The prevalence of schistosomiasis and the distribution of the snail intermediate hosts on three adjoining irrigated estates in the lowveld of Swaziland was investigated. The prevalence rates of Schistosoma haematobium and S. mansoni among estate employees was lower than anticipated and there was a marked difference between the prevalence rates of S. mansoni between estates. The reasons for this and the influence of water supplies and agricultural practice on the prevalence of schistosomiasis are discussed.

Study of a series of lower vertebrates and 2 primates infected with Schistosoma haematobium has revealed their egg producing or egg passing potentials. Viable eggs were not passed by albino or wild rats (R. rattus), or by hedgehogs (Hemiechinus). In hosts passing eggs the counts were not great but data do suggest host-parasite relationships which permit continuance of the parasite cycle. Egg passage was erratic and tended to follow a normal curve, i.e., few eggs at first, building up to a peak period after which the counts usually diminished. There was no close correlation between the sites of egg deposition along the intestinal tract and the numbers of egg produced. The peak of egg production was irregular in time after first egg detection as well as in duration. There was wide range in the percentages of viable eggs passed by different hosts and by individuals of the same species. Data reveal the possibility of lower vertebrates serving as reservoirs should satisfactory circumstances allow.

A new monogenean fluke, collected from the urinary bladder of a megophryid frog, Xenophrys glandulosa Fei, Ye & Huang, 1991 from Mokokchung and Tuensang districts of Nagaland, north-eastern India is described. Of the six genera under the subfamily Polystomatinae (Polystomatidae) known so far, the present form comes closer to Eupolystoma Kaw, 1950; Pseudopolystoma Yamaguti, 1963 and Riojatrema Lamothe-Argumedo, 1964, in all of which the opisthaptor lacks large hooks. However, a combination of characters, namely, shape of the body, rounded or bulbous pharynx, intestinal caeca not joining posteriorly in the opisthaptoral region, ovary located in the anterior third of the body and presence of vaginal apertures, sets the present form apart from all these genera, and also from the known species of Riojatrema. These differences warrant the establishment of a new species and a new genus to accommodate the present form. The validity of this new monogenean, named as Neoriojatrema mokokchungensis after the type locality of the fluke, is discussed.

The effects of cadmium and zinc mixtures at concentrations ranging from 0.1 to 10,000 μg l−1 on the life-span of decaudized cercarial bodies (cercariae that have shed their tails) of Diplostomum spathaceum (Trematoda: Diplostomatidae) was investigated. Cercariae were exposed to metal mixtures of equal and unequal concentrations, and a low-dose pre-treatment followed by a high-dose exposure mixtures. Metal mixtures demonstrated variable effects on decaudized cercariae either by increasing or reducing their life-span compared to single metal exposures dependent on concentration and the type of mixed metal treatment. Prolonged exposure to equal metal mixtures at low concentrations (0.1–100 μg l−1) resulted in a reduction in the life-span of decaudized cercariae at 0.1 and 100 μg l−1 in those individuals decaudized during the initial 24 h exposure period compared with those decaudized during the final 24 h period of cercarial survival, whilst in controls there was no significant life-span change between the two time periods. Decaudized cercariae which were exposed to low concentrations (0.1–100 μg l−1) of equal metal mixtures were also evaluated for their role as an indicator of larval ‘fitness’ for migrating through the tissues of their target fish host for those individuals decaudized during the initial 24 h exposure period, and demonstrated only a limited change in their life-span compared to control and single metal exposures. The importance of metal mixtures in parasite establishment in the fish host is discussed.

Gastrothylax crumenifer haemoglobin was isolated, purified, chromatographed, and its molecular weight determined on a calibrated Sephadex G–100 column as well as by sodium dodecyl sulphate by the former and 16 500 by the latter method. The oxygen affinity of the pigment (P50O2) was found to be 6·1 mm Hg at pH 7·4.

Oligapla manteri sp. nov. is described from the gills of Hernirham phus sp. from Noumea, New Caledonia. It differs from the existing species in the genus, O. oligapta because the atrial spines are res tricted to a circle of 16, the penis is armed with 47 anteriorly directed, pear-like spines, and the sclerotization of the copulation canal is conical. Pseudothoracocotyle scomberomori sp. nov. is described from the gills of Scornberomorus commersoni from Heron Island, and Green Island, Queensland, Australia. The new species differs from the existing species in the genus, P. ovalis, because the genital pore is not sclerotized, there are two pores to the copulation canal, and the clamps are more numerous and larger.

I should like to thank Dr. H. W. Manter of the Department of Zoology, University of Nebraska who very kindly gave me the specimens of Oligapta manteri; Dr. W. W. Becklund of Beltsville Parasitological Laboratory, U.S.A. who kindly lent me cotypes of T. crocea, and Dr. J. C. Pearson of the Department of Parasitology, University of Queensland for his help during the study.

During the course of studies on human filariasis in Fiji in the period 1954–50, two new microfilariae were found in fruit bats. The first was found in the blood of 38 bats out of 111 examined from various islands of the territory. It has recently been described and named Microfilaria fijiensis by Yeh, Symes and Mataika (1958).

During 1928 I was able, as Milner Research Fellow in the Department of Helminthology of the London School of Hygiene and Tropical Medicine, to make an extended survey of the parasites of man and the domestic animals in the British West Indies. A report on the former has already been published (1929). In examining the parasites of domestic animals, I was given every facility by the local authorities, and I am especially indebted to Captain H. V. Metivier, B.Sc., M.R.C.V.S., of Trinidad, whose assistance and knowledge of the local parasitic problems was invaluable.

Haematuria and proteinuria as detected by chemical reagent strips correlated moderately (r=0·7) with prevalence and intensity of infection with Schistosoma haematobium in an area of Anambra State, Nigeria. Differences attributable to age and sex were also reflected in a similar pattern, all peaks occurring in the 5–14 year age group. The differences observed with varying levels of intensity and haematuria at both 10 and 50 erythrocytes/μl (p<0·001) and proteinuria at 0·3 g/dl (p<0·01) were statistically significant. At a proteinuria level of 1 g/dl, the observed differences were however not statistically significant (p>0·5). The percentage of specimens from children (1–14 years) positive for S. haematobium eggs and with at least traces of haematuria and proteinuria (63·4% and 95%, respectively) was higher than in adults (33·3% and 80·2%, respectively). All individuals with more than 50 eggs/10 ml of urine were correctly identified using both indices either separately or in combination. For egg counts of less than 50 egg/10 ml of urine, false diagnosis occurred in only 5% of all specimens examined. The sensitivity and specificity of haematuria and proteinuria at trace quantities was very high, hut haematuria had a higher predictive value for a positive test (PvPt) and was considered the overall better indicator. A combination of both indices did not significantly increase the PvPt. When trace haematuria and moderate proteinuria were combined, both the sensitivity, specificity and PvPt were all above 90%, giving the best overall values in all the combinations made.

The immunological responses in hamsters during treatment with mebendazole against Ancylostoma ceylanicum are studied. Indirect haemagglutination (IHA) counterimmunoelectrophoresis (CIEP), passive cutaneous anaphylaxis (PCA), foot pad swelling for immediate (ITH) and delayed (DTH) types of hypersensitivities were employed for measuring the responses. Serum antibody which was 1:32 before treatment increased to the maximim of 1:512 (control 1:128) on the 10th day and it declined subsequently. The CIEP test was positive for 10 days and then became negative. The PCA test was positive throughout the observation period both in the treated and untreated groups. Foot pad swelling for ITH and DTH responses were comparatively more prominent than in the untreated control up to the 20th day and then both decreased simultaneously. The immunological responses remained prominent for a longer period and decreased more slowly in the untreated control group.

(1) During the routine examination of the fauna of samples of clinker removed from the filter beds of Brent Sewage Farm several species of Rhabdilis were met with, one at least of which cannot be relegated to any species as yet described. A new species is therefore suggested for its reception and the name succaris has been given to suggest its origin from the sewage farm.

(2) An account is given of its structure. While being typical for the genus, the lips and bursal rays do not agree with any known species.

(3) Two distinct strains were reared by means of different culture media, differing quite definitely in length. A thousand worms were measured and these differences were found to remain very constant. The relative measurements have not been materially altered.

(4) The length of the large worms has been diminished by means of a return to the original food.

(5) The cultivated strain shows greater variability than the original strain.

(6) Two graphs and a table summarising the results are shown.

The inhibition of acetylcholinesterase secretion by male and female Heligmosomoides polygyrus was tested on worms taken from experimentally infected mice and maintained for 3 days in vitro in levamisole. The dose inhibiting 50% of enzyme secretion (ID 50) of male worms was twice the ID 50 for female worms. A similar difference was observed in vivo between the dose of levamisole removing 50% (LD 50) of male and female worms from the mouse. Acetylcholinesterase secretion by worms and ID 50 were tested in vitro at 3-weekly intervals from 3 to 21 weeks post infection (WPI). Acetylcholinesterase secretion was always significantly higher for male than for female worms. A decrease of ID 50, correlated with the age of the worms was observed: from 1·5 to 0·5 μg/ml for males and from 0·7 to 0·1 μg/ml for females. These results were confirmed in vivo by a higher efficacy of the anthelminthic at 21 than at 4 WPI.

This study compares the morphology, anatomy, physiology and histochemical distribution of two key enzymes (AcPase and ATPase) in the intestinal trematode Ganeo tigrinum recovered from hibernating and non-hibernating Rana cyanophlyctis and R. tigrina. It has been shown that the torpid state of the host influences its worm so severely that it produces untanned and low quality eggs, the sperm population falls, the rate of worm infection is decreased and the worms do not grow.

AcPase has been shown to undergo significant changes during hibernation, especially in the gut, where extraordinarily high activity seems to be responsible for the autophagy of certain gastrodermal cells. ATPase similarly reveals a decrease in activity in most of the parasite tissues during hibernation. However, its high activity in the parenchyma has been related to the quick transportation of metabolites, representing the threshold concentration necessary for survival and egg production.

Rabbits were experimentally infected with two levels (5000 and 17000) infective larvae of Nematodirus spathiger. Histological (villus length, mucosa to serosa ratio, crypt surface) and biochemical (protein content, alkaline phosphatase and leucine aminopeptidase activities) measurements relating to the small intestinal mucosa were examined along the entire length of the organ. In the proximal intestine, the presence of worms was associated with villus abrasion, increased crypt surface and decreased alkaline phosphatase and leucine aminopeptidase activities. Conversely, beyond the main Site of infection in the distal small intestine, some signs of hypertrophied villi and crypts were noted without any changes in enzyme activities. These distal variations were similar to those previously described in experimental Trichostrongylus colubriformis infections of rabbits. These results tend to confirm the use of the rabbit as an experimental model to study Nematodirus infection. They also suggest that the distal adaptive process in the nematode-parasitized small intestine could occur independently of the worm species.

Rats acquired a degree of protective immunity to reinfection with Angiostrongylus cantonensis after a single infection with 50 infective larvae. Infected rats resisted the establishment of most challenging larvae and protective immunity increased with subsequent reinfections. Part of the primary infection was lost after a superimposed second and also following a superimposed third infection, but the total size of the concurrent adult worm populations remained the same as that from a primary infection. Worms surviving from the primary infection showed enhanced growth after each reinfection but their fecundity was impaired.

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.

The activity, in terms of speed of action, of three anticestode drugs against Hymenolepis nana, both in vivo and in vitro, was investigated. Praziquantel was most effective in vivo, but had little action on adult worms and cysticercoids in vitro. Niclosamide, the least effective in vivo, was highly toxic in vitro. Compound 77–6 killed adult worms and cysticercoids in vitro in 10 min and 15 min respectively at 1000 μg/ml of drug concentration, but its in viro effect was intermediate between that of praziquantel and niclosamide.

One male specimen was collected from the liver of a short tailed wallaby, Macropus brachyurus, which died in the Zoological Gardens, London on 26th September 1960. It is a slender worm 82 mm. in length and 0·41 mm. in maximum width. The anterior extremity is rounded. There is a small buccal cavity and at the base of this there is a prominent cuticularised ring. The cephalic end bears four pairs of submedian papillae and a pair of amphids. The en face view was not studied because of the lack of specimens. The cuticle is transversely striated all over the body and there are bosses like small slightly curved markings on it.

Chamois (Rupicapra rupicapra tatrica) in the Low Tatra National Park are largely infected with the lungworms Mullerius capillaris and M. tenuispiculatus and sporadically with Dictyocaulus viviparus. The mean number of first stage larvae (Ll) per gram of faeces collected at chamois stands over the years 1981–1988 varied between 28.2 ( ± 11.9) and 61.6 ( ± 35.9). The degree of infection in chamois herds was significantly higher in the spring and autumn months, except for the spring of 1981, than in the summer season. The mean number of Ll per gram found in the dissected chamois (lung and intestinal content) varied between 64.53 ( ± 32.7) and 97.5 ( ± 36.4).

The enzyme-linked immunosorbent assay (ELISA) and immunoelectrophoresis (IEP) were used for the serodiagnosis of larval Anisakis simplex infections in man and immunized rabbits. Sephacryl S-300 gel filtration was used for separating crude antigen. Four fractions were obtained. Sera from patients with other helminth infections sometimes cross reacted with Anisakis larval antigens. With IEP, crude antigen is more sensitive than purified antigens. With ELISA, the third fraction is the most sensitive for detecting antibodies to Anisakis larvae in the sera of humans and immunized rabbits.