The combination of sulfadoxine-pyrimethamine (SP) is used as a second line of therapy for the treatment of uncomplicated chloroquine-resistant Plasmodium falciparum malaria. Resistance to SP arises due to certain point mutations in the genes for the dihydrofolate reductase (DHFR) and dihydropteroate synthetase (DHPS) enzymes of the parasite. We have analyzed these mutations in 312 field isolates of P. falciparum collected from different parts of India to assess the effects of drug pressure. The rate of mutation in the gene for DHFR was found to be higher than that in the gene for DHPS, although the latter had mutations in more alleles. There was a temporal rise in the number of isolates with double dhfr mutations and single dhps mutations, resulting in an increased total number of mutations in the loci for DHFR and DHPS combined over a 5-year period. During these 5 years, the number of isolates with drug-sensitive genotypes decreased and the number of isolates with drug-resistant genotypes (double DHFR mutations and a single DHPS mutation) increased significantly. The number of isolates with the triple mutations in each of the genes for the two enzymes (for a total of six mutations), however, remained very low, coinciding with the very low rate of SP treatment failure in the country. There was a regional bias in the mutation rate, as isolates from the northeastern region (the state of Assam) showed higher rates of mutation and more complex genotypes than isolates from the other regions. It was concluded that even though SP is prescribed as a second line of treatment in India, the mutations associated with SP resistance continue to be progressively increasing.Plasmodium falciparum is the most lethal of all human malaria parasites. This parasite causes epidemics in countries where malaria is endemic, resulting in large numbers of deaths. Widespread chloroquine resistance has forced many countries to use alternate drugs for the treatment of falciparum malaria, such as the combination of sulfadoxine and pyrimethamine (SP). However, the parasite can develop resistance to this drug combination as well through mutations in the genes for the enzymes involved in the folate biosynthesis pathway. Such mutations lead to the lowering of the drug binding affinity of the parasite enzymes (18,26,34,36,41). Resistance to pyrimethamine is attributed to mutations in the gene for the parasite enzyme dihydrofolate reductase (DHFR), whereas sulfadoxine resistance is associated with mutations in the gene for the parasite enzyme dihydropteroate synthetase (DHPS). The increased level of resistance has been found to be associated with increased numbers of mutations in the genes for these two enzymes. Multiple mutations in the genes for both enzymes result in SP treatment failure (39). Detection of these mutations in field isolates has been proposed as an alternate strategy for rapid screening for antifolate drug resistance (9,12,16,17,27,38).In India, chloroquine-resistant malaria was first reported in 1973, and since then resistance to ...

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The repellent action of neem oil (extracted from the seeds of Azadirachta indica A. Juss) was evaluated on mosquitoes at two villages near Delhi, India. Kerosene lamps containing neem oil were burned in the living rooms, and mosquitoes resting walls or attracted to human bait were collected inside rooms from 1800 to 0600 h. Neem oil (0.01-1%) mixed in kerosene reduced biting of human volunteers and catches of mosquitoes resting on walls in the rooms. Protection was more pronounced against Anopheles than against Culex. A 1% neem oil-kerosene mixture may provide economical personal protection from mosquito bites.

There was a temporal increase in the number of pfcrt and pfmdr1 2-loci mutations, and this led to the higher level of chloroquine resistance. This is a cause for concern for the antimalarial drug policy in India.