Indirect fluorescent antibody techniques and incubation of sectioned and ligatured larvae have been used to locate the source of azocoll-positivc secretions within the oesophagcal glands of third-stage Anisakis simplex larvae. The “excretory” system, previously suggested as a source of invasive enzymes, docs not seem to be involved. The proteolytic enzyme has trypsin-like properties and evidence is presented for its continuous synthesis during in vitro storage.

A detailed study of the surface topography of the echinostomes Echinostoma revolution and Isthmiophora melis has been carried out using SEM. The tegument of the body surface has a cobblestone-like appearance with interspersed pits. The presence of possible secretory granules is noted. Observations of the anterior end reveal that the collar spines are retractable. An unusual structure is described from the ventral gap of the spiny collar of E. revolutum. The origins of this structure and the possible functions of the spiny collar are discussed. The shape and distribution of body spines is described. Differences in cirrus morphology for the two species are described. The taxonomic position of, I. melis and the significance of cirrus morphology as a useful taxonomic character are discussed. Four types of presumed sensory or secretory structures occur—ciliated, domed, button and bilobed papillae. Their distribution is described and possible functions discussed.

Mierofilariae of Litomosoides carinii and Dipetalonema viteae absorbed about ten times as much diethylcarbamazine (DEC) as did their adults, but bound much less. The higher uptake of DEC by the microfilariae might be related to the fact that DEC is microfilariae Binding of DEC: with the parasites supports the view that the microfilarcidal action begins with the fixation of the drug to the microfilariae.

TPase and SDII activities were studied in various tissues of Ceylonocotyle scoliocoelium maintained in vitro in medium A for 15 days, using standard histochemical techniques. Results were compared with the normal activities of these enzymes in the tissues of worms freshly collected. Low ATPase and SDH enzyme activities in the tissues of cultured flukes indicated their low metabolic rate. Intensity of enzymatic reactions was also found to be tissue specific. The suitability of culture medium ‘A’ for the in vitro cultivation of amphistomes is discussed.

Extracts of Dirofilaria immitis adults and microfilariae cause the dcgranulation of mast cells in rat mesentery when applied in vitro and also cause increased vascular permeability in guinea-pigs and rabbits. Adult worms DUt not microfilariac are able to activate complement in vitro and both stages contain a plasminogen activator. No protcolytic activity or hacmolysins could be detected in cither stage. The possibility that these factors may be important in the pathogencsis of dirofilariasis and in the adverse drug reactions that may follow treatment of microfilaraemic animals with dicthylcarbamazine is discussed.

New host and geographical records and new morphological data are reported on three monogeneans: Encotyllabe spari YAMAGUTI, 1934, Choricotyle hysteroncha (FUJII, 1944) and Pseudotagia cupida (HARGIS, 1956).

Acquired immunity to Nematospiroidcs dubius was studied in the jird. It was found that a primary infection comprising one or two worms was highly immunogenic and the animals were resistant to challenge infection. Abbreviated infections in which the adult worms were eliminated by treatment with pyrantel also elicited strong resistance to challenge indicating that larval parasites as well as adults were involved in acquired immunity. A small proportion of adult worms completed their development in immune jirds and was recovered 11 days after the challenge infection. However, these worms were rapidly eliminated and few survived to day 16. Trickle infections in which the jirds were exposed to very low numbers of worms at regular intervals were unsuccessful in prolonging the duration of a primary infection. It was concluded that the remarkable sensitivity of the jird to infection with N. dubius should enable small quantities of fractionated parasite derived material to be screened for immunogenicity in this host.

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.

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.

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.

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 synthesis and filaricidal activity of l-iso-butoxycarbonyl-4-mcthylpipcrazinc against Litomosoides carinii in Sigmodon hispidus and Dipctaloncma viteae in Mastomys natalcnsis is reported. At an intrapcritoncal or oral dose of 3 mg/kg given for 6 days, the compound removed 91% of the circulating microfilariac but had no effect on adult L carinii. However, it killed all microfilariae and adults of D. viteae at a subcutaneous dose of 50 mg/kg given for 6 days. The compound also possessed ehemoprophylaetic activity against the larvae of L. carinii and D. viteae at a dose of 30 and 50 mg/kg respectively.

Lung infection with Angiostrongylus cantonensis was established in experimentally infected Indian softfurred rats (Millardia meltada) and Indian spiny mice (Mus platythrix). Pulmonary arterial migration occurred earlier (at day 20 after infection) in M. meltada than in Wistar rats. M. meltada and M. platythrix could serve as useful animal models for comparative studies of mechanisms determining host specificity of A. cantonensis.

The utility of the IgG fraction of human filarial serum immunoglobulin in detecting circulating antigen by sandwich enzyme linked immunosorbent assay (ELISA) was studied. 27 of 33 sera from persons with microfilaracmia, 19 of 30 sera from clinical cases of filariasis, 4 of 30 sera from normal persons from a region endemic for filariasis showed the presence of circulating filarial antigen. All the 20 normal sera from the area where filariasis was not endemic gave negative reaction for filarial antigen. Those sera from persons with microfilaracmia that showed the presence of circulating antigen also showed an apparent positive correlation between the microfilarial density and the antigen titre.

The rate of glucose absorption and metabolism and the associated fluid transfer of the small intestine of rats was measured in vitro using an everted sac technique after daily doses of 0, 5, 25 or 225 infective larvae of Nippostrongylus for periods of one to five weeks. Though there were occasional significant changes in the physiology of the intestine there were no obvious patterns or trends with respect to time at any infection level. This differs from the response after a single infection. The possible role of immune adaptation and reduced immunogenicity of the worms during repeated infections is considered.