All three strains of Neotricula aperta (Gastropoda: Pomatiopsidae) sampled from populations in northeast Thailand were found to be compatible with a Schistosoma mekongi isolate from Kratié District, eastern Cambodia. The infection rates were: 3.0%, α-strain; 6.0%, β-strain; and 20.5%, γ-strain. The greater infectivity to the γ-strain, over both the α- and β-strains, was statistically significant. Comparisons of infectivity patterns for the Kratié isolate, with those described in earlier studies using S. mekongi isolates from southern Laos, revealed differences among the strains. The γ-strain of N. aperta is responsible for endemic transmission of human schistosomiasis in southern Laos and at Kratié. Consequently, the findings of this study are of use in the prediction of changes in the distribution of Mekong schistosomiasis, particularly its introduction to northeast Thailand from the neighbouring countries, Cambodia and Laos.

Data are presented on the infection dynamics of the brain-dwelling metacercariae of Diplostomum phoxini (Digenea: Trematoda) parasitizing European minnow (Phoxinus phoxinus) populations in a lowland river (River Endrick) and a highland loch (Loch Maragan) in central Scotland. Prevalence of the parasite approached 100% in all samples taken from both populations over a 12-month period, and within each population the intensity of infection increased with increasing host fork length. However, the two relationships differed, and size-matched minnows from the Endrick exhibited significantly higher intensities than those from Loch Maragan, suggesting that metacercarial acquisition occurred at different rates in the two populations. Data regarding seasonal trends in the acquisition of D. phoxini indicated that fish in both populations become infected with the parasites mainly during the spring and summer, with negligible infection occurring during winter months. Analysis of size-matched fish from individual samples revealed apparent differences in the distribution of D. phoxini within the two host populations. Whereas D. phoxini metacercariae appeared to be overdispersed amongst length-matched fish from Loch Maragan samples, the parasite was distributed normally amongst fish from the Endrick. Possible reasons for the observed differences in the infection characteristics of D. phoxini in the two minnow populations are discussed, with reference to the parasite's transmission dynamics and local environmental conditions.

An infection experiment was conducted to assess the change in the proportions of Steinernema feltiae Filipjev (Site 76 strain) infective juveniles becoming male or female on exposure to the test host Galleria mellonella L. Using a mathematical model for the infection interaction, the per capita probability of penetration per unit time (transmission coefficient), for those juveniles becoming male or female, and the magnitude of the male and female classes in the infective juvenile pool were estimated. The results show that S. feltiae infective juveniles which subsequently become female have a greater probability of invasion into test hosts than their male counterparts, which leads to markedly female biased sex ratios during the initial stages of the infection interaction. As the infection progresses, however, it was found that the sex ratio became balanced. This was because the underlying sex ratio in the infective stage pool was balanced. The implications of this dynamism in the sex ratio of the entomopathogenic nematodes are discussed with respect to the infection interaction, transmission and the likely environment in which the infective juveniles reside.

Monogenean richness of marine fish is highly variable among host families and species. On the basis of 160 fish species selected because their parasite fauna was considered as ‘adequately’ investigated, an attempt was made to find associations between parasite richness and various characters of the hosts. No clear correlation was found with maximal size, although the smallest species (less than 10cm) seem to never harbour monogeneans. Correlations were found with nectonic, migrating and gregarious behaviours. However, taxonomy of fish appears to be extremely important as a determinant of monogenean richness. In the absence of a satisfactory phylogeny of hosts, no attempt was made to control the analysis for phylogeny. However, removing some families characterized by a high parasite richness (sparids, sciaenids, mugilids) shows that the association with gregariousness holds, whereas the others tend to disappear.

Twelve batches of the mollusc Cernuella (Cernuella) virgata (Mollusca: Helicidae) were deposited monthly directly on faeces containing first-stage larvae of Neostrongylus linearis, so that they were naturally infected. Every two weeks the molluscs were examined to study the larval development of N. linearis. No correlation was found between the number of first-stage larvae of N. linearis on the faeces and the number of total larvae and third-stage larvae which developed in the snails. However, a negative correlation was found between temperature and the days needed to reach the different larval stages. Thus, the molluscs harboured third-stage larvae from mid-spring to mid-autumn, the period of time which carries the greatest risk of infection for the definitive hosts.

A survey of 612 black rats, Rattus rattus (282 males and 330 females), for infections with helminth parasites was carried out in Abeokuta, in southwest Nigeria. Three hundred and ninety six (64.7%) were infected with one or more of seven species of helminths comprising three cestodes (Hymenolepis diminuta, Taenia taeniaeformis (cyst) and Raillietina sp.) three nematodes (Mastophorus muris, Trichuris muris and Syphacia sp.) and one acanthocephalan (Moniliformis moniliformis). Although the prevalence of infection in males (76.6%) was more than in females (54.5%) (P< 0.01), there was no difference in the mean intensity of infection, MI, (males = 11.6 ± 0.94, females = 11.1 ± 1.56). Among the different weight classes, rats of 100–130g were more infected (89.3%) and had the highest mean intensity (MI = 21.6) than those that weighed <100g (47.1%, MI = 6.4) and >130g (73.9%, MI = 9.3). Moniliformis moniliformis was the most common species encountered (39.2%) and had the highest mean intensity in both sexes ( = 7.4 ± 0.74). Considering the rat-man proximity, this finding has considerable public health implications.

The relationship between the cercarial allergen and two previously isolated egg allergens (J1, J2) of Schistosoma japonicum was examined especially in terms of the cross-reactivity between them. Semi-purified cercarial allergen (JAC) was obtained from the crude extract of S. japonicum cercariae by gel chromatography on Sephadex G-200. The apparent molecular weight of JAC was estimated approximately as 60–100 kDa. JAC could bind to Con A-Sepharose, indicating its glycoprotein nature. Three groups of BALB/c mice were immunized with JAC, J1 or J2 using A1(OH)3 as adjuvant, and the cross-reactivity of each antiserum was examined by PCA. Anti-JAC, anti-Jl or anti-J2 serum was highly specific to the corresponding antigen. When IgE-ELISA of S. japonicum patient sera was performed using JAC, J1 or J2 as an antigen, the correlation between anti-J1 and anti-J2 (r = 0.78) was high, whereas the correlation between anti-JAC and anti-J1 (r = 0.27) or between anti-JAC and anti-J2 (r = 0.12) was low. These results suggest that most IgE epitopes on cercarial allergen are independent from those on egg allergens in S. japonicum.

Twenty species of helminth parasites were identified from fox, wolf, jackal and wild cat material collected in Greece. Of the 314 foxes (Vulpes vulpes) examined, 18 helminth species were recovered comprising one trematode, eight cestodes, seven nematodes and two acanthocephalans, with the cestode species Mesocestoides sp. (73.2%), Joyeuxiella echinorhynchoides (24.5%) and the nematode species Uncinaria stenocephala (43.9%), and Toxocara canis (28.6%) being the most prevalent. Five cestode and three nematode species were reported from six wolves (Canis lupus), together with one trematode, three cestode and four nematode species from five jackals (Canis aureus) and two cestode and three nematode species from four wild cats (Felis silvestris) examined. The species J. echinorhynchoides, Taenia crassiceps and Onicola canisand the genera Spirometra, Rictularia and Pachysentis are reported here for the first time in Greece. The results are discussed in the light of the feeding characteristics of wild carnivores in rural areas of Greece.

A cross-sectional study on the prevalence of helminths in rural scavenging poultry on six hundred adult chickens selected randomly from six villages in the Morogoro Region, Tanzania during the wet and the dry seasons, was conducted. The trachea and gastrointestinal tract of each bird were examined for the presence of parasites. All chickens were infected with one or several species of helminths, the average being 4.8 ±1.7 helminths per chicken during the wet season and 5.1 ± 1.8 during the dry season. A total of 29 different helminth species were shown in the trachea or the gastrointestinal tract. The following species were identified: Syngamus trachea (0.7% (wet season), 2% (dry season)); Gongylonema ingluvicola (6.3%, 17.7%); Tetrameres americana (54.3%, 60.3%); Dispharynx nasuta (0%, 2.7%); Acuaria hamulosa (8.3%, 19.3%); Ascaridia galli (28.3%, 32.3%); Heterakis gallinarum (74.0%, 78.7%); H. isolonche (18.7%, 5.0%); H. dispar (25.7%, 6.3%); Allodapa suctoria (40.0%, 52.0%); Subulura strongylina (3.3%, 1.0%); Strongyloides avium (0.3%, 3.0%); Capillaria annulata (2.0%, 0.0%); C. contorta (9.0%, 1.0%); C. caudinflata (2.0%, 4.3%); C. obsignata (8.7%, 25.0%); C. anatis (4.0%, 9.0%); C. bursata (1.0%, 2.7%); Raillietina echinobothrida (41.3%, 46.3%); R. tetragona (25.3%, 21.3%); R. cesticillus (8.7%, 2.7%); Choanotaenia infundibulum (0.0%, 3.7%); Hymenolepis carioca (9.0%, 18.0%); H. cantaniana (48.0%, 43.0%); Amoebotaenia cuneata (39.3%, 36.0%); Metroliasthes lucida (1.0%, 0.3%); Davainea proglottina (5.7%, 0.3%) and Polymorphus boschadis (0.3%, 0.0%). No trematodes were found. No correlation was found between season and prevalence, or season and mean worm burdens. Twelve helminths of the species recovered represent new local records.

The life-cycle of the tapeworm Bothriocephalus claviceps (Goeze, 1782) (Cestoda: Pseudophyllidea), a specific parasite of eels (Anguilla spp.), was studied under experimental conditions. It was demonstrated that the parasite completed its development within 4 months at the temperature range of 22–24°C. Embryonic development was finished in 2 days at this temperature, when coracidia spontaneously hatched. The rate of their development was controlled by water temperature, with delayed formation of coracidia at lower temperatures (8 days at 10–12°C). At 2–4 and 6°C, development did not take place but the eggs remained viable; at 33°C the eggs died. The procercoids developed in copepods of the species Macrocyclops albidus, M.fuscus, Megacyclops viridis, Cyclops strenuus, C. vicinus and Acanthocyclops vernalis (Copepoda: Cyclopidae); their development was finished after 8–12 days at 22–24°C. The definitive hosts, eels, acquired infection after ingestion of infected copepods; the prepatent period of the parasite was more than three months. Perch (Perca fluviatilis) and guppies (Poecilia reticulata) were shown to serve as paratenic hosts of the parasite; in guppies, the tapeworms survived up to 14 days after exposure and they developed similarly to tapeworms in the definitive host.

The breed differences in post-parturient rise (PPR) in faecal egg counts in lambing ewes of different breeds naturally infected with Haemonchus contortus were compared. The ewes of Nali, 50% Nali × 50% Russian Merino/Corriedale and 37.5% Nali × 62.5% Russian Merino/Corriedale were treated with fenben-dazole while ewes of the above three breeds as well as 25% Nali × 75% Russian Merino/Corriedale, were kept untreated. Observations from 3 weeks before lambing to 12 weeks post-lambing at weekly intervals revealed that in treated ewes, egg counts of Nali did not differ significantly with 50% Nali whereas 37.5% Nali had significantly higher egg counts than those of Nali and 50% Nali. In untreated ewes egg counts of 50% Nali were significantly higher than that of Nali on some occasions, while 25% Nali had significantly higher egg counts than the other three breeds. None of the ewes from the Nali breed showed signs of haemonchosis, whereas few lambing ewes of the three Nali crosses (50%, 37.5% and 25% Nali) showed signs of haemonchosis and one ewe of the latter breed died.

The migratory pathway of Toxocara canis larvae was determined by infecting mice with a low, medium or high dose of embryonated T. canis eggs and determining numbers of larvae present in the brain, liver, lungs, kidneys and muscle on days 5, 14 and 26 post infection. Variation was seen in the numbers of larvae recorded in the organs of mice which had received the same number of eggs and were at the same stage of infection. This variation was particularly marked in the brain indicating that, for the purposes of behavioural studies, the actual numbers of larvae found in the brain rather than the number assumed from the dose would have to be taken into account when analysing the behaviour of infected mice.

C3H/HeN mice were each infected with 40 Echinostoma trivolvis metacercarial cysts on day 0, given intramuscular injections of dexamethasone (DEX) daily for 30 days, and necropsied on days 5, 8, 12, 15, 20 and 30 p. i. Control mice were each infected with 40 echinostome cysts on day 0, but were not treated with DEX and necropsied on the same days as the DEX-treated mice. DEX treatment caused an inhibition of worm expulsion and suppressed the increase in goblet cell numbers that peaked around day 12 p. i. in the untreated control mice. Increase in the number of mucosal mast cells and eosinophils in the control mice that peaked around day 15 and 12 p. i., respectively, was also suppressed by the DEX treatment. The mean body area of the worms from the DEX-treated mice was about the same as that of the control worms on day 5 p. i., and then significantly greater than the control worms on days 8 and 12 p. i. The worms in the treated mice continued to grow until the end of the experiment, on day 30 p. i. Enzyme-linked immunosorbent assay (ELISA) showed that serum IgM from the treated and control mice increased from day 12 p. i., peaked on day 15 p. i., and then decreased. An IgM titre of the treated mice was slightly higher than that of the controls. No marked rise in IgG and IgA titres occurred throughout the experiment in both groups.

Chromosomes of Acanthocephalus lucii (Muller, 1776) were observed using conventional staining techniques. The number of chromosomes in females and in their developing eggs (2n = 8) as well as the mean (La) and relative length (Lr) of the chromosomes and the localization of the centromere (Ic) were determined. Peculiarities in the behaviour of the chromosomes are also described.

In vitro pairing studies on rediae of Echinostoma trivolvis, E. caproni, Zygocotyle lunata, Ribeiroia sp. and sporocysts from a species of armatae cercaria were undertaken at 22°C in a Petri dish bioassay containing an agar substratum and a Locke's 1:1 overlay. Pairing was arbitrarily defined as larvae in contact or within 1 mm of each other. Intraspecific and interspecific pairing occurred in the bioassay using several larval combinations initially placed 5 or 10 mm apart. Intraspecific pairing occurred with the rediae of Ribeiroia sp. and interspecific pairing was seen between E. trivolvis or E. caproni and Ribeiroia sp. A previous study documented intraspecific and interspecific pairing between rediae of E. trivolvis and E. caproni. Armatae sporocysts did not pair intraspecifically or interspecifically when matched with either E. caproni or E. trivolvis rediae. Intraspecific pairing of Z. lunata or interspecific pairing between Z. lunata rediae and echinostome rediae did not occur. The significance of redial pairing remains unclear.

An attempt was made to identify the filarial specific antigens that are capable of inducing immune response in human filariasis. Lymphocytes were taken from three clinically defined groups living in an endemic area in Madras, namely microfilaraemic (MF) subjects with microfilariae in their blood smear without any clinical symptoms, chronic pathology (CP) individuals with lymphangitis or lymphadenitis in combination with a history of recurrent filarial fevers or lymphoedema, and endemic normals (EN) subjects without microfilariae nor any clinical symptoms of pathology. Lymphocytes from the three groups responded with no significant difference (P = 0.21) in their proliferative index to PPD and PHA, although lymphocytes from MF individuals showed significantly (P < 0.001) less proliferative index to Brugia malayi antigen (BMA) than the CP and EN subjects. This antigen specific cellular unresponsiveness seen in MF patients was not reversed by the addition of recombinant IL-lα, IL-1β, and IFN-γ, but the addition of sera from EN individuals seemed to restore this unresponsiveness (P < 0.001). The peripheral blood mononuclear cells from MF patients secreted more IL-1 in response to BMA induction than the same from CP and EN individuals. A 58 kDa recombinant protein isolated from a Wuchereria bancrofti genomic library (58 kDa) had mounted a higher proliferative response to lymphocytes from all three groups compared to BMA (P < 0.001) indicating the possible use of recombinant filarial protein to mount immunological responses in filarial patients.