Another species in the genus Heterocheilus Diesing, 1839, collected from Trichechus senegalensis, is described. It differs from H. tunicatus in possessing elongate cuticular plaques on the body surface in the oesophageal region, a cuticle-lined vestibule between mouth and oesophagus, and triangular interlabial structures. A comparison is made between specimens of H. tunicatus from T. manatus and the specimens from T. inunguis described in a previous paper (Sprent, 1980).

Excretory/secretory (ES) antigens were obtained by culturing pre-encysted Trichinella spiralis larvae which were recovered from muscles of experimentally infected mice 14–15 days postinfection. Analyses of these antigens (PEL ES) with immunoblotting, SDS-PAGE and Triple Antibody ELISA showed that they yielded a low sensitivity and specificity when tested antisera against the common nematodes of Chinese pigs. As compared to ES antigens from encysted larvae. PEL ES also contained more low molecular mass proteins.

Research on the potato-root eelworm Heterodera rostochiensis has been severely handicapped by the fact that it is virtually impossible to estimate the infectivity of individual cysts. Since the infectivity of an individual cyst is determined by the number of viable larvae present within it, the problem can be settled in one of two ways—either by means of a technique which recovers all the viable larvae and rejects the non-viable or by estimating firstly the total contents and then the proportion of them which is viable. Techniques for the recovery of larvae from cysts have been described by Fenwick (1941) and Fenwick and Franklin (1940). The former of these sought to express soil infectivity directly in terms of available larvae per gm. of soil while the latter was concerned merely with obtaining a representative sample of larvae from a given batch of cysts. Neither claimed to estimate viability of the contents. A further technique (Bracey, 1946) which was described in a paper circulated among interested workers was a modification of that described by Fenwick and Franklin (loc. cit.) and claimed to express viability of cyst contents directly as a percentage.

A study has been made of the form of the larval hooks in the coracidium and procercoid stages of Diphyllobothrium medium, D. ditremum and D. dendriticum obtained from four sources in Great Britain. It has been found that the form of the larval hooks is constant, and that hook types are related to different species. It is concluded that the hooks provide a sound basis for specific identification.

During the course of studies on human filariasis and its vectorsin Fiji, in the period 1954–1956, (Symes, 1957) it was desirableto make a few observations on the dog filaria in order that, whenfound in mosquitoes, its larval stages should not be confused withthose of Wuchereria bancrofti from man.

1. The occurrence of Syngamus nasicola Linstow, 1899, in sheep, cattle and goats in the West Indies is recorded.

2. The species is re-described, on the basis of West Indian material and cotypes from deer and goat.

3. The species is contrasted with S. laryngeus Railliet, 1899, with which it has affinities and has hitherto been thought to be identical.

4. Special emphasis is laid on the use of the internal structure of the buccal capsule in differentiating the two species.

5. Syngamus kingi is compared with S. nasicola and it is concluded that the two species are identical, in which case S. kingi becomes a synonym of S. nasicola.

The aims of the present study were to assess the prevalence of Toxocara infection in household cats and dogs, together with the presence of anti-Toxocara IgG antibodies in humans and the level of egg contamination in soil and vegetable samples from the local environment. Prevalence values of 47.8% of 253 cats and 37.7% of 284 dogs were recorded, together with 35.8% of eggs in soil samples, 25.0% in garden vegetables and in 56.3% of 16 dog-hair samples. The risk of the infection was higher for dogs and cats in households with egg-contaminated soil compared to those without evidence of soil contamination. The high prevalence of dog and cat Toxocara infection and their indiscriminate defecation behaviour contribute to a significant risk of transmission to humans as 58.7% of human blood samples were seropositive for Toxocara. Anthelmintic treatment of dogs and cats, plus educating household members, must be emphasized in any prevention programme in Vietnam.

The general principles underlying the conduct of hatching tests are described. Methods for collection of material, and for its preliminary assay are described; the information gained in this way is then used in designing hatching tests. The interpretation of the data resulting from such tests is described and limits are set between which interpretation is possible.

When the presence of nematodes in plant tissues is known or suspected it is often useful to be able to show the exact situation of the parasites and their biological condition, i.e. whether they are quiescent or active. If plant tissues are teased apart in water active nematodes will be freed and will soon be seen swimming in the water, or, if they are in a state of quiescence, and yet viable, they will revive in an hour or more and become active in the water. Whichever is the case, there may occasionally be some doubt as to whether the nematodes were really in the tissues of the plant or were carried on the outside. The larvae and eggs of most parasitic eelworms are so small that they may easily be overlooked amongst the teased plant tissue, with which there may also be numbers of detached plant hairs closely resembling nematodes in their shape, size and transparency. If the parts of the plants likely to contain eelworms can be stained so that the worms take up the stain in contrast to the plant tissue, and can be seen in their natural position, a much more accurate picture of the situation may often be obtained than that derived from teasing the tissues in water.

Ligophorus belanaki n. sp. and Ligophorus kederai n. sp. are described from Liza subviridis Valenciennes, 1836 and Valamugil buchanani Bleeker, 1854, respectively. Ligophorus kederai n. sp. has fenestrated ventral anchors, while in L. belanaki n. sp. the ventral anchor is not fenestrated. Ligophorus belanaki n. sp. is similar to L. careyensis, one of its coexisting congeners, in the overall shape and size of hard parts, but differs in having a flat median piece in the structure of the AMP (antero-median protuberance of the ventral bar), copulatory organ with non-ornamented initial part and longer vaginal tube, compared to raised median piece in the AMP, ornamented initial part and comparatively shorter vaginal tube in L. careyensis. Ligophorus kederai n. sp. is similar to L. fenestrum, a coexisting congener, in having fenestrated ventral anchors, but differs in having longer points and narrower base. Ligophorus fenestrum, unlike L. kederai n. sp., also possesses fenestrated dorsal anchors. The principal component analysis (PCA) scatterplots indicate that the two new and eight known Ligophorus species from Malaysian mugilids can be differentiated based on the morphometries of their anchors, ventral bars and copulatory organ separately and when combined together. Numerical taxonomy (NT) analyses based on Jaccard's Index of Similarity and neighbour-joining clustering, is used to facilitate comparison of these two new species with the 50 known Ligophorus based on morphological and metric characters. The two new species are different from each other and the other 50 species in the overall shapes and sizes of hard parts, as indicated by the NT analyses.

A survey on Anisakis simplex (sensu stricto (s.s.)) from blue whiting, Micromesistius poutassou, in the north-eastern Atlantic Ocean revealed the occurrence of high infection levels of third larval stages in visceral organs and flesh. Larvae were genetically identified with a multilocus approach as A. simplex (s.s.). Histochemical, immunohistochemical and ultrastructural observations were conducted on 30 M. poutassou specimens. Gonads, pyloric caeca and flesh harboured encapsulated larvae of A. simplex (s.s.) but no intense host reaction was encountered around the parasite in the above organs. In the liver, the most infected organ, the larvae co-occurred with the coccidian Goussia sp. Within the granuloma around the A. simplex (s.s.) larvae, two concentric layers were recognized, an inner mostly comprising electron-dense epithelioid cells and an outer layer made of less electron-dense epithelioid cells. Macrophages and macrophage aggregates (MAs) were abundant out of the granulomas, scattered in parenchyma, and inside the MAs, the presence of engulfed Goussia sp. was frequent. In liver tissue co-infected with Goussia sp. and A. simplex (s.s.), hepatocytes showed cytoplasmic rarefaction and acute cell swelling. Results suggest that the host-induced encapsulation of A. simplex (s.s.) larvae is a strategic compromise to minimize collateral tissue damage around the larval infection sites, to facilitate the survival of both parasite and host.

In epidemiological surveys for urinary schistosomiasis caused by Schistosoma haematobium in communities around Agulu Lake, Anambra State, Nigeria, between 1990 and 1992, the infection was found to be endemic in the area, especially in three towns: Nri, Agulu, and Adazi Nnukwu. The prevalence rates varied between these communities and with the year. Inter-town prevalence rates ranged from 5.96% to 54.00%. Intravillage prevalence rates ranged between 5.50% to 96.43%. Prevalence rates were highest in villages very close to Agulu lake. There was no significant difference in prevalence between the schools. Host age, but not sex, was found to play a significant role in prevalence and intensity of infection. There was also a strong correlation between visible haematuria and egg count per 10 ml urine, but eggs could be isolated in urine samples of different shades of coloration. Analysis of incidence of infection in these communities shows that Schistosoma haematobium incidence is high in Nri (55.17%) and low at Adazi Nnukwu (5.26%). Both Bulinus globosus and B. truncatus were found in the lake and both shed mammalian bifid schistosome cercariae.

Two cases of Nasitrema sp (Trematoda) infection of the bottlenosed dolphin, Tursiops truncatus, are reported and N. attenuata is briefly redescribed. The adults of the trernatode occurring in the nasal sinuses and posterior nasal passage of the dolphins are considered as practically harmless for the host but their eggs, aspirated deep into the bronchial tree, may initiate a foreign-body type of inflammatory reaction in the lungs and continuous aspiration of such eggs may provoke a chronic pneumonic condition.

Cystic echinococcosis (CE) is an endemic helminthic disease caused by infection with Echinococcus granulosus metacestodes. Although CE is endemic in the Balkan region, the exact epidemiology remains unknown. We conducted a case-series study with the aim of evaluating the correlation between seropositivity, socio-epidemiological data, pre-operative treatment with albendazole and viability of protoscolices in human hepatic hydatid cysts. Consecutive patients with hepatic CE underwent surgery to extract E. granulosis cysts. The viability of protoscolices was measured by their ability to absorb 0.1% eosin. Socio-epidemiological data were collected and serological testing was performed. In the present study, 38 patients (28 adults and 10 children) with hepatic CE were treated surgically. The scolex viability test was positive in 30/38 (79%) samples. All patients with non-viable cysts had seronegative results. The viability test was positive in 11/12 (91.6%) adult patients with pre-operative albendazole treatment and in 9/10 (90%) children. Statistically more patients were from an urban area compared with a rural area (65.8% vs. 15.7%). The increasing number of stray dogs shedding E. granulosus eggs in urban public areas in the Balkans might be the reason for the significant difference in the rate of infection between urban and rural areas in the present study. In addition, uncontrolled slaughtering of livestock, common in rural settlements, and feeding the infected viscera to dogs, favour the maintenance of the parasite cycle. We believe that the results of our study will encourage physicians, veterinarians and health authorities to initiate a programme to prevent and control CE in the Balkan region.

The specific gravity of the eggs of the liver fluke Opisthorchis viverrini was determined using a sucrose gradient centrifugation and found to range from 1.2713 to 1.3043. The peak egg count was located at the sucrose fraction with a specific gravity of 1.2814. An attempt to float eggs in saturated sodium nitrate solution, sp.gr. 1.4, failed. Examination of human stool specimens for O. viverrini eggs by simple flotation in saturated sodium nitrate solution and the formol-ether sedimentation technique revealed that the flotation technique was not as efficient as the sedimentation technique. It was suggested that the flotation techniques were inappropriate for the detection of O. viverrini eggs in faeces or contaminated soil.

The major organs, other than lymphatics, of jirds (Meriones unguiculatus) with prepatent and chronic patent infections of Brugia pahangi were studied by standard histological, electron microscopical and fluorescent antibody techniques. Changes observed and not previously described in detail or in large numbers of animals are reported. Multifocal non-suppurative interstitial nephritis was observed in 4% of animals with patent infections of 163 days duration and in 69% of animals with patent infections of 274 days duration. Glomerular changes were not observed in kidneys of any animals infected with B. pahangi. The occurrence of large granulomata composed of lymphocytes, macrophages, eosinophils and giant cells in the liver and smaller granulomata in the spleen correlated with patency of infections but microfilariae or worm antigens were not observed in these areas. Amyloid deposits were demonstrated in the spleens of 4% of animals with patent infections of 163 days duration and in 38% of animals with patent infections of 274 days duration but were not seen in uninfected animals of the same age or animals receiving only challenge inoculations of 28 days duration.

Urine samples were assayed for urinary schistosomiasis in four local government areas (LGA) of Imo State, Nigeria between May 1998 and September 2000. A total of 3504 persons were sampled, with 880 (25.1%) being positive for urinary schistosomiasis, based on records of eggs of Schistosoma haematobium. The prevalence of S. haematobium infection differed in the various LGAs, with Oguta (38.9%) and Owerri-West (10.4%) showing the highest and the lowest values, respectively. Prevalence was higher in males (67.4%) than in females (32.6%) and in subjects 11–20 years of age (31.5%), while prevalence varied among different occupational groups, with farmers ranking the highest (41.6%). Visible haematuria was the predominant symptom (P<0.05). Of 880 persons positive for eggs of S. haematobium, 452 (51.4%) had visible haematuria, followed by suprapubic pains 214 (24.3%) and painful micturition 97 (11.0%). Although 367 (10. 5%) of the sampled subjects with eggs of S. haematobium showed no visible haematuria, 513 (14.6%) clearly demonstrated haematuria.

The following description of a new species of the genus Oswaldocruzia is based on the examination of a considerable number of specimens collected from the intestines of 80 newts caught at Aberystwyth. They were found to be equally common in the Smooth Newt (Molge vulgaris Linn.) and the Palmate Newt (Molge palmata Dum. and Bibr.).

The results are given of the preliminary screening of many organic compounds and pesticides and of a few inorganic compounds on the eggs of T. hydatigena and T. ovis.

Over fifty of these chemicals had little, if any, effect on activity or on hatching, the majority of the others had only an insignificant effect. Moreover, many of the most effective were hindered by the protection of proglottids. Furthermore, some could not be used in practice.