A long-lasting topical deltamethrin treatment to protect dogs against visceral leishmaniasis
Courtenay, Orin, Kovacic, V., Gomes, P. A. F., Garcez, L. M. and Quinnell, Rupert J.. (2009) A long-lasting topical deltamethrin treatment to protect dogs against visceral leishmaniasis. Medical and Veterinary Entomology, Vol.23 (No.3). pp. 245-256. ISSN 0269-283XFull text not available from this repository.
Official URL: http://dx.doi.org/10.1111/j.1365-2915.2009.00815.x
To develop long-lasting, topical pour-on insecticides for dogs to control zoonotic visceral leishmaniasis, two deltamethrin-based formulations (emulsifiable concentrate [EC] and suspension concentrate [SC]) were tested for their efficacy against the phlebotomine sandfly Lutzomyia longipalpis Lutz & Neiva (Diptera: Psychodidae), vector of Leishmania infantum Nicolle (Kinetoplastida: Trypanosomatidae). The entomological outcomes tested were anti-feeding effect (proportion of female sandflies unfed), lethal effect (24-h female sandfly mortality) and these two effects combined, and the insecticide persistence time at 50% (residual activity, RA(50)) and 80% (RA(80)) efficacy. On initial application, the proportions of female flies that demonstrated anti-feeding activity or were killed were similar for both formulations, at 0.93 (95% confidence interval [CI] 0.856-0.977) vs. 0.81 (95% CI 0.763-0.858) (anti-feeding) and 0.86 (95% CI 0.787-0.920) vs. 0.76 (95% CI 0.698-0.817) (24-h mortality) for EC and SC, respectively. The RA50 rates for anti-feeding and mortality caused by the EC formulation were 4.7 months (95% CI 4.18-5.84) and 2.5 months (95% CI 2.25-2.90), respectively, compared with 1.1 months (95% CI 0.96-1.15) and 0.6 months (95% CI 0.50-0.61), respectively, for the SC formulation. The RA50 for the combined anti-feeding and mortality effects of EC was 5.2 months (95% CI 4.73-5.96), compared with only 0.9 months (95% CI 0.85-1.00) for the SC formulation. The four-to six-fold superior residual activity of the EC formulation was attributed to the addition of a solvent-soluble resin in the formulation which improved fur adhesion and acted as a reservoir for the slow release of the active ingredient. These results identify the potential of such a low-cost formulation to reduce the inter-intervention interval to 5-6 months, similar to that recommended for deltamethrin-impregnated dog collars or for re-impregnation of conventional bednets, both of which are currently used to combat Leishmania transmission. Finally, a novel bioassay was developed in which sandflies were exposed to fur from treated dogs, revealing no detectable tolerance (24-h mortality) in wild- caught sandflies to the insecticide formulations up to 8 months after the initiation of communitywide application of the insecticides to dogs.
|Item Type:||Journal Article|
|Subjects:||Q Science > QL Zoology
S Agriculture > SF Animal culture
|Divisions:||Faculty of Science > Life Sciences (2010- ) > Biological Sciences ( -2010)|
|Journal or Publication Title:||Medical and Veterinary Entomology|
|Publisher:||Wiley-Blackwell Publishing, Inc.|
|Official Date:||September 2009|
|Number of Pages:||12|
|Page Range:||pp. 245-256|
|Access rights to Published version:||Restricted or Subscription Access|
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