The mortality of Aedes aegypti mosquitoes increased; (i) immediately following a blood meal containing microfilariae of Brugia pahangi, (ii) when infective larvae began to migrate out of the flight muscles and (iii) when infective larvae were lost from the mosquitoes during a blood meal. When infective mosquitoes took a second blood meal 86–2% of the infective larvae escaped from their bodies. However, only 50–3% escaped when mosquitoes fed through a thin layer of cotton. Infective larvae in the abdomen of the mosquitoes stood the least chance of escaping from the insects. When infective mosquitoes were offered a third blood meal four days later, the proportion of infective larvae in the head and labium had risen from 56–6% in the control group to 660% and 69–4% in the two test groups. At this third feed 54–7% and 75–7% of the infective larvae were lost from mosquitoes with a low and medium pre-feeding worm burden respectively. This suggests that the escape of infective larvae from mosquitoes with only a few worms is less efficient than from mosquitoes with a medium worm burden.

Mel W is a second generation anionic organic arsenical which is filaricidal but has sporadic and unacceptable lethal side effects. Eight new cationic derivatives have now been synthesized in an attempt to avoid the side effects and have been examined for their effects upon adult Brugia pahangi in Meriones unguiculatus. They were all shown to be potent filaricides and the two best compounds, Mel Ga and Mel Cy, were at least 95% effective in killing adult B. pahangi at 5x3–13 mg/kg when injected subcutaneously.

A Fasciola hepatica tegument antigen preparation was obtained from intact adult worms by solubilization with a non-ionic detergent, Nonident P-40. This antigen preparation contains antigens useful for the serodiagnosis of infection with this parasite. However, the antigen preparation is inadequate for use in the enzyme-linked immunosorbent assay (ELISA). The present work demonstrates that fractionation by demulsification of this antigen preparation with ammonium sulphate results in a soluble aqueous phase which contains F. hepatica serodiagnostic antigens which can then be applied to the ELISA. This F. hepatica tegument antigen preparation when used m the ELISA can detect rabbit fascioliasis two weeks after infection, with antibody levels peaking by 10 to 12 weeks of infection.

When mice were treated with 1–25 mg cortisone acetate thrice weekly, recovery of Hymenolepis murissylvaticae was significantly higher than in untreated controls, both in oral infections with six cysticercoids and surgical transplantations of one 7-day or 8-day-old worm. Cortisone treatment also resulted in the worms being located more anteriorly in the small intestine.Evidence of an immunological response against the tapeworm in the intestine is given by: (a) an accelerated rejection of a secondary oral cysticercoid infection and a significant difference of the dry weights of the worms recovered on day 10 in CFLP mice; (b) an accelerated rejection of a secondary surgical infection on days 4 and 6 in CFLP mice and on days 3 and 4 in NMRI mice; (c) an accelerated rejection of a secondary surgical infection given 3 and 6 months after the primary immunizing infection in SWlSS-albino mice.

In Ascaris suum chitin is formed in the zygote immediately after oocyte fertilization, and its synthesis is completed in the eggs from the distal half of the uterus. Incorporation of radiocarbon [C] glucose into chitin of the eggshell was 40-fold higher than incorporation of [C] glucosamine. The same rank order also holds for the incorporation of label from these isotopes into the glycogen of the ovaries. A large part of the radiolabel was incorporated first into oocyte glycogen and only after fertilization was it incorporated into eggshell chitin. Actinomycin D inhibited chitin synthesis in the eggs from the distal half of the uterus and it significantly reduced incorporation of radiocarbon from glucose into chitin.

On the basis of esterase localization the complete nervous system has been visualized in Olveria indica Thapar & Sinha, 1945, a paramphistome from the rumen of cattle, recorded for the first time from the north-east region of India. The basic number of posterior longitudinal nerves (i.e., 3 pairs) is the same as in other paramphistomes; four pairs of anterior longitudinal nerves are present, there being an extra pair of pharyngeal nerves. Conspicuous differences in the innervation patterns were observed, mainly in the innervation of the genital atrial region and acetabulum. The presence of prominent longitudinal connections, joining the anterior and posterior dorsal nerves and the anterior and posterior ventral nerves on either side, is a feature not hitherto found in other paramphistome species. The details of the course of all the nerves and their branches are discussed.

Cytochemical localization of the enzyme phenol oxidase in Neomurraytrema tengra has been studied. Results reveal that the enzyme reacts with substrates such as catechol, hydroquinone, pyrogallol, dopa, doparmine, epinephrine and tyramine, but not with tyrosine and protocatechuic acid. Thus it shows activity with a wide range of phenols, aminated, mono and diphenols and also with deaminated and decarboxylated, di- and polyphenols. The maximum activity of the enzyme occurs between 40°C and 50°C with a pH optimum of 6–6.

In different areas of the world, strains of Echinococcus granulosus have been described which appear to vary in their infectivity, and laboratory primates have been used as indicators of their infectivity to man. This phenomenon was evaluated in Kenya for hydatid material of human, camel, cattle, sheep and goat orgin. Viable eggs, produced by experimental infections in dogs with larval material from all the above intermediate hosts, were fed separately to four baboons (Papio cynocephalus) in each case. Baboons were autopsied between 373 and 501 days following infection and the liver, lungs, heart, spleen and kidneys were thoroughly inspected. Hydatid cysts were recovered from two baboons in each of the camel, sheep and goat groups, three baboons in the cattle group and none of the baboons in the human group. Fertile cysts were found in the cattle and goat groups and it is suggested that the baboon could be used as an experimental model for this parasite.

The dynamics of secondary infections with Hymenolepis citelli in mice are described. A primary infection of one and six cysticercoids for 21 days sensitized CFLP male mice against homologous challenge infections. Acquired resistance was manifested mainly as stunting/destrobilation of secondary worms. The severity of stunting depended on the intensity of the primary infection. Secondary worms were not expelled more rapidly than primary worms but the protective response retards growth early in challenge infections. Sensitization of mice for seven days with six or 24 cysticercoids did not confer a measurable protective response, whereas priming by the same regime for 21 days induced a significant Protective response. Acquired resistance to challenge waned with time in the absence of the primary Worms. The growth and survival of a six-cysticercoid primary infection was enhanced by the administration of the immunosuppressant drug cortisone acetate. Worms from cortisone-treated mice Were heavier than those from untreated controls. Acquired resistance to homologous challenge was also Partially ablated in cortisone-treated mice. It is suggested that rejection of primary infections and stunting/destrobilation of secondary worms may be immunologically mediated.

The phenol oxidase of a monogenean, Paramazocraes thrissocles, oxidizes phenolic amines more effectively than other phenols studied. Based on the substrate specificity, the probable substrate for eggshell formation has been suggested. The enzyme shows the pH optimum of 7–2. At 40°C it shows maximum activity. Proenzyme is activated by metal ions and detergents. Copper chelating compounds strongly inhibit the enzyme.

The presence of circulating immune complexes (CIC) in the sera of dogs infected with Dirofilaria immitis was detected by using a Clq-binding enzyme-linked immunosorbent assay. Specificity of this assay with different concentrations of heat-aggravated canine IgG (ACG) was observed, i.e., the ELISA readings, expressed as ug equivalents ACG/ml, increased with increasing amounts of ACG. The intra-assay variability was below 10%. The CIC levels of infected and uninfected dogs were 177–0± 104–7 ug/ml and 22–8±45–8 ng/ml (mean±SD), respectively. The highest level was observed in 12 dogs with amicrofilaraemic infection. Age distribution of CIC levels in the 23 infected dogs also showed a significant positive correlation. These findings suggested that the CIC are present in the sera of dogs with dirofilariasis and may relate to canine glomerulonephritis.

In a flock of 20 ewes naturally infected with those parasites of sheep most common in Greece, and kept indoors during the whole trial, oxfendazole at the dose rate of approximately 2–9 and 2–8 mg/kg body-weight was tested as a 4 g bolus containing 112 mg active ingredient and a 2–265% suspension. The evaluation of its efficacy was based on the necropsy findings which were also supported by faecal egg counts. No differences in efficacy were noticed between the two formulations of the drug. Both bolus and suspension proved to be 100% effective against Haemonchus contortus, Ostertagia circumcincta, Trichostrongylus axei, T. colubriformis and Chabertia ovina. The efficacy against Cooperia oncophora, Nematodirus spathiger, Bunostomum trigonocephalum, Oesophagostomum columbianum and Moniezia expansa could not be evaluated, because these species, though not found in any of the treated animals, were found in fewer than three controls.

In four experiments, mice harbouring an average 50, 76 or over 200 Schistosoma japonicum female worms were not resistant when challenged six to eight weeks after infection. The female worms from these single sex infections were stunted and immature (average length 4–6 mm) and induced no overt pathology in the host. Male worm burdens of 60, 135 or 140 also induced little or no resistance to challenge in the host. The males from these single sex infections were fully grown for their age (average length 9 mm) and burdens of 135 or 140 induced distended hepatic portal veins and marked deposition of pigment in the livers of infected mice.