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A field trial was carried out in West Java to investigate the potential for control of fasciolosis of antagonism between larvae of Fasciola gigantica and Echinostoma revolutum in Lymnaea rubiginosa. The trial was undertaken in 26 farmers' irrigated rice fields, each chosen because it was adjacent to a cattle pen the effluent from which flowed into or was used as fertiliser in the rice field. Fourteen of the fields chosen at random were retained as controls and received no treatment while in 12, faeces from 5 to 15 ducks containing eggs of E. revolutum were introduced to the rice from a duck pen located over the effluent drain from the cattle pen before it emptied into the adjacent rice field, or at the site bovine faeces was added to the field as fertiliser. After harvest significantly fewer L. rubiginosa were found infected with F. gigantica in fields where duck and cattle dung entered the field together than in control fields, supporting a conclusion that this method of biological control would reduce the infectivity of rice fields fertilised with bovine dung (which are those with the highest potential for being a source of infection with F. gigantica). Positive features of using dung from ducks infected with E. revolutum to control F. gigantica are the minimum additional work and disruption to existing farming practices required to implement the scheme, the common natural infection with E. revolutum in village ducks, and effectiveness of dung from 5 to 15 ducks, a number commonly kept by farmers. 相似文献
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This paper describes a method for counting eggs of F. gigantica in bovine faeces that optimizes the proportion of eggs recovered and the repeatability of estimates. The method uses 3 g
of faeces suspended in 0.05% Tween 20. The suspension is passed through three 6 cm diameter sieves in tandem to remove fibrous
debris, with respective apertures of 1 mm, 450 μm, and either 266 or 200 μm. The filtrate is allowed to sediment for 3 min
in a conical flask; the sediment is recovered, then resuspended in 200 ml of 0.05% Tween 20 and allowed to sediment. After
3 min the sediment is washed in a sieve with an aperture of 53 μm, which retains the eggs. Eggs suspended in 15 ml of 1% methylene
blue are counted using a dissecting microscope. Use of Tween 20 instead of water as the suspending agent for faeces gave a
significant threefold increased the proportion of eggs recovered and reduced variability between repeated counts. This method
is able to detect about one-third of the eggs present. It was concluded that the high proportion of F. gigantica eggs lost may be due to the presence of hydrophobic and covalent bonds on the eggs that bind them to debris, with which they
are discarded. 相似文献
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Eggs of F. gigantica were placed in dung heaps that were located in the shade or exposed to sun light, and examined at intervals for up to 14
weeks. The rate and extent of decline in viability of eggs was greater in dung exposed to sun light than in shaded dung. This
difference was attributed the higher temperature in dung in sun light, owing to the effect of direct sunlight and to a higher
rate of fermentation in exposed than in shaded dung. It was concluded that strategies for storing dung that would reduce the
risk it poses for infecting L. rubiginosa with F. gigantica when used as fertilizer in rice fields include storing dung in sun light rather than in the shade, preferably in a thin layer
to allow sunlight to heat and desiccate it, and mixing a carbohydrate with the stored dung to increase heat through fermentation. 相似文献
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Studies were undertaken on the viability of the metacercariae of Fasciola gigantica when stored in water at 13˚C for periods up to 23 weeks, exposed to the sunlight for up to 8 h or stored at a range of temperatures and humidities for
up to 10 weeks. Excysted metacercariae were catergorized microscopically as viable (motile and undamaged), dubious (not motile
and undamaged) or dead (visible necrosis). The infectivity of viable and dubious metacercariae and unselected reference metacercariae
held in water at 7˚C for 20 days or longer was assessed by comparing numbers of flukes recovered from infected Merino sheep. Mean recovery rates
were 54.6%, 7.2% and 37.2%, respectively, for viable, dubious and unselected metacercariae. Metacercariae immersed in water
remained viable longer than those allowed to desiccate. Viability was promoted by decreasing temperature and increasing humidity.
Exposure to direct sunlight killed metacercariae within 8 h. Results indicated that in lowland Indonesian irrigated rice paddies,
metacercariae immersed in water are likely to survive for less than 5 weeks while those that become desiccated will survive
less than 2 weeks. This information, together with the option of exposing fresh rice stalks to direct sunlight before feeding
them to livestock, can assist farmers in reducing infection with F. gigantica. 相似文献
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Suhardono S. Widjajanti P. Stevenson I. H. Carmichael 《Tropical animal health and production》1991,23(4):217-220
Summary The efficacy of triclabendazole (TCBZ) against natural infections with Fasciola gigantica was evaluated in a field study using
102 Indonesian cattle. The animals were divided into two groups; one received TCBZ at 12 mg/kg orally every eight weeks for
one year while the other remained untreated. Relative to controls theFasciola faecal egg count in treated animals was significantly reduced (P<0·01) to almost zero at all observations. There were no
differences between the groups in blood values and body mass gain. Plasma glutamate dehydrogenase (GLDH) levels in treated
animals were reduced to within normal values, whereas those in controls remained above normal throughout. Although plasma
gamma glutamyl transferase (GGT) levels remained within the normal range in both groups they were consistently higher in control
than in treated animals. However, both GLDH and GGT levels in control animals were considerably lower than those reported
by others in experimental low-level chronic fasciolosis, which suggests that only mild liver damage was caused by small numbers
ofF. gigantica in these animals. In addition to considerations of disease prevalence and economic data from abattoirs, control strategies
for fasciolosis in Indonesian cattle require an evaluation of losses due to subclinical disease.
Resumen Se evaluó en el campo, la eficacia de triclabendazole (TCBZ) contra infecciones naturales conFasciola gigantica, utilizando 102 bovinos indonesios. Los animales se dividieron en dos grupos; uno recibió TCBZ en dosis de 12 mg/kg oralmente cada ocho semanas por un a≈no, mientras que el otro permaneció sin tratamiento. En comparación a los controles, los conteos de huevos de fasciola en los animales tratados se redujeron significativamente (P<0·01), hasta casi cero en todas las observaciones. No hubo diferencias entre los grupos en cuanto a valores sanguineos y ganacia de peso. Los niveles plasmáticos de deshidrogenasa glutámica se redujeron a valores normales en los tratados, mientras que en los controles permanecieron por encima de los valores normales. Aunque los valores plasmáticos de gama glutamil transferasa permanecieron dentro de los valores normales en ambos grupos, éstos fueron consistentemente mayores en los controles que en los tratados. Sin embargo, ambos niveles enzimáticos en los animales controles, fueron considerablemente más bajos que aquellos informados por otros investigadores, en fascioliasis crónica de nivel bajo, lo que sugiere que solamente se produjo un da?o hepático menor en estos animales experimentales. La fascioliasis en Indonesia requiere una evaluación de las pérdidas debido a la enfermedad subclínica.
Résume L'efficacité du triclabendazole (TCBZ) contre les infestations naturelles àFasciola gigantica a fait l'objet d'une évaluation sur le terrain portant sur 102 bovins ceux-ci ont été divisés en 2 groupes, l'un recevant le TCBZ à la dose de 12 mg/kg par voie orale toutes les 8 semaines pendant un an, l'autre restant non traité, à titre de témoin. En ce qui concerne les contr?les, le nombre d'oeufs deFasciola chez les animaux traitès a baissé de fa?on significative (avecP<0,01, atteignant presque 0 pour toutes les observations). On n'a noté aucune différence entre les deux lots quant aux valeurs hématologiques et au gain corporel global. Les niveaux plasmatiques de la déhydrogénase du glutamate (GLDH) sont descendus chez les animaux traités au dessous des valeurs normales, alors que chez les animaux témoins ils se sont constamment maintenus au dessus. Quoique les taux plasmatiques de la gamma glutamyl-transférase (GGT) soient restés á l'intérieur des variations normales dans les 2 groupes, ils ont été régulièrement plus élevés dans le lot témoin que dans le groupe traité. Cependant les 2 niveaux (GLDH et GGT) chez les animaux témoins ont été considérablement moins élevés que ceux indiqués par d'autres auteurs dans la fasciolose chronique experimentale de faible intensité, ce qui montre queF. gigantica en petit nombre a causé seulement une légére atteinte hépatique chez ces animaux. En complément des considérations relatives à la prévalence de la maladie et aux données économiques recueillies dans les abattoirs, les stratégies de lutte contre la fasciolose bovine en Indonésie passent par une évaluation des pertes consécutives aux aspects subcliniques de la maladie.相似文献
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