[Role of goat in transmission of schistosomiasis japonica III Effect of temperature and humidity on survival of eggs in goat feces and egg survival in natural environments].

OBJECTIVE: To investigate the survival of Schistosoma japonicum eggs in goat feces in natural marshlands and the factors affecting its survival, so as to provide evidences for understanding of the role of eggs in goat feces in the transmission of schistosomiasis and the development of the interventions pertaining to disease control and elimination. METHODS: The goat animals of schistosomiasis japonica were modeled in laboratory, and the feces of infected goat were collected. In laboratory, the effects of environmental temperature and water content in goat feces on egg hatching were evaluated, and in the field, the effect of duration of goat feces on marshland on egg hatching and the effect of direct sunshine on egg survival were evaluated. RESULTS: At 25°C in laboratory, the hatching rate of eggs in goat feces washigh-positively correlated with the water content in goat feces (r = 0.87). If the water content reduced to 7.6% in goat feces, the eggs in goat feces lost the ability to hatch. Under the same water content in goat feces, the hatching rate of eggs gradually decreased with the extension of the duration of exposure of goat feces to -5 °C, which reduced to 0 following 5 h exposure. At 5, 15 and 25 °C, the hatching rates of eggs gradually decreased with the extension of the duration of exposure of goat feces, and themiracidium hatching ratesof eggs were 2.3%, 5% and 0.9% respectively following the exposure for 52 d. At 35°C, the hatching rate of eggs gradually decreased with the extension of the duration of exposure, which reduced to 0 following 13 d exposure. In winter (-2-10 °C), the hatching rate of eggs gradually decreased with the extension of the duration of exposure of goat feces on marshlands, which reduced to 0 after 21 d of exposure, and in spring (16-19 °C), the hatching rate of eggs gradually decreased with the extension of the duration of exposure of goat feces on marshlands, which reduced to 0.9% after 5 d of exposure. At the same time point on the same marshland, the hatching rate of eggs in goat feces exposed to marshlands with direct sunshine was lower than that without direct sunshine. CONCLUSIONS: The survival of S. japonicum eggs in goat feces is associated with environmental temperature and water content (humidity) in goat feces, and the temperature and humidity are major natural factors affecting egg hatching.

[Role of goat in transmission of schistosomiasis japonica III Environmental contamination by goat feces and prediction of environments at high risk of S. japonicum infection].

OBJECTIVE: To quantitatively estimate the range and area of environmental contamination by the feces of Schistosoma japonicum-infected that were freely grazed, so as to provide the theoretical evidence for the scientific assessment of the role of the freely grazed goat in the transmission of schistosomiasis japonica and development of control strategy. METHODS: All the fecal samples excreted by the infected goat at daytime (12 h) were collected by using a self-made goat fecal collector, weighed and counted. The quantity and dispersal of the feces excreted by the freely grazed goat at daytime under a natural condition were investigated, and the walking route and speed of the freely grazed goat at daytime were recorded with a multifunction GPS data logger. The maximum range and area of the environment contaminated by the feces of the freely grazed goat at daytime were estimated, and the maximum range and area of the Oncomelania hupensis snails that may be infected by the schistosome miracidium released from the eggs in the fecal samples of the freely graze goat at daytime were calculated. RESULTS: During the walking along the marshland at daytime (12 h), the quantity of the feces execrated by the freely grazed infected goat was (232.8 ± 39.8) g per goat, and the fecal samples were composed of (819.2 ± 152.1) pellets. The goat had a mean walking speed of (0.522 7 ± 0.099 7) km/h, and the longest distance, largest radius and largest range of walking activity were (6.272 4 ± 1.195 8) km, 3.136 2 km and (3 191.113 0 ± 1 189.709 4) hm2 at daytime, respectively. The area of the snails that may be infected by the miracidium released from the eggs in the fecal samples of the freely graze goat (range of key regions for infected snails detection and control) at daytime was estimated to be (3 210.717 5 ± 1 190.907 3) hm2. CONCLUSIONS: The intensity of environmental contamination by the eggs in the fecal samples of the freely grazed goat is linked to the number of infected goat. The contamination range caused by the feces of the freely grazed goat with fixed fences is relatively stably kept within the walking range at day-time, and the range and area of goat fecal contamination is associated with the number of households that breed goat and the distribution of goat fence. The area of the snails that may be infected by the miracidium released from the eggs in the fecal samples of the freely graze goat is larger than the area of setting contaminated by the eggs in the goat feces, indicating that the range of infected snail examination and control is larger than the range of goat feces detected.

[Role of goat in transmission of schistosomiasis japonica III Development of goat feces collector and optimization of fecal hatching technique].

OBJECTIVE: To develop a simple, feasible goat feces collector to improve the collection accuracy and integrity of goat fecal samples without pollution, and to modify the miracidium hatching test with a plastic tube to achieve simple, standard and comparative procedures, so as to provide technical support for pathogenic diagnosis and scientific research of goat schistosomiasis japonica. METHODS: According to the body features of goat in marshland regions, a goat fecal collector, which was made of coarse fabric cottons, was devised, which was able to be fixed onto the goat buttocks and avoid urine pollution. Prior to miracidium hatching test, the goat fecal samples were pieced by using a mechanical method instead of the conventional artificial piecing method, and the effect of mechanical piecing treatment on miracidium hatching was evaluated. A filter membrane was added between the tube and rubbery ring to block the floater in fecal residues into the tube. The effects on miracidium hatching by using thin fat-free cotton, thick fat-free cotton, nylon gauze at 100 pores/25.4 mm2 and 150 pores/25.4 mm2 were compared. RESULTS: The goat feces collector was composed of foreleg fixing garment, hindleg fixing garment and stool bag. The functions of the fixing garment were as a fixed collector to allow non-shift and tolerance of weight during goat activity, while the major function of stool bag was in storage of stool. The goat activity did not affect by the use of collector, and all fecal samples were excreted to the bag. This collector was easy to perform and could avoid urine pollution, which was reusable after cleaning. Prior to miracidium hatching, the goat fecal samples, together with water, were pieced at 18000 to 23000 r/min for successive three times in a cooking machine, of 10 s each time at an interval of 5 s. Mechanical piecing had no clear-cut effect on miracidium hatching of eggs in fecal samples. A total of 541, 620, 344 and 211 miracidia were detected by using the miracidium hatching test with nylon gauze at 100 pores/25.4 mm2 and 150 pores/25.4 mm2, thin fat-free cotton and thick fat-free cotton respectively, indicating a better detection efficacy by using nylon gauze at 100 pores/25.4 mm2 and 150 pores/25.4 mm2. CONCLUSIONS: The goat fecal collector is a easy-to-perform, accurate, unpolluted and reusable device to collect goat feces, which is suitable for pathogenic diagnosis of goat schistosomiasis. Mechanical piecing and use of nylon gauze at 150 pores/25.4 mm2 allow a simple, accurate and stable technique for parasitological diagnosis of schistosomiasis japonica, which provides a reliable tool for schistosomiasis control and research.

[Role of goat in transmission of schistosomiasis japonica â £ Schistosome development in goat and egg count and distribution in goat feces].

OBJECTIVE: To describe the growth and development of Schistosoma japonicum in goat and the intensity and temporal distribution of eggs excreted by goat feces, so as to provide baseline data for the control and elimination of the role of goat in the transmission of schistosomiasis. METHODS: The goat animal models of schistosomiasis were established, and stool samples were collected for parasitological examinations. The number of adult worms recovered, variation of schistosomes in goat at different time points post-infection, number of eggs in schistosomes, variation in number and temporal profiles of eggs excreted from goat feces were observed. RESULTS: Of the 6 schistosome-infected goat, 415 adult worms were recovered, with a mean adult worm recovery of 34.58% (range, 23.00% to 45.50%). Among the 5 goat infected with 200 cercariae each, 47, 93, 77, 74 and 73 adult worms were recovered 2, 5, 8, 11 and 14 months post-infection, respectively. There were (200.00±42.33), (226.20±45.88), (168.20±25.85), (183.80±55.13) and (190.80±53.53) eggs detected in female schistosomes. The mean prepatent period of eggs excreted by 10 infected goat was (37.7±3.02) d. From 2 to 14 months post-infection, 7 batches of goat feces were hatched, and there were 30, 23, 14, 1 and 2 times for miracidium intensity of "++++", "+++", "++", "+" and "-", respectively, with 42.86%, 32.86%, 20.00%, 1.43% and 2.86% constituent ratios of miracidium intensity. CONCLUSIONS: Approximately 1/3 S. japonicum cercariae may develop to adults in goats post-infection, and the prepatent period of eggs is (37.7±3.02) d. There is no remarkable decrease seen in the number of adult worms, eggs in female schistosomes and eggs in goat feces within 14 months post-infection. Our findings suggest a long duration for infected goat in the transmission of schistosomiasis, and there is no evidence to prove the "self-cure" phenomenon in goat, indicating that goat is an important source of infection for schistosomiasis japonica.