Changes in the enteric vasculature of mice infected with Schistosoma mansoni.

Mesenteric and intestinal vasculature of mice infected with S. mansoni was injected transaortically with a silicone elastomer. The mesenteries and intestines were then cleared and examined with a stereomicroscope. Marked tortuosity and dilatation of mesenteric and intestinal veins and arteries were found to be confined to areas of oviposition and were associated with small arteriovenous shunts which were not present in control animals or areas of intestine devoid of eggs. These findings suggest that splanchnic arterial-portal venous shunts add a hyperkinetic component to intrahepatic portal venous obstruction and synergistically result in portal hypertension.

Intestinal parasites of sympatric Pan troglodytes and Papio Spp. at two sites: Gombe (Tanzania) and Mt. Assirik (Senegal).

Experimental and clinical parasitology need natural baselines or "controls". We present normative data intestinal parasite loads in two genera of African primates. Wild Pan troglodytes and Papio spp. were studied at two sites: Gombe in Tanzania (P. anubis) and Mt. Assirik in Senegal (P. papio). Presence or absence of parasites, especially nematodes, was recorded from fecal specimens. Gombe's primates were more often infected than were Mt. Assirik's. At Gombe, but not at Mt. Assirik, chimpanzees seemed to have a higher incidence of infection than baboons. Comparison of three baboon troops yielded apparent differences in prevalence of infection. No differences in infection were found between the wet and dry seasons in Mt. Assirik's chimpanzees.

Probstamyria gombensis sp. n. (Nematoda: Atractidae) from the chimpanzee.

The worm is distinguished by the presence of both unequal spicules and a gubernaculum in the male and also the elongated nipplelike tip of the right spicule. P. gombensis was found to be a common parasite within a troop of feral chimpanzees living in Gombe National Park, Tanzania.

Superinfection of Biomphalaria glabrata with Schistosoma mansoni.

Biomphalaria glabrata 2 to 12 mm in diameter were exposed to 1 miracidium of Schistosoma mansoni and after 15, 30, or 60 days were reexposed to the homologous strain. The criterion of superinfection was the subsequent escape of cercariae of both sexes. Opposite sex superinfection was acquired by 45 of 106 snails of various sizes, all of which were in the group reexposed at 30 days. The observations confirm those of Kagan and Geiger and suggest that in the schistosomes a maximizing of the number of intermediate hosts with larval populations of both sexes may be an adaptation having a high species survival value.

The intestinal parasites of a community of feral chimpanzees, Pan troglodytes schweinfurthii.

Fecal specimens from 32 champanzees living in Gombe National Park, Tanzania, were examined. Six species of helminths and 2 species of ciliates were found: Probstmayris gombensis File (in press), Strongyloides fuelleborni von Linstow 1905, Necator sp., Oesophagostomum sp., Abbreviata caucasica von Linstow 1902, Trichuris sp., Troglodytella abrassarti Brumpt and Joyeux 1921, and an unidentified ciliate. None of the parasitic infections were heavy. This is the first such survey of the chimpanzee in its natural habitat.

Ultrastructure of the sporocyst wall during excystation of Isospora endocallimici.

Sporocysts of Isospora endocallimici, a parasite of marmosets, were exposed to minimal essentials medium (MEM) or a trypsin-bile salt solution (TBS) and then fixed and prepared for transmission electron microscopy. Excystation occurred in TBS but not MEM. The sporocyst wall has 2 layers, a thin outer layer (15 to 110 nm thick) and a thick inner layer (65 to 180 nm thick), which is composed of 4 separate curved plates. The outer layer consists of 1 to 3 membranes interspersed with lipid droplets. In the inner layer, a thin layer of material connects the peripheral margins of 2 apposing plates. Immediately beneath this layer, a thin strip of material is interposed between the 2 apposing plates. Ultrastructural changes preparatory to excystation occur primarily in the inner layer of the sporocyst wall. The TBS acts upon the site of apposition between 2 plates causing the interposed strip to swell and separate from the margin of each plate which leads to collapse of the sporocyst. As the sporocyst collapses, the margins of each curved plate curl inward toward the center of the sporocyst.

Electrophoretic studies on the digestive gland esterases of some biomphalarid and lymnaeid snails.

Because of the problems encountered in the classification of snails of medical importance, biochemical methods have been sought to help clarify the situation. Of these, the separation of the enzymes of adult snails by electrophoresis seems the most promising but very few attempts have been made so far to use the results for taxonomic studies. The purpose of the present study was to evaluate the use of the enzyme systems of neotropical planorbid and of lymnaeid snails to elucidate their taxonomy and also snail-schistosome relationships at the species and population levels.The findings show the characteristic electrophoretic patterns of digestive gland esterases of the planorbid and lymnaeid snails used, as well as their variation and the level of such variation among certain populations and the consistency of the patterns among others. The results also show that, in general, the extent of variation between some populations of the same species is greater than the differences between species of the same group. However, at the specific level, there are similarities suggesting close relationships between some populations of Biomphalaria glabrata and B. tenagophila on the one hand, and of certain populations of B. peregrina and of B. obstructa on the other hand.The present study has thrown some light on the question of electrophoretic variation in enzymes, and the ways in which this can be applied to studies of the genetics of snails. A correlation is suggested between certain patterns that indicate biochemical similarities or differences among the planorbid snail populations and the susceptibility of the species or the population to infection with the schistosomes.

Leprosy in wild armadillos (Dasypus novemcinctus) of the Texas Gulf Coast: epidemiology and mycobacteriology.

A significant prevalence of leprosy has been demonstrated in wild Louisiana armadillos. The Texas Gulf Coast still has endemic human leprosy, and recent mores in Texas have markedly increased armadillo-human contact. Armadillos were screened by physical examination, and by ear-snip and slit-scrape technique. Animals that screened "positive" were sacrificed and necropsied under aseptic conditions. Liver, spleen, gross lesions, and four groups of lymph nodes were cultured for mycobacteria and were studied histologically. Base ratios and DNA homology with Mycobacterium leprae were determined on mycobacteria from two armadillos (and two tissues from one of these); these studies indicate that the organism found in Texas armadillos is M leprae. Twenty-one of the armadillos were leprous--4.66%. The local prevalence varied from 1.0% to 15.4%. Epidemiologic implications of these findings and the occurrence of other concomitant mycobacterial infections are discussed.