An infection with Angiostrongylus cantonensis, the main causative agent for human eosinophilic encephalitis, can be acquired through the consumption of the freshwater snail Pomacea canaliculata. This snail also provides a suitable model to study the developmental morphology and behavior of A. cantonensis larvae, facilitated by the snail's distinct lung structure. We used microanatomy for studying the natural appearance and behavior of A. cantonensis larvae while developing within P. canaliculata. The distribution of refractile granules in the larval body and characteristic head structures changed during the developmental cycle. Two well-developed, rod-like structures with expanded knob-like tips at the anterior part were observed under the buccal cavity as early as the late second developmental stage. A "T"-shaped structure at the anterior end and its tenacity distinguished the outer sheath from that shed during the second molting. Early first-stage larvae obtained from fresh rat feces are free moving and characterized by a coiled tail, whereas a mellifluous "Q"-movement was the behavioral trait of third-stage A. cantonensis larvae outside the host tissue. In combination, the distribution of refractive granules, distinct head features, variations in sheaths, and behavioral characteristics can be utilized for differentiation of larval stages, and for distinguishing A. cantonensis larvae from those of other free-living nematodes.

New research has shown that mefloquine, an arylaminoalcohol used against malaria, is active against Schistosoma japonicum and Schistosoma mansoni in vivo. To enhance our understanding of the potential mechanism of action of mefloquine against schistosomiasis, we examined the dynamics of histopathological changes in adult S. japonicum. Mice infected with S. japonicum for 35 days were treated intragastrically with a single dose of mefloquine (400 mg/kg). One to 35 days after mefloquine administration, drug-induced histopathological alterations were studied. Twenty-four hours after treatment, S. japonicum showed signs of degeneration, including focal roughing and swelling of the tegument and/or muscles, dilatation of the gut, focal desquamation of gut epithelial cells, and a decrease in pigment particles. There was extensive degeneration of vitelline cells and appearance of pigment particles visible in the cytoplasm in female worms. The extent and severity of histopathological changes increased over time; 48 h posttreatment, two thirds of female worms and a quarter of male worms were classified as dead. Three to 14 days posttreatment, typical histological changes observed in surviving male worms were vesiculation, swelling of parenchymal tissues, and dilatation of gut. In females, there was disintegration and infiltration of inflammatory cells, forming dead worm abscesses and early stage of dead worm granuloma. Finally, 35 days posttreatment, only dead male and female worm granuloma were found. Our results provide further evidence of in vivo activity of mefloquine against adult schistosomes.

BackgroundCystic echinococcosis is a serious zoonotic infection worldwide caused by metacestodes of Echinococcus gruanulosus. Mebendazole and albendazole are the only two drugs used in the treatment of this disease with cure rates only about 30% due to the poor oral absorption. Thus an alternative treatment for this disease is needed.MethodsA mebendazole oily suspension (MBZ-OS) was prepared and orally administrated to mice infected with echinococcus cysts for 8 months at 12.5 mg/kg and 25 mg/kg for 14 consecutive days. Mebendazole suspended in 1% tragacanth (MBZ-1% tragacanth) served as treated control. In addition, liver and serum samples were collected from these treated mice (25 mg/kg) for histopathology examination and liver function test. For pharmacokinetic analysis, plasma, parasite (cyst wall and cyst fluid) and tissue samples were collected at 0.25, 0.5, 1, 2, 4, 8, 16 and 24 h after orally administrating MBZ-OS and MBZ-1% tragacanth to E. granulosus-infected mice at 25 mg/kg. These samples were then processed and quantitatively analyzed by HPLC.ResultsThe administration of MBZ-OS resulted in a treatment efficacy with the cyst weight reductions higher than 80%, significantly better than the corresponding MBZ-1% tragacanth groups. The better treatment efficacy of MBZ-OS was related to the higher drug concentration in plasma, parasites and tissues. It was also shown that the injury of the liver was not significantly altered by taking MBZ-OS compared to the untreated control.ConclusionThese findings demonstrate that MBZ-OS is a promising new formulation of MBZ for treatment of hydatid diseases without showing significantly liver toxicity.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-014-0589-0) contains supplementary material, which is available to authorized users.

Background: Cystic echinococcosis is a serious zoonotic infection worldwide caused by metacestodes of Echinococcus gruanulosus. Mebendazole and albendazole are the only two drugs used in the treatment of this disease with cure rates only about 30% due to the poor oral absorption. Thus an alternative treatment for this disease is needed.

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