Search

Cercariometry provided information on diurnal fluctuation, seasonal and spatial distribution of cercariae in the suitable natural water bodies. There was an apparent mismatch between the results of cercariometry and snail sampling. Water, which cercariometry showed to contain cercariae was potentially infective, although the resultant worm load of sentinel rodents may not bear a linear relationship with cercarial density. Cercariometry has some weakness in practices and analysis of data, however, it provides the valuable information on the active transmission sites of schistosomiasis.

Some field trials have already demonstrated the high antischistosomal potential of combination therapies using Artesunate (ART) and current antimalarial drugs (Boulanger et al., 2007; Mohamed et al., 2009; Sissoko et al., 2009). The antischistosomal effects of these drugs are noteworthy, especially when they are used for the treatment of malaria in schistosomiasis endemic areas. However, the antischistosomal effects of Amodiaquine (AQ), Primaquine (PQ), Chloroquine (CQ) and Pyrimethamine (Py) have never been assessed by in vitro incubation. The objective of the present study is to assess the in vitro effects of current antimalarial drugs on the egg productivity of adult worm pairs of S. mansoni and their survival times. The effect of the current antimalarial drugs Mefloquine (MQ), quinine (QN), AQ, PQ, CQ, Sulfadiazine (Sf) and Py on the egg output of adult worm pairs of Schistosoma mansoni and their survival times during in vitro culture were assessed at a concentration of 10 μg/ml. AQ, PQ, CQ and Py significantly inhibited the daily egg output of paired female worms at a concentration of 10 μg/ml during the 1 or 2-day in vitro cultivation. However, QN and Sf did not significantly affect the daily egg output during the 8-day incubation. One-day exposure to MQ killed all paired male and female adult worms. AQ and PQ significantly decreased the survival of both paired male and female worms during the 14-day incubation, but QN, CQ, Py and Sf did not exert any similar effect. The present result is consistent with an assessment of the antischistosomal effects of artemisinin-based combination therapy in malaria and schistosomiasis co-endemic areas. [ABSTRACT FROM AUTHOR]

An attempt was made to examine the long-term impact of the introduction of communal piped water supply on pattern of water use and transmission of schistosomiasis haematobia in an endemic area of Kenya. In the study area, Mtsangatamu, a control program based on repeated selective mass-chemotherapy had been carried out for 6 years from 1987 to 1993. The pre-treatment overall prevalence and intensity of infection in 1987 were 59.2% and 10.9 eggs/10 ml of urine (Muhoho et al., 1997). During the control program, the prevalence was kept at a low range of 20 to 40% (Muhoho et al., 1994). At the end of the program, in 1994, gravity-fed water supply was provided to the village. Although the water facilities were damaged by flooding in 1998, new and further expanded gravity-fed water supply facilities consisting of 7 standpipes were introduced in 2000. The follow-up survey done in 1999 revealed reduced prevalence and intensity of infection, i.e. 23.0% and 1.2 eggs/ 10 ml of urine (unpublished data). The present study was carried out in 2006, 6 years after the last mass-chemotherapy. Urine examination showed that the prevalence and intensity of infection had return to 52.2% and 7.4 eggs/10 ml, nearly the same level as the pre-treatment level. The results of our study demonstrated that, over the long-term, the gravity-fed water supply facilities had little impact on the overall prevalence and intensity of infection in this village. However, analysis of the spatial pattern of infection, observation of human water contact at the river and a questionnaire on water use shed light on the possible impact of water supply on human water contact. The younger people (5-19 years old) with easy access to the standpipes showed a lower prevalence and intensity of infection, while the relationship was not clear in other age groups. The result of the questionnaire indicated that the long distance from household to standpipe was the major factor limiting the use of the communal tap water. Most of the villagers who used piped water as the main source of water lived within 800 m of the nearest standpipe, and villagers who used river water exclusively lived beyond that distance. Observation of water-related activities at the communal water facilities also indicated that the residents who lived near standpipes used the piped water more frequently. The frequency of total visits to river water sites did not differ between residents who lived near and far from the standpipe. However, water contact in the form of playing, the highest risk behavior, was observed exclusively among children who lived far (>250m) from standpipes, although the number of observations was small. The present study demonstrated that the water facilities had little effect on the dispersed population but might have a beneficial effect on some villagers given easy access to standpipes. [ABSTRACT FROM AUTHOR]

Abstract: Experimental vaccination with radiation-attenuated cercariae (RAC) confers possible practical levels of resistance to challenge infection by humoral and by cellular mechanism. Here, we aimed to identify possible vaccine antigens by using specific IgG antibody from RAC vaccinated miniature pig. Two milligrams of soluble egg antigen (SEA) or schistosomal worm antigen preparation (SWAP) was fractionated using two dimensional liquid chromatography (proteome PF 2D) consisted of high performance chromatofocusing (HPCF) and high resolution reversed phase chromatography (HPRP). Of the 42 HPCF fractions of SEA or SWAP, 26 (61.9%) or 15 (35.7%) showed positive dot blot reaction with RAC vaccinated serum respectively. The dot blot positive fractions were applied to the second HPRP column. One hundred and seven out of 26×96 of SEA fractions and 18 out of 15×96 SWAP fractions reacted with RAC vaccinated serum. From the positive fractions we chose 17 of SEA and 10 of SWAP that had no reactivity with normal cercariae infected (NCI) sera and had single peak of 214 nm; and automated N-terminal amino acid sequence based on in situ Edman Reaction was conducted. Four sequences were obtained and applied to the homology search in NCBI database. A total of eight candidate genes were listed up and their cDNA clones from schistosomula stage were obtained. Two of the recombinant proteins (AAW27472.1 and AXX25883.1) showed strong reactivity with the RAC vaccinated serum but marginal with NCI serum. This protocol using proteome PF 2D could be applicable in identifying immunoreactive proteins from crude extract for the development of vaccines or for diagnostics. [Copyright &y& Elsevier]

As part of a search for good animal models for human schistosomiasis, two miniature pigs of the CLAWN strain (C-1, C-2) were inoculated percutaneously with 200 Schistosoma japonicum cercariae of the Chinese strain, and the subsequent infection was monitored parasitologically, pathologically and serologically. Egg excretion into feces began at 5 weeks post-infection (p.i.) and became pronounced from 8 weeks to 17–20 weeks p.i. The average number of eggs in 1 g feces of each pig at the peak period between 8 and 20 weeks were 288 and 277, respectively. C-1 and C-2 were killed and perfused at 27 and 47 weeks p.i. and adult worm numbers recovered were 35 and 15, respectively. C-2 had at least four pairs of viable mature worms but no detectable fecal eggs for a month before perfusion, suggesting that any produced eggs were not excreted into the feces during this period. Egg deposits associated with inflammatory reactions were observed by histological examination of the liver, spleen, pancreas, mesenteric lymph nodes, lung, and small intestine. This suggests that reduced fecal excretion of eggs into the feces did not correlate to reduced parasite numbers in the chronic phase of schistosomiasis. This is the first report showing the miniature pig to be a potential model for human S. japonicum infection. [Copyright &y& Elsevier]