Irradiation of the infective larvae of Gaigeria pachyscelis Railliet and Henry, 1910 with gamma rays upto 160 Kr had no significant effect on the in vitro survival of these larvae for a period of 49 days, maintained either at room temperature (32.2–39.4°C) or at 4°C. However, the behaviour of the irradiated larvae in the lamb host was much changed, as shown by a marked reduction in the worm establishment and the development of stunted and sterile worms from these larvae. As the level of irradiation increased, there was a corresponding decrease in the subsequent worm establishment. It was found that male larvae are more sensitive to the effects of irradiation than female ones, particularly at higher levels.

The results of a vaccination trial in lambs with gamma-irradiated infective larvae of Gaigeria pachyscelis are described. A single percutaneous (P/C) vaccination of lambs with 2000 infective larvae irradiated at 40 Kr induced the development of resistance. The vaccinated lambs successfully resisted a lethal challenge infection of 5000 non-irradiated larvae 3 months later. In the vaccinated lambs, the manifestations of resistance were shown by marked reduction in the worm establishment, development of retarded and functionally sterile worms and absence of clinical signs of hookworm disease after the challenge infection.

A new species of polystomatid monogenean, Eupolystoma anterorchis sp. n. is described from the urinary bladder and kidneys of Bufo pardalis from the Cape Peninsula, Republic of South Africa. It is distinguished from other Eupolystoma species, and from all other species except one within the Polystomatidae, by the anterior pre-ovarian extension of a large proportion of the testis follicles. This and other morphological characteristics are incorporated into an amended generic diagnosis.

The morphology of E. alluaudi from Bufo regularis in West Africa is also described. The known range of this species is enlarged with new geographical records in the Cameroun and Ethiopia, and a new host record from Nectophrynoides malcolmi.

Material from each area shows that the eggs of Eupolystoma spp. complete development in utero and that all developmental stages of the parasite occur side by side within the same host individual. This represents a significant evolutionary departure from the pattern of transmission typical of Polystoma in most of the other anuran hosts.

Only three of the four species assigned to the genus Cooperioides are considered valid and are redescribed. The fourth species Cooperioides kenyensis Daubney, 1933 is considered a synonym of Cooperioides hamiltoni (Mönnig, 1932) Mönnig, 1933. A key to the species of the genus is given and their hosts and geographical localities are listed.

Thirty-eight spotted ground squirrels, Spermophilus spilosoma were examined for endoparasites, and 31 of them were infected with one or more species. Helminths found were Hymenolepis citelli, Citellina triradiata, Physaloptera massino, and Trichuris sp. The protozoan Eimeria larimerensis was also found. Citellina triradiata is redescribed. This is the first report of any helminths from this squirrel.

The amphistome Cotylophoron cotylophorum feeds entirely on semidigested rumenal contents (plant material living bacteria, and protozoa). Morphological and histochemical studies have been made of the digestive system. Two types of cells occur in the caecal epithelium, the first type were larger and cuboidal with granular cytoplasm containing a high amount of RNA and proteins. The second smaller type were fewer, and contained pyknotic nuclei; their cytoplasm was vacuolated. The cells of the first type bear microvilli at the luminal surface. The surface coat consists of saliva resistant acetylated acid mucopolysaccharides containing hyaluronic acid with carboxyl polyanions. Intense activities of acid phosphatase, glucose-6-phosphatase, and ATPase, and moderate activities of nonspecific esterase and lipase are localized at the brush border. The functional significance of the surface carbohydrates and the hydrolytic enzymes has been discussed in relation to digestion and absorption of nutrients.

Oesophagostomum multifoliatum, previously known to occur only in Kenya, Rhodesia and Tanzania, was found on the Jos Plateau of Nigeria in cattle. Of the 120 cattle examined post-mortem, 78 (65%), were found to be infected. The faecal egg, of which only the size was hitherto known, is described and figured; it shows striking similarities to that of Nematodirus. The possibility is expressed that O. muitifoliatum might have been mistaken for the more familiar but closely related species O. radiatum and O. columbianum or its egg with that of Nematodirus; it is probable that it is much more widespread than hitherto thought.

Immersion of Biomphalaria pfeifferi in 1.5% glucose solution showed that the snails did not absorb any glucose during the first six hours but that almost 30% of the glucose was absorbed after 24 hours. The glycogen content of such “glucose-fed” snails was much higher than that of control normal snails. Cercariae of S. mansoni collected from the former snails exhibited a much lower level of death (20%), during penetration of mouse skin, than that of control normal cercariae (36%).

It is suggested that death of S. mansoni cercariae during penetration of mammalian host skin is probably due to exhaustion of their energy reserves.

Morphological variations in Onchocerca armillata and O. gutturosa, from buffalo and cattle, with special reference to male tail and cuticular ornamentation, have been studied from a large collection of worms available from the infected aortae and ligamentum nuchae, procured from slaughter houses at 3 different localities in Uttar Pradesh, India. Seven variations in the disposition of caudal papillae in males in O. armillata and 14 in O. gutturosa are described. The prevalence of these two Onchocerca species in bubaline and bovine populations appears to be widespread.

The ascaridoid nematodes with more than two uterine branches, which occur in snakes and lizards, are grouped into three genera: (1) Polydelphis (without interlabia, with four uterine branches) containing the type species, P. anoura, occuring in Old World Pythons, with P. brachycheilos as a species dubium. (2) Travassosascaris, a new genus with interlabia and with four uterine branches, with type species T. araujoi (new name for P. quadrangularis (Schneider) of Araujo, 1969) occuring in New World rattlesnakes. (3) Hexametra, (without interlabia, with six uterine branches) containing species in lizards and snakes. In lizards, H. hexametra (type species), H. applanata, H.angusticaecoides and H. rotundicaudata are tentatively differentiated. In snakes, two Hexametra species are tentatively differentiated: (1) H. boddaertii (with three synonyms) in New World pit vipers and colubrids; (2) H. quadricornis (with twenty-two synonyms) in Old World viperids, elapids and colubrids. The morphology, host range, geographical distribution, development and harmful effects of these species are discussed.