Various mammals were evaluated as experimental models of adult Taenia solium. Suppressed and nonsuppressed hosts were used as experimental models. Infections were performed per os with cysticerci obtained from pigs; immunosuppression was induced with methyl prednisolone acetate at intervals of 10-14 days after infection. Tapeworms developed in hamsters, gerbils, and chinchillas but failed to develop in rabbits, cats, pigs, and rhesus monkeys. In infectable animals, treatment with the steroid facilitated maintenance and development of the parasite, and more tapeworms were obtained. Mature and some pregravid proglottids were recovered from hamsters and gerbils, whereas a gravid T. solium was obtained from a chinchilla at 12 wk postinfection. Eggs recovered from the chinchilla transformed into cysticerci in a pig 12 wk after oral infection. The T. solium-chinchilla experimental system seems to be an alternative definitive host for this parasite and thus the basis for a great diversity of studies.
Abstract. To determine markers of Taenia solium transmission and risk factors in an urban community, we studied 1,000 soldiers from a military camp in Mexico City and their relatives. Serum samples were used to detect antigens and antibodies and fecal specimens were examined for Taenia coproantigens and helminth eggs. Prevalences of 12.2% and 5.8% for cysticercosis were found among soldiers and their relatives, respectively. Taeniasis was found in 0.5% and none of the groups, respectively. Relatives of soldiers positive for cysticercosis and taeniasis markers ate more pork from street stores than restaurants or markets compared with relatives of soldiers without these indicators of infection. Also, 12.0% of the relatives of positive soldiers had a history of expelling tapeworm proglottids in the feces in contrast to 3.7% of the family members of the control group. Prevalence values and risk factors in this urban population are similar to those of previous studies performed in rural populations.Taeniasis and cysticercosis caused by the tapeworm Taenia solium are prevalent in humans in many developing countries of Latin America, Africa, and Asia that lack proper sanitary infrastructure and adequate hygienic conditions. 1,2 As a result of migration from endemic areas, an increase in neurocysticercosis cases has also occurred in developed countries. 3 Human neurocysticercosis is a disabling and occasionally fatal disease.
Cysticerci of Taenia crassiceps reproduce asexually by exogenous budding in the rodent intermediate host, and can experimentally develop to the adult stage within the small intestine of golden hamsters. In the present study, we report the loss of cysticercus infectivity for hamsters after maintaining the strain for 4 yr by consecutive peritoneal passage in mice. Larval infectivity was restored after a cysticercus from the WFU strain developed into a gravid tapeworm after being passaged through a dog. The eggs of this tapeworm were infective for mice, which subsequently developed cysticerci with renewed capability for infecting experimental hamsters. An in vitro evagination assay was also conducted using eleventh-generation WFU strain cysticerci, as well as second- and fourth-generation dog-derived cysticerci. Significantly higher (P < 0.0001) evagination was observed for 5-mo-old dog-derived and WFU infrapopulations when compared with respective evagination values for 9- and 12-mo-old infrapopulations. The extent of evagination was linked to the capacity of cysticerci to infect hamsters, so that greater evagination resulted in a higher infectivity for hamsters and vice versa.
Experimental infections in golden hamsters with viable Taenia solium metacestodes were used to study by light and electron microscopy the implantation site of the adult tapeworm in the intestinal wall. Implantation sites from 3-, 4-, 10-, and 40-day infections were located in the upper third of the duodenum, excised and fixed in Zenker's or Karnovsky's solution, embedded in Polybed resin, and sectioned longitudinally to observe the position of the worm on the intestinal wall. The scolex of the tapeworm was situated between host villi, with the rostellum penetrating the intestinal wall and the suckers entrapping adjacent villi. Serial sections through several whole implantation sites revealed that the worm was anchored to the host by all 4 suckers simultaneously, each of which was located at a different level and had entrapped intestinal villi in its cavity. Host tissue within the suckers was damaged, exhibiting various degrees of cell lysis and necrosis of epithelial and submucosal cells. The tegumentary surface and microtriches of the scolex were well preserved, with occasional coalescence of tegumentary microvesicles in 10- and 40-day-old infections; microtriches were in direct contact with the damaged host tissue. This study is the first morphological and ultrastructural description of the attachment of T. solium to the intestinal wall employing an experimental model, the results of which may contribute to a better understanding of the biology of human tapeworm infections.
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