An investigation was made of the pathological, haematological and biochemical aspects of naturallyoccurring bovine fascioliasis in the Sudan. 228 animals infected with Fasdola gigantica and 25 non-infected controls were used in the study.

The infected cattle revealed emaciation, typical liver pathology, and, occasionally, lesions in the lung and the pancreas. Analysis of their sera also showed reduced albumin values, increased globulin concentrations and decreased albumin/globulin ratio, in addition to increased arginase activity. The serum iron concentration, on the other hand, was decreased, while the total iron binding capacity increased and the resultant iron saturation values reduced. Haematological findings in the infected animals included reduced erythrocyte counts, decreased haematocrjt values, increased mean corpuscular volumes, eosinophilia and decreased neutrophil, lymphocyte and monocytc counts.

It was shown that ultra-violet radiation has a damaging effect on cercariae of Schistosoma mansoni and S. haematobium which are similarly influenced. Radiation of cercariae for intervals as short as 5–20 seconds markedly increased their mortality during penetration of host skin and inhibited migration of schistosomula in the lungs beyond days 3–4 post-infection. No mature adult worms were recovered from the liver and mesenteric veins of animals infected with irradiated cercariae. The practical significance of the cercaricidal property of ultra-violet radiation is discussed.

Studies were made of the fate of irradiated cercariae of Schistosoma mansoni, during their migration as schistosomula in the definitive host, by direct recovery of intact schistosomula from the skin and lungs and of adult worms from the liver of infected mice. Gamma radiation (6000 r) inhibited the migration and maturation of S. mansoni schistosomula to the adult stage. Penetration of irradiated cercariae into host skin proceeded normally and the first site of damage was in the lungs, but the majority of irradiated schistosomula were probably destroyed in the liver. The efiects of gamma radiation compared with those of ultra-violet radiation on cercariae of S. mansoni are discussed.

Sporocysts capable of producing active miracidia were recovered from the upper branchial chamber of the snail species, Melania tuberculata and M.scabra. The non-ocellate miracidium was characterised by the presence of 22 epidermal plates in four tiers, an apical gland with four nuclei and two penetration glands. Sporocysts were of two types, one producing active miracidia and the other in which daughter sporocysts and miracidia were found. These sporocysts were characterised by the presence of bunches of circular muscles at intervals and also by the presence of a network of muscle fibres at the anterior and posterior one fifth regions. Development of the miracidia took place in compartments. Histochcmical tests were carried out as regards glycogen, protein, lipids and phosphomonoesterases.

A medicated diet containing 0.3% thiabendazole fed continuously to 26 mice for 7 days removed 9 out of 11 (82%) Hymenolepis nana, (one tapeworm remaining in each of two mice), 17 out of 17 (100%) Syphacia obvelata and 8 out of 8 (100%) Aspiculuris tetraptera infections. By contrast in 26 non-treated mice 9 out of 10 Hymenolepis, 17 out of 18 Syphacia and 8 out of 8 Aspiculuris infections persisted through the 7 day treatment period, and at post mortem examination 38 Hymenolepsis, 1,562 Syphacia and 4,911 Aspiculuris worms were recovered. In a second experiment 100% removal of 23 Hymenolepis and 20 Syphacia infections was obtained after 14 days medication of 38 mice. High activity against both roundyvorms and tapeworms of mice was thus obtained using one single drug. Some unexplained deaths amongst inbred strain C3H/Hef Nimr mice occurred within seven day's of the continuous medication.

Migration and distribution of Ancylostoma caninum larvae in the tissues of Swiss albino mice infected with 500,1000, 2000 and 4000 larvae was studied. Larval migration and distribution in the different tissues was earlier in mice infected with a dose of 4000 larvae and more larvae were expelled from the gastrointestinal tract of heavily infected (2000 dose) mice. With an infective dose of 1000 larvae, the percent larval yield was higher than in other two groups (500 dose and 2000 dose) showing poor expulsion. Larval migration in the lungs was high even on the 1st day in heavily infected groups. Migration of larvae into the muscles, particularly of the head, neck and thorax took place on the very first day and was proportional to dose level. Larval count was higher in the muscles of the head and neck until the 9th day, after which it was high in the thoracic and other regions.

Capillaria papuensis sp. nov. is described from specimens collected from the gastro-intestinal systems of 14 pigs from two villages in Papua New Guinea. It differs from C.gastrosuis and C. suis in the number and location of papillae in the vulval region, the sculptured surface of the eggs, a sub-terminal anus in the female and in the length of the spicule and bilateral caudal alae in the male. The species inhabits the epithelium of the tongue, where clusters of eggs move towards the surface with the growth of the epithelium and are subsequently swallowed. The pathological changes in the infected epithelium are minimal. The prepatent period is approximately eight weeks.

The worm recoveries of two different strains of Schistosoma haematobium from male hamsters and their egg-laying capacities are studied. The infection rates obtained, the growth of worms and the distribution of eggs in hamster tissues are compared with those previously described for other strains of S. haematobium.

Previous studies have shown that different geographical strains of Schistosoma haematobium have specific characteristics which reflect the infra-specific variations of this complex species (Webbe and James, 1971a, b; James and Webbe, 1973). The present paper records further observations on two strains of the parasite from the Sudan (Khartoum) and South Africa (Nelspruit).

100 male T.O. strain laboratory mice were divided into 4 equal groups: (I) 25 were injected intramuscularly with an antigen prepared together with Freund's adjuvant; (II) 25 injected with antigen alone; (III) 25 infected subcutaneously with 8 live plerocercoids of the same species; (IV) 25 served as controls. 4 weeks later all mice were given 6 live plerocercoids orally. The presence of acquired immunity in group III was shown by a significant reduction in the numbers, size and motility of challenge worms. The host response was greater in all the immunized groups than in the controls.

The activity is reported of certain clinical and experimental schistosornicides against schistosomula, 3 week old, and adult worms of Schistosoma mansoni maintained in vitro. Since the test method is not sufficiently selective for use with random compounds, it is concluded that meaningful screening for potential schistosomicides cannot at present by carried out in vitro.