Migration and distribution of Ancylostoma caninum larvae in the tissues of Swiss albino mice infected with 500,1000, 2000 and 4000 larvae was studied. Larval migration and distribution in the different tissues was earlier in mice infected with a dose of 4000 larvae and more larvae were expelled from the gastrointestinal tract of heavily infected (2000 dose) mice. With an infective dose of 1000 larvae, the percent larval yield was higher than in other two groups (500 dose and 2000 dose) showing poor expulsion. Larval migration in the lungs was high even on the 1st day in heavily infected groups. Migration of larvae into the muscles, particularly of the head, neck and thorax took place on the very first day and was proportional to dose level. Larval count was higher in the muscles of the head and neck until the 9th day, after which it was high in the thoracic and other regions.

A detailed redescription of Gazellostrongylus lerouxi and Paracooperia serrata was given from specimenscollected from antelopes in Kenya. It was felt that there was no justification for the synonymy of the genus Gazellostrongylus with Paracooperia. Gazellostrongylus was placed in the tribe Ostertagiea.

Infective stage Brugia pahangi that were reared in Aedes aegypti survived equally well in cats that hadpreviously been immunized against mosquito tissue and in a normal cat. The survival of third, fourth, juvenile, adult and microfilarial stages of B. paliangi that were recovered from cats was similar in jirds that had been immunized against cat antigens and in normal jirds. Host antigenic determinants were not detected on the surface of larvae in substantial amounts using fluorescent antibody techniques. It is unlikely that B. paliangi evades the immune response of its vertebrate hosts by masquerading as ‘self’ behind host antigens.

Colonies of Culicoides nubeculosus and C. variipennis were established at Winches Farm Field Station, St. Albans.

Both species of midge were found to be susceptible to infection with Onchocerca cervicalis microfilariae. Infection was achieved either by engorging through a chick skin membrane on a suspension of microfilariae in blood, or by feeding upon a horse naturally infected with O. cervicalis microfilariae.

A large proportion of the microfilariae ingested by the midges penetrated into the haemocoel and migrated first to the thoracic flight muscles and then to the head. Larval development occurred during migration and 3rd stage (infective) larvae of O. cervicalis reached the head of infected midges (kept at 23°C.) 14–15 days after engorgement.

Ninety-seven cliff swallows, Petrocheilidon pyrrhonota, were examined from North-eastern Colorado. Five species of nematodes (Hadjelia pyrrhonotae sp. n., Acuaria sp., Microtetrameres inermis, Splendidofilaria sp., Diplotriaena sp.); four species of trematodes (Concinnum minor sp. n., Brachylecithum marinholutzi, Plagiorchis maculosus, Stomylotremagratiosus); and two species of acanthocephala.(Mediorhynchusgrandis, Mediorhynchus papillosus (juveniles)) were recovered. All eleven species of helminths represent new host records. Six new records (Hadjelia pyrrhonota, Microtetrameres inermis, Concinnum minor, Brachylecithum marinlwlutzi, Plagiorchis maculosus, Stomylotrema gratiosus) were established for Colorado. Five new records (Hadjelia pyrrhonota, Microtetrameres inermis, Concinnum minor, Brachylecithum marinlwlutzi were established for North America.

Alkaline phosphatases from different trematodes occupying the same habitat have identical pH optima but different levels of enzyme activities. Isoparorchis hypselobagri, from the fish Wallago attu, shows four to six times more enzyme activity than Fasciolopsis buski, Gastrodiscoides hominis and Echinostoma malayanum, from the pig Sus scrofa, and Fasciola gigantica, Gigantocotyle explanatum, Cotylophoron cotylophorum and Gastrothylax crumenifer, from the buffalo Bubalus bubalis.

At least two peaks of activity at different levels of pH were obtained for each trematode examined. Both Gastrodiscoides hominis and Isoparorchis hypselobagri enzymes had three peaks of alkaline phosphatase activity.

The optimum temperature for maximum enzyme activity was 40°C, above which rapid inactivation occurred. At temperatures below 40°C, the enzymes of fish and mammalian trematodes did not behave similarly; I. hypselobagri enzyme being active over a wider range of temperature (20°–40°C.

Various concentrations of KCN and arsenate proportionately inhibited enzyme activity. NaF did not significantly influence enzyme activity, while Mg++ and CO++ acted as activators. The extent of inhibition or activation of enzyme activity of different trematodes varied, probably due to species differences. Both inhibition and activation of I. hypselobagri enzyme was higher than in the case of other trematodes.

Capillaria papuensis sp. nov. is described from specimens collected from the gastro-intestinal systems of 14 pigs from two villages in Papua New Guinea. It differs from C.gastrosuis and C. suis in the number and location of papillae in the vulval region, the sculptured surface of the eggs, a sub-terminal anus in the female and in the length of the spicule and bilateral caudal alae in the male. The species inhabits the epithelium of the tongue, where clusters of eggs move towards the surface with the growth of the epithelium and are subsequently swallowed. The pathological changes in the infected epithelium are minimal. The prepatent period is approximately eight weeks.

Mice were immunized to the intestinal stage of T. spiralis by using infections terminated with methyridine before production of newborn larvae had commenced. The muscle larvae which encysted following a normal complete challenge infection were reduced by 87 and 95% in immunized mice. No statistically significant reduction in a challenge infection of intravenously injected parenteral larvae was produced (8% and 15% actual reduction). Previous work has shown that adult worms in a challenge infection are stunted and expelled earlier as well as haying a reduced fecundity; it is concluded that the immunity generated by the intestinal stage is largely specific in its action to that phase in a challenge infection.

Four species of anoplocephaline cestodes were found in wild rabbits collected throughout Britain in 1962 and 1972, i.e. since the great reduction in rabbit numbers following the introduction of myxomatosis in 1953. They were Cittotaenia pectinata (Goeze, 1782), C. denticulata (Rudolphi, 1804), C. ctenoides (Riehm, 1881) and Andrya cuniculi (Blanchard, 1891). C. pectinata and C. denticulata were relatively common with a respective prevalence of 25% and 8% in two samples totalling 442 rabbits and were widely distributed throughout Britain. C. ctenoides was rare and only recorded from seven localities, although these were spread throughout Britain. A. cuniculi was also rare being known from four counties in England and five islands off southern England and Wales. C. pectinata was the only species found in hares and its prevalence was low at 6%. The records are shown plotted on to 10 km square distribution maps.

The pathology associated with the early migratory phase of infection by the sparganum larvae of Spirometra theileri (Baer, 1925) Opuni and Muller, 1974 (Pseudophyllidea: Diphyllobothriidae), has been investigated in TO strain mice and in rhesus monkeys (Macaca mulatto). All infected mice developed haemorrhagic skin lesions and oedema of the joints and often ascites and peritonitis 3–6 weeks after infection. There was a 25% mortality in mice given plerocercoids orally, 37.5% in those injected with procercoids intraperitoneally. From eight weeks after infection larvae in both mice and monkeys were at various stages of encapsulation. One monkey which died three weeks after oral infection with 100 procercoids had developed ascites, haemorrhagic lesions and an acute peritonitis; infarcts were observed in the liver, lungs and spleen.

Two cases of Nasitrema sp (Trematoda) infection of the bottlenosed dolphin, Tursiops truncatus, are reported and N. attenuata is briefly redescribed. The adults of the trernatode occurring in the nasal sinuses and posterior nasal passage of the dolphins are considered as practically harmless for the host but their eggs, aspirated deep into the bronchial tree, may initiate a foreign-body type of inflammatory reaction in the lungs and continuous aspiration of such eggs may provoke a chronic pneumonic condition.

The worm recoveries of two different strains of Schistosoma haematobium from male hamsters and their egg-laying capacities are studied. The infection rates obtained, the growth of worms and the distribution of eggs in hamster tissues are compared with those previously described for other strains of S. haematobium.

Previous studies have shown that different geographical strains of Schistosoma haematobium have specific characteristics which reflect the infra-specific variations of this complex species (Webbe and James, 1971a, b; James and Webbe, 1973). The present paper records further observations on two strains of the parasite from the Sudan (Khartoum) and South Africa (Nelspruit).

2 678 naturally infected cataleptic ants of the species Formica pratensis were divided into three categories depending upon their size viz., large, medium and small, and were dissected to elucidate the intensity of infection with Dicrocoelium dendriticum. 2 233 (83.4 percent) were positive for metacercariae. The maximum number of metacercariae isolated in the three categories were 443 252 and 176 respectively. The average number of metacercariae varied greatly in the 3 categories, though no appreciable difference was observed in the percentage of infected ants. The presence of even a large number of metacercariae in the abdomen of ants seemed to cause few harmful effects.

100 male T.O. strain laboratory mice were divided into 4 equal groups: (I) 25 were injected intramuscularly with an antigen prepared together with Freund's adjuvant; (II) 25 injected with antigen alone; (III) 25 infected subcutaneously with 8 live plerocercoids of the same species; (IV) 25 served as controls. 4 weeks later all mice were given 6 live plerocercoids orally. The presence of acquired immunity in group III was shown by a significant reduction in the numbers, size and motility of challenge worms. The host response was greater in all the immunized groups than in the controls.

Two new species of Calostraurus Sandars, 1957 (Cestoda: Davaineidae) are described from Australian marsupials, C. thylogale from Tliylogale biltardierii and C. mundayt from Potorous apicalis. A redefinition of the genus is given together with tabulated features of the species.

Fresh eggs obtained from female Nematospiroides dubius were cultured at temperatures ranging from 5°C to 33°C. Hatching occurred between 5°C and 30°C; third stage larvae were obtained between 5°C and 25°C. The minimum time required from hatching to development to the third stage was 3.6 days (at 20°C) and the maximum was seven days (at 5°C). Larvae cultured at higher temperatures were smaller than those cultured at lower ones.

Egg excretion of S. mattheei was studied for about a year from man, baboons and cattle living in their normal environment. Although the excretory pattern was not unequivocal from man, there was a tendency of egg counts to decline with time: the baboons showed a seasonal pattern and the cattle a stable pattern throughout the year.

The activity is reported of certain clinical and experimental schistosornicides against schistosomula, 3 week old, and adult worms of Schistosoma mansoni maintained in vitro. Since the test method is not sufficiently selective for use with random compounds, it is concluded that meaningful screening for potential schistosomicides cannot at present by carried out in vitro.

The rate of escape of the third-stage larvae of Brugia pahangi from Aedes togoi which were allowed to probe on a cat and a mouse at time intervals of 5, 10, 20. 30 and 60 seconds was studied. The rate of escape of third-stage larvae at all time intervals was greater during probing on the cat than on the mouse, and was in a logarithmic linear relation to the length of probing time by the mosquito host. The greatest loss (91.35%) of third-stage larvae was in mosquitoes which fed on a cat until fully engorged. There was a remarkable rate of escape (57.41%) within 5 seconds. This striking rate of escape of third-stage larvae may have important implications on filariasis transmission. Most larvae migrated towards the proboscis and head of mosquitoes during these feeding periods. Nearly equal numbers of third-stage larvae escaped from mosquitoes which fed to repletion for more than 60 seconds on a mouse and from those which probed for more than 60 seconds on the same mouse but did not engorge. This confirmed our view that filling up of the stomach with blood does not constitute the single factor in causing the release of third-stage larvae from the mosquito host.

The effect of the sex of the intermediate host on the growth and development of the metacestodes of Taenia crassiceps has been investigated. Three different strains of mice were used, the C R S, L A C A and C F L P strains and two strains of metacestode, the Toi and the E R S strains.

The results show that metacestodes of T. crassiceps grow and multiply more rapidly in female than in male mice, although both sexes are equally susceptible to the infection. The origin of the parasite, i.e., from a rat or mouse host, affects the parasite growth.