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Abstract Background Hookworm is still one of the three main soil-transmitted helminths prevalent in China, and 39 million cases infected with hookworm were estimated in China in 2006. Results The main approach to the control of hookworm infections in China consists of large-scale deworming, rebuilding sanitation systems in rural areas and health education. The availability of low-cost, safe and single-dose albendazole make large-scale deworming programs possible in China. Currently, sanitary latrines with three-cells are recommended by government for the control of soil-transmitted helminths, since 35% of helminth infections and 83% of worm eggs could be reduced after using this kind of sanitary latrine. In addition, economic prosperity contributes greatly to the reduction of hookworm prevalence, but the inequity of economic and social development among different regions of China provides a scenario that the worst threat of hookworm infection is located in the poorest areas of southern and central China. Therefore, it is necessary to put more investments into prophylaxis and treatment of hookworm in these poor regions. Conclusion Although the prevalence of hookworm infection has fallen significantly in the last 15 years in China, the current strategy for controlling hookworm infections still needs to be strengthened along with the three-pronged approach, e.g. distributing anthelmintic drugs in schools and undertaking large-scale of hookworm deworming, improving water supplies and sanitation, and proper health education.

Objective: To evaluate the effects of a aminoalcohol-carbazole compound BTB3 against Echinococcus granulosus in vitro., Methods: The protoscoleces from sheep and germinal cells from secondary-infected mice were cultured and treated with 1, 2, 4, 8, 10 and 20 μg/ml BTB3 for 3 days. The viability of protoscoleces and cells was determined by the methylene blue exclusion method and CCK-8 assay. Meanwhile, the effect of 10 μg/ml BTB3 on germinal cells was assessed by scanning electron microscopy（SEM）. The metacestodes were treated with 1, 5 and 10 μg/ml BTB3 for two weeks, and the integrity of the metacestodes was evaluated by SEM., Results: The 10 μg/ml and 20 μg/ml BTB3 caused a death rate of （100.0±0.0）% and （85.2±7.2）% respectively for protoscoleces. As the concentration decreased, the death rate remained below 10%. Moreover, the activity inhibition rate on germinal cells was about 100% for 8, 10 and 20 μg/ml BTB3, and was reduced with the decrease of BTB3 concentration other than the afore-mentioned three. SEM revealed detachment, shrinkage, and cavitation of germinal cells after BTB3 treatment. And the metacestodes all showed the loss of turgidity after BTB3 treatment for 14 days, which indicated cell detachment and uneven distribution of cells in internal cyst of metacestodes., Conclusion: BTB3 has strong effects against Echinococcu granulosus protoscoleces, germinal cells and metacestodes in vitro, which make it a potential drug against hydatid diseases.

Objective: To investigate the effect of Eucalyptus robusta leaves extract against Echinococcus granulosus protoscolices in vitro., Methods: Mature leaves of Eucalyptus robusta were collected on 24th day in each month from January to December 2012, and air-dried in the room. Ultrasonic extraction of the leaves was done with 4 solvents with different polarity, petroleum ether, dichloromethane, ethyl acetate and anhydrous ethanol. Protoscolices were incubated with the extract at various concentrations for 72 h, and mortality and median lethal dose（LC50） was calculated., Results: The extracts were different in characteristics and yield. The petroleum ether extract was in the form of black oil, while dichloromethane, ethyl acetate and anhydrous ethanol extracts were in the form of dark green, pink and white powder respectively. The average yields by petroleum ether, dichloromethane, ethyl acetate, and anhydrous ethanol were 4.4%, 2.1%, 2.3% and 2.3%, respectively. The extract yield was highest for petroleum ether, with a yield of 5.4% in May. The mortality of protoscoleces in all monthly groups of petroleum ether and dichloromethane extracts reached 100% with the concentration of 100 μg/ml and the same mortality reached in most groups of petroleum ether extracts with the concentration of 50 μg/ml. The effects of dichloromethane extracts were less than petroleum ether extracts, but significantly stronger than those of ethyl acetate and ehanol extracts. Further studies conducted on petroleum ether and dichloromethane extracts showed, the lethal effect of petroleum ether extract ranked in month of preparation from strong to weak as June>March>November>April>February>May>October>August>December>July>January>September. In June, the LC50 was 2.577 μg/ml and 95% confidence interval was 0.85-6.22 μg/ml. The lethal effect of dichlorom ethane extract ranked in month of preparation from strong to weak as November>May>October>April>July>December>June>September>August>February>March>January. In November, the LC50 was 21.85 μg/ml, and 95% confidence interval was 12.38-36.28 μg/ml., Conclusion: The Eucalyptus robusta leaves contain potential compounds against Echinococcus granulosus. Further experiments of isolation, analysis and identification are needed.

Eucalyptus is a fast-growing plant with rich activities. The roots, stems and leaves of Eucalyptus all have medicinal values. Extracts from different parts of various kinds of Eucalyptus show antiparasitic effects, not only the repelling and killing effects on ectoparasites such as ticks and mites, but also the antiparasitic activities against endoparasites such as helminth and protozoa. This paper reviews the effects of Eucalyptus extracts and their chemical componets on protozoa including flagellates, sporozoan and ciliates.

Objective: To study the metabolism of niclosamide in plasma, and the protective effect of its oral administration on Schistosoma japonicum cercarial invasion in mice., Methods: Twenty-four female Kunming mice were randomly divided into 8 groups, each with 3 mice. Each mouse was treated orally with 120 mg niclosamide per kilogram of body weight (120 mg/kg). The plasma samples were collected at 0.25, 0.5, 1, 2, 4, 8, 16, and 24 h after treatment by retro-orbital blood sampling. The blood drug concentration was determined by HPLC. The pharmacokinetics parameters were calculated such as peak concentration (Cmax), peak time (Tmax), mean residence time (MRT), and elimination half life (T½). Thirty Kunming mice were randomly divided into 6 groups. Among them, 5 groups were treated orally with 40, 80, 120, 160, and 200 mg/kg niclosamide, respectively. The remaining untreated group served as control. One hour post-treatment, each mouse was infected with 40 ± 2 Schistosoma japonicum cercariae. Another 35 mice treated with 200 mg/kg niclosamide were randomly divided into 7 groups. Mice in each group were infected with 40 ± 2 S. japonicum cercariae on 0.25, 1, 4, 8, 12, and 24 h after treatment, named as group A, B, C, D, E, and F. Five untreated mice served as control (group G). All mice were sacrificed 35 days post-infection. Mean worm burden and worm reduction were calculated., Results: At a dose of 120 mg/kg niclosamide, the blood drug concentration was (0.40 ± 0.28) µg/ml at 0.25 h post-treatment, reached a peak of (0.91 ± 0.34) µg/ml at 1 h, and decreased to (0.49 ± 0.38) µg/ml at 2 h, and got close to 0 at 16 h. The mean residence time (MRT) in mice was (6.78 ± 1.47) h, and the elimination half time was (6.80 ± 7.05) h. No significant difference was found in worm burden between different dose groups and control group (P > 0.05). The mean worm burden in group A was significantly lower than that of the control (P < 0.05) with a mean worm reduction of 79.1%. And there was no significant difference in worm burden between other groups and the control (P > 0.05)., Conclusions: The blood drug concentration increases rapidly by gavage administration of 120 mg/kg niclosamide, reaching to the maximum concentration at 1 h post-treatment. It shows a certain potective effect of oral administration of 200 mg/kg niclosamide on Schistosoma japonicum cercarial invasion at 0.25 h after treatment.

Parasitic infections, especially the gastrointestinal and lung nematode infections, are most common in livestock in temperate areas, and it is the major constraints affecting livestock production. In grazing season, outdoor activities of animals cause inconvenience to the application of antiparasitic drugs. Therefore, controlled drug delivery systems can prolong the effect time and reduce the difficulty of drug administration. This review summarizes several types of long-term delivery devices and dosage forms including intraruminal devices, long-acting injectables, in-situ forming implants, novel microparticles and nanoparticles. Their advantages and drawbacks are dicussed.

Objective: To determine the contributions of main chemical compositions of extracts of Eucalyptus camaldulensis represented by GC/MS elute peaks to the molluscicidal activities, and explore a shortcut of looking for the effective components from natural products., Methods: E. camaldulensis leaves were collected consecutively in 12 months at the same place, extracted with dichloromethane, analyzed by GC/MS, and their LC50(s) of molluscicidal activities were tested according to the method recommended by WHO. The correlation of the main components in 12 extracts and their molluscicidal activities were analyzed by the grey relative correlation analysis model with software GTMS 3.0., Result: All the dichloromethane extracts of eucalyptus leaves showed excellent molluscicidal activities with the highest LC50 of 0.257mg/L and 0.242mg/L for the samples in June and July and the lowest LC50 of 6.802 mg/L and 5.406 mg/L in December and January respectively. The structures of 16 main chemical components were elucidated by GC/MS and NIST Mass Spectral Library, most of which were monoterpenes and sesquiterpenoids. The gray correlation coefficients with activity were all over 0.5, the first five over 0.9 were 4,4, 8-Trimethyltricyclo [6.3.1.0 (1,5) ]dodecane-2,9-diol, (-)-Spathulenol, a structural isomer of (-)-Spathulenol, Eucalyptol and Ledol., Conclusion: The most main ingredients in the dichloromethane extracts of E. camaldulensis leaves show good correlations with the molluscicidal activity, which suggests that the molluscicidal role is synergistically played by the multiple components together.

Objective: To observe the ultrastructural alterations of adult Schistosoma japonicum induced by synthetic trioxolane OZ78., Methods: Eight out of ten mice infected with 40-60 S. japonicum cercariae for 35 d were treated orally with OZ78 at a single dose of 400 mg/kg. Four groups of two mice were killed at 24 h, 3 d, 7 d, and 14 d post treatment, and schistosomes were recovered by perfusion technique, fixed, and examined by transmission electron microscopy. Schistosomes obtained from the remaining two untreated mice served as control., Results: After infected mice were treated with OZ78 for 24 h, the prominent alterations in tegument of both male and female worms were observed, which revealed in flattened surface due to swelling of cytoplasmic processes, irregular expansion in distal end of cytoplasmic processes accompanied by decrease in rod-like and discoid-like secretory bodies, focal lysis of tegumental matrix; fusion of some cytoplasmic processes to form a large piece, disruption or disappearance of basal membrane, and destruction of internal structures in sensory organelles. In the subtegument, no or slight swelling and focal lysis of muscle bundles were seen, while the syncytium beneath the muscle showed enlargement of nucleus with indistinction of partial nuclear membrane, formation of small vacuoles due to focal lysis of chromatin, and emergence of degenerated mitochondria in perinuclear cytoplasm. As to parenchymal tissues, the major alterations included degeneration of mitochondria, formation of some small vacuoles and myelin-like structures. In gut epithelial cells, the prominent alterations were irregular enlargement of nucleus with light lysis of nucleoli and fusion of partial bi-layer nuclear membrane, degeneration of mitochondria in cytoplasm and collapse of microvilli. At this time point, in the vitelline cells of female worms, the most significant alteration was the collapse of many vitelline droplets, which led to release of the vitelline balls, followed by their lysis and fusion. Three to 7 d post treatment, the damage to the worms aggravated either in extent or in severity along with time. The significant damages to male and female worms were fusion of cytoplasmic processes, peeling or collapse of damaged cytoplasmic processes resulting in exposure of muscle bundles, severe destruction of sensory organelles and syncytium, focal or extensive swelling and lysis of muscle bundles, emergence of some larger piece of degenerated parenchymal tissues and severe damage to the gut epithelial cell. While in the vitelline cells of female worms, decrease in the number of vitelline droplet, focal lysis of nucleus and extensive lysis of parenchymal tissues among the vitelline cells were also observed. Fourteen days post OZ78 dosing, male and female worms which survived the treatment showed some renovation in damaged tegument and subtegument, while most gut epithelial cells and vitelline cells still revealed in prominent injury., Conclusion: The results demonstrate that OZ78 possesses an extensive damage to the ultrastructure in tegument and subtegument tissues including syncytium, parenchymal tissues, gut epithelial cells, and vitelline cells of adult S. japonicum.

Objective: To observe the change in serum levels of alanine aminotransferase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), direct bilirubin (DBL), indirect bilirubin (IBIL), albumin (ALB) and globulin (GLB), and mouse liver ultrastructure during 1-16 weeks of albendazole treatment., Methods: 180 female Kunming mice were divided randomly into albendazole treatment group and negative control group. Each mouse of albendazole treatment group was treated with 136.3 mg/(kg x d) albendazole. The mice in control group were given same amount of physiological saline. After 1, 2, 4, 6, 8, 10, 12, 14 and 16 weeks of treatment, 10 mice from each group were randomly selected, serum samples were collected and analyzed for the above seven liver function indices. Pathological changes of liver were observed by transmission electron microscopy. Linear regression analysis was conducted for the relationship between liver function indices(dependent variable) and pathological scores (independent variable)., Results: During 1-16 weeks of albendazole treatment, there was no significant difference in serum levels of DBL, IBIL, ALB and GLB between albendazole treatment group and control group. Compared with other treatment period, after 12 weeks of treatment the serum levels of ALT (55.2 +/- 23.7), AST(176.4 +/- 49.2) and ALP(141.1 +/- 19.4) in albendazole treatment group were higher than that of the control (35.5 +/- 8.6, 108.2 +/- 21.9, 84.0 +/- 24.8) (P < 0.05). After 2, 8, 10, 12 and 14 weeks of treatment, the pathological score of albendazole treatment group was 11.8 +/- 4.8, 10.6 +/- 4.8, 13.6 +/- 3.5, 29.8 +/- 10.7, and 5.6 +/- 2.5, respectively, which was higher than that of the control (0.8 +/- 0.4, 1.2 +/- 0.8, 2.4 +/- 2.0, 1.2 +/- 0.4, 1.4 +/- 1.1) (P < 0.05). Among the three liver function indices AST, ALT and ALP, AST was the best fit index for linear regression. The regression formula was Y = -17.616 + 0.188X., Conclusion: Long-term treatment with albendazole at a dosage of 136.3 mg/(kg x d) for mice can cause significant elevation of serum levels of ALT, AST and ALP, and result in mild pathological changes in the liver.

Synthesized fenbendazole prodrug N-methoxycarbonyl-N'-(2-nitro-4-phenylthiophenyl) thiourea (MPT) was analyzed in vitro in artificial gastric juice, intestinal juice and mouse liver homogenate model by using HPLC method, and metabolic curve was then generated. MPT was tested against Echinococcus granulosus protoscolices in vitro. The result showed that MPT could be metabolized in the three biological media, and to the active compound fenbendazole in liver homogenate, with a metabolic rate of 7.92%. Besides, the prodrug showed a weak activity against E. granulosus protoscolices with a mortality of 45.9%.

Prodrug strategies have been used for drug optimization to overcome the drawbacks in pharmaceutics, pharmacokinetics and pharmacodynamics. Most enzymes involved in prodrug biotransformation are hydrolases, in which esterase and amidase have been widely researched. This review summarizes the recent progress in antiparasitic prodrugs based on both targets.

Mebendazole is currently used in the treatment of hydatid disease. Its poor absorption from the gastrointestinal tract and low bioavailability aroused further research on new formulations of mebendazole to increase the bioavailability and improve the therapeutic efficacy. This review summarizes the recent research progress.