Excito-repellency effect of deltamethrin on triatomines under laboratory conditions.

This work demonstrates that deltamethrin in low doses produces an excito-repellency effect on triatomines, as already observed for mosquitoes. A wooden box covered with a cloth impregnated with deltamethrin at doses of 2.5 and 5mg ai/m2 was utilized for the experiment. The triatomine species studied were Triatoma infestans, Panstrongylus megistus, Rhodnius neglectus and Triatoma sordida. Adults were released in one of the sides of the box and their position was noted in subsequent periods. The observations were realized on the day the cloth was impregnated and subsequently repeated at 30 and 60 days for T. sordida; on day 120, the remaining species were included. Insect mortality and attempts at flight from the box were also observed. Excito-repellency was evident for all species and doses up to day 120. The only species that attempted to fly was P. megistus. The excito-repellency effect may be considered as an additional advantage to the insecticide power, as it should be able to prevent the installation of new colonies by females that fly into the homes, and at the moment of the spraying, it should promote the flushing out of triatomines from the wall crevices and from other shelters.

Chagas disease vector control in Tupiza, southern Bolivia.

Heavy domestic and peridomestic infestations of Triatoma infestans were controlled in two villages in southern Bolivia by the application of deltamethrin SC25 (2.5% suspension concentrate) at a target dose of 25 mg a.i./m2. Actual applied dose was monitored by HPLC analysis of filter papers placed at various heights on the house walls, and was shown to range from 0 to 59.6 about a mean of 28.5 mg a.i./m2. Wall bioassays showed high mortality of T. infestans during the first month after the application of deltamethrin. Mortality declined to zero as summer temperatures increased, but reappeared with the onset of the following winter. In contrast, knockdown was apparent throughout the trial, showing no discernible temperature dependence. House infestation rates, measured by manual sampling and use of paper sheets to collect bug faeces, declined from 79% at the beginning of the trial to zero at the 6 month evaluation. All but one of the houses were still free of T. infestans at the final evaluation 12 months after spraying, although a small number of bugs were found at this time in 5 of 355 peridomestic dependencies. Comparative cost studies endorse the recommendation of large-scale application of deltamethrin, or pyrethroid of similar cost-effectiveness, as a means to eliminate domestic T. infestans populations in order to interrupt transmission of Chagas disease.

Effect of deltamethrin spraying on the sandfly populations in a focus of American cutaneous leishmaniasis.

The effect of deltamethrin of the sandfly population in a focus of American Cutaneous Leishmaniasis in Viana, Espírito Santo State is described. The phlebotomine population density was determined inside and outside houses during a one year period in a treated and untreated area. The results showed a significant reduction in the number of sandflies inside houses in the treated area compared with both the untreated area and the same area before spraying. Despite having a residual action for 12 months after spraying the insecticide was ineffective outside houses. It is concluded therefore that deltamethrin is an efficient insecticide for reducing the number of phlebotomine sandflies inside houses.

[Biological susceptibility of Triatoma sordida and Triatoma infestans to deltamethrin and lambdacyhalothrin under field conditions]. / Suscetibilidade biológica do Triatoma sordida e Triatoma infestans a deltametrina e lambdacyhalotrina em condições de campo.

The biological susceptibility of Triatoma sordida and Triatoma infestans to deltamethrin and lambdacyhalothrin was evaluated in three homogeneous groups of houses in the municipality of Posse, Goiás. Each group of houses was treated according to one of the following protocols: deltamethrin 5% wetted powder at 25 mg a.i./m2; deltamethrin 5% concentrated suspension at 25 mg a.i./m2; and lambdacyhalothrin 10% wetted powder at 30 mg a.i./m2. Monitoring of susceptibility to the insecticides was done after 90, 210, 270 and 360 days after the spraying. Each test consisted of an exposure of 10 third-instar nymphs of each species for every house. The insects were kept in contact with the sprayed wall for a period of 72 hours in plastic containers developed by WHO for studies with adult mosquitos. Thirty days after the exposure the death numbers were scored. Results demonstrate persistent activity of the three insecticides for up to a year after spraying and equal biological susceptibilities for both Triatoma sordida and Triatoma infestans to each formulation.

[Effectiveness evaluation of deltamethrin (K-othrin 50FW), in low doses, in the control of triatominae in Sao Sebastiao do Umbuzeiro, Paraiba]. / Avaliação da eficiência de deltametrina (K-othrine 50FW), em doses baixas, no controle de triatomíneos em são Sebastião do Umbuzeiro, Paraíba.

We tested deltamethrin (K-Othrine 50 FW) in the control of triatomine bugs, in an semi arid area with about 56.6% of houses bug infested. We used in 402 Domiciliary Units, 125, 75, 60 or 50 ml per pump of 10 liters, equivalent, if applied on 250 m2, to 25, 15, 12 and 10 mg/m2. The invasion, colonization and cumulative indices in the houses and the positivity index in shelters near houses were very low and similar in the four groups during the 15 months of evaluation, indicating that lower doses could replace 25 mg/m2. T. infestans, followed by T. pseudomaculata, predominated in and near the houses, after spraying.

Direction of the mental canal in human mandibles.

The direction of the mental canal was calculated in the horizontal and vertical planes with a view to aiding anaesthetic techniques. Based on our data, it is advisable to give the following approximate inclinations to the needle when penetrating the mental canal in anaesthetic procedures: 55 degrees postero-anteriorly in relation to a horizontal plane and 40 degrees latero-medially in relation to a horizontal line tangent to the body of the mandible at the level of the mental foramen.