Update: Chloroquine-Resistant Plasmodium falciparum -- Africa
The first confirmed cases of chloroquine-resistant Plasmodium
falciparum acquired in Africa were reported in 1978 (1) and
occurred
in non-immune travelers who had been in East Africa for relatively
short periods of time. These reports of chloroquine-prophylaxis or
treatment failures were substantiated by serial parasitologic and
clinical observations of each infection and, when available,
in-vitro
confirmation of drug resistance. CDC continues to monitor the
status
of chloroquine-resistant P. falciparum malaria in East Africa (2).
Recent reports document that the transmission of resistant
parasites
is now occurring more widely in Africa than was previously
described
(2).
During the past year, confirmed chloroquine-resistant
infections
have been described from specific areas in Zambia (3) and Sudan
(4);
previously, Kenya, Tanzania, Uganda, Madagascar, and the Comoros
Islands were acknowledged to have transmission of
chloroquine-resistant P. falciparum. It remains unclear whether
these
countries have nationwide transmission of disease and whether
contiguous countries are similarly affected. In addition, a few
apparent chloroquine-resistant infections have been reported in
Malawi
and northeastern Zaire. It may now be prudent to advise travelers
to
these specific suspect areas that they may be at risk of acquiring
chloroquine-resistant malaria. While such anecdotal reports may
reflect the spread of chloroquine-resistant P. falciparum in
Africa,
they require further confirmation; great caution should be
exercised
in interpreting case reports of drug-resistant malaria.
Studies in several West African countries, as well as a recent
assessment of drug susceptibility of P. falciparum infections in
western and central Zaire, have failed to demonstrate
chloroquine-resistance (5). These experiences emphasize the
importance of rigorously applying accurate drug-susceptibility
testing
procedures and adhering to the accepted World Health Organization
definitions of drug resistance (6).
Since health professionals frequently advise travelers of
health
risks that may be incurred during travel, they should be aware of
the
changing distribution of chloroquine-resistant malaria in Africa.
CDC
has published recommendations for malaria chemoprophylaxis for
travelers to affected areas of East Africa (2); Fansidar*
(sulfadoxine
500 mg plus pyrimethamine 25 mg) one tablet weekly PLUS chloroquine
300 mg (base) once weekly is currently recommended. Weekly doses
of
Fansidar and chloroquine may be taken together on the same day. It
should be noted, however, that this combination may not be
completely
effective in preventing episodes of symptomatic malaria, as
prophylaxis failures with sulfonamide-antifolate combination drugs
have occurred (7,8). Travelers should be advised that any acute
febrile illness may be malaria and that medical attention should be
sought, regardless of whether chemoprophylaxis is being taken.
Further updates of this rapidly evolving situation will be
published as accurate information becomes available. An expanded
discussion of the recommendations for the prophylaxis of malaria is
available in Prevention of Malaria in Travelers, 1982 (9).
Reported by Malaria Br, Div of Parasitic Diseases, Center for
Infectious Diseases, CDC.
References
CDC. Chloroquine-resistant malaria acquired in Kenya and
Tanzania--Denmark, Georgia, New York. MMWR 1978;27:463-4.
CDC. Revised recommendations for malaria chemoprophylaxis for
travelers to East Africa. MMWR 1982;31:328-30.
Kofi Ekue JM, Ulrich A, Njelesani EK. Plasmodium malaria
resistant
to chloroquine in a Zambian living in Zambia. Br Med J
1983;286:1315-6.
Al Tawil N, Akood MA. Response of falciparum malaria to a
standard
regimen of chloroquine in Khartoum province, Sudan. World
Health
Organization, WHO/MAL/83.991.
CDC. Unpublished data.
Bruce-Chwatt LJ, ed. Chemotherapy of malaria, 2nd ed. World
Health Organization, Geneva, 1981.
Markwalder KA, Meyer HE. Possible sulfadoxine-pyrimethamine
resistance in Plasmodium falciparum malaria from Kenya
(letter).
Trans R Soc Trop Med Hyg 1982;76:281.
Stahel E, Degremont A, Lagler U. Pyrimethamine/sulfadoxine
resistant falciparum malaria acquired at Dar es Salaam,
Tanzania
(letter). Lancet 1982;1:1118-9.
CDC. Prevention of malaria in travelers 1982. MMWR 1982;
31;1S-28S.
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