S. bovis is an economically important parasite of cattle and possibly of sheep and other domestic stock in many African and Mediterranean countries. Control of this infection by chemotherapy and mollusciciding is impractical and this has stimulated interest in vaccination. Previous work in sheep with the Central and South African species S. mattheei has led to the development of an effective vaccine which incorporates irradiated schistosomula produced by artificial transformation of cercariae. In the present experiments a similar S. bovis vaccine has been used in sheep. Fifteen 5 month old Border Leicester × Suffolk crossbred wethers were divided into three groups, two were vaccinated with either 10000 or 20000 6 krad irradiated S. bovis schistosomula, and the third kept as unvaccinated controls. All sheep were challenged with 6700 normal S. bovis cercariae.

Worm recoveries and tissue egg counts at necropsy showed that vaccination with 10000 irradiated schistosomula produced a reduction of 71% in the mean worm burden resulting from challenge of the controls and the mean densities of eggs in the tissues were reduced by 75–82%. Immunization with 20000 irradiated schistosomula was not more effective. Histopathological observations showed that both groups of vaccinated sheep had much milder lesions in the intestines than the non-vaccinated controls. There was also a clear reduction in the severity of liver lesions in 4 of the 5 sheep given the lower dose of irradiated schistosomula but the livers of sheep vaccinated with 20000 irradiated schistosomula had severe and widespread lesions due mainly to a massive accumulation of eosinophils and other inflammatory cells around the vessels.

Schistosoma mansoni cercariae labelled with 75Se-methionine were used to study host-finding capacity by determining the radioactivity of exposed mouse “target” tails. Possible interfering effects of some aquatic vertebrates and invertebrates, plants and algae and secretions and excretions of aquatic organisms were examined.

A marked interferent effect due to predatory behaviour was produced by Cyclops strenuus (Copepoda), Daphnia pulex and D. longispina (Cladocera), Notodromas monacha and Cypria ophthalmica (Ostracoda) and Lebistes reticulatus (guppy). Bufo bufo (Amphibia) and Planaria lugubris (Turbellaria) interfered significantly, presumably by secreting cercaricidal toxins. Several other organisms apparently produced no interference. The interferent effect of the plant species Ceratophyllum demersum, Elodea canadensis, Lemna minor, Ranunculus aquaticus, Holcus lanatus (grass) and Botryococcus braunii was particularly pronounced when they were confined to the surface layer of the water. Several other species did not interfere with host-finding.

The susceptibility of Bulinus truncatus, B. tropicus, B. natalensis, B. coulboisi, B. globosus, B. cernicus and B. wrighti to Schistosoma haematobium from Egypt were examined. Eighteen different populations of B. truncatus were investigated.

A new method of measuring the compatibility between schistosomes and the intermediate snail hosts, the total cercarial production per 100 exposed snail, is introduced.

All B. truncatus populations became infected and could be divided in four groups according to the total cercarial production per 100 exposed snails. In the first group the cercarial production varied from 250 000 to 500 000 and in the last group between 5000 and 20 000. The first group had a high infection rate of 62 to 100% and a low mortality of approximately 10% and the last group showed a very low infection rate and a high mortality.

B. globosus (Rhodesia), B. cernicus and B. wrighti became infected, while B. globosus (Zaire), B. coulboisi, B. natalensis and B. tropicus were refractory.

The shortest prepatent period was 26 days at a room temperature of 26°C. The maximum cercariae production for one snail in one day was 600 and the longest duration of infection was 200 days.

Experimenting with different doses of miracidia, 5 to 50 per snail, resulted in a one hundred per cent infection and a low mortality of 10%. There was only a slight variation in the cercarial production.

3 × 10−6M praziquantel fails to completely paralyse miracidia and cercariae in a short time but they are not infective when maintained in the solution. 3 × 10−5M praziquantel prevents infected snails shedding cercariae but does not kill daughter sporocyts or developing cercariae. As the action of praziquantel on adult worms is not blocked by 10−2M mecamylamine, pempidine or carbachol, but is reduced by calcium deplection, it is suggested that praziquantel may act by permitting calcium influx to muscle cells causing them to contract.

The alterations of mast cell counts induced in the gut of swiss albino mice by infection with Ancylostoma caninum larvae have been studied, both in single and multiple infections. It was found that mast cell rise was greater in females than males. In singly infected animals, mast cell increase was influenced by the infective dose of inoculated larvae. In case of repeatedly infected mice, mast cell counts were decreased because of their earlier degranulation.

Certain phosphatases have been localized by histochemical techniques in various tissues of a pigeon cestode, Raillietina (Raillietina) johri. Acid phosphatase (AcPase), alkaline phosphatase (AlPase) and adenosine triphosphatase (ATPase) were present in almost all structures: tegument; subtegumental muscles; subtegumental cells; excretory canal; tsetes; sperm ductules; vas deferens; cirrus sac; cirrus; ovary; receptaculum seminis; vagina; vitelline gland cells; oocytes; uterus; embryonated eggs. AlPase was absent in parenchyma, spermatocytes, spermatids and spermatozoa. AlPase activity was more intense in the tegument of mature gravid proglottides. AcPase and ATPase were visualized in various stages of spermatogenesis of the parasite. ATPase activity was also observed in chromosomes. 5'-nucleotidase (AMPase) activity was restricted to embryonated eggs only. Functional significance of these phosphatases is discussed.

Six species of strigeoid trematodes are reported from Malaysia. One new genus and 3 new species are described: Apatemon (Apatemon) jamesi sp. n. (Strigeidae); cercaria Cotylurus sullivani sp. n. (Strigeidae); Neodiplostomum (Neodiplostomum) sp. (Diplostomatidae); Fibricola ramachandrani (Diplostomatidae); Pseudoscolopacitrema otteri gen. n. et sp. n. (Diplostomatidae); and cercaria Cyathocotyle malayi sp. n. (Cyathocotylidae). The life cycles of A. jamesi and C. malayi have also been investigated.

During the period October 1972 to July 1973 inclusive, 450 pigs of various age groups, belonging mainly to the native breed (white variety), born and raised on the Jos Plateau, Nigeria, were examined for helminth infections. Post-mortem worm recovery indicated that 15 species of helminths were present: Hyostrongylus rubidus, Ascarops strongylina, Physocephalus sexalatus, Ascaris suum, Globocephalus urosubulatus, Strongyloides ransomi, Trichuris suis, Oesophagostomum quadrispinulatum, Oesophagostomum dentatum, Metastrongylus salmi, Stephanurus dentatus, Cysticercus cellulosae, Cysticercus tenuicollis, hydatid cyst of Echinococcus granulosus and sparganum of Spirometra erinacei.

The records of A. strongylina, P. sexalatus, O. quadrispinulatum, M. salmi, C. tenuicollis, hydatid cyst and sparganum are new for pigs in Nigeria.

It is possible that pigs may play some role in the local epizootiology of C. tenuicollis and E. granulosus. C. cellulosae, E. granulosus, S. erinacei, A. suum and T. suis may be of significance as zoonoses.

Dunnifilaria dilli, a new species of filariid from Rattus koratensis from Thailand is described. Adult worms were recovered from the lymphatic system. They differ from D. ramachandrani in their location in the host, the tail length, the shape of the spicules, and in the number of caudal papillae. Microfilariae are much smaller and unsheathed. Additional hosts include R. rattus and R. sabanus.

Aspects of the life cycle of Asymphylodora tincae have been studied in a small lake near Amsterdam. Bithynia tentaculata, being the only snail species that was very numerous in the lake, was the first as well as the main second intermediate host; adult trematodes were found exclusively in the tench, Tinca tinca. A small part of the cercariae that penetrate into B. tentaculata was able to develop into progenetic specimens. A morphological description is given of the following stages of A. tincae: adult, egg, redia, cercariaeum, metacercaria and progenetic stage. The cercariaeum is identified as Cercariaeum paludinae impurae De Filippi, 1854.

It is concluded that A. tincae is a species, capable of large variation regarding both morphological structure (e.g. body spination, size) and life cycle.

The genus Multicaecum Baylis 1923, sensu Hartwich 1957, was found to be heterogeneous, comprising species which are relegated to two distinct genera, namely Multicaecum Baylis, 1923 and Brevimulticaecum. The latter name is derived from the subgenus Brevimulticaecum Mozgovoy, in Skrjabin, Shikhobalova, and Mozgovoy, 1951 by raising it to generic rank and emending the definition. Multicaecum contains a single species, agile Wedl, 1861 occurring in Crocodylus spp. in Africa, India and Australia, and is characterized by smooth rounded lips, each with a dentigerous ridge comprising small sharp denticles. The excretory pore is level with the nerve ring or behind it, and the ventricular appendices are long and slender. The species gangeticum Maplestone 1930 and quadrata Linstow 1904 are excluded from Multicaecum and regarded as species inquirendae incertae sedis. Brevimulticaecum contains five species occurring in the caimans and the alligator of the New World: baylisi Travassos, 1933 (type species; acuticauda Schuurmans-Stekhoven, 1937 is placed in synonomy under baylisi); stekhoveni Baylis, 1947; tenuicolle Rudolphi, 1819; and two new species. Brevimulticaecum spp. are characterized by flat lips with alate margins and notches, without dentigerous ridges, excretory pore in front of or at nerve ring and the ventriculus with short appendices. The significance of this proposal is discussed in relation to the other genera of ascaridoid nematodes in crocodilians.