Inorganic elements as micronutricnts play a vital role in metabolism and in immune mechanisms (Ballerker & Prasad, 1983) and a significant role in the physiology of parasites. Their importance is shown by the harmful effects of mineral deficiencies in the host diet, particularly on gastro-intcstinal parasites (Von Brand, 1966). The presence of aluminium, cadmium, iron, manganese, nickel, sodium and tin has been shown in the corpuscles of Echinococcus granulosus which causes hydatid disease in man (Agosin, 1968). In this preliminary report, the quantities of trace elements in hydatid fluid from sheep and man are reported to show their possible importance as nutrients or as cofactors in the metabolism of the parasite.

Eggs of Trichostrongylus vitrinus in faecal pellets deposited on grass plots each month from April 1981 to March 1982 developed into infective larvae. From October to March development was slow and mortality of the pre-infective stages was very high. From April to September development was more rapid. The weather was generally dry and mortality of the pre-infective stages was high on plots with short herbage but was lower on most of the plots with long herbage, especially in July and August. In the laboratory, development of eggs into infective larvae was completed at temperatures ranging from 4°C to 27°C in faecal pellets which were either kept moist or dried out slowly, but not in faecal pellets which dried out rapidly. The rate of development increased as the temperature rose. Infective larvae survived for up to 16 months on the herbage of grass plots; some survived during very cold weather in the winter of 1981/82. In the laboratory, infective larvae suspended in tap water survived even longer at 4°C and 10°C but not at higher temperatures. They were rapidly killed by continuous freezing. They Survived for up to 8 weeks when subjected to desiccation, The relationship between climatic conditions and the development and survival of the free-living stages is discussed

Wild rats and molluscs were examined for Angiostrongylus cantonensis infection on Viti Levu, Fiji. A. cantonensis were recovered from 29–6% (16/54) of Rattus rattus and 59–5% (25/42) of R. exulans. A. cantonensis like larval nematodes were found in all of four slugs, Laevicaulis alte, and ten of 20 unidentified land snails. The larvae developed to adult A. cantonensis in the pulmonary arteries of laboratory rats 40 to 42 days after ingestion. This is the first record of A. cantonensis in Fiji.

Third-stage larvae (L3) of Anisakis simplex of a known minimum age of 60 to 61 weeks, the oldest of which may have spent at least three years in herring, were artificially excapsulated in saline and appeared healthy. A small proportion succccded in penetrating the gut wall of rats. The length distribution of L3 of minimum age 18 to 23 weeks did not differ significantly from that of larvae of minimum age 60 to 61 weeks.

In the desert city of Beersheba, Israel, a survey was made of the infection rate of Toxocara canis in dogs. 3.0% of dogs destroyed at the municipal dog pound had intestinal T. canis. 7% of faecal samples gathered from day care centres throughout the city were shown to contain T. canis eggs. This low rate of infection could possibly be explained by the hot, arid climatic conditions which may render eggs non-infective or by the sandy soil in the area that may cover faeces containing T. canis ova and make the eggs unavailable to other dogs.

The effects of Astiban, Lucanthone, Hycanthone and Niridazole on autophagic activities in the gastrodermis of Schistosoma mansoni were determined in vivo, using different dosage levels and dosage times. With Astiban, high levels of autophagy were observed in the gastrodermis 2 hours after an injection of the drug into the mouse, and this response had declined by 20 hours, marking a recovery by the parasite from the drug. Hycanthone and Lucanthone produced an autophagic response several days after the onset of treatment, and no recovery was observed in the morphology of the gastrodermis after the drug was discontinued. The effects of Niridazole on the gastrodermis were to produce the most dramatic ultrastructural changes after high doses and over several days of treatment. With all the drugs examined, gastrodermal autophagy was characterized by the formation of vacuoles containing cell components, lipid droplets and sometimes hydrolytic enzyme reaction product. The autophagic vacuoles appeared to be formed by the sequestration of cytoplasmic material by the basal membrane infoldings, and the transfer of enzymes into the vacuole from within the limiting membrane. The residues from intracellular digestion appeared to be emptied into the caecal lumen.

Treatment with praziquantcl at the beginning of the lumen phase of Hymenolepis nana in mice showed conclusively that: (i) the mouse given eggs of H. nana produces two separate immune responses against reinfection, one directed exclusively against the tissue phase of egg challenge (early response), the other against the lumen phase of cysticcrcoid challenge (late response); (ii) a tissue phase of egg inoculation is not necessary for initiating the late response but is necessary to provoke the early response; and (iii) H. nana expresses several stage-specific immunogens through its development in the mouse host.

A consistent and reproducible method is described for isolating pure populations of microfilariae of Litomosoides carinii, Brugia pahangi, B. malayi and Dipetalonema viteae, free of cells, from blood, by density gradient centrifugation on Percoll in 0.25M sucrose. The recovery of the microfilariae was 85 to 97%.

Infectivity, growth and development were studied in 23 one-day-old domestic chicks each fed 25 pre-selected metacercarial cysts of Echinostoma revolutum. All chicks were infected at necropsy one to 44 days postexposure with one to 18 flukes/chick. From the 575 cysts fed to chicks, 145 (25%) flukes were recovered from the ileum, caeca, rectum-cloaca and bursa of Fabricius. Length measurements on 113 uncurled flukes fixed in hot alcohol-formalin-acctic acid showed that worms grew slowly to 1.0 mm by day 3, rapidly to 6 mm by day 14, and less rapidly to 9 mm by day 36. Worms became ovigcrous by day 9. As worms aged in the chick, the body length increased relative to the width, the acetabulum shifted more antcriad and the size of the excretory bladder increased.

Medium in which T. canis larvae had been cultured was applied to a Sephadex G-25 gel column and four fractions (Fr. 1-Fr. 4) were isolated. Each fraction was administered to mice by implanting a mini-osmotic pump into the peritoneal cavity and the subsequent peripheral blood eosinophilic counts were recorded. Mice given Fr. 1 showed a markedly greater eosinophilic response than did those given the other fractions. Complement activation by each fraction was investigated using normal human serum. Fr. 1 and Fr. 3 had a capacity to activate complement. The results suggest that Fr. 1 may be not only antigenetic and allergenic but also could induce eosinophilia and activate complement.

Double counterimmunoelectrophoresis, with a novel well format, was used as a sensitive technique for the rapid detection of circulating antigen and antibody in mice infected with Trichinella spiralis. In a primary infection, soluble antigen was initially detected in day 13, followed by a second wave on day 41. Circulating antibody was first apparent on day 34, increasing in intensity and number of precipitation bands until day 102. The first peak of circulating antigen is indicative of non-complexed antigen released from the developing larvae in striated muscle cells, whereas the presence of antigen late in infection is indicative of electrophoresislabile immune complexes. On reinfection (day 35 of primary) circulating antigen was present which could be attributed to products of resident primary infection muscle larvae.

Jirds were given a chcmoprophylactic inoculation of flubendazole (FMBZ) and then five injections of infective larvae of Brugia pahangi whilst still protected by the FMDZ. When the drug was thought to be noneffective the jirds (and controls) were given a challenge infection of B. pahangi larvae. By comparison with control jirds the trcatcd-infectcd-challcnged jirds had 40% fewer adult worms. The control treated-challenged jirds contained mostly sterile female worms showing that they were still partially protected by FMBZ but worms numbers were not significantly reduced as compared with untreated controls.

The four species of the genus Strongylus Müller, 1780, namely, S. equinus, S. edentatus, S. vulgaris and S. asini were examined with the scanning electron microscope (SEM). The buccal cavity of each species was cut transversely and longitudinally and the scanning electron micrographs illustrate the shape of the buccal cavity and the dorsal gutter. The micrographs also show the presence of denticles near the oral rim of the buccal cavity of S. edentatus and the shape of the teeth in the buccal cavity of S. equinus, S. vulgaris and S. asini. The bursa of the four species has three symmetrical lobes, one dorsal and two lateral. The length of the three lobes in relation to each other varies between the species. The genital cone has a single large ventral papilla, a pair of dorsal raylets, a median dorsal cuticular appendage and a variety of cuticular appendages lateral and ventral to the cloaca. The development and arrangement of these components differs between the four species of the genus and can be used as a supportive character for specific identification.