Haemonchus contortus originally derived from an Ontario field strain was used to infect laboratory rabbits. Both ensheathed and artificially exsheathed larvae were given at doses of up to 10 million larvae per rabbit. Only artifically exsheathed larvae were infective and a dose of at least 50,000 was required to produce a significant level of infection.

H. contortus completed its development in the rabbit, but at a slower rate than in the sheep. Although a few fecund females were found 35 days after infection no eggs were observed on faecal examination. A high proportion of early fourth stage larvae were recovered from numerous rabbits including some which were examined well beyond a postinfection period when all worms should have been in the adult stage. This phenomenon occurred when freshly harvested and exsheathed larvae were used. Post-exsheathed cold conditioning of larvae at 5°C further increased the proportion of early fourth stage larvae (maximum proportions were found after 21 and again after 79 days of cold conditioning and thereafter declined). Whether such larvae were inhibited cannot be stated definitely. However, several of these larvae contained crystalline rods within their soma, and the structure of the crystals was similar to those previously described from inhibited H. contortus larvae recovered from sheep.

It was concluded that the laboratory rabbit could be a useful host for further studies on some aspects of the biology and pathogenicity of H. contortus.

Irradiated cercariae, irradiated schistosomula, or hcterologous infections were used to vaccinate sheep against Schistosoma mattheei infection. In the first experiment four doses of I04 S. mattheei cercariae irradiated at 6Kr were administered to sheep by percutaneous infection at 4 week intervals. This induced a 74% reduction in a challenge infection compared to control sheep while only 13% protection was achieved in a third group of sheep immunised with normal cercariae of the heterologous parasite S. mansoni. No significant differences were seen in histopathology of the liver of any of the sheep but the pathological changes were more severe in the large and small intestines of sheep vaccinated with the heterologous parasite. In the second experiment with irradiated cercariae only one or two immunising exposures were used. The degree of protection in the adult worm load (9–11%) was not significant and no significant differences were noticed in the pathology of the vaccinated and control animals. In the third experiment four doses of irradiated organisms were used to vaccinate five groups of sheep: 3Kr or 6Kr cercariae were administered by percutaneous infection; 6Kr skin-transformed scbistosomula were administered by intramuscular injection; the same 6Kr skin-transformed schistosomula were given by intravenous injection and 6Kr syringe transformed schistosomula were administered by intramuscular injection. The degree of protection (determined as the reduction in worm burden) achieved by these different procedures was respectively 72%, 61%, 77%, 56% and 78%. These results indicate the possibility of making a live vaccine against ovine schistosomiasis and show that effective immunisation is not dependent on the presence of a mature worm infection or on cercarial penetration of the skin by the immunising infection.

An extract of the snail Bulinus (Physopsis) africanus, the intermediate host of Schistosoma haematobium, was used as the antigen in haemagglutination tests in a survey of the prevalence of anti-snail antibodies in various population groups. It was found that sera from known bilharzia-infected individuals and randomly selected individuals from bilhanda endemic areas had significantly higher incidences as well as higher titres of antibodies to this snail antigen than non-infected individuals and individuals from non-endemic areas.

Six transformation techniques ((i) incubation of cercariae in isotonic; medium; (ii) penetration of isolated skin; (iii) stimulation with crude egg lecithin; (iy) mechanical disruption by passage through a syringe and 21 gauge needle; (v) by whorling of cercariae with a vortex mixer; (vi) syringe transformation followed by incubation) were evaluated. The organisms produced were assessed for infectivity for mice by 6 different routes of infection (percutaneous, intradermal, subcutaneous, intra-peritoneal, intravenous and intramuscular). At perfusion the largest numbers of adult worms were recovered from mice injected intramuscularly with organisms produced by the syringe technique and control mice given cercariae percutaneously. The peak for migration of schistosomula (following syringe transformation and intramuscular injection) through the lungs and the appearance of adult worms in the mesenteries was shown to be similar to cercariae administered percutaneously.

Immature and mature stages of the sheep amphistome Cotylophoron cotylophorum have been analysed histochemically for their lipids. Excretory ducts of the immature worms were the common sites for the accumulation of neutral lipids (triglycerides) and phospholipids which showed very sparse distribution at the corresponding sites in the adult. Phospholipids and lipoproteins observed in the tegument of the adult could not be seen in the immature form. Intestinal caecae of both forms showed the presence of diffused and granular lipids which were relatively less in the immature. The possible physiological significance of these differences in the lipid contents of the immature and mature forms has been discussed.

Five desert sheep were exposed to 5000 or 10000 Schistosoma bovis cercariae each, and the parasitological, clinical and pathological parameters were recorded. The pre-patent period was approximately 7 weeks and from that time onwards, the animals became progressively ill and emaciated. Following necropsy at the 12th week, a percentage schistosome recovery ranging from 36%—63.6% was found, and there were high egg densities in the intestinal tract and the liver. These organs revealed severe pathological lesions which were described in detail along with the changes occurring in other tissues.

Infection of dogs with E. granulosus is recorded for the first time in the State of Kuwait and observations on 204 dogs from different suburbs showed an infection rate of 23.039%. Cattle, sheep, goats and camels killed for public consumption in the period 6th April to 6th May, 1975, in a slaughter house were inspected and the rate of infection with E. granulosus cysts was recorded. The possible methods of transmission from animals and dogs to man is discussed.

Scheloribates laevigatus (Koch, 1836) and Scliehribates fimbriatiis (Thor, 1930), predominant species of oribatids in soil of Bombay region, were experimentally exposed to infection by uniform suspensions of eggs of Moniezia expansa and M. benedeni. The percentages of mites infected and the average number of cysticercoids developing were observed in 12 sets of experiments. The mites were more readily infected with eggs of M. expansa than with those of M. benedeni. S. laevigatus were infected with M. expansa and Jess with M. benedeni than S.fimbriatus.

A modification of the Kato thick smear technique, the Bell filtration technique, and a digestion method were investigated to determine the relative merits of each for the detection of schistosome eggs in human faecal samples. The modified Kato technique was the method of choice because it was sensitive, simple to perform, and suitable for field use. The Bell filtration technique was equally sensitive in detecting light infections, but was more tedious and more complicated to perform than the thick smear technique.

F151 was a potent filaricide against adult Brugia pahangi in cats and jirds.

HOE 33258 did not kill adult worms in cats but had a marginal effect on adult worms in the peritoneal cavity of jirds. It was not immediately microfilaricidal in cats but the microfilarial counts of treated cats fell within a few weeks of treatment.

The reaction product, or mixture, of these two compounds (V5851 = E) was strongly macrofilaricidal m cats and jirds.

Neodiplostomum (Conodiplostomum) ramachandrani sp. n. is described from Rattus muelleri in Kepong, Selangor, Malaysia. It is characterised by having symmetrical dumbell-shaped testes, and vitellaria as a single ventral band in the hindbody. The taxonomic relations ofNeodiplostomum, Conodiplostomum and Fibricola are discussed and possible significance of the fluke as an ecological indicator noted.

By means of scanning electron microscopy, stalked protrusions were observed arising from the outer surface of intact brood capsules of Echinococcus granulosus. Histological studies showed these protrusions to be developing protoscoleces. However, complete development is not attained and the protoscoleces eventually die. It is suggested that external development is a result of overcrowding within the brood capsule.

The intrauterine development of Brugia pahangi embryos was followed from after fertilization to birth, using light and electron microscopy. The origin and development of the sheath of the microfilaria and its Possible role in the nutrition of the developing embryo were particularly investigated. Comparisons were drawn with the intrauterine development of other filarial species. The egg shell of the B. pahangi embryo js distinct from the oolemma and forms the sheath of the microfilaria. It is suggested that the electron dense material released by cells of the uterine wall and passing along the channels between the egg shells of adjacent embryos is nutritive. The death of large numbers of developing embryos in the central uterine Jumen is probably caused by overcrowding as their size rapidly increases, leading to nutritional deficiency.

The effects of levamisole on adults, third stage infective larvae, and microfilariae of Brugia pahangi were studied in in vitro culture and in vivo against developing stages in the vector mosquito and in infected cats. In vitro the drug was effective only at dose levels much higher than can be tolerated by mammals. It was active against the developmental stages of the worm in the vector Aedes aegypti.

The drug was strongly microfilaricidal in cats but less effective against adult worms.

The bionomics of the free-living larvae of Dictyocaulus filaria on pasture, and the transmission of infection between lambs, were studied during different seasons of the year m North-East England.

The rate of development of first-stage larvae to the third stage took 4–9 days in late spring and summer, 1½–4 weeks in autumn and 5½–7 weeks in winter. The proportion of first-stage larvae developing to the third stage ranged from 10–28% in autumn and winter, and 2–25% in spring and summer. The rate of mortality of the third-stage larvae was approximately logarithmic in nature, although the survival time was shorter in spring and summer than in autumn and winter. Third-stage larvae were able to survive from autumn until the spring of the following year in sufficient numbers to perpetuate transmission but not to cause clinical disease.

Analyses of primary infections of Nematospiroides dubius in male and female laboratory mice show that on days 4–6 post-infection worms occupy up to 50% of the small intestine but as the age of the infection increases worm populations are highly aggregated in relation to the anterior sections of the small intestine. Individual worms are also shown to be aggregated with respect to each other. Between days 42 and 60 postinfection, although the pattern of distribution of N. dubius along the small intestine does not significantly change, survival of worms is influenced by both age and sex of ASH/CSI S.P.F. mice, reasons for which are discussed in the light of previous work on primary infections of N. dubius in other strains of laboratory mice

Schistosoma rodhaini is a parasite of rodents and dogs in some parts of Africa, south of the Sahara (Schwetz, 1952; Deramée et aly 1953; Berrie & Goodman, 1962; Nelson et al.f 1962). Occasional human infections have also been reported (Haenens & Santele, 1955).

The only comprehensive study reported in the literature on the histopathology of S. rodhaini is that of Thienpont et al. (1953) in naturally infected dogs. Saoud et ah (1966) briefly described the tissue reactions in chronic heavy infections of the Kenya strain in hamsters. It has been found that the pancreas is one of the visceral organs seriously involved in schistosomiasis rodhaini of hamsters.

The haemoglobins of six different species of trematodes: Gastrothylax crumenifer, Srivastavaia indica, Gigantocotyle explanatum, Fasciolopsis buski, Gastrodiscoides hominis Isoparorchis hypselobagri and their three different hosts: Bubalus bubalis, Sus scrofa, and Wallago attu were spectrophotometrically investigated, and were found to contain porphyrin IX as the common prosthetic group. Oxyhaemoglobin, carbonmonoxy-haemoglobin and reduced haemoglobin of all 6 species of trematodes and their 3 hosts under study gave similar absorption maxima. Distinct differences were, however, observed in the nature of the spectral curves of cyanmethaemoglobin which exhibit 2 absorption maxima in the β and the α region in the case of al trematodes whereas in the case of similar host haemoglobin derivatives only one single broad peak in the 536–540 nm region was obtained. With respect to pyridine derivatives all the trematode haemoglobins show a sharp peak in the α region and a minor hump in the β region except Gastrothylax crumenifer. All three host pyridine haemoglobin derivatives show only a single broad peak at 570 nm.

Infection with the cyclophyllidean tapeworm Mesocestoides sp.is recorded in British wild red foxes (Vulpes vulpes crucigera) from Scotland and South East England. Previously, the occurrence of this parasite in Great Britain has been rarely reported, but the results of the present study indicate that vulpine infection may be common.