The tail chamber's role in the survival and infectivity of Proterometra macrostoma (Digenea: Azygiidae) was investigated. Intact cercariae and cercarial bodies dissected from tails were incubated for 14 h in artificial pond water (APW) and cercarial infectivity was assessed in laboratory infections of the bluegill sunfish, Lepomis macrochirus. Although most cercariae stopped swimming and settled to the bottom after 14 h, survival and infectivity of bodies from intact cercariae did not decrease significantly during this period. All isolated bodies survived in APW, but they were 54% less infective. By contrast, infectivity of isolated bodies did not decrease significantly in an artificial snail saline. The results indicate that maximum infectivity in P. macrostoma is sustained throughout the swimming phase because of the tail chamber which protects the body from the effects of osmotic stress.

The present paper describes the size range of Ternidens deminutus from human and baboon hosts in Rhodesia and discusses the possible reasons for the differences noted.

Using transmitted light and the scanning electron microscope, the external morphology of T. deminutus has been re-studied and compared to investigations by other authors using transmitted light microscopy alone.

The paper also illustrates the value of the scanning electron microscope in morphological studies in helminthology, especially when used in conjunction with the light microscope, to give an excellent three-dimensional picture of the species under investigation.

It is intended to follow this work with further studies on the anatomy, histology, ultrastructure and histochemistry of Ternidens deminutus.

1. Two new species (Postharmostomum ntowi and Eptsthmium ghanense) and one previously described species (Episthmium africanum) of digenetic trematodes are recorded from the domestic fowl in Ghana.

2. A key has been provided for identification of all the species of Postharmostomum occurring in chickens.

3. Episthmium africanum is recorded for the first time from the domestic fowl.

Desmidocercella leiperi n.sp. from Ardeola grayii is described in detail and compared with other related species.

Two species of Oxyspirura are recorded from new hosts. Oxyspirura mansoni from Galloperdix spadicea and O. (Cramispirura) popowi from Copsychus saularis.

Two new species of Oxyspirura are described, O. (Cramispirura) indica n.sp. from Kittacincla malabarica and O. buccosulcata n.sp. from Temenuchus pagodartum.

Monanema globulosa (Nematoda: Filarioidea) was recovered from four species of rodents in Kenya, with a prevalence of up to 94% in the striped mouse, Lemniscomys striatus. The adult worms are site-specific to the pulmonary arteries and release sheathed microfilariae that travel via the blood to the skin. Densities of microfilariea in the ears (mf/mg) were five to eight times greater than in any other region of the body and were directly proportional to the number of adult worms present. Highest concentrations of microfilariae in the skin were reached after 100 to 200 days and low numbers persisted in most animals for approximately 500 days.

Third-stage larvae from ticks (Haemaphysalis leachii) injected subcutaneously into jirds migrated widely through the body during early development. Moults occurred twice, after 5 to 10 days and 25 days, and the mean prepatent period was 75 (range 69 to 88) days. A mild eosinophilia developed which peaked after 29 days. Adults in the lungs provoked widespread and intense perivascular cuffing and more localized hypertrophy and fibrosis of the intima in arterioles. Dead adults caused granulomata which obliterated smaller vessels. Microfilariae in the skin elicited no local tissue reaction, but some which invaded the eyes caused a monocyte infiltration of the cornea. It is concluded that the parasite is well adapted to its natural hosts and that it has potential as a rodent model for human onchocerciasis because of the localization of microfilariae in the skin.

T cell populations and IL-3 mRNA expression were analysed in mesenteric lymph node cells and intestinal intraepithelial lymphocytes (IEL) in Strongyloides ratti- infected mice. On days 7 and 12 post-infection, 2.6 times as many mesenteric lymph node cells were present in S. ratti- infected mice compared with uninfected mice. Although the percentages of CD3+, CD4+ and CD8+ cells decreased during infection, the absolute numbers of these cell types increased on day 7 due to an overall increase in the mesenteric lymph node cell number. The CD4/CD8 ratio in IEL was increased on day 5, whereas no significant change in the CD4/CD8 ratio was observed in the mesenteric lymph node cells. Expression of IL-3 mRNA, which is an important cytokine for the induction of murine mucosal mastocytosis and S. ratti- expulsion, was examined in mesenteric lymph nodes and IEL of uninfected and infected mice. IL-3 mRNA was detected in mesenteric lymph nodes of S. ratti-infected mice but not detected in the lymph nodes of uninfected mice. IL-3 mRNA was detected in IEL from both infected and uninfected mice with an 20-fold increase in expression in IEL of infected mice. Overall, IL-3 mRNA levels were higher in IEL than in mesenteric lymph nodes following S. ratti- infection. Expression of IL-4, IL-10, stem cell factor (SCF or c-kit ligand) and IFN-γ mRNA was also examined in these two tissues. IL-10 mRNA was not detected in any tissue examined and IFN-γ mRNA levels were unaltered as a result of an S. ratti- infection. Elevated expression of mRNA for SCF (5-fold) and IL-4 (20-fold) was observed in the mesenteric lymph nodes of infected mice. In contrast, SCF mRNA levels were similar in IEL of uninfected and infected animals and only a modest increase in IL-4 mRNA was observed in IEL of infected mice.

The present paper presents the results of an analysis of the inorganic elements detected in Ternidens deminutus from human and baboon hosts. It reports on the presence of Zn, Fe, P, Ca, Cu, Mg, mn and K in the worms and notes especially that worms from humans contained a higher percentage of body weight of Zn than those from baboons, a finding in agreement with an earlier EDAX analysis of the pigment granules of this species.

The kinetics of the lymphoblast response in mice during the course of a primary infection with Hymenolepis nana was measured by the in vivo uptake of 125IUdR. The response was most marked in tissues local to the site of infection, involving to nodes draining the small intestine but not other areas, e.g., inguinal lymph nodes. A close correlation between these responses and the course of inflection was observed. Uptake of 125IUdR was greatest in the mesenteric lymph node (MLN) but the peak reached in this organ was later than that in Peyer's patches (PP), small intestine (SI) and spleen (S). The increase in lymphoblast activity of the MLN was similar with Trichinella spiralis; no significant blast cell response to inflection with H. diminuta was found till day 9 after injection, the results being similar to those obtained when H. nana inflections were established using cysticercoids rather than eggs. It has been shown that the increase in lymphoblast activity was closely correlated with the presence of cells which are most effective in adoptive transfer immunity. A dose-dependent effect was detected in blast cell activity of MLN in different inflection levels with T. spiralis and H. nana.

The infectivity of the eggs of Asian Taenia sp. for humans is not known. Using baboons (Papio hamadryas) as a model to extrapolate the findings, three animals were exposed per os with 1000, 10,000 and 50,000 infective eggs of theAsian Taenia sp. The serological, biochemical, haematological and parasitological (based on necropsy) results show that baboons are refractory to the infection. It is concluded that the Asian taeniid eggs may fail to develop in man.

Twenty species of helminth parasites were found in the alimentary canal of thirty mallard caught in the decoy at Slimbridge.

Immune responses to immunization and infection with Trichinella spiralis and T. britovi were studied in NIH high-responder mice. Overall it was shown that T. britovi was the more immunogenic, immunization and challenge with this species giving greater host-protective immunity. This greater immunogenicity was reflected in higher proliferative responses when mesenteric node lymphocytes (MLNC) from immunized mice were restimulated with T. britovi antigens in vitro and in higher levels of T helper 2 (Th2) lymphocyte-dependent specific IgG1 antibody responses against this species. MLNC from mice immunized against T. britovi released more IL-5 when restimulated in vitro, again suggesting a greater T helper 2 subset response, but after infection the highest levels of IL-5 were recorded from MLNC taken from T. spiralis challenged mice. These data are discussed in relation to current understanding of immunological differences between species and isolates of the genus Trichinella.

The stem eelworm Anguillulina dipsaci (Kühn) Gerv. & v. Ben., is responsible for disease in numerous plants, amongst which are teazle, Dipsacus fullonum L., the type host and red clover, Trifolium pratense L. In both cases seed harvested from infected plants will often be infected by the stem eelworm in spite of the greatest care in dressing the seed.

Kühn (1857) in describing the parasite for the first time said:— The seeds of the diseased teazles differ from those of the healthy ones. They are not half so large nor so sharply angular. Whilst the pappus of the healthy seed is stalked that of the diseased seed is sessile and almost twice as large. The worms do not completely fill the diseased seed but occur within the atrophied ovule and also as small clumps of worms within the tissue of the abnormally thickened seed coat. The worms are found not only within the diseased seeds but in all other parts of the head including the pith where they cause not only abnormal growth but death and brown discolouration of the tissues.

Although the morphology of the adult stage of the majority of the helminthic parasites of domestic stock is now well known there still remains a considerable amount of work to be done on the larval stages of these worms. Some of the more recent researches on the infective stage of human and other hookworms have shown that a close study of the morphology reveals appreciable differences between the larval stages of closely allied species and that the differences can be used as diagnostic characters.

The complex life cycle of taeniids represents an ideal model of a multi-host system. The complexity of these parasites can therefore cover the epidemiological issues of the interface between wild and domestic animals, especially once spatial overlap between wild and domestic definitive and intermediate hosts occurs. Here we use the occurrence of Taenia ovis krabbei in two model areas as an example of this epidemiological complexity. In two contiguous areas in the Italian northern Apennines, two hunted roe deer (Capreolus capreolus) showed numerous cysticerci in the muscles of their whole body and an adult tapeworm was recorded in a semi-stray dog (Canis lupus familiaris). Through molecular typing of the mitochondrial cytochrome c oxidase I (cox1) gene, cysticerci and the adult tapeworm of T. krabbei were identified. Taenia krabbei cysticercosis was recorded for the first time in Italy. Although the role of dogs in the parasite's life cycle emerges, the overlap between wild and domestic definitive hosts and the increase of wild population densities raise concerns about the temporal (old or new) introduction and the spread of this parasite by one of these canid species (wolf (Canis lupus) or dog). Although T. krabbei is not a public health issue, economic concerns emerged for hunters and meat producers, related to the damage of carcasses by cysticerci. Therefore, there is a need to evaluate the spread of T. krabbei in the intermediate and definitive host populations, and to ensure the relevant sanitary education for hunters in order to avoid practices that could favour the spread and maintenance of its life cycle.

Praziquantel (PZQ) remains the only drug of choice for the treatment of schistosomiasis, caused by parasitic flatworms. The widespread use of PZQ in schistosomiasis endemic areas for about four decades raises concerns about the emergence of resistance of Schistosoma spp. to PZQ under drug selection pressure. This reinforces the urgency in finding alternative therapeutic options that could replace or complement PZQ. We explored the potential of medicinal plants commonly used by indigenes in Kenya for the treatment of various ailments including malaria, pneumonia, and diarrhoea for their antischistosomal properties. Employing the Soxhlet extraction method with different solvents, seven medicinal plants Artemisia annua, Ajuga remota, Bredilia micranta, Cordia africana, Physalis peruviana, Prunus africana and Senna didymobotrya were extracted. Qualitative phytochemical screening was performed to determine the presence of various phytochemicals in the plant extracts. Extracts were tested against Schistosoma mansoni newly transformed schistosomula (NTS) and adult worms and the schistosomicidal activity was determined by using the adenosine triphosphate quantitation assay. Phytochemical analysis of the extracts showed different classes of compounds such as alkaloids, tannins, terpenes, etc., in plant extracts active against S. mansoni worms. Seven extracts out of 22 resulted in <20% viability against NTS in 24 h at 100 μg/ml. Five of the extracts with inhibitory activity against NTS showed >69.7% and ≥72.4% reduction in viability against adult worms after exposure for 24 and 48 h, respectively. This study provides encouraging preliminary evidence that extracts of Kenyan medicinal plants deserve further study as potential alternative therapeutics that may form the basis for the development of the new treatments for schistosomiasis.

Larvae of a species of Proteocephalus were observed in the intestines of larvae of Sialis lutaria (Insecta: Megaloptera) in a single locality at prevalence levels of up to 40% and over a period of three years. The cestodes were plerocerciform in character and up to 3 mm in length, having undergone some growth and development in the insect. Comparison of scolex morphology with that of adult Proteocephalus spp. obtained from fish in the same river suggests the most likely identity of the parasite is P. filicollis. Support for this suggestion came from the recovery of two parasites from experimentally infected sticklebacks, Gasterosteus aculeatus. This is the first record of a proteocephalid larvae from an insect, and so also from S. lutaria, and of a proteocephalid using a second, additional invertebrate host. The use of S. lutaria is so far known only from this one locality and may reflect the peculiar, but continuing, ecological conditions there, but it is suggested that the ability to use S. lutaria as an additional host may be associated particularly, though not exclusively, with parasites of sticklebacks.

Cercariae of Schistosoma bovis, S. intercalatum and S. haematobium were radiolabelled by individual exposure of their respective host snails to 75Se-methionine in 1 ml water for a period of 20 hours. Maximum cercaria-bound radioactivity was obtained four to seven days after labelling of snails, but detectable levels of radioactivity incorporation were obtained with all three species for a period of 32 days. The radiolabelling procedure did not interfere with the production of cercariae or with the biological characteristics of the labelled larvae. The described research opens the way for the application of various radioisotope tracer systems in studies on host-parasite relationships between cercariae and schistosomula of terminal-spined species of schistosomes and the final host.

Syngamus trachea is one of the more difficult parasitic worms to dislodge owing to its position in the trachea. Many contrivances such as twisted feathers and spirals of fine wire have been used for the mechanical removal of the worms. In the hands of experts, they may be reasonably effective, but much injury frequently follows their use by amateurs, and the damage is often severe enough to cause the death of the bird. Anthelmintics which may be administered in food and water are seldom excreted by the lungs or are excreted in such low concentration as to be ineffective. Garlic oil and salicylic acid have been used, but are only very slightly effective and cannot therefore be considered as satisfactory treatments. Many so-called gapeworm cures consist largely of substances which stimulate the respiratory musculature and induce a sudden explosive cough.

Miracidia of Echinostoma caproni were exposed to solutions varying in salinity, pH, and temperature in 1 ml concavity slides. Half-lives of the miracidial populations were determined and longevity curves constructed to find maximum life spans of the miracidia in the different conditions. Control miracidia in aquarium water at pH 7.2 and 22°C. had a half-life of 3.6 h and a maximum life span of 9 h. Miracidia of E. caproni were not very tolerant of saline solutions from 0.1% to 0.4%, the latter being lethal within an hour. A bimodal effect was found with exposure to aquarium water of varying pH, with a peak at pH 5 in acid solutions and pH 9 in alkaline solutions. Miracidia tolerated pH ranges from 3 to 11 exhibiting half-lives of 2.4 h or greater in these solutions. At lower than ambient temperatures, E. caproni miracidia lived longer, the greatest being a half-life of 5.0 h and a maximum life span of 15h at 5°C. At warmer temperatures, the half-life was reduced until lethality was reached at 40°C. ANCOVA analysis of log transformed longevity curves supported the observation that in pH trials many miracidia survived initially with a major die-off after 3.3 h. The opposite trend of early die-off and gradual mortality of the survivors was supported in the temperature trials.

The subchronic effect of copper and mercury on selected immunological parameters in guinea pigs with experimental ascariasis was studied. Cupric sulphate and mercuric chloride administered for 28 days did not suppress the levels of specific circulating antibody in a subsequent Ascaris suum infection. Intoxication of animals significantly inhibited the phagocytic activity of peritoneal macrophages throughout the experiment. Ascaris suum infection elevated macrophage phagocytic activity but values remained significantly lower in comparison with infected non-intoxicated animals. Both the concurrently administered metal compounds changed the phagocytic ability of polymorphonuclear leucocytes in the blood.

The intensity of infection assessed by the number of Ascaris larvae migrating in the lungs of animals currently intoxicated with both the metal compounds increased by 28.6%, compared with controls.