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Biomedical subjects

D S Dinesh

Publications and source records attributed to D S Dinesh.

6 recordsLinked to original sources

Vector control in leishmaniasis.

Indoor residual spraying is a simple and cost effective method of controlling endophilic vectors and DDT remains the insecticide of choice for the control of leishmaniasis. However resistance to insecticide is likely to become more widespread in the population especially in those areas in which insecticide has been used for years. In this context use of slow release emulsified suspension (SRES) may be the best substitute. In this review spraying frequencies of DDT and new schedule of spray have been discussed. Role of biological control and environment management in the control of leishmaniasis has been emphasized. Allethrin (coil) 0.1 and 1.6 per cent prallethrin (liquid) have been found to be effective repellents against Phlebotomus argentipes, the vector of Indian kalaazar. Insecticide impregnated bednets is another area which requires further research on priority basis for the control of leishmaniasis. Role of satellite remote sensing for early prediction of disease by identifying the sandflygenic conditions cannot be undermined. In future synthetic pheromons can be exploited in the control of leishmaniasis.

Allethrins↗

Morphological variations in Phlebotomus argentipes (Diptera: Psychodidae) Annandale and Brunetti.

Morphological variations were observed in Phlebotomus argentipes, the vector for visceral leishmaniasis reported from the endemic states of Bihar, West Bengal and Uttar Pradesh. The taxonomic features distinguishing vector and nonvector species of P. argentipes were relative length of ascoid and antennal segment IV. Three morphotypes were characterized as <0.4, = 0.4 and >0.4 respectively. Other characteristics of wing width, wing length, eye, style, antennal segment III, IV, V was found statistically significant (p<0.05) and eleven other morphological measurements were not significant. This study suggests three different morphotypes of P. argentipes in these three endemic states. The genetic and reproductive isolation among such morphotypes will establish the variability in further studies.

Animals↗

Seasonal and nocturnal landing/biting behaviour of Phlebotomus argentipes (Diptera: Psychodidae).

The nocturnal activity of Phlebotomus argentipes (Diptera: Psychodidae), the main vector of Leishmania donovani in India, was studied throughout a year, with monthly collections, between 18.00 and 06.00 hours, of the sandflies landing on 15 humans and 15 cows in the village of Bahapur, Patna district. The cattle appeared to be better as bait, since more than five female P. argentipes were caught on them for each one caught on the human bait. Overall, although P. argentipes were caught during each collection hour from 18.00--06.00 hours, the numbers caught landing/biting peaked at 23.00--24.00 hours. There were, however, slight seasonal variations in the timing of this peak in activity. The numbers of P. argentipes caught/collection night also varied with season, being significantly higher during the summer than during the rainy season or winter (P < 0.01 for each), and apparently inversely correlated with rainfall. Male P. argentipes were caught in much higher numbers than the females of this species, with female:male ratios of 1:8 for the flies caught on human bait and of 1:13 for those collected from cattle. If the probability of a female P. argentipes being infected with L. donovani does not vary with season, peak transmission of this parasite to humans probably occurs between February and May, at the middle of night.

Animals↗

Screening sandflies for natural infection with Leishmania donovani, using a non-radioactive probe based on the total DNA of the parasite.

Digoxigenin-labelled total, Leishmania donovani DNA was used as a probe to detect the parasite in Indian Phlebotomus argentipes. The probe was quite sensitive, detecting as little as 0.3 pg parasite DNA, equivalent to approximately 100 parasites. Positive signals could be detected in 12 (32%) of the 38 small (two- to 30-fly) pools of the wild-caught P. argentipes investigated and in a pool of 10 laboratory-bred P. argentipes fed on a patient with post-kala-azar dermal leishmaniasis. None of the wild-caught P. papatasi, P. sergenti or Sergentomyia sp. or of the newly emerged, laboratory-bred P. argentipes investigated were positive by this probe. The results indicate that such a probe may be very useful in screening sandflies for L. donovani, and so detecting the main vectors and transmission pathways of this parasite, in India and elsewhere.

Animals↗