A simple method for the collection of third-stage larvae of Necator americanus has been described. This technique provides repeated recovery of very clean larvae from cultures in moderate numbers.

During studies on the ecology of fish helminths, the tapeworm Proteocephalus torulosus (Batsch, 1786) was frequently found in the intestine of the blue bream (Abramis ballerus) from the Oder River (Germany/Poland). In total, 633 fish, ranging between two and 16 years old, were sampled at monthly intervals over a two year period during 1993–1995. Statistically significant differences in the seasonal occurrence of the parasite in its fish host were observed. In 1993, the prevalence remained at a high level, ranging between 61.9 and 100%. During the summer of 1994, this value decreased to 5.5% and remained low for the rest of the year. The pattern of mean intensity of infection was similar to that of the prevalence. In 1993, the mean intensity varied between 8.4 and 31.8 worms per infected fish, with a continual loss of worms being observed in the summer of 1994. Changes in the amount of suspended particulate matter in water have been identified as the main cause of these observed differences in the course of infection of blue bream.

The morphogenesis and the distribution along the digestive tract of Trichostrongylus retortaeformis(Zeder, 1800) (Nematoda) were studied in detail in one of its natural hosts, Oryctolagus cuniculus. Worm-free rabbits were each infected with T. retortaeformis larvae and were killed at 12 h post-infection (HPI) and on each day from 1 to 15 days post-infection (DPI). The distribution of worm populations along the small intestine was assessed. At the different dates of infection, more than 80% of the population was recovered from the first third of the intestine with more than 50% occuring in the first 30 cm. For each date, morphological descriptions of the different stages of the life cycle were also provided. In addition, adult worms collected from naturally infected rabbits from France were redescribed.

A new genus and species of filarioid worm is described from the peritoneal cavity of fruit bats, Pteropus hawaiiensis from Fiji and the name Chiropterofilaria brevicaudata n. sp. is given to it. The microfilaria is described. This appears to be the first record of a nematode from this host. The new genus is differentiated from its nearest genus Lemdana in that the spicules are only slightly unequal; and in the female worms, the oesophagus usually make several turns around the vagina before joining the intestine. From the same host, a second microfilaria, Microfilaria fijiensis n. sp. is described, the adults of which were not found.

Neoheterakis chapini n.g., n.sp. (Nematoda: Heterakoidea) is described from the caecum of a Congopeacock Afropavo congensis Chapin, 1936. The diagnostic features of the subfamily Spinaspidoderinae are extended to accomodate the new genus.

Although several records now exist of the occurrence of Capillaria (Hepaticola) hepatica (Bancroft, 1893) as a natural infection of the wild rabbit the attempts which have been made to infect this host with eggs obtained from an infection in the rat have not been completely successful. Nishigori (1925) states that although this parasite can infect the rabbit and shew some development it does not reach maturity, while Saito (1925), in the English account of his paper given in The Japan Medical World states that “In the rabbit the larva might develop into maturity and cause pathological changes but do not multiply.”

Inbred jirds (Meriones unguiculatus) were divided into three groups; each animal in two of the groups was infected with 30 infective larvae (L3) of Litomosoides carinii. When these infections were patent, the jirds of one of the two infected groups plus those of the third group were injected with 30 L3 L. carinii each. All animals were killed either on day 14 or 24 after the second infection for the recovery, enumeration and measurement of all worms and developing larvae. Challenge larvae were stunted (smaller) and fewer than control larvae. Additionally, fewer challenge larva were recovered on day 14 than on day 24, indicating that migration to the pleural cavity was retarded.

Brachylaemus arcuatus and Plagiorchis (Multiglandidmns) mmris are recorded for the first time from the fox and sheep respectively.

By combining a number of well-known but scattered results, a theoretical model has been constructed to explain the observed quadratic increase in sample variance of egg counts over sample mean with increasing egg concentration. Our contention is that the over-dispersion arises because of inherent variation in volumetric deliveries of faecal suspension onto the counting slide. Even though the observed variation of volumetric deliveries appears to be small, we have shown that it is adequate to cause a considerable increase in egg count variance over mean at not unreasonably high concentrations.

Two new species of Calostraurus Sandars, 1957 (Cestoda: Davaineidae) are described from Australian marsupials, C. thylogale from Tliylogale biltardierii and C. mundayt from Potorous apicalis. A redefinition of the genus is given together with tabulated features of the species.

Detailed studies were carried out to assess the infection characteristics of the antelope schistosomes in BALB/c mice and Mastomys coucha. Both schistosome species reached sexual maturity in these hosts. However, they differed markedly in terms of egg production rates and preferred sites of tissue egg deposition. Tissue egg deposition commenced between 4 and 5 weeks in the case of Schistosoma margrebowiei and between 6 and 7 weeks in the case of S. leiperi. Tissue egg accumulation rates of S. leiperi were calculated to be 334 and 311 eggs/gravid worm pair/day in mice and M. coucha, respectively. The fecundity of S. margrebowiei was found to be substantially greater (approximately 5 times; daily output ranging from 1600–1900 eggs/gravid worm pair). While S. leiperi infections remained relatively stable in both hosts during the study period (i.e. up to 15 weeks after onset of egg laying), S. margrebowiei infections were observed to deteriorate rapidly in M. coucha.

Mice infected for one to eight weeks with Trichinella spiralis cleared either 51Cr-labelled sheep red blood cells (SRBC) or I-polyvinyl pyrrolidone (PVP) given intravenously. PVP was cleared more rapidly from the blood of mice infected for one week than from uninfected mice with older infections which behaved in a similar manner to the controls. SRBC were consistently cleared faster from the blood of mice infected for one week than from normal mice. If the infections were older than this a more rapid clearance was also demonstrated as long as the infections were reasonably heavy.

Rats are known to be relatively resistant to infection with Echinococcus multilocularis. However, when rats are inoculated with the parasite tissues, E. multilocularis proliferates slowly at first but after 6 months the cysts increase in size considerably and contain large numbers of protoscoleces. As rats survive for 18 months or longer, approximately 100 ml of packed protoscoleces can be produced from each rat. A comparison of the antigenicity of the protoscoleces and microvesicles by immunoblot methods showed that both Em18 and Em16 are shared components between both protoscoleces and microvesicles, although the latter have some additional antigenic components. In antigens prepared from protoscoleces, the banding patterns around Em18 were much simpler than those from microvesicles. Therefore, for serodiagnosis of E. multilocularis, antigens should be carefully prepared from protoscoleces rather than microvesicles from the rat.

The survival characteristics of Cercaria chackai, the larval form of the curious ectoparasitic digenetic trematode Transversotrema chackai, in sea water, sea water diluted with deionized water in different proportions, deionized water, pond water and tap water were studied. Naturally shed, fresh cercariae had the maximum life span of 20 h 40 min in pond water at salinity 17·8‰, pH 6·45, O2 5·76ml/l and temperature 31·5°C. With increase in salinities beyond 17·8‰, survival time was drastically reduced and beyond 23·58‰,, was restricted to a few minutes. In sea water with a salinity of 38·3‰, the maximum survival time was only 8 min. Below 17·8‰ salinity, although the survival time was less, the difference was not very marked and even in tap water with no salinity, the cercariae lived up to 19 h 50 min. In deionized water the maximum survival time was only 3 h 15 min. Since pond water at pH 6·45 allowed maximum survival time, it is presumed that the cercariae preferred a slightly acidic medium. As temperature was maintained constant and oxygen was available, neither of these two factors, apparently, affected the survival pattern. It is concluded that C. chackai is a typical freshwater form showing considerable tolerance to fluctuations in salinity although the family Transversotrematidae is considered to have a marine origin.

Anguillonema iranicum n. sp. is described and illustrated as the second species of this genus from Iran, based on morphological, morphometric and molecular characteristics. It is identified by a short, thin body, a continuous lip region, six lines on the lateral field, a short, thin stylet, a posteriorly located pharyngo-intestinal junction to excretory pore, the presence of a post-vulval uterine sac, vulval position at 89% (87.4–89.9%) of body length, an elongate conoid tail with a rounded to pointed tip and not dorsally bent, and common functional males with short spicules and lacking a bursa. Morphological differences between the new species and the three known species of the genus, namely A. amolensis, A. crenati and A. poligraphi, are discussed. Molecular phylogenetic studies of the new species using partial 18S rDNA sequence revealed that it formed a sister clade with three species of Howardula, one species of Anguillonema and one unidentified isolate. In phylogenetic analyses using partial sequences of 28S rDNA D2-D3 segment, the new species formed a clade with two isolates of Parasitylenchus. A key to identification of Anguillonema species is also presented.

Over the last century in the uplands of Scotland, the extent of heather moorland which supports high densities of mountain hares Lepus timidus has diminished and has gradually been replaced by large-scale commercial forestry plantations or expanding natural woodlands. The potential impact of such a change in land use on host–parasite interactions was investigated by comparing the intensity and prevalence of infection of hares by parasites in two separate habitats: a large hare-fenced young forestry plantation and the adjacent open moorland. Carcasses were collected in November 1990 from within both habitats and after the woodland had been enclosed for nine months. Age, sex, fatness (kidney fat index) and degree of infection of hares were noted. Two parasites were recorded: the nematode Trichostrongylus retortaeformis and the cestode Mosgovoyia pectinata. Clear differences in the intensity of infection of adults occupying the different habitats had occurred in the nine months since woodland enclosure. Adult mountain hares in the woodland had levels of infections approaching four times that observed in hares occupying the open moorland and although not significant, the prevalence of infection was greater in hosts inhabiting the woodland than the open moorland. It is suggested that the parasite–host relationship differs between the two habitats and as heather-dominated moorland landscapes become more fragmented with the increasing establishment of woodlands, the impact of parasites on the life history strategies of mountain hares needs to be reconsidered.

The ultrastructure of various regions of the male reproductive tract and the prostate gland of Cotylophoron cotylophorum (Trematoda: Digenea) is described. The internal lining of the entire male duct system is syncytial in nature, and regional variation is quite evident. The syncytial epithelium of the vas deferens and seminal vesicle is very thin, flat and lamellate and the lumen is packed with spermatozoa. In the pars musculosa (PM) the syncytium is also flat but lamellae are sparsely distributed and anastomosed at places to form loops. The syncytium of the PM is invested by several layers of circular and longitudinal muscle. The pars prostatica (PP) is lined by an uneven but moderately thick syncytial epithelium with nuclei projecting into the lumen. The syncytium bears numerous very long lamellae. The ejaculatory duct epithelium is devoid of lamellae. It is even and moderately thick throughout. The prostate gland cells are uneven in outline and bear long ducts which open into the lumen of the PP. They show an ultrastructural organization suggestive of protein secretion.