Sera of Sudanese patients with active infections of Schistosoma mansoni or S. haematobium were tested in immunoblots for their reactivity with Mr31/32 000 proteins of adult S. mansoni (Sm31/32). All sera from patients with intestinal (n=123) and all but one from those with urinary schistosomiasis (n=35) had antibodies against Sm31/32. These and additional data suggest that both specificity and sensitivity of Sm31/32 to detect schistosome infections are close to 100%. Antibodies against these proteins developed also in monkeys after experimental infection with S. haematobium. Sm31/32 antigens reacted in immunoblots as a doublet with most S. haematobium-patient sera and as a broad band with many S. mansoni-sera suggesting that at least two components are present in the molecular weight region of Mr31/32 000. The data demonstrate the potential use of Sm31/32 from adult worms to diagnose patients with intestinal or urinary schistosomiasis in endemic areas.

An average of 11% of adult Schistosoma curassoni were recovered from 200 albino mice which had been infected subcutaneously with 150–250 cercariae. Worms were primarily found in the portal veins. The average number of intrauterine eggs per female during the first 100 days p.i. was 13 and the average number of eggs produced per female worm was 103 per day for the first 60 days post oviposition. The majority of eggs were recovered from the liver (98·3%). The oograms were determined until day 95 p.i. For screening of antischistosomal drugs it is recommended not to use infections older than 60 d.p.i.

Faecal cultures were established using bovine faeces containing known numbers of eggs from either Oesophagostomum radiatum, Haemonchus placei, Cooperia pectinata or a mixture of all three. A substantially greater percentage of larvae was recovered from cultures of O. radiatum and C. pectinata than was recovered from cultures of H. placei. The same pattern was observed in mixed cultures although yields of larvae from all species in mixed cultures were significantly reduced (p<0·001). The lower recovery of H. placei was not associated with a lower viability of H. placei eggs. Of the three different methods of harvesting larvae, the jar and mesh recovery technique was the least effective and significantly fewer larvae were recovered with this technique than with the Baermann and inversion techniques (p<0·05). The results are discussed with reference to the use of faecal culture and larval differentiation in the diagnosis of mixed species nematode infections of cattle.

The consequences of previous and concurrent infection with two related species of cestodes, Hymenolepis nana and H. diminuta, were studied in CD1 mice. A H. diminuta infection strongly affected the establishment and the survival of a secondary H. nana egg or cyst infection administered 30 days later. An infection of 20 H. nana eggs strongly protected against a 5-cyst H. diminuta challenge, whereas an infection of 10 H. nana cysts was ineffective; 20 H. nana eggs also protected against a challenge with 5 cysts of H. diminuta administered 5 days later. No effects were observed in either parasite during a concurrent infection established by administration of cysts. An H. nana egg-infection was unable to affect the establishment of a secondary H. nana cyst-infection given 1 month later; however a significant decrease in growth was found. Similar results were found when a primary H. nana egg-infection was followed 5 days later by the homologous cyst-infection. But an infection with 5 H. nana cysts was unable to protect against a homologous challenge of 5 cysts or 20 eggs. The reciprocal cross immunity between the heterologous parasites and the failure of protection of homologous challenges are discussed in relation to light infections.

Of 3200 buffaloes examined at Bareilly abattoir 915 (28·6%) were positive for hydatidosis. The hydatid infected organs were lungs (60%), liver (32%), spleen (4%), kidneys (2%), heart (0·9%) and brain (0·1%). The number of hydatid cysts encountered in lungs of an individual buffalo was 1–9 and 1–7 in liver. One buffalo liver showed severe hepatomegaly, cirrhosis and had an exceptionally high number of hydatid cysts. Infectivity studies in pups showed 16–29 per cent worm establishment with the presence of shelled eggs within the uterus of the parasite on day 45 post-infection.

Laboratory hamsters (Mesocricetus auratus) were infected with Echinostoma revolutum (Trematoda). Immunoelectrophoretic studies of hamster serum showed no demonstrable antibody response to E. revolutum. Histopathologic examination of intestinal tissue of infected hamsters showed erosion of intestinal villi and lymphocytic infiltration as the primary host response. Spleens from infected hamsters were hyperplastic during the first 3 weeks of infection and atrophic from 4 to 8 weeks postinfection. Hamsters were unable to acquire a resistance to E. revolutum infection. Lack of resistance was demonstrated in hamsters where the parasite infection was no longer detected based on the absence of eggs in the faeces; these hamsters were then reinfected. Hamsters treated with the anthelmintic oxyclozanide were also reinfected with E. revolutum.

The daily cercarial output of two Nigerian strains of Schistosoma haematobium in sympatric Bulinus truncatus, B. globosus and B. senegalensis was measured at weekly intervals from the start of emission to the snails' death. In all cases cercariae were released throughout the life of the host, with no cases of “self cure”. Patterns of output through the course of infections in B. truncatus and B. senegalensis were similar to those reported for S. haematobium by other workers, with daily production of cercariae rising to a peak within a few weeks of the onset of shedding, then declining until the host's death. In the longer lived B. globosus production was significantly higher, but declined to very low levels after the initial peak; in some individuals cercarial output remained very low, while others showed a second period of high cercarial emission. The relative compatibility of each host-parasite combination is discussed.

Schistosoma haematobium miracidia were collected from a locality with a high prevalence of human infection with the animal parasite, S. mattheei, which hybridizes with S. haematobium, and from 2 localities with negligible infection rates. The terebratoria of the miracidia from these localities were compared with each other, with laboratory maintained S. haematobium and with four populations of S. mattheei by means of scanning electron microscopy. It was found that the terebratorial membrane of certain of the S. haematobium miracidia from the locality with a high S. mattheei prevalence in humans, resembled the more intricate membrane of S. mattheei. This suggests introgressive hybridization between S. haematobium and S. haematobium x S. mattheei.

The long-term infection with Schistosoma mansoni (Gezira strain—Sudan) was studied in the Nile rat (Arvicanthis niloticus) to investigate the ‘self cure’ phenomenon. The results indicated that while a considerable number of worms and eggs were still recovered by week 28 post-infection, elimination of some of the worms occurred by week 20.

Data presented in this study highlight the potential of allozyme electrophoresis in providing unequivocal genetic evidence for the identification of life cycle stages, particularly where species have complex life cycles. Adults of the nematode Echinocephalus overstreeti parasitize the elasmobranch Heterodontus portusjacksoni. The putative larval form which is morphologically dissimilar is found in two species of marine molluscs, Chlamys bifrons and Pecten albus. Electrophoretic analysis indicated that the adult and larval forms shared alleles at all of the 34 enzyme loci established. Furthermore, there were no fixed allelic differences between larval forms from different mollusc species.

Five, 20, and 80 cysticercoid infections of Hymenolepis diminuta were established in 1-, 2- and 5-month-old male Wistar rats. Worm numbers, dry weights and egg outputs were determined on day 28 post infection. Worm recovery was found to be independent of cysticercoid dose in 1-month-old rats, but density-dependent in older rats. Density dependence affected both worm dry weight and egg production in all 3 age classes of host studied. However, at the highest dose both dry weight and egg production were significantly decreased in 2- and 5-month-old rats compared with 1-month-old rats. The results cannot be explained solely in terms of competition for a resource, and suggest that immunological mechanisms may have an important role in the “crowding effect”.

Ascorbic acid levels were found to be closely related to different stages of growth and maturity of Avitellina centripunctata, Moniezia expansa, and Stilesia globipunctata from goats and sheep and of Raillietina echinobothrida from fowl. The ascorbic acid level in avian parasites was higher than that in mammalian. The level was highest in immature proglottides and lowest in gravid proglottides.

Histochemical tests indicate the presence of tanning precursors namely protein, phenols and phenolase in the vitelline glands of the temnocephalid Paracaridinicola platei. This suggests the occurrence of a tanned egg shell in this organism, a feature it shares with many other parasitic and free living platyhelminths. The large eggs are laid singly and are attached to the gill lamellae of the host.