Echinococcus Multilocularis Cysts Research Articles

Echinococcus multilocularis in the cotton rat. The effect of preexisting subcutaneous cysts on the development of a subsequent intraperitoneal inoculum of protoscolices.

Cotton rats were inoculated subcutaneousîy with small cysts of Echinococcus multilocularis and challenged intraperitoneally with 100 protoscolices 40 days later. Subcutaneous cysts which attained weights of more than about 5 g effectively suppressed the establishment, growth, and transperitoneal dissemination of the challenging infection. Normal cotton rats, inoculated intraperitoneally with 100 protoscolices, characteristically developed massive cysts which weighed, on the average, 31 g and consisted of about 31 cyst clusters. In contrast, animals which already harbored large, subcutaneous cysts developed only very mild infections following intraperitoneal reinoculation. Such hosts supported never more than two small, intraperitoneal cysts with a mean total weight of less than 1 g. The intensity of this suppression was underscored by the fact that even a single protoscolex or a small vesicle of E. multilocularis inoculated intraperitoneally into normal cotton rats could give rise to 11 g of cyst material distributed among as many as 87 cyst clusters.

Acceleration of the growth of populations and of the multiplication of tetrathyridia of Mersocestoides corti Hoeppli, 1925 (Cestoda: Cyclophyllidea) by some cytostatic agents.

Experiments with tetrathyridia of Mesocestoides corti implanted intraperitoneally into LDF1, SEC, and SWR mice showed that a single injection of cyclophosphamide, 200 mg/kg 1 day after infection, increased the total biomass of tetrathyridial populations in mice dissected 50 days later by 50 to 200%. Similar, though less pronounced, increases in the total biomass of populations were produced by dactinomycin, 0.35 mg/kg once a week, for 4 to 6 weeks. The average size of individual tetrathyridia decreased despite a considerable increase in the total biomass of their populations.The parasiticides lucanthone, which inhibits the growth of Echinococcus multilocularis cysts, and quinacrine, which is inactive in this respect, accelerate the growth of the biomass of tetrathyridial populations much less than the cytostatic agents cyclophosphamide and dactinomycin.

Attempts at chemotherapy of Echinococcus multilocularis infections in rodents.

Attempts were made to inhibit the growth of vegetatively propagated Echinococcus multilocularis cysts in mice by using two antischistosomals, two antimalarials, two organophosphorous parasiticides, and one cytostatic, cyclophosphamide. Of these only the latter and lucanthone inhibited the growth of cysts; 7 to 14 injections of 100 mg/kg of lucanthone inhibited it by 30 to 60%. A single injection of cyclophosphamide, 200 mg/kg, 1 week after infection, inhibited the growth by 75 to 90%. This retardation was still apparent 3 months after the injection of cyclophosphamide.

Cyclophosphamide and the survival time of mice infected with Echinococcus multilocularis cysts

One injection of cyclophosphamide, 200 mg/kg, given to LDF1 mice 1 week after the intraperitoneal implantation of Echinococcus multilocularis cysts, prolonged the survival time of females by about 30%, and that of males by over 50%. An additional injection of this drug, 100 mg/kg, 1 month after the first injection, did not further prolong survival.

Preparation and Evaluation of Antigens for Use in the Serologic Diagnosis of Human Hydatid Disease

Summary Two of the parasite antigens identified in sheep hydatid fluid were demonstrated in extracts of Echinococcus multilocularis cysts. Serologic reactivity of the crude extract and fractions of the antigen appeared to be associated with the presence of at least one of these components. Fractionation of Emc antigen by a column chromatographic method in which the antigen was cycled through a G-50 Sephadex column followed by a cycle through a long G-200 Sephadex column separated measurable amounts of nonspecific proteins, but did not “purify” the parasitic material. Gel-diffusion showed the most serologically reactive fraction (M200A) to contain at least five of the nine components in the original crude extract. The antigenic fraction M200A was stable and reacted with the same degree of sensitivity and specificity as SHF antigen in the HA test for the diagnosis of hydatid disease.

SOME PRELIMINARY OBSERVATIONS ON THE DEVELOPMENT OF ECHINOCOCCUS IN VITRO

A variety of media and techniques has been employed in attempts to grow various stages of Echinococcus in vitro. Whole, intact Echinococcus multilocularis cysts and undifferentiated cystic material proliferate readily in chemically defined media, but except for a single occurrence, no scoleces developed within the new vesicles. Scoleces can be induced to develop either toward the tapeworm stage or the vesicular larval stage by altering the medium. In the first case, the scoleces increase in size, the excretory system becomes prominent, and segmentation is advanced; gonads have not developed in any medium yet employed. Scoleces may vesiculate in several ways; ultimately, they become vacuolated, the suckers are absorbed, the hooks shed, and a thin, laminated membrane is laid down. Local internal thickenings probably represent secondary brood capsules or scoleces.