A study was carried out in four vifiages of Makenene Sub-Division some 85 km north-west of Yaounde, between November 1993 and March 1994 to assess the prevalence and intensity of schistosomes and other helminth infections among senior primary school pupils aged 9–16. An extensive questionnaire was used to collect sociodemographic information and information on water-related activities.

The overall prevalence of S. mansoni infection was 228 (23.6%) while S. haematobium infection was practically non-existent 03 (<1%). Infection rates with intestinal nematodes were very high, up to 98% in some villages. Prevalence rates of schistosomiasis varied significantly (P<0.05) between vifiages with the highest (36.2%) recorded in Makenene. Infections with other parasite species encountered were significantly different (P<0.01) while a marked association was observed between water contact activities and the distribution of S. mansoni infections. However, S. mansoni infection intensities were not significantly different (P>0.05) between those with a history of previous infection and treatment and those without.

The karyotypes of the two amphistomes Calicophoron microbothrium Fischoeder, 1901 and Carmyerius gregarius (Looss, 1896), Stiles & Goldberger, 1910 from Egyptian ruminants were studied using the air drying technique. The two species have similar number of chromosomes (n = 9), but differ in chromosome morphology. All the chromosomes of C. microbothrium are subtelocentric, except the first and the fifth are metacentric, whereas the chromosomes of C. gregarius are submetacentric, subtelocentric and acrocentric. Some cells in the two species showed tetraploidy. The results are discussed in terms of the phylogenetic relationship of different amphistomes.

Eighty three carcasses of pigs were examined at three abattoirs in Moshi, Arusha and Mbulu in northern Tanzania. Taenia solium metacestodes were found in all the three abattoirs with an overall prevalence of 13.3%. During routine meat inspection in Kiboroloni, Moshi 6.2–6.9% of the pigs were found to harbour T. solium metacestodes. The mean number of hooks on the protoscolices was 27 and the length of the small hooks varied from 105 mm to 130 μm while that of the larger hooks varied from 168 mm to 174 mm confirming that the cysts were metacestodes of T. solium. Although cystlike lesions were recovered from livers of both pigs and cattle, no booklets of sizes in the range of 5–37mm were found indicating that no Taiwan Taenia metacestodes were recovered during carcass examination.

Cross-resistance between Strongyloides venezuelensis and S. ratti was tested in mice. The mice were immunized with S. ratti and challenged with infective filariform larvae or larvae recovered from the lungs of mice, of a heterologous species, S. venezuelensis. In this system, cross-resistance was expressed to the intestinal stage but not to the migrating stage of the parasite. Anti-interleukin (IL)-5 monoclonal antibody (mAb) treatment showed that peripheral blood eosinophilia after infection with both species of the genus Strongyloides was dependent on IL-5. Cross-resistance expressed to the intestinal stages was inhibited partially by injection of anti-IL-5 mAb.

Natural populations of the freshwater gastropods Bithynia tentaculata, Gyraulus convexiusculus, Helicorbis coenosus, Indoplanorbis exustus, Lymnaea acuminata, L. luteola and Vivipara bengalensis, were examined from October 1985 to September 1986 at seven transmission sites for paramphistomiasis, fascioliasis and other gastropod-borne infections in Aligarh, northern India. Gastropod diversity and the type and abundance of vegetation were highest at sites containing permanent water bodies. The distributions of H. coenosus and L. acuminata were positively correlated with the type and abundance of vegetation at these sites. Ephemeral water bodies contained B. tentaculata, I. exustus and L. luteola which were resistant to desiccation during the hot season. Aestivation in these gastropods preceded pronounced breeding activity which began with the onset of the monsoon season. Multivariate analysis (by principal components) was used to investigate relationships between each species of gastropod, their site of occurrence and levels of infection with larval helminths. Seasonal variations in numbers and size class structure in these gastropods were found to influence their prevalences of infection with larval helminths. Metacercarial and cysticercoid infections were more prevalent in smaller size classes of B. tentaculata and V. bengalensis, whereas larval paramphistomes were more prevalent in larger size classes of G. convexiusculus, I. exustus and L. luteola. Attempts were made to equate these findings with seasonality in egg shedding by certain species of adult paramphistomes occurring in domestic ruminants.

Baboons vaccinated intramuscularly with three times 9000 20 krad irradiated Schistosoma haematobium schistosomula at monthly intervals were exposed percutaneously to either a single mass challenge of 3000 (VMC) or ten, weekly trickle challenges of 300 (VTC) normal S. haematobium cercariae. Unvaccinated mass (MCC) or trickle (TCC) challenge controls were exposed simultaneously. Faecal and urine egg production was delayed in the vaccinated groups which also had reduced adult, particularly female, worm recoveries. Total faecal, urine and tissue eggs were lower in the vaccinated groups, as also were the size of granulomata and the gross pathology and severity of inflammatory responses in the bladder and ureters, except for an increased proportion of tissue eggs in the livers of vaccinated animals. Differences in pathology between groups were less marked in the other organs. Most indices were reduced in the trickle versus the mass challenge control groups. Some of these trends were statistically significant, mostly in the trickle vaccination group (VTC), but others were not. Compared with the appropriate unvaccinated controls, the percentage reduction for the trickle challenge (VTC) group (73%) was three times greater than that of the mass challenge (VMC) group (23%). Overall, the protective effect of vaccination was more clearly demonstrated in the trickle than in the mass challenge groups. This conclusion is based on a single experiment. Nevertheless, because trickle infections probably approximate more closely to what humans receive naturally, it is recommended that they should be used for future testing of all potential vaccines in baboons.

A simple technique using modified Mallory stain in the transferral of Gyrodactylus specimens from ammonium picrate-glycerin to a permanent mountant is described. Hamuli, their connecting bars and the penis sclerites are well defined by the technique as are muscles and tendons, cell nuclei, tegument and gland cells. As well as being useful in the study of general anatomy, the technique enhances the observation of the taxonomically important ventral and dorsal bars. In order to show this, improved illustrations of the dorsal and ventral bars of G. turnbulli are given along with explicit demonstrations of differences in morphology of the ventral bars of G. bullatarudis and G. rasini - two easily confused species.

This investigation deals with the evaluation of the in ovo technique for the cultivation of trematodes. The technique has previously been used for the maturation of digenetic flukes and the establishment of life cycles in the laboratory but it was not known if the adult flukes produced were morphologically comparable to those found in their natural hosts. Three species of microphallids, Microphallus similis, M. pygmaeus and Maritrema arenaria were used. Metacercariae of each species were inoculated into fertile hen's eggs which were incubated at 41°C for 120 hours. The adult flukes recovered were stained and mounted and morphonietric measurements obtained were compared to definitive descriptions of the three microphallid species. The results showed that the in ovo technique provided adult flukes which were indistinguishable from those occurring in natural hosts.

The total DNA of two morphologically similar cestode species of the genus Proteocephalus parasitizing coregonid and salmonid fish, P. exiguus La Rue, 1911 and P. neglectus La Rue, 1911, was compared. The methods of DNA analysis involved digestion of the total DNA with restriction endonucleases and Southern blotting hybridization with the ribosomal DNA probes pSM 889, pSM 389 and pSM 890. No inter-specific variation was found between the two proteocephalid species. Distinct differences in RFLP patterns were recorded between two geographically distinct population of P. neglectus after BspRI digestion; after EcoRI digestion and following hybridization with the 32P-labelled probe pSM 890 and after BamHI digestion and hybridization with the 32P-labelled probe pSM 889. The high degree of genetic similarity revealed in the two Proteocephalus spp. could be a further argument for the conspecifity of both taxa.

A gelatin-agar bolus, designed and developed for the administration of metacercariae of the liver fluke Fasciola hepatica, was evaluated in adult Holstein Friesian cattle. The metacercariae, enclosed within a gelatin capsule, were placed inside the bolus and delivered to each animal using an oesophageal balling gun. At slaughter, 13 weeks after challenge, an average of 25% of the challenge dose was recovered from each liver. This percentage recovery is similar to that obtained with other known methods. The new bolus, however, offers improved handling qualities. In addition, the bolus also has potential for improving a number of other techniques including those for the administration of other parasites, compounds or chemotherapeutic agents.

Suspensions of embryonated (L2) Toxocara canis and T. cati eggs were maintained under freezing conditions in order to study the impact on their long term viability The eggs had been removed from the uteri of adult Toxocara spp. worms and the suspended in a 0.4% formalin solution before being frozen in 20 ml plastic tubes in the freezer compartment of a domestic refrigerator. Assessment of embryonated egg viability over a period of 34 days was conducted by microscopic examination under a high light intensity Embryonated T. cati eggs were found to exhibit a greater resistance to freezing than those of T. canis. A difference in the size, design of the egg shell or the metabolism of the larval form may have accounted for the observed differences in the percentage viabilities over time between the two species of Toxocara.

The in vitro cultivation technique of Echinococcus granulosus protoscoleces usually states the necessity of a biphasic medium with a solid protein substrate for strobilar development to take place; otherwise, in a monophasic medium, protoscoleces follow a vesicular development. However, in some monocphasic cultures, the development of several strobilate individuals (in different quantities and stages of development, depending on the culture) were observed. The only known diference form cultures made previously and snice, where the development was vesicular, was the batch of foetal calf serum used in the constitution of the liquid medium, and this is presumed to be the cause of this unexpected strobilar development.

Eleven artificial infections of oribatid mites of the genusScheloribates with Moniezia expansa eggs were made. The percentage of surviving mites in the infected groups was lower (62 to 82%) than in the uninfected control group (90%). None of oribatids with cysticercoids in their body cavity contained mite eggs. The established prevalence and average cysticercoid number in surviving mites were 50.00 to 95.12% and 1.3 to 2.8 respectively.