health Unit, Kampala, Uganda; Office of Medical Svcs, Dept of State, Washington, D.C. Malaria Br, Div of Parasitic Diseases, National Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: In Uganda, the increase in malaria among U.S. personnel was attributed to poor adherence to both recommended malaria chemoprophylaxis regimens and use of personal protection measures during a period of increased malaria transmission and intensified chloroquine resistance in sub-Saharan Africa. The findings in this report underscore the need to provide initial and continued counseling regarding malaria prevention for persons living abroad in malaria-endemic areas -- preventive measures that are also important for short-term travelers to such areas.

Mefloquine is an effective prophylaxis regimen in Africa and in most other areas with chloroquine-resistant P. falciparum; however, in some areas (e.g., Thailand), resistance to mefloquine may limit its effectiveness. In Africa, the efficacy of mefloquine, compared with chloroquine alone, in preventing infection with P. falciparum is 92% (1 ). Mefloquine is safe and well tolerated when given at 250 mg per week over a 2-year period. The risk for serious adverse reactions possibly associated with mefloquine prophylaxis (e.g., psychosis and convulsions) is low (i.e., 1.3-1.9 episodes per 100,000 users {2}), while the risk for less severe adverse reactions (e.g., dizziness, gastrointestinal complaints, and sleep disturbances) is similar to that for other antimalarial chemoprophylactics (1).

Doxycycline has similar prophylactic efficacy to mefloquine, but the need for daily dosing may reduce compliance with and effectiveness of this regimen (3,4). Chloroquine alone is not effective as prophylaxis in areas of intense chloroquine resistance (e.g., Southeast Asia and Africa). In Africa, for persons who cannot take mefloquine or doxycycline, chloroquine and proguanil is an alternative, although less effective, regimen. Chloroquine should be used for malaria prevention in areas only where chloroquine-resistant P. falciparum has not been reported.

Country-specific recommendations for preventing malaria and information on the dosage and precautions for malaria chemoprophylaxis regimens are available from Health Information for International Travel, 1992 (i.e., "yellow book") (5) or 24 hours a day by telephone or fax, (404) 332-4555.

References

1. Lobel HO, Miani M, Eng T, et al. Long-term malaria prophylaxis with weekly mefloquine in Peace Corps volunteers: an effective and well tolerated regimen. Lancet 1993;341:848-51.

2. World Health Organization. Review of central nervous system adverse events related to the antimalarial drug, mefloquine (1985- 1990). Geneva: World Health Organization, 1991; publication no. WHO/MAL/91.1063.

3. Pang L, Limsomwong N, Singharaj P. Prophylactic treatment of vivax and falciparum malaria with low-dose doxycycline. J Infect Dis 1988;158:1124-7.

4. Pang L, Limsomwong N, Boudreau EF, Singharaj P. Doxycycline prophylaxis for falciparum malaria. Lancet 1987;1:1161-4.

5. CDC. Health information for international travel, 1992. Atlanta: US Department of Health and Human Services, Public Health Service, 1992:98; DHHS publication no. (CDC)92-8280.

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