Hamsters experimentally infected with Opisthorchis viverrini had significant depression of the antibody response to sheep red blood cells. The depression was more severe with prolonged infections. Lymphoproliferative response to phytohaemagglutinin stimulation was also depressed when compared with uninfected controls. The immunodepression in these animals was abolished by anthelmintic treatment, suggesting that the immunodepressive effect is reversible and is associated with active infection.

The infectivity of Hymenolepis nana eggs from faecal pellets in the rectum of mice was compared with that of the eggs in gravid proglottids of adult H. nana and with that of the eggs in excreted faecal pellets to find out a simple method for collecting H. nana eggs of high infectivity to mice. Eggs from faecal pellets in the rectum showed higher infectivity than those from gravid proglottids and as high infectivity as those from gravid proglottids selected by a watch-glass rotation technique. Eggs in faecal pellets in the rectum did not lose infectivity until 4 h after they were excreted and exposed to the air at room temperature (27–28°C) with relative humidity of 35–40%. However, the eggs lost infectivity significantly 17 h after excretion onwards.

The formation of the egg mass in the ootype, containing the oocyte, vitelline cells, numerous spermatozoa and Mehlis’ gland secretion marks the beginning of eggshell formation. Mehlis’ gland cells pour their lipoprotein secretion into the ootype; this secretion forms a thin template around the egg mass and upon this template the shell globules are deposited. Eggshell formation begins in the proximal uterus and is completed in the middle uterus. The eggshells are devoid of phenols and phenolase indicating that hardening is not by quinone tanning. The eggshells contain keratin and are stabilized by disulphide linkages.

Mebendazole (3.3 μmol), causes in vitro glycogen depletion and inhibits glucose uptake in Avitellina lahorea. Inhibition of non-specific phosphomonoesterases and adenosine triphosphatase by mebendazole is discussed in the light of the role of phosphatases in uptake mechanisms. Mebendazole has no effect on hexokinase which has broad substrate specificity but influences the activities of some glycolytic enzymes such as phosphorylase, phosphoglucomutase and glucose-6-phosphatase. Thus, it appears that mebendazole also acts to disrupt certain enzymes of carbohydrate metabolism which may ultimately cause death of the parasite.

In field experiments, conducted on parasite-free grass plots in two consecutive summers, artificially prepared cow pats containing Cooperia oncophora eggs were inoculated with the nematode-trapping fungus Arthrobotrys oligospora. Numbers of infective C. oncophora larvae isolated from the pats as well as from the surrounding herbage were subject to an approximately teh-fold reduction as compared with numbers in fungus-free pats and herbage surrounding these. This reduction was undoubtedly a result of entrapment of the parasite larvae within the faecal pats.

Vitelline gland development and incomplete parthenogenesis in 65-week-old female Schistosoma mansoni from single sex infections is described. Vitelline gland development was restricted to the extreme posterior end of each worm and the developed vitelline lobules showed the normal sequence of development and maturation. The ovary, however, was always in an immature state. Egg production occurred although the eggs were non-viable.

The results suggest that, whilst male stimulation is not necessary to initiate vitelline gland development and egg production, it appears to be essential for the complete maturation of the ovary. The possible importance of ovarian maturation to the production of viable eggs is discussed.

Chromosomal complements of an oocyte and a fertilized ovum from the ootype of Isoparorchis hypselobagri Billet, 1898 have been studied. Twenty diploid and 10 haploid chromosomes have been observed. In the karyotype the presence of five submetacentric, four acentric and a pair of sex chromosomes provide a significant cytotaxonomic information.

A marked strain variation in eosinophilia following oral infection with Toxocara canis eggs was observed in mice. Mutual radiation chimeras between high and low responder mice in terms of eosinophilia were made and compared with the respective donor and recipient for eosinophilia after the infection. As a result, the degree and time course of eosinophilia in chimeric mice were similar to those in donors. The result suggested that genes which regulate inheritance of the trait, marked eosinophilia in T. canis-infected mice, might be expressed in bone marrow derived cells.

The diploid chromosome number of Protostrongylus rufescens is 2n=11 for males and 2n=12 for females. So, the sex determinism mechanism is XO/XX. The study of the genetic behaviour of this species has been made. In diakinesis stage the bivalents show typical tetrads with cross, Ø, and lineal configurations. The division of the sexual chromosome is prereductional for the first meiotic division.

The growth of Philophthalmus gralli from jordan was studied experimentally by inoculating 10 excysted metacercariae around the right eye of 47 day-old chicks. The growth rate was slow in the first three days during which flukes did not exceed 0·30 mm long. Then growth become rapid reaching 2·70 mm long on day 24. This was followed by a low growth rate during which the flukes grew from 2·70 mm to 2·90 mm on day 40. The flukes started to appear in the left eye on the day 12 post-inoculation of metacercariae in the development of P.gralli from Jordan was the same as of other species of Philophthalmus. However, a sixth stage, post-maturation stage, is suggested in addition to the 5 developmental stages of Philophthalmus. The ratio of the transverse diameter of the ovary to that of testes in the post-maturation stage was 1:1·1–1:1·2.

Prevalence and intensity of helminth parasites are described for a sample of 102 Jamaican anole lizards representing 6 species (Anolis lineatopus lineatopus, A. I. neckeri, A. grahami, A. valencienni, A.opalinus, A. sagrei, A. garmani). Fifty nine per cent of lizards were infected with 5 species of nematodes, 16% with one acanthocephalan, 7% with two digeneans, and 4% with a single cestode species. Infection intensity was generally low (intensity range 1–5) although two species of nematode occurred in very large numbers (intensity range 1–436). Helminth prevalence patterns and species composition reflected differences in anole habitats rather than ecomorphs, and were uncorrelated with the genetic relatedness of indigenous versus introduced anole species.

Results of an epidemiological survey carried out in 88 slaughterhouses in Italy from 1979 to 1983 are reported. Data have been compared to national surveys previously conducted in 1955 and from 1968 to 1978. Analysis of various factors affecting the incidence of the disease in different areas of the country are reported.

This paper reports the experimental transmission of a bird parasite into jirds. Infective larvae of Cardiofilaria nilesi obtained from laboratory colonized Coquillettidia crassipes mosquitoes which had fed on an infected chicken were inoculated subcutaneously into jirds. The number of larvae per jird varied from 10 to 228. Microfilaraemia appeared 22 to 89 days after inoculation of the infective larvae. Experiments were carried out with 24 jirds through six generations extending over a period of 22 months and 17 produced patent infections. At present 8 infected jirds are being maintained in the laboratory; their patent periods ranging from 6 to 13 months. However, the longest patent period observed was about thirteen months. The percentage of adults recovered in autopsied jirds ranged from 0 to 40 with an average of 16. The chicken showed a microfilarial periodicity with the peak microfilarial density around 2200 hours. However, in jirds there was a change in sub-periodicity. This model in the jird may be very useful for the screening of filaricides and in immunological work.

Adult males of Schistosoma mansoni were preincubated in 5-hydroxtryptamine (5HT) and processed through the glyoxylic acid fluorescence technique to visualize 5HT-containing neural elements. 5HT flourescence was seen as a series of cross-sectional rings beginning behind the ventral sucker toward the tail end. The rings were connected by two lateral nerve cords running longitudinally along the whole lenght of the worms.

The initial pathway of skin penetrating larvae of Strongyloides ratti inside the host is not systemic and could well involve local components of the lymphatic system. The experiments described were an attempt to detect an effect on immunity depending on whether larvae of a challenge infection were committed to a pathway through heavily primed or lightly primed lymph nodes. Female rats were immunised by subcutaneous injection into the right forearm of 1000 heat killed, or 1000 live, third stage larvae of S. ratti. Animals given living parasites were placed on a diet containing 0·1 or 0·2% thiabendazole 48h or 36h after ifection. Challenge infections of <100 larvae (‘exact’ doses) were applied on day 21 to either the right or left flank and, similarly, to controls that had received the anthelmintic but not the priming infection. Heat killed parasites elicited no response at all. Priming with live larvae stimulated a significant immunity (16% and 37% depression in 2 experiments), but there was no difference between rats whose challenge was on the same side as the priming dose and those which had the contralateral treatment. The significance of these results to theories of pathfinding in general, and to practical immunology, is discussed.

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.

Dogs, naturally infected with Dirofilaria immitis, were treated with the residues of the alcoholic extracts of the rhizomes of Zingiber officinale (ginger). Twelve subcutaneous injections of the extract given at 100 mg/kg reduced microfilarial concentration in blood by a maximum of 98%. Fifty five days after the last injection there was 83% reduction in microfilarial concentration suggesting partial destruction of adult worms. Half of the treated dogs showed some lethargy at the beginning of treatment possibly due to the mass annihilation of microfilariae in blood.