Effectiveness and tolerance of long-term malaria prophylaxis with mefloquine

Article Abstract:

Visitors, such as missionaries, businesspeople, and Peace Corps volunteers, to areas where malaria is endemic are at high risk for contracting the disease, particularly since the spread of chloroquine-resistant malaria. Between 1986 and 1989 in West Africa, the incidence of infection of Peace Corps volunteers with Plasmodium falciparum malaria (a malarial strain) increased from 6 to 24 cases per 100 volunteers, in spite of weekly chloroquine phosphate prophylaxis. To compare the effectiveness of chloroquine treatment with prophylaxis using mefloquine (a drug approved by the Food and Drug Administration in 1989), Peace Corps volunteers choose one of four anti-malaria drug regimens: mefloquine taken every two weeks; weekly chloroquine; weekly chloroquine phosphate plus proguanil hydrochloride; or weekly chloroquine plus sulfadoxine. The subjects were monitored at regular intervals. Results for 3,698 person-months of drug use (526 volunteers between October 1989 and April 1990; not all subjects were in the study for the full period) showed that the incidence per 100 cases of P. falciparum infection for volunteers who took mefloquine or chloroquine was 1.0 and 2.7, respectively. Mefloquine was 68 percent more effective than chloroquine; since high-risk subjects were urged to select the mefloquine regimen, it is likely that the drug was even more effective than this. However, the effectiveness of mefloquine was considerably lower than expected from earlier research. This may have been because of decreased drug blood levels, reducing the efficacy of the treatment. All cases of malaria developed during the second week of the dosing schedule, when blood levels were at their lowest. New dose recommendations for this drug have now been made by the Centers for Disease Control. Mefloquine was not associated with more side effects than chloroquine. Compliance with the dosing regimen was apparently a problem for many volunteers, and adherence to a weekly regimen is now recommended. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects

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Imported Plasmodium falciparum malaria in American travelers to Africa: implications for prevention strategies

Article Abstract:

Malaria acquired by travelers to countries where the disease is endemic has increased in recent years, as the resistance to chloroquine (an antimalarial drug) has increased among Plasmodium falciparum (a parasite that causes malaria). The number of P. falciparum infections among people who travelled to Africa increased from 140 to 309 between 1984 and 1988. To learn more about the transmission of these infections and the epidemiology of this form of malaria, data from the years 1981 through 1988 were analyzed by the Centers for Disease Control (CDC). The surveillance system for recording malaria cases is explained. Results showed an increase in infections between 1981 and 1988 from 83 to 309; rates in West and East Africa are reported separately. Most P. falciparum infections incurred in East Africa were among whites, while more than half the cases from West Africa occurred in blacks. The majority of patients in East Africa (96 percent) were older than 10; this was true of 81 percent of those who acquired West African infections. A smaller proportion of people who contracted malaria in West Africa than in East Africa were travellers. Most (91 percent) of those who acquired the disease in East Africa had used drugs to prevent malaria; only 42 percent of those infected in the West had done so. In fact, the proportion of patients in West Africa who used prophylaxis increased from 10 to only 48 percent between 1985 and 1988, a time when the number of infections tripled. The results indicate three things about malaria prevention in Africa: the efficacy of chloroquine has declined; malaria transmission is intense in West Africa; and travelers to West Africa are not diligent in practicing chemoprophylaxis. Another drug, mefloquine hydrochloride, is now recommended by the CDC for travelers to Africa. Better information concerning malaria and its prevention should be provided to people who contemplate such travel. (Consumer Summary produced by Reliance Medical Information, Inc.)

Demographic aspects, Africa, Chloroquine

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Change of dosing regimen for malaria prophylaxis with mefloquine

Article Abstract:

A new dosing schedule is recommended for mefloquine, the drug currently recommended by the Centers for Disease Control (CDC) for people who travel to regions where malaria caused by drug-resistant strains of Plasmodium falciparum is endemic. The schedule calls for once-weekly dosing, with the first dose to be taken one week before travel. The drug should be taken for the duration of travel and for four weeks after leaving these regions. The previously recommended schedule called for weekly dosing for four weeks, then dosing every second week; this led to reduced effectiveness. This was noted because all failures of prevention occurred during the second week of the two-week period, when blood levels of mefloquine were at their lowest. Although no serious reactions to the drug have been noted when it is used prophylactically, reactions have been reported, particularly when it was taken to treat malaria. Certain people (e.g. children who weigh less than 30 pounds, pregnant women, people with epilepsy or psychiatric disorders) should not take mefloquine. Additional classes of individuals are listed. Health information on this topic is available through CDC's telephone information system 24 hours a day: the number is (404) 332-4555. Mefloquine can be difficult to obtain in the US, but prescriptions from this country will be honored in airport pharmacies in Frankfurt and Paris (both major airports). Prescriptions filled at Heathrow Airport (London) must be written in Great Britain. The airport physician can write them in Brussels. A combination of mefloquine and pyrimethaminesulfadoxine is sold in some countries under the name Fansimef R. This is not the same as mefloquine and should not be used for malaria prophylaxis. (Consumer Summary produced by Reliance Medical Information, Inc.)

Dosage and administration

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