Histochemical tests were done on newly excysted metacercariae and worms recovered from an abnormal host (rat) and the definitive host (dog) for some oxidoreductases, phosphatases and glycosidases. The results demonstrate that rat worms have enzymatic distribution and intensities more similar to those of metacercariae than to adult worms from dogs. Ultracytochemical examination of acid and alkaline phosphatase and Mg-ATPase activity was also carried out. Acid phosphatase activity occurred exceptionally in the excretory bladder and caeca of dog worms. No activity was observed in rat worms except for lysosomal granules in the tegument. Alkaline phosphatase activity was exhibited in the excretory bladder in both dog and rat worms. Mg-ATPase activity occurred in the tegument and parenchymal cells in dog worms and in the excretory bladder in rat worms. In metacercariae, little or no reaction for these enzymes was present except for Mg-ATPase activity on the excretory ducts. These observations, together with the histochemical results, indicate that metabolic activity in rat worms is higher than in metacercariae although it is strongly reduced compared with dog worms.

Ancylostoma ceylanicum and Nippostrongylus brasiliensis decarboxylated most of the amino acids examined, but only a few at signficant rates. The former nematode in general possessed higher activites. Striking differences between the two parasites were, however, noticed regarding the metabolism of some of the amino acids. For instance, while alanine followed by asparate produced highest amounts of 14CO2in the presence of A. ceylanicum, proline exhibited maximum decarboxlation in case of N. brasiliensis. Tyrosine, on the other hand, did not libreate detectable CO2with either parasite. Likewise, although large number of amino acids underwent transmination with 2-oxoglutarate, only some of them elicited appreciable activity for any two parasites.

1. Biomphalaria p. nairobiensis, B. p. ruppelli and B. s. tanganyicensis have been found to be moderately susceptible to S. rodhaini from Kenya. A. glabratus from Puerto Rico is partially susceptible to the parasite. However, B. s. sudanica, B. dlexandrina, A. glabratus (Puerto Rico, albino strain) are refractory to infection with the same parasite from Kenya.

2. The present results together with those of some previous investigators suggest the existence of geographical strains of S. rodhaini.

The course of infection of chickens experimentally infected with C. nilesi suggested an immune response against the microfilariae. Autopsy findings of 6 experimentally infected chickens are given. In a chicken which received 32 infective larvae, when the peripheral blood was microfilaria negative for a period of 10 days, autopsy revealed 2 live active female and 3 live active male adult worms. These, when implanted in a clean 3 week old experimental chicken, produced a peripheral microfilaraemia for a further 63 days. When no peripheral microfilariae were detected for a period of 17 days, the recipient chicken was autopsied and microfilariae were found in the lung impression smears, although none of the implanted adult worms were found.

The morphology, structure and nocturnal subperiodicity of the microfilariae are described.

The occurrence of Bilharzia infection in Cyprus was first recorded by Dr. George A. Williamson in a paper entitled “Bilharzia hæmatobia in Cyprus,” published in the British Medical Journal of 27th September, 1902.

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.

A case of human infection with Physaloptera causing an abscess in the neck of a patient in Hyderabad is recorded. The structure of one of the worms recovered, a female, is described and compared with that of other species recorded from mammals in India, but in the absence of the male it is not possible to determine the species.

Fertile eggs of Toxocara pteropodis, passed in the faeces of juvenile flying-foxes, were ovoid to spheroid in shape with a diameter range of 80–110 µm. The shell was often seen to comprise 4 layers: a fine inner lipid layer, a thicker clear chitinous layer, an equally thick outer vitelline layer and a pitted outermost, proteinaceous uterine layer of variable thickness. Infertile eggs were less uniform in shape and generally did not have well-defined shell layers, the formation of which is triggered by sperm penetration of the oocyte. The eggs of this species are bulkier than those of related ascaridoids, apparently because of a thicker external coat which, while not providing mechanical strength, is thought to protect against desiccation. Scanning electron microscopical findings suggest that the outer layer is not applied directly by uterine cells, but forms by the gradual deposition of secretions in the uterine lumen, regardless of whether the oocyte has been fertilized.

A specimen of Cysticercus tenuicollis is described, which contained many daughter cysts in various stages of development. One of these cysts was a well developed daughter cysticercus.

The daughter cysts at all stages of development, are lined internally by a distinct cuticle, and have no scolices. The daughter cysticercus, like the parent bladder, has an outer cuticle and a well developed scolex and receptacular appendage.

There is evidence for regarding the daughter cysticercus as having been formed from a daughter cyst by a process of evagination of the latter in such a way that the cuticle has come to lie on the outside, rather than by a process of vesiculation of a scolex.

The daughter cysts appear to be homologous with the brood-capsules of Echinococcus. They are not strictly homologous with daughter hydatids or daughter coenuri.

To determine the minimum effective dose of praziquantel against Hymenolepis diminuta in rats, 5.0 mg/kg, 2.5 mg/kg, 1.0 mg/kg, 0.5 mg/kg, 0.1 mg/kg, or 0.05 mg/kg praziquantel were given to each of five experimentally infected rats in six groups. Faecal samples from each rat were examined for worms on day 10. Based on the results of faecal examination and autopsy, the minimum effective dose of praziquantel against Hymenolepis diminuta in rats was determined to be 0.5 mg/kg.

For the first time the development of the excretory system Levinseniella brachysoma metacercariae (Trematoda: Microphallidae) obtained experimentally from Gammarus oceanicus has been described. The bladder wall of 8-day post-infection (P.I.) larvae consists of a syncytium covered with microvilli. Its cytoplasm contains well-developed rough endoplasmic reticulum (RER), free ribosomes, small oval dense mitochondria and numerous large membrane-bounded (about 5 μm in diameter) spherical granules. Later the size of the excretory bladder and the number of nuclei and RER cisternae increases. The large spherical granules disappear completely but spherical dense bodies (up to 4 μm in diameter) devoid of limiting membranes appear. The bladder lining forms thick columnar projections directed towards its lumen. Accumulations of microlamelli occur only on the lumen surface between adjacent projections. By the 42nd day P.I. the bladder wall has two separate components: the columnar projections and the syncytium between them.

A retrospective analysis of slaughterhouse records during the pre-veterinary-organized meat inspection era (before 1970) for cysticercosis and hydatidosis in food animals showed that parasitic cysts were documented but not identified and that the numbers of slaughtered animal species harbouring various parasitic cysts were not recorded. Since the various parasites which the meat inspectors observed were not identified, the prevalence of species encountered could not be determined.

An analysis of abattoir records during the veterinary meat inspection era showed that Cysticercus bovis and C. cellulosae infections were documented in cattle and pigs respectively. Moreover, hydatid cysts were detected in cattle, pigs, sheep, goats and camels.

The data obtained from this survey cannot be wholly relied upon as accurate, but it can be used as a baseline for the proper evaluation of the status of these zoonotic parasitic diseases in future co-ordinated researches.

Two types of neurosecretory cells (NSC), large a cells and small β cells were detected on the basis of their size and characteristics as shown by aldehyde fuchsin and chrome haematoxylin-phloxin staining. A histochemical survey of the neurosecretory material indicates that it is a glycoprotein. Phosphatases and esterases present in NSC probably help in the transfer of metabolites and their hydrolysis and in the control of secretory material produced in a NSC, while SDH provides the necessary energy for the synthetic activity of the latter. The role of neurosecretion in governing the reproduction of this parasite is discussed.

In a study of the morphology of the posterior ends of O. tricuspis, it could firstly be recognized that not only the adult females but also the LII to LIV possess five cusps. They have apparently been partly overlooked by microscopic examination because of their appearance in different optical planes.

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.

Early studies by light microscopy provided preliminary data on the fine structure of Strongylus vulgaris (Looss 1900). The present study employed transmission electron microscopy to investigate particular structures in the buccal capsule especially the dorsal gutter (DG) and teeth. The DG is a tube containing the terminal duct of the dorsal oesophageal gland (DOG) surrounded by two concentric canals. Putative pores indicated in the wall of the DG seen in other studies are revealed as honey-combed, fibrous, structures on each side of the ventral lamella. This lamella is formed by the wall of the DG internal canal running the length of the DG. Secretions of the DG canals are released through the dorsal gutter duct (DGD) which passes through the teeth bases at the base of the buccal capsule. Teeth have a vesicular cytoplasmic core containing various organelles.

A checklist of larval digeneans parasitising molluscs from inland waters of Argentina is presented here. Based on the bibliographical survey of 113 scientific articles and nine theses published between 1930 and 2021, 213 digeneans were found, which were distributed within 13 superfamilies and 35 families. The parasites were identified in 102 locations, encompassing eight of the sixteen biogeographical provinces in Argentina. Digeneans were found in 34 mollusc species (31 gastropods and three bivalves) belonging to 17 genera. The available data are presented for each digenean species, and included host information, localities, prevalence values, type of habitat, life cycle information (natural or experimental host), and information on material and genetic sequences deposited in repositories. Only 21.1% of individuals were identified to species level, and 8.5% to genus level. In addition, the genetic sequences of only 10 species (4.7%) were available at GenBank. This survey constitutes the first checklist of parasitic helminths in molluscs from inland waters of Argentina.

Adult stages of Euclinostomum heterostomum (Rudolphi, 1809) were collected from the oral cavity and oesophagus of Bulbicus ibis in Liberia, West Africa. Structural relationships within the trematodes are clarified. A prepharynx from the oral sucker leads to a well developed pharynx to which the intestinal caeca communicate via a bulb-shaped oesophagus. The origin and extent of gonadal ducts are described including a Laurer's canal, whose aperture is dorsal. A discussion of the characters previously used to differentiate species of Euclinostomum corroborates the views expressed by Ukoli (1996) that the genus consists of two distinct species, E. heterostomum (Rudolphi, 1809) and E. multacaecum Tubangui and Maslungan, 1935. E. shrjabini Kurashvili, 1948 is proposed as a synonym of E. heterostomum. A compilation of the range in measurements of the adult and metacercarial stages of E. heterostomum is presented in the form of a table.

Viktorocara torea and Sciadiocara tarapunga n. spp. are described from specimens from the gizzards of Haematopus ostralegus finschi and Larus novaehollandiae scopulinus respectively. All hosts were collected in the South Island, New Zealand. V. torea is characterised by the possession of the doubly bifid apices to the long spicule and absence of a subterminal spicular spur; presence of six preanal papillae, the first and second widely spaced: the muscular region of the oesophagus constituting about one quarter of the total length of the oesophagus. S. tarapunga is similar to S. umbellifera, but differs in having the muscular region of the oesophagus shorter than the glandular region, a more slender body in both sexes, much smaller spicules (78–91 μm and 275–359 μm) with the right spicule not more than one-third as long as the left one. The long spicule bears a pair of similar, rounded, laterally placed spatulate apices. It is suggested that Sciadiocara umbellifera of previous authors may encompass more than one species.

The catchment area of the Volta River covers an area of 153,000 sq. miles of which approximately 64,000 sq. miles is located in Ghana. This forms about 70 per cent of the total area of the country. Most of the catchment area in Ghana consists of savanna; including the Guinea savanna of the Northern region, the derived savanna of Northern Ashanti adjacent to it on the south, and the coastal savanna which is separated from the interior savanna by a broad belt of tropical forest. With the exception of some of the headwaters of the Afram the tropical forest is drained by smaller rivers including the Tano, Ankobra and the Pra which are not part of the Volta Basin. Most of the Volta catchment area lies in an area with a well defined wet season occurring between June and September.

In May 1964, the huge dam across the Volta River at Akosombo was completed and the dendritic Volta Lake began to form. It reached its full size after the rainy season of 1968 when it covered an area of approximately 3,275 sq. miles.