ABSTRACT
Context: Resistance to antimalarial drugs is one of the major challenges for malaria elimination. In India, artemisinin combination therapy (artesunate-sulfadoxin pyrimethamine) was introduced in place of chloroquine (CQ) for the treatment of uncomplicated falciparum malaria in 2010. Periodical monitoring of polymorphisms in antimalarial drug resistance marker genes will be useful for assessing drug pressure, mapping and monitoring of drug resistance status; and will be helpful for searching alternative treatments. Objectives: This study was conducted to study the polymorphisms in antimalarial drug resistance marker genes among clinical Plasmodium falciparum isolates collected from Kolkata after 10 years of artemisinin-based combination therapie (ACT) implementation. Materials and Methods: Blood samples were collected from P. falciparum mono-infected patients and polymorphisms in P. falciparum CQ resistance transporter (pfcrt), P. falciparum multidrug resistance (pfmdr-1), P. falciparum dihydrofolate reductase (pfdhfr), P. falciparum dihydropteroate synthetase (pfdhps), pfATPase6 and pfK-13 propeller genes were analysed by polymerase chain reaction and DNA sequencing. Results: In pfcrt gene, C72S, and K76T mutation was recorded in 100% isolates and no mutations was detected in any of the targeted codons of pfmdr-1 gene. A double mutant pfcrt haplotype SVMNT and wildtype haplotype NYD in pfmdr-1 were prevalent in 100% of study isolates. Triple mutant pfdhfr-pfdhps haplotype ANRNI-SGKAA was recorded. No polymorphism in pfK13 gene was documented in any of the isolates. Conclusions: Observed wild codon N86 along with Y184 and D1246 of pfmdr-1 gene might be an indication of the reappearance of CQ sensitivity. The absence of quadruple and quintuple haplotypes in pfdhfr-pfdhps gene along with the wild haplotype of pfK13 is evidence of ACT effectivity. Hence, similar studies with large sample size are highly suggested for monitoring the drug resistance status of P. falciparum.
ABSTRACT
CONTEXT: Both malaria and lymphatic filariasis (LF) are mosquito-borne diseases caused by protozoal and nematode parasites, respectively, and are serious public health problem in India. Although the vectors of the diseases are different, they can coexist in favorable conditions. Fever is the common symptom for both the diseases, but the emphasis is given for diagnosis and treatment of malaria due to its life-threatening severity, LF remained neglected. Detection and management of microfilaria are equally important. During the diagnosis of malaria, a few microfilaria were detected, which prompted us to undertake this study with following objectives. OBJECTIVES: The objective of the study was to determine the incidence of microfilaremia among the febrile patients attending for malaria diagnosis. SUBJECTS AND METHODS: Thick and thin peripheral blood smears from all patients attended were examined following Giemsa staining. Different malarial indexes were analyzed. RESULTS: Out of 8681 patients examined, 1778 were positive for Plasmodium vivax and 328 for Plasmodium falciparum with a slide positivity rate 20.48%. Twenty-six patients were positive for microfilaria of Wuchereria bancroftii among which five were coinfected with P. vivax and one with P. falciparum. Most of the microfilaria-positive patients were adult and originally from northern districts of Bihar. CONCLUSIONS: High incidence of microfilaria among febrile patients attending for malaria is alarming for urban Kolkata. Although the patients were originally from Bihar, they are staying in Kolkata for a long time, might be a source for transmission. Epidemiological study by collecting night blood samples and entomological survey is highly suggestive to explore local transmission if any.
ABSTRACT
Rational use of insecticides, as advocated by World Health Organisation, plays a crucial role for vector control in eliminating visceral leishmaniasis from endemic countries. Emergence and spread of resistance among vector sand flies is of increasing concern for achieving these goals. Information on insecticide susceptibility status of sand fly populations and potential association between the former and polymorphisms in the insecticide target genes is important for formulating proper vector control measures. The present study was designed to evaluate the susceptibility status of vector sand fly species (Phlebotomus argentipes) against deltamethrin (type II pyrethroid), DDT (organochlorine) and malathion (organophosphate) and to detect polymorphisms in voltage gated sodium channel (vgsc) gene and investigating their association with type II pyrethroid and DDT susceptibility in three Kala-azar endemic districts of West Bengal, India. Adult sand flies were collected from human dwelling and cattle sheds of the study areas and subjected to insecticide bioassay using insecticide impregnated papers as per WHO protocol. Polymorphisms in domain II segment 6 of vgsc gene of pyrethroid and DDT susceptible and tolerant P. argentipes were detected by DNA sequencing. P. argentipes population of the study area was found to be susceptible to deltamethrin and malathion with corrected mortality rate between 98.02% to 98.80% and 98.81% to 100% respectively, but resistant to DDT (corrected mortality rateâ¯=â¯65.62%-76.33%). Two non-synonymous mutations L1014S and L1014F were detected of which L1014F was found to be associated with deltamethrin/DDT resistance. The replacement of DDT by synthetic pyrethroid is aptly done by national vector borne disease control programme (NVBDCP). The prevalence of L1014F mutation in vgsc gene and its association with type II pyrethroid tolerability is an indication of emergence of resistance against it. Malathion may be used as an alternative in the study areas if needed in future. Similar studies at a regular interval are highly suggested for monitoring susceptibility of used insecticide and to detect early signs of emergence of resistance against them.
