ABSTRACT
BACKGROUND: Anopheles stephensi is a key urban malaria vector in the Indian subcontinent and Middle East including south and southeast of Iran. Wide application of insecticides resulted in resistance of this species to various insecticides in these regions. This study was conducted to reveal the role of metabolic mechanisms in the development of resistance in An. stephensi to DDT and cyfluthrin. METHODS: Field mosquito specimens were collected from Chabahar Seaport, southeast corner of Iran, in 2015. Insecticide susceptibility and enzyme assays were conducted as recommended by WHO. RESULTS: Mean enzyme ratios were 3.95 and 3.04 for α- esterases and 2.40 and 1.97 for ß- esterases in the DDT and cyfluthrin- resistant populations correspondingly compared with the susceptible strain. The GSTs enzyme mean activity ratios were 5.07 and 2.55 in the DDT and cyfluthrin- resistant populations compared with the susceptible beech strain. The cytochrome p450s enzyme ratios were 1.11 and 1.28 in the DDT and cyfluthrin- resistant populations respectively compared with the susceptible beech strain. CONCLUSION: Metabolic mechanisms play a crucial role in the development of DDT and cyfluthrin resistance in An. stephensi, therefore, further evaluation of the mechanisms involved as well as implementation of proper insecticide resistance management strategies are recommended.
ABSTRACT
The early diagnosis of visceral leishmaniasis (VL) using Direct Agglutination Tests (DAT) and its treatment and control are essential actions taken in rural health centers in endemic foci of the infection based on the national protocols set by the Iranian Ministry of Health and Medical Education. Eleven clinically confirmed VL patients with typical VL symptoms and negative results of DAT, admitted to the pediatrics department of Valiasr Hospital in Meshkinshahr underwent parasitological tests. 7 of the total of 11 patients had positive result of bone marrow puncture smears and all of them had negative results of DAT. Thus factors that had led to false negative DAT results were examined. The patients' blood samples were collected in microhematocrit tubes using the finger prick technique, centrifuged and their plasma then separated. The complete medical history of the patients was taken using a questionnaire. The laboratory staff therefore checked the quality of anti-leishmania antigen, materials and equipment used. The patients' medical history showed that they had all been administered corticosteroid medications such as dexamethasone or hydrocortisone prior to visiting the laboratory. The DAT was repeated in these patients 2-3 weeks after their last administration of corticosteroids. The antibody titers were positive this time. A total of 3 of the collected specimens (27.3 %) showed a titer of 1.3200, 5 (46 %) showed a titer of 1.1600 and 3 (27.3 %) a titer of 1.800. Due to the effects of some medications, particularly corticosteroids, on serological tests, the patients' full medical history should be taken prior to performing this test and physicians working at endemic regions of this infection should be notified about these drug interactions.
ABSTRACT
OBJECTIVE@#To evaluate the bioefficacy of α-cypermethrin impregnated into long lasting insecticide treated nets (LLITNs-INTERCEPTOR®) against main malaria vector, Anopheles stephensi (An. stephensi).@*METHODS@#The effectiveness of bed net impregnated with α-cypermethrin (INTERCEPTOR®) with washing was evaluated. The washing procedure and bioassay tests were carried out according to the WHO-recommended methods. Malaria vector, An. stephensi was exposed to impregnated bed net for three minutes and then mortality measured after 24 h recovery period. Knockdown was also measured according to the logarithmic times.@*RESULTS@#Result of cone bioassay method showed that bioefficacy of α-cypermethrin decreased from 100% in unwashed to 15% in 20 washes. KT(50) was measure as one minute in one wash and increased to 40 min in 20 washes.@*DISCUSSION@#Findings of this study provide guideline for malaria vector control authorities and people using pyrethroid-impregnated bed nets.
