Water decoction of the leaves of Andrographis paniculata killed in vitro the microfilaria of Dipetalonema reconditum in 40 min. Three subcutaneous injections of the extract into infected dogs at 0·06 ml per kg bodyweight reduced the number of microfilariae in blood by more than 85%. The larvae were not totally eliminated with more infections but the reduced microfilarial level persisted. No toxiceffect of the extract was observed in rabbits. The treated dogs became lethargic initially for a week, probably due to the mass killing of microfilariae.

Three Jersey bull calves were immunized by subcutaneous injections of sonicated Onchocerca lienalis microfilariae suspended in phosphate buffered saline, and three control animals were injected with medium only. All calves received booster injections 27 days later, and were challenged with live microfilariae 44 days after the booster. Following challenge, only the immunized animals developed an elevated level of circulating eosinophils. When necropsied ten days after challenge there was a 97% reduction in recoveries of microfilariae from immunized animals compared to challenge controls. In human onchocerciasis it is the microfilariae which are the principal cause of pathology, and we believe that studies on O. lienalis in both the natural bovine host and in inbred rodents provide a promising model to investigate immunity to Onchocerca microfilariae.

A medium containing inorganic salts, vitamins and amino-acids is described for the in vitro cultivation of the amphistome, Orthocoelium scoliocoelium, from the rumen of buffalo. Based on the properties of rumen fluid, this medium promoted and sustained normal egg production, at 37°C temperature and pH 7·4 to 7·8 for 15 days. In contrast to other media used, no patho-physiological alterations except abnormal cytoplasmic lipid, were detected. Since the parasites produced normal eggs, it is concluded that this medium is suitable for short-term cultivation of the parasites.

Mortality and infectivity or Schistosoma mansoni cercariae were tested against various concentrations of controlled release copper sulphate (EC-8) and tributyltin fluoride (CBL-9B). The results indicate that survival of cercariae varied with concentrations of molluscicide and times of exposures. Statistical analysis reveals that LC50 and LC90 for EC-8 were 1·8mg/1/hour and 1·82 mg/1/hour while LC50 and LC90 for CBL-9B were 16·8 μg/1/hour and 21·7 μg/1/hour respectively. Sublethal concentration of both molluscicides reduced cercarial infectivity considerably. The doses of 0·25 to 0·5 mg/1/hour for EC-8 and 2·0 to 6·0 μg/1/hour for CBL-9B were found to be sufficient to inhabit cercarial penetration of the host skin.

Anisakis sp. larvae when incubated in vitro produced secretions/excretions which released the dye from an azocoll substrate, indicating protease activity. The optimal conditions for enzyme release and activity were a temperature of 37°C and a pH of 7·5. In addition the larvae showed peak behavioural activity at 37°C, the body temperature of the final, marine mammalian host. The results are discussed in relation to their possible significance to the invasion of the various hosts in the life-cycle.

This study compares the morphology, anatomy, physiology and histochemical distribution of two key enzymes (AcPase and ATPase) in the intestinal trematode Ganeo tigrinum recovered from hibernating and non-hibernating Rana cyanophlyctis and R. tigrina. It has been shown that the torpid state of the host influences its worm so severely that it produces untanned and low quality eggs, the sperm population falls, the rate of worm infection is decreased and the worms do not grow.

AcPase has been shown to undergo significant changes during hibernation, especially in the gut, where extraordinarily high activity seems to be responsible for the autophagy of certain gastrodermal cells. ATPase similarly reveals a decrease in activity in most of the parasite tissues during hibernation. However, its high activity in the parenchyma has been related to the quick transportation of metabolites, representing the threshold concentration necessary for survival and egg production.

In lambs under six months of age infected with 10,000 H. contortus third stage larvae two effects were observed as a result of the treatment regimes administered: 1. Reduced adult worm burdens, indicating protection, occurred in the animals treated with combined transfer factor, adult parasitic antigen and precipitated immunoglobulin whereas other treatment combinations produced no significant effects. 2. Defined patterns of histological changes in the abomasa were associated with each treatment and cumulative effects were recognized when combined treatments were given. The responses induced by transfer factor treatment suggest the development of a hypersensitivity reaction outwith the changes seen in primary H. contortus challenge.

Parasitological and clinico-pathological aspects of Schistosoma intercalatum infection in sheep were studied after exposure to 5000 cercariae per animal. It was shown that the infection, in spite of relatively high tissue egg counts, only gave rise to low-grade clinico-pathological manifestations with almost unaffected blood parameters. The parasites were mainly located in the lower part of the intestinal tract, and the number of eggs being passed in faeces was very low.

The effects of infection with plerocercoids of Spirometra mansonoides on tissue glycogen deposition of rats was determined. Hypophysectomized rats infected for two days had higher liver glycogen concentrations than controls and this effect was greatest after one week. Elevated liver glycogen associated with plerocercoid infection was observed in fed animals both at the beginning and at the end of the light period as well as after an overnight fast. Glycogen phosphorylase (1,4αD glucan: orthophosphate α glucosyltransferase EC 2.4.1.1.) was inhibited but glucose-6-phosphatase (EC 3.1.3.9) was unaffected in the livers of infected hypophysectomized rats. While this effect is similar to actions of both growth hormone and insulin, plerocercoid infection had no influence on glycogen of cardiac or skeletal muscle at any time. Plerocercoid infection had no effect on the glycogen concentration of any tissue of intact rats.

The nematode family Trichostrongylidae is divided into six subfamilies Trichostrongylinae, Libyostrongylinae, Haemonchinae, Cooperiinae, Ostertagiinae and Graphidiinae which are briefly reviewed. The key is based mainly on specimens examined by the authors and includes one genus in the Trichostrongylinae, three genera in the Libyostrongylinae, six in the Haemonchinae, seven in the Cooperiinae, 17 in the Ostertagiinae and two in the Graphidiinae. Pseudostertagia, Pararhabdonema, Parostertagia, Obeliscoides and Travassosius are briefly described, figured and considered as genera of uncertain affinities. Nine genera, namely, Moguranema, Neocooperia, Bergheia, Mazamastrongylus, Paramecistocirrus, Ostertagiana, Ostertamia, Graphidiella and Trichostrongyella, specimens of which have not been available to the authors for examination, are listed giving details of host, habitat and geographical location, together with a summary of the diagnostic characters as described by the original authors.

Brugia-type microfilariae were noted in a Madras tree shrew, Anathana ellioti (Waterhouse) from Andhra Pradesh, India. This is a new host record, the first report from the genus Anathana and the second report from the tree shrews.

Homogenates of the metacercariae of Clinostomum complanatum showed two peaks for the hydrolysis of p-nitrophenyl phosphate at pH 4·5–5·0 and 11·0; specific activity at pH 5·0 was 0·017 µmol p-nitrophenol/mg protein/min and 0·0049 µmol p-nitrophenol/mg protein/min at pH 11·0 at 37°C. Maximal activities of acid and alkaline phosphatases were observed at 50° and 40°C respectively. Both enzymes reached maximal rates after 50 min of incubation. Linearity in enzyme activity was noticed with increasing homogenate concentrations for both enzymes. The Km for p-nitrophenyl phosphate was 1·1 mM with a Vmax of 0·018 units/mg protein for acid phosphatase and 1·6 mM with a Vmax of 0·0052 units/mg protein for alkaline phosphatase. Sodium arsenate and sodium fluoride inhibit and Mg++ and Co++ stimulate both enzymes. Polyacrylamide gel electrophoresis showed one cathodic band each for both the enzymes.

The surface microtopography of Calicophoron papillosum (Stiles & Goldberger) and C. calicophorum (Fischoeder), inhabiting the rumen of sheep, has been studied by SEM. In C. papillosum, conspicuous transverse ridges encircle the mid-body, gradually lessening dorsally towards the posterior end. The general body surface is aspinose and smooth except for minute bead-like tubercles in the circumoral area. Two types of putative sensory structures—domed aciliate papillae and tegumental pits—are present. Their characteristic aggregation in certain regions and their distribution in other parts of the body is described. A unique pattern of ridges, confined only to the base of the genital papilla and the genital atrium, has been observed. In C. calicophorum, tegumental folds encircle the body, these are more numerous near the anterior end and fewer posteriorly. The oral area has numerous concentric folds with domed aciliate papillae; between or on the papillae are tegumental elevated pits from the centre of which a knob-like structure protrudes. These sensory structures occur to a lesser extent in the acctabular area.

An adult female Dipetalonema setariosum (Mönnig 1926) recovered from the pleural cavity of Meriones libycus and bearing an adherent cell mass was examined by means of electron microscopy. The host reaction consisted exclusively of macrophages and was associated with disruption of the cuticular membrane and invasion of the cuticle itself. There was no evidence of prior activity by other cell types. Initiation of damage appeared to be associated with the release of lysosomal enzymes by the macrophages. Within the reaction a localized breaching of the cuticle had occurred and cells had penetrated the internal tissues of the worm. It is suggested that macrophages may play a role in the elimination of effete worms from an established population.

Infection of a dog with Strongyloides stercoralis filariform larvae resulted in a persistent infection. Patent infections were not seen in rabbits, guinea-pigs, rats and 11 inbred strains and one outbred strain of mice. Manipulation of factors known to influence S. ratti infections in mice, such as age and sex of the host and the route of larval presentation, did not facilitate the appearance of rhabditiform larvae in the stools. Administration of immunosuppressive doses of corticosterioids to rabbits, guinea-pigs and C57B1/6 mice did not permit complete development. Similarly, the course of infection was not altered in T cell-deficient hypothymic (nu/nu) mice. The fate of filariform larvae applied to the skin of mice was ascertained; filariform larvae were observed to migrate from the skin via the lungs to the muscles within several days of infection. Although S. stercoralis does not develop to maturity in the small intestine of mice, this system does allow in vivo studies of the actions of anthelmintics against filariform larvae as well as a number of aspects of the immune response to this parasite.