It was determined to examine whether rats injected with non-viable oncospheres of Asian Taenia or Taenia saginata became resistant to challenge infection with eggs of Taenia taeniaeformis, since (a) metacestodes of Asian Taenia and T. taeniaeformis develop in the liver of pigs and rats, respectively, and (b) Asian Taenia and T. saginata have human origins. Rats injected intravenously or subcutaneously with complete Freund's adjuvant with non-viable oncospheres of Asian Taenia showed statistically significant resistance to challenge infection with eggs of T. taeniaeformis, whereas those injected with non-viable oncospheres of T. saginata did not show any resistance.

In order to establish a simple means of handling eggs of taeniid cestodes under non-biohazardous conditions, gravid segments of Taenia taeniaeformis were fixed in ethanol or formalin or were frozen. In vitro hatching of oncospheres was carried out by the 0.5% sodium hypochlorite method using eggs isolated from the nonviable and viable segments. No oncospheres hatched from formalized eggs, whereas almost all oncospheres hatched from all other eggs but the number of oncospheres recovered was highly variable. Oncospheres hatched from eggs isolated from frozen segments were highly fragile. The highest figures for in vitro hatching of oncospheres were recorded when eggs isolated either from segments fixed in 70% ethanol or from viable segments were used.

The ultrastructure of the reproductive system of adult male Trichinella spiralis has been examined, particularly to assist in recent advances such as the localization of target antigens of protective immunity and the mode of immune attack. The male reproductive system consists of a single tube with a hairpin-like bend, composed of a basal lamina, epithelial cells, rachis, circumferential and constrictor muscles, and germinal cells. The organs were surrounded by basal lamina and haemolymph. Germinal cells in different stages of maturation were found on the wall of the testis along its entire length. As the maturation of germinal cells proceeded, the cells moved towards the lumen of the testis. The germinal cells had a row of vesicles (cup-shaped structures) at the cell periphery. The mature sperm, lacking flagella and an acrosome, were stored in the seminal vesicle. The cytoplasm of the epithelial cells of the seminal vesicle and ejaculatory duct was filled with distended rough endoplasmic reticulum (rER) and exocrine granules which appeared homogenous and of medium electron density. The granules appeared to discharge to the lumen.

Angiostrongylus vasorum infection was detected for the first time in eight foxes (Dusicyon vetulus) captured in the south of the State of Minas Gerais, Brazil. Two crossbred dogs were successfully infected orally with larvae from the foxes' faeces.

The migratory route of Toxocara canis in the mouse includes two phases: a hepato-pulmonary phase and a myotropic-neurotropic phase. A study was made of the migratory behaviour of larvae one year post-inoculation (p.i.) comparing the results to those obtained at the end of an initial experiment (day 63 p.i.). The larval distribution per organ was already definitive at 9 weeks p.i. The total parasitic load showed a reduction when the experiment was prolonged for one year.

A previously reported recombinant λ Ts39 fusion protein (FP) derived from Trichinella spiralis larvae was purified by affinity chromatography using an anti-β-galactosidase antibody conjugated column and the effect of FP on induction of a protective response in mice was studied. BALB/c mice were injected three times at weekly intervals with FP emulsified in an equal volume of Freund's complete adjuvant and one week after the last injection mice were each challenged with a lethal dose of 1200 L1 larvae of Trichinella spiralis. As a result, the FP induced significant protection. Mice were also infected orally with 250 L1 larvae each after injection of the FP. On the 35th day of infection, immunized mice with the FP harboured 78% fewer muscle larvae than saline controls. Also, the numbers of adult worms in the small intestine were smaller in FP injected mice than saline controls on day 6 and 9 of the infection. These results suggest that the recombinant λ Ts39 FP is a potentially valuable antigen for vaccine development.