No description available.

Brugia malayi is one of the causative agents of the disabling and disfiguring disease known as Lymphatic Filariasis (LF). This infection is a well-established ailment in tropical and subtropical countries and recently the drug ivermectin has been introduced for the LF control programs. Ivermectin (IVM) is an excellent microfilaricide, but is not markedly macrofilaricidal. However, it causes a long-lasting reduction in the production of new larvae by female worms, suggesting that adult stages are affected. However, the mechanism by which IVM produces such effect in the adult worm is not well understood. One major reason is our incomplete understanding about the biological effect of IVM on adult stages. The present study was carried out to examine the in vitro effects of IVM on B. malayi adult worms using Brugia-gerbil animal model. And also to have some leads in understanding the drug-uptake and location of probable targets in the worm body by using fluorescent labeled IVM and confocal microscopy. / The antifilarial effects of IVM were examined using three parameters: mf release by female worms, and motility, and viability in both male and female worms. The results reported in this study demonstrate that although IVM did not kill the adult worm, but showed significant antifilarial effects on B. malayi adult stages when examined in an in vitro system. Confocal microscopy images of the worms incubated in bodipy FITC-IVM showed strong specific localization signal in the anterior cephalic region of both male and female worms. These observations suggest the early/initial interactions of the drug with its probable receptors that could be located specifically in the head region.

A current initiative to eliminate lymphatic filariasis (LF), headed by the World Health Organization, aims to interrupt transmission of the disease through yearly community-wide treatment with the broad spectrum anthelmintic albendazole (ABZ), in combination with ivermectin (IVM) or diethylcarbamazine (DEC). Over the years, the use of both ABZ and IVM in the treatment of veterinary parasites has led to widespread anthelmintic resistance against these drugs. In this study, we genotyped microfilaria of Wuchereria bancrofti, a causative agent of LF, in order to detect the presence of mutations which confer ABZ resistance in other parasites, and we identified such mutations in worms obtained from untreated patients in Ghana and Burkina Faso, West Africa. Microfilaria from patients who had been treated with ABZ + IVM, had a significantly higher frequency of the resistant genotype, and this frequency was even higher in worms from patients that had received two rounds of treatment. In addition, the untreated population of microfilaria had an excess of homozygotes in the population. This excess homozygosity was equivalent to a Wright's Inbreeding Statistic of FIT= 0.44, and we found that the population was significantly subdivided between patients. In order to better understand the mechanisms and factors involved in the potential spread of ABZ resistance, caused by such mutations, through a population of Culex-transmitted W. bancrofti, we developed a deterministic model that incorporates genotype structure into the epidemiological model EPIFIL. This model predicts that the combination of ABZ + DEC leads to stronger selection for the resistant genotype than ABZ + IVM, and that drug efficacy assumptions are an important factor affecting the spread of drug resistance. Treatment coverage, non-random mating, initial allele frequency and number of treatments also had substantial impact on the speed and magnitude of the spread of ABZ resistance. When we expanded this model to include potential IVM-resistance alleles we found that, under ABZ + IVM treatment, selection for resistance to either drug is enhanced by the presence of resistance against the second drug. Similarly, excess homozygosity caused by parasite non-random mating may increase selection for a dominant IVM resistance allele through enhancing the spread of a recessive ABZ resistance allele. Resistence developed more slowly when it was inherited as a polygenic trait. Results from this study suggest that resistance monitoring is crucial, as resistance may not be apparent until treatment is stopped, recrudescence occurs and treatment is reapplied.

No description available.