During the intramolluscan larval development of Schistosoma haematobium (Algerian strain) in Bulinus truncatus, two replication processes of daughter sporocysts occur. Replication by direct sporocystogenesis appears more important than sporocystogenesis post cercariogenesis. These mechanisms assure a periodic renewal of the sporocyst stock in the snail host and seem to be synchronized with the development of cercarial generations. The succession of several generations of cercariae is responsible for the alternation of high and low periods of productivity.

The scheme proposed for the intramolluscan development of S. haematobium is compared with those described for S. mansoni and S. bovis and interpreted in terms of demographic strategies adapted to a better exploitation of the snail host.

An eosinophil chemotactic factor (ECF) was partially purified from plerocercoids of Spirometra erinacei by a combination of anion-exchange chromatography on DE52 and gel filtration on Sephacryl S–200. The molecular weight of ECF was estimated to be 25 000–45 000 by high-pressure liquid chromatography. The ECF was bound with concanavalin A-Sepharose. The ECF was sensitive to periodate oxidation and to heating (56°C, 30 min). On isoelectric focusing, eosinophil chemotactic activity was clearly revealed at pI 4·1. These results suggest that ECF of S. erinacei plerocercoid is an acidic glycoprotein. An intradermal injection of ECF induced eosinophil attractions in the normal guinea pig skin.

The sensitivity and specificity of double immunodiffusion (DID), indirect haemagglutination test (IHA), immunoelectrophoresis (IEP), counterimmunoelectrophoresis (CIEP) and enzyme-linked immunosorbent assay (ELISA) were evaluated and compared using saline extracted of Taenia solium larval scolex and its Sephadex G-200 fractionated 1st and 2nd peak as antigens. Various immunodiagnostic tests gave different results with different antigens. Highest sensitivity (92·5%) was obtained with ELISA using 1st peak antigen and lowest sensitivity was obtained with DID. However, 88·4% and 84·6% sensitivity was obtained with IHA and CIEP respectively using scolex antigen. CIEP gave better results as compared to IEP. Crude antigen gave high sensitivity but less specificity. It was concluded that CIEP can be used as a field test for the anti-mortem diagnosis and ELISA can be employed for laboratory confirmation of T. solium cysticercosis in pigs using frationated 1st peak antigen.

The effect of intestinal flora on the establishment, development and pathogenicity of Ascaris suum larvae in piglets (Large White breed) was investigated. The infected piglets with Ascaris and Escherichia coli showed signs of pneumonia, cough with respiratory difficulties initially even though these moderated with time. They lost appetite and showed signs of unthriftiness with loss of weight. The packed cell volume was normal but the differential leucocyte counts of the pigs infected with Ascaris larvae and bacteria had high neutrophils, unlike the very high lymphocyte count observed in piglets with ascarids only. The piglets had generalized serous atrophy of body fat. The pericardial and perirenal fats were gelatinous. There was a firm and nodular grey and red hepatization with abscess pockets in the intermediate and anterior one third of the diaphragmatic lobes of the lungs. The liver contained greyish-white and depressed focus immediately dorsal to the area of attachment to the gall bladder with multifocal areas. There was no significant gross lesion in the control animals. Cultural and microscopic examinations of some internal organs of the infected animals showed that bacteria were carried to the lungs by the migrating Ascaris larvae. The combined synergistic effect of Ascaris larvae and E. coli was also investigated and it was concluded that the two agents (A. suum larvae and E. coli) worked together synergistically.

Hymenolepis murissylvatici elicits a humoral response in serum and in the intestine of the mouse from which it is immunologically rejected. In serum, significant differences were recorded 3 days after reinfection, while in intestinal lavages it takes place from day 9 after reinfection. In serum the response is largely the result of IgG and IgM antibodies whereas in the intestine, IgA is the most abundant antibody. Although specific IgE could not be demonstrated in serum, it was present in intestinal lavages, although rather late (i.e. day 14 after reinfection). Treatment of young worms in vitro both with immune serum or intestinal lavages had no apparent effect on their viability. Immune serum produced a complement independent precipitation on the surface of the worms in vitro. This reaction did not affect viability or infectivity of the parasite, as demonstrated by the successful implantation of treated worms in recipient mice. The above-mentioned results, together with the knowledge that the Hymenolepis model has no tissue stages and causes no tissue damage, make it probable that further study of this model will reveal some specific intestinal immunological reactions.

This study investigates the level of helminthic infestation in better-cared-for dogs in a middle-class community in suburban Kingston. A canine zoographic study was conducted, and fresh faecal deposits were collected and analysed for helminth life-cycle stages. The survey indicated that 73% (n=93) of households in the study area owned one dog or more (mean=1·4). Resident's attitudes towards canine management suggested that the dog population was, in general, restricted to the residential estate, and most owners claimed to have dewormed their dogs at least as young animals. Of 141 faecal specimens, 58% contained eggs or larvae of one or more of eight helminths: Uncinaria stenocephala (26%), Ancylostoma sp. (23%), Trichuris vulpis (9%), Toxocara canis (8%), Spirocerca lupi (6%), Strongyloides sp. (6%), Apophallus sp. (4%) and taeniids (1%). There was a high level of multiple infection in the host animals, with approximately one fifth of the infected samples containing three or more helminth types. Infection intensity was apparently low, but some dogs harboured heavy worm loads.

The present study investigated the suitability and importance of buffaloes, camels, sheep, goats and pigs in maintaining the life-cycle of Echinococcus granulosus in Aligarh, India. A total of 565 (36%) of 1556 buffaloes, 20 (2%) of 1208 goats, 5 (1%) of 559 pigs, 6 (6%) of 109 sheep and two of three camels were found to harbour hydatid cysts. The frequency distribution of the hydatid cysts in each intermediate host species was over-dispersed and in buffaloes cyst fertility increased with increasing cyst size. Of 2171, 95 and four buffalo, goat, and camel cysts examined 327 (15%), two (2%) and three cysts respectively were fertile. No pig or sheep cysts were found to contain protoscoleces. The unfenced buffalo abattoir and the large number of dogs allowed access to the abattoir coupled to the number of buffaloes slaughtered in comparison to the other potential hosts, indicates that the buffalo is the most significant host for maintaining the life-cycle of the parasite in this area of India. Applicable control measures for the region are suggested.

During one year 1249 male cattle were examined for Mammomonogamus laryngeus infections in the slaughterhouse at Kandy, Sri Lanka. The overall prevalence was 40% with only light monthly variations (34 to 52%). The infection rate was highest (47%) in 2 to 2·5 year old animals. In infected animals an average of 6·4 parasite pairs was found with higher numbers in older animals. The majority of worms were located on the posterior side of the epiglottis. Lesions observed were mucosal plugs at the site where the parasites were attached to the mucosa and moderate to severe erosions and ulcers in other zones.

A total of 444 adult frogs (Rana temporaria) were obtained from three sites in the east of Ireland. Oswaldocruzia filiformis was present at all times of the year; overall, 64% of the frogs were infected, with a mean burden of 5 worms/frog. Most of the parasites were in the first half of the small intestine. A single gross lesion associated with a high worm burden is described. Female parasites were more abundant than males. Most parasitic stages of O. filiformis overwintered in hibernating hosts. Seasonal patterns in the levels of parasitization were not discerned. The intensity of infection was significantly greater in female than male frogs at one of the sites. There was little correlation between the size of host and degree of parasitization. None of the 45 frog tadpoles examined harboured O. filiformis. Frogs became infected by August of their first year.

It has been established that the wall of the metacercarial cyst of the strigeid digenean Apatemon (Australapatemon) minor from the leech Erpobdella octoculata shares with Apatemon (Apatemon) gracilis the remarkable ability to expel the metacercaria forcibly from the cyst, an event which presumably occurs when the cysts are eaten by the bird definitive host. When cysts of A. minor are treated in vitro with a solution containing a mixture of bile salts and trypsin following pretreatment with acid pepsin, the metacercaria is expelled in an explosive manner through a canal at the narrow end of the pear-shaped cyst. This expulsion is produced by a sudden and substantial inward expansion of the birefringent wall, as a consequence of which the cyst lumen is virtually eliminated. Expulsion of the metacercaria in this explosive manner also occurs when similarly pretreated cysts are exposed to either bile salts alone or to trypsin, but cysts treated with the latter take longer to respond. When the cyst wall is perforated with a needle, inward expansion of the wall occurs and the metacercaria is forcibly ejected through the perforation. A variety of other pretreatments and treatments was tested but pepsin appears to be the most effective “primer”, apparently producing localized changes which permit the exit of the metacercaria. These observations are discussed in relation to the mechanism of expulsion.

Third larval stages (L3) removed from fish fillets, fourth larval stages (L4) raised in in vitro culture, and adults of Pseudoterranova decipiens, collected from grey seal (Halichoerus grypus) stomachs, were exposed to the broad spectrum anthelmintic, ivermectin. L3 and L4 parasites were exposed, in vitro, to 500, 100, 50, 20, 5 and 1 μg/ml concentrations of the drug, in culture media. Adult P. decipiens were exposed in vitro to a concentration of 500 μg/ml ivermectin, only. Controls consisted of parasites placed in culture media alone or culture media plus drug vehicle. These three developmental stages of P. decipiens were all found to be susceptible to the effects of ivermectin.

Inorganic analysis of Ascaridia galli has shown the levels of sodium, potassium, copper, magnesium, calcium, zinc, iron, nitrogen, phosphorus, sulphur, chlorine and cobalt (expressed as percentage of dry weight) to be higher in females than in males.

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.