Transplanted infections of Dipetalonema viteae and Brugia pahangi have been evaluated as tools for experimental chemotherapy. Attempts were made to establish these filariae in similar pharmacokinetic sites within the same host, so that direct comparisons of in vivo drug susceptibilities could be made. Unfortunately, it was not possible to establish B. pahangi in the subcutaneous tissues, the preferred site of D. viteae. Therefore, intraperitoneal B. pahangi and subcutaneously implanted D. viteae in gerbils were used for the study. D. viteae infections were significantly enhanced by concomitant infections with B. pahangi, while B. pahangi infection rates were unaffected by the presence of D. viteae. Experiments with amoscanate, CGP6140 and Mel W demonstrated the importance of employing both B. pahangi and D. viteae for antifilarial discovery work and the fundamental effect of parasite location on drug efficacy. D. viteae rapidly migrate from the peritoneal cavity of gerbils following implantation; twenty one hours after infection 73% of transplanted worms were found in the subcutaneous tissues. It was shown that the migration response could be used as a stringent parameter for demonstrating antifilarial activity. D. viteae were exposed to antifilarial drugs for 24 hours in vitro, washed and implanted into the peritoneal cavity of gerbils. At autopsy, 5 days later, 10−8M ivermectin and milbemycin D had prevented migration; CGP6140, amoscanate, suramin, flubendazole and furapyrimidone were also detected at <10−6M using this parameter. In all cases the migration response was more sensitive to drugs than parasite kill. Ivermectin's ability to inhibit worm migration through the tissues is discussed, with respect to the role of itinerant males in the reproductive cycle of Onchocerca volvulus.

Ovine and equine protoscoleces of Echinococcus granulosus were cultured for 26 days with our without praziquantel and viability assessed, by eosin exclusion, for cultures in various drug concentrations (50, 250 and 500 μg/l) and periods of exposure (1, 3 or 7 days (d)) before removing/‘rescuing’ to drug-free medium. Drug efficacy was proportional to drug concentration and to length of exposure. At higher drug concentrations shorter exposures were required to produce the effect of continuous drug treatment, 1d therapy at 500 μg/l killing 96% ovine protoscoleces by day 14 whereas 7d therapy at 50 μg/l was required to produce a similar effect. Equine protoscoleces appeared marginally less susceptible than those of ovine origin. The relevance of the results in the need for peri-operative prophylaxis against spilled protoscoleces in man is discussed.

A series of monoclonal antibodies was prepared against tegumental and internal antigens of Fasciola hepatica by immunizing mice with whole adult-fluke homogenates prior to harvesting the splenic lymphocytes for fusion. Preliminary screening by the Indirect Fluorescent Antibody technique indicated the occurrence of discrete groups of monoclonals differing from one another in tissue-specificity but within which IFA labelling patterns were fairly consistent. Representative hybridomas for 5 of these groups were stabilized and used to produce ascites fluid in mice. By application of an immunogold labelling technique it was possible to map the distribution of antigens for which each monoclonal antibody had affinity throughout the tissues of 4-week and 12-week flukes. Several monoclonals specifically labelled antigenic determinants on the important tegumental antigen T1. However the distribution of gold colloid labelling suggested that epitopes other than that normally exposed to the infected host were recognized; and several monoclonals specifically attached to T1 antigen in the tegument of juvenile worms only. The glycocalyx of the gut and excretory system of flukes shared T1 antigenicity with the tegument. Monoclonal antibodies were produced against an internal immunogen associated with ribosomes and heterochromatin in active protein-producing cells, and against interstitial material of adult flukes. Monoclonals against antigens in parenchymal cell cytoplasm and in mature vitelline cells were recognized but the corresponding hybridomas were not stabilized.

Various populations of laboratory bred bulinid snails were exposed to miracidia of Schistosoma bovis from Mbozi. The parasite is naturally transmitted by Bulinus globosus in the area. Laboratory infection revealed a good relationship with B. forskalii and B. globosus from Mbozi and a population of B. forskalii from Dar es Salaam (infection rates 100%, 63·6% and 41·7% respectively). Populations of B. globosus and B. nasutus from Dar es Salaam were refractory. It appears that both snail species (B. globosus and B. forskalii) present in Mbozi district transmit S. bovis.

Schistosoma curassoni has been recovered from cattle in northern Nigeria. Rectal scrapings of 90 cows slaughtered at the Kano abattoir, Kano, Nigeria during March and April 1986 revealed a prevalence of 7·8% S. bovis and 2·2% S. curassoni. Further examination of the mesenteric and rectal veins of 502 cows showed that the overall prevalence of schistosomiasis was 31·1%. Local Bulinus globosus were infected successfully in the laboratory with S. bovis miracidia.

Comparative efficacy of mebendazole and flubendazole, a p−fluor analogue of mebendazole against the encysted larvae of Trichinella spiralis (USA strain) in the diaphragm of mice and rats were studied in order to provide a better understanding of the structure-activity relationship within the benzimidazole series. Drugs given 10–100 mg/kg/day for 3 consecutive days (35–37 days post-infection) or at 300 mg/kg, 35 days post infection were significantly effective in decreasing early encysted larvae in mice. No significant differences in effectiveness against the early encysted larvae could be observed between the drugs under the present experimental conditions. Mebendazole was found to be more effective that flubendazole in decreasing old encysted larvae in mice treated 70–72 days post-infection based on a comparative study of their ED50 values. When rats were given the drugs at the dose of 10 mg/kg/day for 3 consecutive days, mebendazole was significantly effective against both early and old encysted larvae while flubendazole was not.

In an experimental larval infection of Ancylostoma caninum in mice, the efficacy of various anthelmintics against the larvae migrated and established in the brain is reported for the first time. Albendazole and flubendazole were the most effective drugs. Thiabendazole, benacil, phenacizole, oxfendazole and mebendazole showed significant larvicidal activity. Tetramisole, levamisole, fenbendazole, Sch 18099, pyrantel pamoate, morantel tartrate and oxantel pamoate did not show any significant activity even at relatively high dose levels.

Faecal specimens randomly taken from 232 healthy dogs living in the area of Thessaloniki were screened for internal parasites. In 39·2% of the examined dogs excretion of Sarcocystis bovicanis (1·3%), Isospora ohioensis/burrowsi (3·9%), Giardia lamblia (0·8%), Hammondia heydorni (0·4%), Dicrocoelium dendriticum (0·8%) Diplopylidium nolleri (0·4%), Joyeuxiella pasqualei (0·8%), taeniids (0·4%), Toxocara canis (22·4%), Toxascaris leonina (1·3%), Uncinaria stenocephala (3·0%), Trichuris vulpis (2·6%), Spirocerca lupi (0·4%), or Linguatula serrata (0·4%) was detected. The overall rate of infection did not show any significant difference concerning sex or age. T. canis, however, was significantly more often found in the youngest age group (1–3 months).

The secondary response of eosinophilia has been studied in mice infected with A. suum. In mice infected orally with 1000 A. suum eggs, larvae disappeared from the body within two weeks after infection. The number of peripheral blood eosinophils decreased to the pre-infection level within eight weeks. A typical secondary response of IgG antibody production to egg antigen was found after reinfection with 1000 eggs. The number of peripheral blood eosinophils increased more rapidly after reinfection than after the primary infection. However, the peak number of eosinophils after reinfection was similar to that after primary infection, and the long-lasting characteristics of eosinophilia after reinfection did not differ from those after primary infection. These results suggest that the secondary response of eosinophilia is characterized by a rapid increase in the number of eosinophils in A. suum-reinfected mice.

Rabbits were vaccinated once, by subcutaneous and intradermal injection, with sonicates of oncospheres (TpO) or conditioned media from in vitro maintained mature metacestodes (TpMcES) of Taenia pisiformis. Extracts were either incorporated into or mixed with unilammelar liposomes (reverse phase evaporative vesicles) or emulsified in Freund's Incomplete Adjuvant (FIA). Control groups received liposomes or FIA without antigen, or antigen preparation without adjuvant. Rabbits were challenged orally two weeks after vaccination with approximately 1500 eggs of T. pisiformis and necropsied eight weeks after challenge. A mean of 155 cysts was recovered from seven control rabbits. A 67% reduction in peritoneal cyst numbers was obtained in TpO–IFA vaccinated rabbits compared to 75% for the TpO–liposome entrapped group. The highest level of protection (86%) was obtained when TpO was mixed with but not entrapped in liposomes. Only 32% and 39% reduction in peritoneal cyst numbers was obtained after immunizing with the TpMcES preparation in liposomes or IFA respectively, however >85% of peritoneal metacestodes were dead (necrotic or calcified) and suggests a different immune response than occurs after vaccination with oncosphere extracts. Specific anti-oncospheral or anti-metacestode ES antibody (IgG) responses at two weeks post vaccination were similar in rabbits immunized with liposome or IFA associated extracts.

Three week old Schistosoma mansoni, cultured for up to sixty days after exposure to ethyl methane sulphonate, showed extensive ballooning which often involved most of the worm's body. Other changes included tegumental breakdown which was expressed in varying degrees from mild hernia to total disruption of body shape. Increase in gut size involved stretching of the epithelium and inclusions ranging from masses of disrupted tissue to large, dark opaque masses. Masses were also occasionally seen in the fluid filled spaces of worms. Evidence of hyperplasia was not observed in any of the histological examinations performed.

The intestines of normal and resistant LAF mice were subjected to histologic study to determine the timing and mechanisms of resistance to reinfection by Heligmosomoides polygyrus. During reinfection third-stage larvae are less able to penetrate the intestinal wall.

Larvae which are able to encyst develop at a slower rate and provoke an increase in nonspecific inflammation around their cysts. After emergence from intestinal cysts, preadults are rapidly lost, but at no time were injured or destroyed larvae or adults noted.

Exsheathed larvae were injected via tail vein into control, sensitized and resistant BALB/c mice. The inflammatory response around entrapped larvae in the lung was measured at 1, 2, 4, and 8 days. A heightened inflammatory response, consisting primarily of polymorphonuclear cells with some round cells which peaked in size on day 2, was observed in both sensitized and resistant mice. A similar heightened inflammatory response was also observed in both AKR (non-resistant) BALB/c (resistant) mice vaccinated subcutaneously with exsheathed larvae.

Two populations of Apodemus sylvaticus, one in deciduous woodland and another in coniferous forest in Co. Down, Northern Ireland, were trapped at monthly intervals over 33 months. The dynamics, reproduction and age structure of the mouse populations differed between years with over a 40 fold range of population size. Nine species of helminths were recovered from the alimentary tract and associated organs of the mice. The prevalence and mean worm burden of the cestodes, Catenotaenia lobata, Hymenolepis hibernia and Taenia taeniaeformis varied erratically. The trematodes, Corrigia vitta and to a lesser degree Brachylaima recurva, had seasonal changes in abundance. The nematodes Capillaria murissylvatici and Nematospiroides dubius had strongly seasonal cycles of abundance associated with the onset of host reproduction. Trichuris muris was the rarest helminth. Despite protracted periods of absence this species maintained a seasonal increase in mean worm burden in late winter. The nematode, Syphacia stroma, had a weakly seasonal pattern of dynamics. The bases of these cyclical and non-cyclical dynamics of the helminths of A. sylvaticus are discussed.

A technique is described whereby young adult Moniliformis moniliformis, aged up to 7 days, can be transferred via the oral route from one rat to another. The method is dependent on giving the recipient rats a dose of Cimetidine (0·25 ml/250 g body weight of a solution containing 950 mg/ml) 1 h before transfer. Cimetidine functions as an H2-receptor antagonist and gastric acid secretion in the rat is inhibited temporarily. The technique does not appear to interfere with the reproductive biology of the parasite.