The relationships between the number of infective larvae (L3s) to which animals were exposed and the establishment of A. ceylanicum and N. americanus in hamsters were examined. There was no evidence of density-dependent constraints on the establishment of A. ceylanicum in the range 10–1000 larvae, but an experiment in which the range was extended to 1500 L3s gave a significant negative correlation between the magnitude of the infecting dose and percentage establishment. Even so the percentage reduction was relatively small, approximating to 0·89% per 100 larvae administered, and in practice density-dependent constraints on establishment are unlikely to affect experiments with this species in which much lower doses (<250 L3) are generally employed. The range of doses for N. americanus L3s was smaller (10–400). Of the four experiments reported, two gave a significant reduction of establishment with increasing dose and two did not. When the data was split into low doses (<100 L3s) and high doses (>100 L3s), falling establishment with increasing dose was only detected in the lower dose range. There was no difference in the establishment when doses of 100 L3s were compared with 250 or 400 L3s. On balance, it was concluded that density-dependent constraints on establishment of N. americanus in hamsters were not marked and would have little significant effect on experiments utilizing fewer than 200 L3s (approximately 7·6% reduction between 10 and 200 L3s). These results are discussed in relation to host regulation of hookworm burdens.

The prevalence of Toxocara vitulorum in cattle around Bursa, Turkey, was surveyed by faecal examination of eggs. The average infection rate among 11 towns was 5·1% in calves younger than 6-months-old, and 2·2% in all ages of animals. T. vitulorum was found to be prevalent in two different areas of Bursa. Third stage larvae were found in one milk sample and therefore galactogenic transmission was suggested. Experimental incubation of eggs showed that the optimum temperature for development was 20 to 30°C and eggs could survive under low temperature, indicating that grazing in the contaminated pasture may accelerate the transmission of eggs to cows. Mode of farming, therefore, affects the infection rate of T. vitulorum and may explain the difference in the rate between the two areas.

Dissolved carbon dioxide was deemed not to be an important factor in the activation of Taenia taeniaeformis oncospheres. Rabbit bile was found to provide the most appropriate whole bile for in vitro activation of oncospheres

A total of 2.8% (5 of 176) sera from schoolchildren and university students were seropositive for hydatidosis (Echinococcus granulosus) by the ELISA IgEtest. The prevalence of seropositivity was 4·5% among females of all age groups (5–24 years) and among males of the age group 18–24 years. Males of the age group (5–17 years) were seronegative. The ratio of seropositivity between schoolboys and schoolgirl was 1:4. Sera collected from 1085 university students, aged 18–24 years, and from 1656 outpatients from northern and central Jordan, and the Jordan River valley, when tested by the IHA test, revealed the presence of antihydatid agglutinating antibodies in 5·16% (56 of 1085) and in 3·6% (60 of 1656) respectively, with a male to female infection ratio of 1:3 in the unviersity students and 1:1·1 in the outpatients. Intensity, prevalence and cyst fertility of E.granulosus increased increased in sheep with age. The results of this study indicate that hydatidosis is in an endemic steady state in Jordan with estimated economic losses if JD 3·0 (=US $ 4·4) per infected sheep.

Contamination of 13 sandpits in public parks in Hyogo Prefecture, Japan, by Toxocara eggs and animal faeces was studied. All 13 sandpits were contaminated with faeces. The mean number of faeces found in 1 m2 of the sandpits was 35, from which the number of faeces in each sandpit was estimated to be 261 to 2205. Toxocara eggs were detected in 12 of the 13 sandpits, each examined 4–15 times; the overall prevalence was 92%. The eggs were not always distributed in the same pattern, but in general, eggs were numerous on the sandpit surface but also present at depths of about 35 cm. Of the eggs recovered, 63% were fully embryonated. Of the 13 sandpits examined, two were heavily contaminated by eggs, and all but one of the others were mildly contaminated. The difference between heavy and light contamination was not related to differences in the environment or in the number of faeces; the cause is unknown.

All 23 6–8-week old outbred female ICR mice, each fed 100 metacercarial cysts of Echinostoma caproni, were infected on days 2, 4, 6, and 8 postinfection (PI) with a mean of 45 worms/host. To examine worm distribution in the mouse, the small intestine was divided into five equal sections (segments 1–5 beginning with the pylorus). Worms were found mainly in segments 3 and 4 and were never found in segment 1. Mean body area of worms fixed in 10% neutral buffered formalin (NBF), hot alcohol-formalin-acetic acid (AFA) and aceto-carmine increased slowly until day 4 and then rapidly until day 8 PI. There was a significant difference in the mean body area of worms fixed in hot AFA, NBF, and aceto-carmine on all days except 4 and 6. Distinction of the ovary and ootype was apparent by day 6 and uterine cooling was observed by day 8 PI. Only 2 of 50 worms showed eggs in the uterus on day 8 PI.

Immunological memory generated by infection with S. ratti was studied separately in the migratory and intestinal phases in mice. Protection against reinfection in the migratory phase was 96–98% at 2 weeks but significantly decreased to 60% at 12 weeks after the primary infection. However, protection in the intestinal phase was 96% even 12 weeks after the primary infection. Recall of immunity against the intestinal phase persists for longer than that against the migratory phase in mice.

A probable case of vertical transmission of Onchocerca volvulus microfilariae in Dass Bauchi State, Nigeria is presented. A 28-week-old male child delivered by a 39-year-old Fulani woman suffering from onchocerciasis was positive for O. volvulus microfilariae based on skin snip examinations. The child had general pruritic rash and intermittent fever. Although the child's skin snip on re-examination five weeks later was positive, the fever had gradually subsided.

A total of 1590 human appendices were collected and examined histologically for evidence of pinworm infection. The incidence of infection in appendices was 2·39%. In examining 100 appendices by both the histological and the parasitological methods, 3 and 7 samples respectively were seen to be infected by pinworm.

The usefulness of hatched but non-activated oncospheres as a candidate vaccine was evaluated using a Taenia taeniaeformis/rat system, since preparation of these oncospheres in vitro is known to be very simple. The findings were: (1) rats vaccinated with non-viable oncospheres became completely resistant to challenge infection; (2) intra-venous injection was the most effective to induce complete resistance; (3) a single oncosphere was sufficient to induce complete resistance in infected rats, whereas approximately 50 and 500 non-viable oncospheres were required to evoke strong and complete resistance, respectively, in vaccinated rats. The usefulness of non-viable oncospheres without adjuvant is discussed.