The results of a 5 year study of helminth parasites of Mus spretus, are reported. Six nematode and 5 cestode species were identified but no helminth showed 100% prevalence in M. spretus, the most commonly encountered nematode and cestode species being Syphacia obvelata (46·6%) and Taenia taeniaeformis (22·4%). Among the more unusual helminth species identified was Eucoleus bacillatus, a capillariid nematode inhabiting the stomach musculature. This species was identified in 3 of the 5 years of the study. The results are discussed in the broader context of previous studies and the epidemiology of rodent helminth infections in general.

Male Hisex chicks were used in two experiments to investigate the interaction between Ascaridia galli infection and supplemental copper from basic and neutral salts. This was assessed by means of body weights, mortality, parasite burden and liver copper level. Cu2(OH)3Cl reduced the number of parasites but CuSO4.5H2O and CuCO3.Cu(OH)2.nH2O did not affect the parasite burden.

This paper describes a study carried out in a rural area of Ghana on the drinking water sources and other determinants of dracunculiasis (guinea worm disease). The results confirm the association between water source choice and the prevalence of the disease. A logistic regression model was used to show the combined effect of several behavioural, biological, and environmental risk factors. The important behavioural factors were related to the head of household, fetching of water, travelling, and farming. Age was found to be an important biological risk factor for dracunculiasis, but the greatest relative risk applied to those who had suffered from guinea worm disease in the previous year. Although males were significantly more infected than females when analysing the raw data, sex did not prove to be a significant risk factor in this model. Village of residence was an important environmental risk factor for dracunculiasis. Factors related to socio-economic status were not associated with the risk of infection. The paper concludes by presenting the policy implications of the study findings.

The serum antibody response (total, and isotypes IgG1, IgG4, IgM, IgA and IgE) to Guinea worm infection was examined in humans from a highly endemic area of northern Ghana by ELISA and SDSPAGE/Western blot techniques using an adult D. medinensis antigen. Sera were obtained early and late in the peak transmission period, from persons with patent and postpatent infections, as well as from persons from the same endemic area who claimed never to have had Guinea worm infection. To observe for potential cross-reactions in the tests, sera were also obtained from areas with no transmission of Guinea worm from patients with hookworm. O. volvulus and W. bancrofti infections, and from non-infected controls. Sera from persons living in the Guinea worm endemic area reacted extensively with Guinea worm antigen in both tests, and large numbers of bands were produced in the Western blots (up to 35 identified for some sera). For most antibody isotypes, the ELISA absorbance values obtained with sera from the same individuals varied between the two transmission seasons, with the highest titres present towards the end of the peak transmission period. The mean antibody titres for persons in the patent and postpatent infection categories were not significantly different when sera were obtained at the same season of the year. Persons from the endemic area, who claimed never to experience patent infections, also had antibodies to Guinea worm, although at significantly lower mean levels than for the patent and postpatent categories. The highest specificity in the ELISA and the most homogenous Western blots were obtained when detecting for antibodies of the IgG4 isotype.

Sera of 908 blood donors, average age 35 years, living in towns and villages of the Slovak Republic were tested for Toxocara canis antibodies using an ELISA-IgG test. The seroprevalence in the healthy population was estimated at 13·65%. Antibodies were predominantly demonstrated in the sera from persons living in rural communities (17·09%) compared to the sera investigated from urban communities (11·82%). Women had a significantly higher seropositivity than men. The serological response in 2703 sera from patients suspected of toxocarosis was compared with their clinical manifestation, sex and age. Toxocara antibodies were found in 27·41% of suspected patients. Although the seroprevalence in adults was significantly higher among women than men, in children, boys had a higher seroprevalence than girls. The main clinical manifestations were leucocytosis and eosinophilia (46%), ocular disorders (36%), lung, liver and neurological disorders (26%). The most severe forms of this disease were observed in 2 to 5-year-old children with geophagy.

The transmission of bovine Onchocerca spp. in Britain was investigated by studying the Ceratopogonidae and Simuliidae which attacked bait cattle between April and October at two sites in North Wales, where either Onchocerca lienalis and O. gutturosa (Cynwyd), or O. lienalis alone (Pentrefoelas) occurred. Based on the relative abundance of each species, their seasonal variation in abundance and preferential feeding sites on cattle, the presence of Onchocerca sp. infective larvae and the development of patent infections in bait cattle, vectors were identified as Simulium ornatum s.1. at Pentrefoelas and S. reptans at Cynwyd (0·5% and 1·5% of parous flies infective, respectively). There was no significant difference between the lengths of the infective larvae from vectors at either site (Pentrefoelas: mean = 543·5 μm, SD = 29·45; Cynwyd: mean = 550·86 μm, SD = 35·26; p > 0·1), which were consistent with descriptions of O. lienalis. The identity of a vector for O. gutturosa was not determined and the role of certain candidates is discussed. In this respect, the absence of Culicoides nubeculosus was notable. Transmission of Onchocerca sp. was limited to a short period of about 8 weeks, by a combination of vector abundance and parasite uptake from dermal skin layers, and a mean daily temperature requirement of 15°C or more for complete parasite development in the vector. The effect of this temperature restriction in relation to the geographical distribution of the two species is discussed.

The isoenzymatic pattern of glucose 6-phosphate dehydrogenase (abbreviation G6PD) from Ascaris suum has been studied by vertical polyacrylamide gel (PAGE) and horizontal starch gel electrophoresis. After polyacrylamide gel electrophoresis, two stained zones could be identified. One corresponded to tetrazolium oxidase activity; since this zone was stained even in the absence of glucose 6-phosphate (G6P), non-specific staining could be detected. In the other zone of activity, seven regularly-spaced bands were identified by staining in the presence of G6P and NADP as substrates. By using starch gel electrophoresis, different electrophoretic patterns for G6PD have been observed in the muscular sac, intestine and reproductive system from A. suum. The existence of three different alleles of G6PD in the same individual suggests the existence of at least two genes for this enzyme.

Infection with Oesophagostomum sp. appears to be extremely common in man in northern Togo and Ghana Adult specimens were recovered from the intestinal lumen by treatment with pyrantel pamoate and the morphological characteristics of oesophagostomes of man could for the first time be compared with information available on the morphology of oesophagostomes of monkeys. The observations and measurements demonstrated that the species involved is Oesophagostomum bifurcum and that the eggs of this species cannot be differentiated from those of Necator americanus. Both infections occur simultaneously in the population involved. The L1 larvae, too, cannot be differentiated from hookworm L1 larvae. The L3 however, are characteristic. Diagnoses of human Oesophagostomum infections is based on the detection of these larvae in coprocultures. In the present paper, the eggs, the L1 and L3 larval stages and the adults, carefully described and photos are given.

An optimum protocol for the cryopreservation of third-stage larvae (L3) of Angiostrongylus cantonensis was determined by: (i) use of different dimethyl sulphoxide (DMSO) concentrations; (ii) use of different FBS concentrations in RPMI-1640 medium; and (iii) variation in the thawing temperature. Studies showed that with Concentrations of DMSO at 4·8% and FBS at 40% and a thawing temperature of 43°C, L3 survival assessed by motility was highest at 56%. The infectivity of the cryopreserved L3 of A. cantonensis was 20% compared to controls obtained from slugs.

Specific immunoreactive components present in crude somatic extract and in excretory-secretory (ES) products of Gnathostoma spinigerum advanced third-stage larvae (L3) were identified by Western blotting and their diagnostic potential evaluated by indirect ELISA. Although both crude antigen preparations were highly complex, the ES antigen gave a more satisfactory diagnostic result. Most G. spinigerum specific components present in the somatic and ES preparations had molecular weights below 29 kD and were not glycosylated, judging from the concanavalin A staining pattern. Specific diagnostic antigens were prepared by subjecting the crude preparations to SDS-PAGE. Low molecular weight components were identified and electroeluted from the gel. Excess SDS was removed by the use of an ion retardation resin. The antigens obtained by this relatively simple procedure were found to be highly specific for G. spinigerum. Sensitivity, specificity, and positive and negative predictive values for the assay using the fractionated somatic antigen were 100%.

Laboratory experiments were performed to investigate the ability of isolates from the predacious fungus species Arthrobotrys conoides (one isolate) and A. robusta (four isolates) to trap and kill infective Haemonchus placei larvae. Three groups for each isolate were formed: group 1, fungi and infective larvae; group 2, fungi; group 3, infective larvae. There were statistically significant differences (P<0.05) between the antagonistic effects of three isolates of A. robusta, but there was no such difference between the isolate of A. conoides and isolates of A. robusta. This result indicates that there can be a variation in the predatory capacity of different isolates within a single fungus species. After 20 days of assay, there was greater recuperation of infective H. placei larvae in group 3 compared to group 1.

Rabbits were experimentally infected with two levels (5000 and 17000) infective larvae of Nematodirus spathiger. Histological (villus length, mucosa to serosa ratio, crypt surface) and biochemical (protein content, alkaline phosphatase and leucine aminopeptidase activities) measurements relating to the small intestinal mucosa were examined along the entire length of the organ. In the proximal intestine, the presence of worms was associated with villus abrasion, increased crypt surface and decreased alkaline phosphatase and leucine aminopeptidase activities. Conversely, beyond the main Site of infection in the distal small intestine, some signs of hypertrophied villi and crypts were noted without any changes in enzyme activities. These distal variations were similar to those previously described in experimental Trichostrongylus colubriformis infections of rabbits. These results tend to confirm the use of the rabbit as an experimental model to study Nematodirus infection. They also suggest that the distal adaptive process in the nematode-parasitized small intestine could occur independently of the worm species.

Total ecdysteroid-like immunoreactive material was assayed and quantified in adults of the parasitic nematode N. brasiliensis during the intestinal phase in the rat in order to detect possible physiological fluctuations in titre. Worms of the same sex isolated from one rat were pooled in order to quantify ecdysteroids using enzyme immunoassay (EIA). The concentration of ecdysteroids fluctuated during adult life according to the sex and the age of the parasite. Important differences of levels of ecdysteroid-like compounds between the two sexes of parasites were noted particularly at 128 and 168 h post-infection. The peak at 128 h, present in female, but not in male worms, corresponds to the time of egg-laying. Following HPLC-EIA analysis, the presence of ecdysone, 20-hydroxyecdysone and apolar ecdysteroid-like material was ascertained during this peak. The physiological role and the possible origin of ecdysteroids in this nematode are discussed.

Attempts have been made to increase the survival rate of third-stage larvae of Parastrongylus cantonensis during cryopreservation. Parasites were obtained from experimentally infected snails, Biomphalaria glabrata. The maximum non-toxic concentrations of cryoprotectants dimethyl sulphoxide (DMSO) and glycerol were determined as 10% v/v in NCTC 109 medium. Different pre-cooling times and serum additives were assayed to determine their effects on the viability of larvae. Larvae pre-cooled at –20°C for 15–20 minutes before transfer to –70°C had the optimum survival rate. The presence of serum was essential for further cooling to –196°C. There were no differences between native and heat-inactivated sera on the larval viability. The survival of larvae recovered after storage at –196°C was higher in sera collected from the rat, man, or fetal calf than in sera collected from the mouse, dog, or horse. Viability assessed by mouse-infections showed that thawed larvae retained infectivity for susceptible hosts, but it was significantly lower than that of unfrozen control worms.

Infective larvae (third-stage larvae) of both Angiostrongylus cantonensis and A. costaricensis from their snail intermediate host were subjected to either X-ray or gamma-ray irradiation. The viability of the irradiated larvae was assayed by oral inoculation of the larvae into rodents (A. cantoflensis in mice and rats, A. costaricensis in mice only). From the results of worm recovery, the minimal dose of irradiation that inhibited the infectivity of the third-stage larvae of A. cantonensis and A. costaricensis was 2 and 4 kGy, respectively.

Second-stage larvae of Toxocara canis were maintained in vitro for one year. Susceptibility of the larvae to drugs was evaluated by means of minimal larvicidal concentration (MLC) and larval bursting percentage. MLCs of citral and decanoic acid were almost constant throughout all stages of incubation. However, bursting percentage markedly varied within the first 20 weeks of incubation. Therefore, while larvae are available for use in the MLC assay at any stage of incubation, those beyond the first 20 weeks after incubation should be used for the bursting assay to obtain reproducible results.

A metastrongyle worm extracted from the anterior chamber of the right eye of a patient in Sri Lanka belongs to the genus Parastrongylus and probably to a yet undescribed species, related to P. cantonensis well known to infect man. It is mostly a parasite of rodents, wandering in man and unadapted to this host. Evidence for this lack of adaptation are that the specimen is undergoing necrosis (teratological specimen) and is located in an organ with little immunological defences.

The development of the tapeworm Proteocephalus torulosus (Batsch, 1786) (Cestoda: Proteocephalidae), a parasite of cyprinid fish, was studied in the intermediate host under experimental conditions. The eggs of P. torulosus were typified by a relatively small outer envelope (hyaline membrane) and a thick middle layer surrounding the oncosphere. Incubation of P. torulosus eggs at different temperatures revealed the ability of some oncospheres to survive and remain infective to the intermediate host for up to 5 weeks at 5–7°C, 12 days at 10–12°C, and 8 days at 20–22°C. Of 8 copepod species used in these experiments, complete development of larvae was observed only in Cyclops strenuus. Growth was completed in 9–12 days at 20–22°C and four weeks at 9–10°C. During development the cercomer was not observed. The infectivity of larvae from C. strenuus for the definitive hosts, cyprinid fish, was very low and only one chub of 26 fish used for feeding experiments (21 chub, Leuciscus cephalus, 3 bleak, Alburnoides bipunctatus, 1 rudd, Scardinius erythrophthalmus—all the family Cyprinidae, and 1 loach, Noemacheilus barbatulus—the family Cobitidae) became infected.

The inhibition of acetylcholinesterase secretion by male and female Heligmosomoides polygyrus was tested on worms taken from experimentally infected mice and maintained for 3 days in vitro in levamisole. The dose inhibiting 50% of enzyme secretion (ID 50) of male worms was twice the ID 50 for female worms. A similar difference was observed in vivo between the dose of levamisole removing 50% (LD 50) of male and female worms from the mouse. Acetylcholinesterase secretion by worms and ID 50 were tested in vitro at 3-weekly intervals from 3 to 21 weeks post infection (WPI). Acetylcholinesterase secretion was always significantly higher for male than for female worms. A decrease of ID 50, correlated with the age of the worms was observed: from 1·5 to 0·5 μg/ml for males and from 0·7 to 0·1 μg/ml for females. These results were confirmed in vivo by a higher efficacy of the anthelminthic at 21 than at 4 WPI.