A modified quick-Kato technique and the Stoll dilution method for the diagnosis of Opisthorchis viverrini infection were compared from the standpoints of both replicability and sensitivity. One Stoll dilution preparation and two modified quick-Kato smears were prepared from single stool specimens collected from 221 persons in a village in north-eastern Thailand. Stool examinations were made in duplicate for each technique by two examiners, and the averages of the raw egg counts were used to estimate the intensity of infection. Statistical analyses revealed that the modified quick-Kato technique was slightly more sensitive, and thus would detect more positives, but was lacking in replicability and hence less suitable for measurement of individual intensity of infection. We therefore recommend the Stoll dilution technique for field surveys and measurement of individual intensity of 0. viverrini infection.

The Introduction should read as follows:

INTRODUCTION

The Transversotrematidae is believed to be the smallest family of marine trematodes and is restricted to the Indo-Pacific region (Cable, 1974). The members of this family occupy an ectoparasitic niche, inhabiting the recesses beneath the scales of freshwater, brackish-water and marine fishes. Of the seven species in the genus Transversotrema Witenberg, 1944, the cercariae of T. patialense (Soparkar, 1924) Yamaguti, 1958, T. laruei Velasquez, 1958, T. soparkari Pande & Shukla, 1972 and T. chackai Mohandas, 1973 are already known. The larval form of the type species T. haasi Witenberg, 1944, and of T. licinum Manter, 1970 and T. chauhani Agarwal & Singh, 1981 and the adult of Cercaria koliensis Olivier, 1947 are yet to be discovered. The known cercariae develop in gastropod molluscs of the genera Melania or Thiara. An interesting feature in this group is the report of natural infections of Transversotrema haasi and T. licinum in marine fishes. As the adults are found in marine, brackish and freshwater fishes but none of the cercariae have been recorded from marine molluscs, it was thought worthwhile to study the effects of salinity, pH and O2 on survival of the cercaria of T. chackai, found in Melania tuberculata and M. scabra living in fresh and brackish water conditions.

Factors which influence the establishment of tetrathyridia of Mesocestoides corti in mice following inoculation per os were examined. Only a proportion of the tetrathyridia penetrate the gut wall and gain access to the peritoneal cavity and liver, and most of these penetrate through the wall of the small intestine. It appears that tetrathyridia must attach to the intestinal mucosa and commence penetration immediately or they pass into the large intestine and are voided. Establishment was not influenced by strain, sex or age of host. However, the temperature at which tetrathyridia were maintained before inoculation did influence their ability to penetrate the intestinal wall. Additionally it appears that tetrathyridia have to undergo a morphological change before or during, this penetration phase.

Larval Anisakis 7·7 to 23·6mm long from euphausiids, and larvae 18·0 to 21·9mm long from a teleost fish were morphologically and morphometrically alike and fitted the description by Beverley-Burton, Nyman & Pippy (1977) of A. simplex L3. Three small larvae, 4·2 to 5·9mm long, from euphausiids resembled L3 in anterior but not in posterior morphology; their tails lacked a mucron but, in two of them, cuticular separation at the posterior extremity revealed clearly the mucron characteristic of L3 within. These small larvae are identified as L2 of A. simplex in the process of moulting to L3. Japanese reports of typical L3 from 6·9 to 32·7 mm long in euphausiids, the occurrence in teleosts of typical L3 from only 8·8 to over 30 mm long, and the present observations strongly suggest that the moult from L2 to L3 occurs in euphausiids and begins when the larvae are about 4–6 mm long. Although it appears, therefore, that only one moult occurs in the egg of A. simplex (i.e. ensheathed L2 hatches), two moults there have been reported for various terrestrial and certain aquatic ascaridoids (i.e. ensheathed L3 hatches). The morphology and homology of the lips and associated sense organs of A simplex L3 are discussed relative to that of a ‘typical’ adult ascaridoid.

A main conclusion is that euphausiids in the North-East Atlantic and northern North Sea, and perhaps universally, are major intermediate hosts of A simplex. The status as hosts of squid and teleosts harbouring L3 is discussed. An extensive literature is reviewed in relation to the present observations.

Experimental investigations of the subcutaneous infection of third-stage larvae of Nippostrongylus brasiliensis reveal discrepancies between the actual and intended inoculum, and also variability between replicate inocula. Emphasis is thus placed on the importance of obtaining accurate estimates of the level of confidence associated with inoculum size. Under specified laboratory conditions, the retention of infectivity of N. brasiliensis larvae was found to be age-dependent, with a maximum of between 120 and 156 days. The motility of the larvae was not found to be indicative of their ability to complete migration and to become established in the small intestine of the host following subcutaneous inoculation.

The development of Schistosoma margrebowiei in hamsters, mice and gerbils has been studied following infection by cercariae obtained from laboratory-infected Bulinus natalensis. The rate is compared with that of other schistosome spp. and found to be very fast. In vitro development was slower and did not proceed beyond the closed-gut stage.

Albino mice were infected per os with 1000 infective larvae of Ancylostoma caninum and pulmonary superoxide dismutase activity was studied after completion of lung migration. The total superoxide dismutase activity per mg of lung protein was elevated by 15% in infected mice. Of the two forms of superoxide dismutases studied, that containing Cu-Zn was elevated by 44%. this suggests that A. caninum in mice may result in histopathological changes leading to transient pulmonary oxygen toxicity.

Larvae and adults of Strongyloides ratti were examined for collagenolytic activity on 14C proline-labelled, native, guinea-pig skin collagen substrate. The activity was measured by determining either the amount of hydroxyproline released or the amount of radioactivity in the solubilized fraction of the collagen substrate. Bacterial collagenase was used for enzyme control and trypsin served as substrate control. No collagenolytic activity was found in living larvae, their extracts or metabolites. The collagenolytic activity of the metabolites of adult worms appeared weak, whereas that of the extracts of the adults was pronounced. It is suggested that collagenase is active in the adult females at the time of migration in the intestinal mucosa during oviposition.

The prevalence of schistosomiasis and the distribution of the snail intermediate hosts on three adjoining irrigated estates in the lowveld of Swaziland was investigated. The prevalence rates of Schistosoma haematobium and S. mansoni among estate employees was lower than anticipated and there was a marked difference between the prevalence rates of S. mansoni between estates. The reasons for this and the influence of water supplies and agricultural practice on the prevalence of schistosomiasis are discussed.

The cement glands of Acanthocephalus serendibensis have been studied, using some routine histological and histochemical procedures. There are six multinucleate syncytial glands which produce a granular secretion which is a protein-mucosubstance complex, the mucosubstance component being of the neutral type. The secretion granules are seen in the body of the glands as well as in the reservoirs and ducts. The granules presumably coalesce to form the so-called cement which is discharged during copulation and seals off the genital region of the female after copulation and insemination.

Monanema globulosa (Nematoda: Filarioidea) was recovered from four species of rodents in Kenya, with a prevalence of up to 94% in the striped mouse, Lemniscomys striatus. The adult worms are site-specific to the pulmonary arteries and release sheathed microfilariae that travel via the blood to the skin. Densities of microfilariea in the ears (mf/mg) were five to eight times greater than in any other region of the body and were directly proportional to the number of adult worms present. Highest concentrations of microfilariae in the skin were reached after 100 to 200 days and low numbers persisted in most animals for approximately 500 days.

Third-stage larvae from ticks (Haemaphysalis leachii) injected subcutaneously into jirds migrated widely through the body during early development. Moults occurred twice, after 5 to 10 days and 25 days, and the mean prepatent period was 75 (range 69 to 88) days. A mild eosinophilia developed which peaked after 29 days. Adults in the lungs provoked widespread and intense perivascular cuffing and more localized hypertrophy and fibrosis of the intima in arterioles. Dead adults caused granulomata which obliterated smaller vessels. Microfilariae in the skin elicited no local tissue reaction, but some which invaded the eyes caused a monocyte infiltration of the cornea. It is concluded that the parasite is well adapted to its natural hosts and that it has potential as a rodent model for human onchocerciasis because of the localization of microfilariae in the skin.

Six dogs infected with Dirofilaria immitis and known to develop shock-like reactions after administration of diethylcarbamazine (DEC) were given ivermectin 50μg/kg orally. None of the dogs showed any adverse reaction and subsequently all reacted to DEC 20mg/kg orally.

A new genus is proposed for Orneoascaris [ = Amplicaecum] alata (Baylis, 1947) Le Van Hoa, 1960. The new genus is defined and differentiated from Orneoascaris by the posterior position of the vulva and by the wide cervical alae. It is differentiated from Ophidascaris by fewer postcloacal papillae and spicules less than half the length of the ejaculatory duct. From both genera alata differs in the unique form of the lips and in the more extensive U-shaped enlargement of the nucleus of the dorsal oesophageal gland. It is suggested that this species is a specialized form, possibly of neotropical origin.