Chemical ovacidal measures as applied to Taenia hydatigena, Taenia ovis, Taenia pisiformis, and Echinococcus granulosus

Production of monoclonal antibodies for the identification of the eggs of Taenia solium

Two antibodies, one monoclonal and one polyclonal, were produced and used to identify Taenia solium eggs, using the enzyme-linked immuno-electrotransfer blot technique (EITB). Different life-stages of Taenia solium and T. saginata, including eggs from gravid proglottids recovered, post-treatment, from patients infected with the tapeworms, and eggs of Diphyllobothrium pacificum and Hymenolepis nana from other patients were tested with these antibodies. The monoclonal antibody only recognized the eggs and immature proglottids of T. solium. The polyclonal antibody, however, not only reacted with the eggs, cysticerci and immature proglottids of T. solium but also with the eggs and immature proglottids of T. saginata. The sensitivity and specificity of the EITB were both 100% using the monoclonal antibody but only 78% and 60%, respectively, using the polyclonal antibody. Diagnostic bands for T. solium eggs corresponded to proteins of 22.5 kDa using the polyclonal antibody and 22.5-37 kDa using the monoclonal antibody. Species-specific fluorescence was obtained with an anti-T. solium monoclonal antibody which bound to egg-derived oncospheres of T. solium but not to those of T. saginata.

Influence of environmental factors on the infectivity of Echinococcus multilocularis eggs

The sensitivity of eggs of Echinococcus multilocularis to environmental and controlled laboratory conditions was tested. Egg material was exposed and the infectivity was subsequently monitored by in vitro activation and by oral infection of the natural host, Microtus arvalis. To study the impact of environmental conditions in an endemic area of south-western Germany, eggs were sealed into bags of nylon mesh and exposed to the natural climate during various seasons. The maximal survival time of eggs was 240 days in an experiment performed in autumn and winter and 78 days in summer. A study of the tenacity of eggs under laboratory conditions revealed a high sensitivity to elevated temperatures and to desiccation. At 45 degrees C and 85-95% relative humidity the infectivity was lost after 3 h as well as after 4 h exposure to 43 degrees C suspended in water. Exposure to 27% relative humidity at 25 degrees C as well as exposure to 15% relative humidity at 43 degrees C resulted in a total loss of infectivity within 48 and 2 h, respectively. Temperatures of 4 degrees C and of -18 degrees C were well tolerated (478 days and 240 days survival, respectively), whereas exposure to -83 degrees C and to -196 degrees C quickly killed off the eggs (within 48 h and 20 h, respectively). Eggs of E. multilocularis were not killed off by exposure to various commercially available disinfectants applied according to the manufacturers' instructions and by exposure for 24 h to low concentrations of ethanol. Irradiation with 40 krad. from a 137Caesium source prevented the development of metacestodes but allowed seroconversion of infected rodents.

Hydatidosis and cysticercosis: the dynamics of transmission

The infective pattern of taeniids in their intermediate hosts is determined by the complex interaction of parasite- and host-related factors. Many of these have been examined in this review, but particular emphasis has been placed on environmental factors that affect the free-living egg. While number, infectivity and distribution of eggs are among the important factors determining the infective pattern, the dynamics of this aspect of transmission have been previously neglected. The biotic potential of the large taeniid tapeworms is enormous. Eggs deposited on pasture are subjected to the microclimatic effects of the environment. They seem to tolerate a relatively wide temperature range. Heat down to -30 degrees C. However, they are rapidly killed by low humidity at all temperatures. Under more favourable conditions, they have finite life spans largely determined by the environmental temperature. At deposition, the egg population seems to be at various stages of maturity. Immature eggs appear to be able to mature under suitable environmental conditions and to become infective. They then age, and their infectivity to the intermediate host declines. At the population level, the changes in infectivity with time are determined by the relative stages of maturity within the egg population and the temperatures that it experiences. Under certain circumstances the infectivity of a given population may increase temporarily. The movements and defaecation habits of the definitive host determine the primary site of egg deposition. However, evidence is accumulating that considerable dispersion occurs almost immediately afterwards. Eggs have been shown to disperse up to 80 m within 10 days and there are indications that small numbers travel much further. Intermediate hosts, such as cattle and sheep, generally avoid grazing areas contaminated with faeces. Thus, dispersal enhances the chance of the eggs being ingested. The combination of high biotic potential and long-range dispersal means that individual infected definitive hosts can be responsible for infecting intermediate hosts over a very wide area. Although various possible agents have been suggested, the mechanisms responsible for disseminating eggs are still uncertain.(ABSTRACT TRUNCATED AT 400 WORDS)

[Hatching And Activation Of Some Cestode Ova: The Effects Of Various Artificial Hatching-Activating Solutions Upon The Some Cestode Ova]

The effects of various digestive enzymes, fresh biles, and bile acids on the hatching and activation of the eggs of Taenia saginata, T. pisiformis, T. solium, Hymenolepis nana, and Moniezia expansa have been investigated. On the basis of the results of the present study author attempted to elucidate the specificity of host-parasite relationships in the tapeworm infections. The results were summarized as follows: 1)In case of the ova of T. saginata, pretreatment with artificial gastric juice before contact of intestinal juice is required to bring the disintegration of the embryophore and activation of the embryo. However the ova of T. solium and T. pisiformis may be disintegrated and activated directly into the artificial intestinal juice without the above pretreatment. Among the digestive enzymes applied in this experiment, trypsin was found most effective on the hatching. 2)No hatching of the ova of H. nana and M. expansa was observed in the above artificial hatching-activating solutions. 3)The fresh biles and bile salts were more effective on the hatching and activation of Taeniid ova than sodium taurocholate and sodium deoxycholate. 4)It is turned out that the digestive enzymes or bile acids in the intermediate hosts may, not apparently be essential factor of determining the specificity of host-parasite relationships.