Resurgence of malaria in Mumbai--is escalating chloroquine resistance a cause?

OBJECTIVES: Given the steep increase in the incidence of malaria in the city of Mumbai in the nineties, we decided to study the causes for the same as well as analyse the resistance pattern of P. falciparum in the city. METHODS: Smear positive cases of acute uncomplicated P. falciparum malaria who presented to us in 1994, 1995 and 1996 were analysed for their response to full dose chloroquine (25 mg/kg over 3 days). Samples of those patients who satisfied criteria for in vitro resistance testing to chloroquine and other antimalarials, were also studied. Chloroquine level in all patients was studied on Day 3 by HPLC. In vivo response to chloroquine was studied in 30, 71 and 78 patients while in vitro response was studied in 17, 35 and 30 patients respectively in the above years. RESULTS: We found in vivo chloroquine resistance figures of 36.78%, 45% and 53.8% in the years '94, '95 and '96 and the in vitro resistance figures of 41.17%, 54.28% and 66.6% in the same years. CONCLUSIONS: Our previous studies documenting 15% chloroquine resistance in 1993 and the increasing incidence in subsequent years suggests resistance to chloroquine as one of the causes of resurgence and maintenance of malaria in the city. If patients of uncomplicated P. falciparum malaria are to be treated with chloroquine, rigorous monitoring for nonresponse and timely rescue medication is necessary. Alternative antimalarial drugs such as mefloquine, artemisinin derivatives and sulfadoxine-pyrimethamine should be used in patients where this is not possible.

Efficacy of sulfadoxine-pyrimethamine in chloroquine resistant falciparum malaria in Bombay.

Several reports have confirmed the existence of chloroquine resistant Plasmodium falciparum malaria in Bombay. In the management of these cases, of the therapeutic options available, sulfadoxine-pyrimethamine (SP) (administered as a single dose) is preferred, since quinine has to be administered over a period of 7 days while mefloquine is yet to be marketed in India. With increasing reports of falciparum malaria resistant to SP from Thailand and Africa, the present study was conducted to determine the efficacy of SP in the treatment of chloroquine resistant falciparum malaria cases in Bombay. 17 uncomplicated falciparum malaria patients documented to be resistant to chloroquine (10 RI, 5 RII and 2 RIII) by the WHO (1973) in-vivo extended field test criteria and by estimation of plasma chloroquine levels by High Performance Liquid Chromatography were included in the study. These adult patients were then treated with a supervised single dose of 3 tablets of SP and peripheral blood smears were then repeated on days 3, 4, 5, 7, 14, 21, 28, 35 and 42 after treatment. 14 patients responded and were sensitive while 3 patients showed RII grade resistance to SP. These 3 patients then responded to a 7 day course of quinine (30 mg/kg/day)+doxycycline (100 mg/day). These results thus document that SP can be used as an effective second-line antimalarial drug. However one should monitor the patient for plasmodial resistance to sulfadoxine-pyrimethamine.