Susceptibility and irritability of adult forms of main malaria vectors against insecticides used in the indoor residual sprays in Muzaffargarh District, Pakistan: a field survey.

In southern Punjab, Pakistan, Muzaffargarh District is known to have insecticide-resistant Anopheles and drug-resistant Plasmodium spp. In this part of the country, five anopheline mosquitoes, Anopheles stephensi Liston, Anopheles culicifacies Giles, Anopheles fluviatilis James, Anopheles superpictus Grassi, and Anopheles subpictus Grassi (Diptera: Culicidae) are known as malaria vectors. Among these, An. culicifacies is the primary and An. stephensi is the secondary malaria vector. Outbreaks of malaria usually occur after rainy episodes. We conducted field surveys to collect field strains of An. culicifacies and An. stephensi mosquitoes from different areas of Muzaffargarh District. We determined susceptibility and irritability levels of their adult stages to the discriminative dose of different insecticides. For this purpose, we used World Health Organization's established criteria for assessment. Mortality was calculated after 1 h exposure and for 24 h recovery period for various insecticides. An. stephensi was found to be significantly resistant to dichlorodiphenyltrichloroethane (DDT, an organochlorine), dieldrin (a chlorinated hydrocarbon), and malathion (organophosphorus), with lethal times (LT50) of 83.17, 52.48, and 37.53, respectively. However, the species was significantly sensitive to permethrin, deltamethrin (pyrethroids), and fenitrothion (organophosphate) with LT50 of 2.85, 2.34, and 13.18, respectively. Among these, permethrin showed more promising results against adult An. stephensi. When analyzed for irritancy, we found that among pyrethroids, permethrin was the most irritant insecticide for both An. stephensi and An. culicifacies. DDT and dieldrin showed least irritancy with 0.42 +/- 0.08 and 0.77 +/- 0.12 takeoffs per minute per adult, respectively, against An. stephensi. The mean number of takeoffs per minute per adult with permethrin showed significant irritancy for permethrin when compared with DDT. Based on this study, we conclude that the use of organochlorine (DDT) and chlorinated hydrocarbon (dieldrin) should not be reintroduced in Malaria Control Programme in Pakistan until there is enough evidence to do so at any stage in future, and the use of pyrethroids should continue, with preference to permethrin for better control of malariaby indoor residual spraying.

Morphological and molecular characterisation of Echinococcus granulosus in livestock and humans in Punjab, Pakistan.

Cystic echinococcus poses an important economic and public health problem to Pakistan. Our study determined the prevalence and genotypes of Echinococcus present in domestic livestock and humans in Punjab, Pakistan. Out of 39,738 animals examined, 6.67% of animals were found infected. The prevalence and fertility of hydatid cysts was highest in camels (prevalence 17.29%; proportion fertile 95%), followed by sheep (prevalence 7.52%; proportion fertile 86.4%), buffalo (prevalence 7.19%; proportion fertile 84.3%), goats (prevalence 5.48%; proportion fertile 79.09%) and cattle (prevalence 5.18%; proportion fertile 75.25%). Phylogenetic analysis of the cytochrome oxidase-1 gene revealed that the common sheep strain (G1) and buffalo strain (G3) are cycling among livestock in Punjab and that these strains are highly adapted to goats, camels and cattle. Both human cysts were found to belong to the common sheep strain (G1) of E. granulosus, reinforcing this strain has the most potential for zoonotic transfer. Both morphological and molecular results support earlier studies suggesting that Echinococcus of sheep and buffalo origin is phenotypically and genetically similar which adds further evidence to support its recognition as one species viz, Echinococcus granulosus sensu stricto.