The population dynamics of Labratrema minimus (Stossich, 1887) metacercariae (Trematoda, Bucephalidae) were studied in its second intermediate fish host Atherina boyeri from Salses-Leucate lagoon (Northwest Mediterranean Sea, South of France), during the cercarial shedding period. The infection parameters (prevalence and mean abundance of infection) showed the high susceptibility of silversides (juveniles and adults) to infection. The observed variation in the mean abundance of infection with respect to time and host size was explained by (i) the susceptibility of A. boyeri to multiple successive infections (increase in abundance of infection with host length and raising of parasite burden until August) and (ii) the loss, probably by more rapid death, of heavily infected silversides from each host size group (decrease in abundance of infection in September within each host size group, stability of the parasite burden within the older class of hosts over the whole period, premature decrease in the condition factor in August). Finally, it was deduced that the infection pattern observed over the May–September period was a dynamic process controlled by: availability of infective cercariae, influx of newborn silversides free of metacercariae until September, high susceptibility of juvenile and adult A. boyeri to infection, metacercarial loss and probably by parasite-induced host mortality.

The enzyme-linked immunosorbent assay (ELISA) and immunoelectrophoresis (IEP) were used for the serodiagnosis of larval Anisakis simplex infections in man and immunized rabbits. Sephacryl S-300 gel filtration was used for separating crude antigen. Four fractions were obtained. Sera from patients with other helminth infections sometimes cross reacted with Anisakis larval antigens. With IEP, crude antigen is more sensitive than purified antigens. With ELISA, the third fraction is the most sensitive for detecting antibodies to Anisakis larvae in the sera of humans and immunized rabbits.

In epidemiological surveys for urinary schistosomiasis caused by Schistosoma haematobium in communities around Agulu Lake, Anambra State, Nigeria, between 1990 and 1992, the infection was found to be endemic in the area, especially in three towns: Nri, Agulu, and Adazi Nnukwu. The prevalence rates varied between these communities and with the year. Inter-town prevalence rates ranged from 5.96% to 54.00%. Intravillage prevalence rates ranged between 5.50% to 96.43%. Prevalence rates were highest in villages very close to Agulu lake. There was no significant difference in prevalence between the schools. Host age, but not sex, was found to play a significant role in prevalence and intensity of infection. There was also a strong correlation between visible haematuria and egg count per 10 ml urine, but eggs could be isolated in urine samples of different shades of coloration. Analysis of incidence of infection in these communities shows that Schistosoma haematobium incidence is high in Nri (55.17%) and low at Adazi Nnukwu (5.26%). Both Bulinus globosus and B. truncatus were found in the lake and both shed mammalian bifid schistosome cercariae.

The tegument of juvenile Paramphistomum epiclitum and Fischoederius elongatus (Paramphistomidae: Digenea) resembles those of other digeneans. Seven types of papillae were observed, mostly on the oral and acetabular surfaces, and increase in number during migration. Also evident are two types of secretory body (T1 and T2) which are synthesized separately in tegumental cytons underlying the syncytium. Exocytosis of T2 bodies occurs at the apical membrane and appears to contribute to a fibrous glycocalyx. The tegumental syncytium lining the pharynx and acetabulum is thinner and has a higher capacity for vacuolation than the general tegument. These may represent important sites for osmoregulation. The absence of mitochondria from the tegument in migrating juveniles suggests limited involvement in energy demanding processes. Pigmentation of the subtegument is first evident in mature cercariae and is progressively eliminated during migration.

In order to investigate the experimental transfer of Paragonimus westermani from rodents to rodents following subcutaneous and intraperitoneal routes, 13 rats and 23 mice were inoculated with a total of 115 (1 mature and 114 immature) worms of P. westermani subcutaneously and intraperitoneally. The age of worms before transfer was 25–193 days. The transfer was performed immediately after worm collection from rodents which were killed at various intervals from 4 to 144 days after infection. The location, development and size of worms were recorded. An infection rate of 58% (or 21/36) was demonstrated in rodents after experimental transfer of P. westermani by intraperitoneal and subcutaneous routes. Twenty-seven worms were recovered, giving a worm recovery rate of 23.5%. The rate was significantly higher by the subcutaneous route (34.8%) than by the intraperitoneal route (20.7%) but no difference was found between mice (23.9%) and rats (23.0%). The sizes of worms in the abdominal cavity, pleural cavity and thoracic muscles of mice, and in the leg muscles of rats were much less than in the pleural cavity and lung cysts of rats. A mature worm (7×5 mm) and numerous eggs were found in the uterus and pleural cavity of one rat. It is evidence that these rodents are unfavourable definitive hosts of P. westermani, because the worm size, infectivity, maturation and egg production are usually very low. However, the worms are usually widely distributed in their rodent hosts and remain small in size for a long period. Therefore, these rodents are good paratenic hosts for P. westermani and can play an important role in infecting cats and dogs with P. westermani in the laboratory.

Thirty-four albino mice were each exposed to 20 cercariae of Schistosoma japonicum by the intraperitoneal or percutaneous route and killed after 60–127 days. The peritoneal cavity of each mouse was flushed and worms in the portal vein system were perfused with citrated saline. After sedimentation, washings were examined microscopically. Mature worms were only found in the portal vein system. The worm recovery rate was much higher by percutaneous infection (61.2%) than by intraperitoneal (37.1%). The encapsulated egg granulomas were observed either in the peritoneal cavity or on the intestinal wall; the mean number of encapsulated egg granulomas was also higher in the former (1.6) than in the latter (0.6). The average number of eggs per granuloma was very similar by both routes (10.7 and 11.4). The mean size of encapsulated egg granulomas (529 μm) was increased correspondingly with the number of eggs (range 181–985 μm). The percentage of viable eggs within the granulomas in the peritoneal cavity (77%) was much higher than those on the intestinal wall (18%). Encapsulated egg granulomas were usually ovoid although some had an irregular shape.

The viability rate of hydatid cysts was investigated in animals slaughtered in the abattoir of Thessaloniki, Macedonia, Greece. Two hundred sheep (100% infection rate), 106 cattle (56.6% infected), 203 pigs (9.3%) and 52 goats (15.4%) were examined. All fertile cysts contained viable protoscoleces. In sheep there was a mean of 1.1 (29.8% of total cysts) fertile cysts per animal containing 297.3 (81.3%) viable protoscoleces. The percentage of viable protoscoleces in the lungs was 82.3% and in the liver 71.2%. In cattle there was a mean of 0.1 (6.6% of total) fertile cysts per animal containing 46.4 (72.2%) viable protoscoleces. The percentage of viable protoscoleces in the lungs was 69.5 and in the liver 87. In swine there was a mean of 0.02 (9.5% of total) fertile cysts per animal containing 32.0 (76.8%) viable protoscoleces. The percentage of viable protoscoleces in the lungs was 97.1 and in the liver 68.9. In goats there was a mean of 0.1 (12.5% of total) fertile cysts per animal containing 12 (54.6%) viable protoscoleces. The percentage of viable protoscoleces in the lungs was 54.4% but no fertile cysts were found in the liver.

The trapping capability of Arthrobotrys oligospora and A. conoides (Hyphomycetales) against third stage larvae (L3) of Haemonchus contortus (Trichostrongylidae) was evaluated in an in vitro trial. Arthrobotrys oligospora showed a 35.87% and 25.71% trapping effectiveness against H. contortus infective larvae at 18 and 25°C, respectively; whereas the trapping capability of A. conoides was 92.17% and 90.40% at the same temperatures, respectively. Microscopic examination demonstrated that A. conoides spontaneously developed a large quantity of three-dimensional loops before the nematodes were added. Neither of the two species studied developed three-dimensional adhesive loops at 30°C, consequently no trapped nematode was observed. In a second trial, the trapping capability of A. conoides against H. contortus (L3) and second stage larvae (J2) of Nacobbus aberrans (Pratylenchidae), was evaluated at 25°C. The trapping capability shown by A. conoides was higher than 90% for both kinds of nematode. The possible use of A. conoides to control ovine haemonchosis is discussed.

In a survey carried out in 1991–1992 in the town of Yirka in Northern Israel, 49 dogs were examined for Echinococcus granulosus infection and abattoir data, based on organs condemned for the presence of parasites, was collected. The presence of E. granulosus by arecoline test was demonstrated in 7 (14.2%) of the dogs examined, but no parasites were found in the intestines of five stray dogs shot in the area. A survey of sheep slaughtered in the local abattoir during a one-month period revealed Echinococcus cysts in 10% of the 255 animals examined. No Echinococcus parasites were detected in 21 dogs examined 3 months after the initiation of praziquantel treatment. Echinococcosis seems to be a very serious public health problem in Israel and a control programme needs to be given a high priority.

The distribution and host range of Sanguinicola armata, S. inermis and S. volgensis in British freshwater fish are described. S. inermis has been recorded in carp Cyprinus carpio, crucian carp Carassius carassius and tench Tinca tinca in southern, central and eastern England and in koi carp imported from Japan. S. armata has been detected in pike Esox lucius and tench and S. volgensis has been found in chub Leuciscus cephalus, dace Leuciscus leuciscus, perch Perca fluviatilis, roach Rutilus rutilus and pike in southern and eastern England. The first record of the co-occurrence of two species of Sanguinicola (S. inermis and S. volgensis) in a British inland water is reported. The importance of blood flukes and the role of anthropochore movement of fish hosts in dissemination of S. inermis are discussed.

This paper reports the development of the canid filarial worm, Dipetalonema dracunculoides, in the brown dog tick, Rhipicephalus sanguineus by determining whether development is similar within larval, nymphal and adult stages of infected ticks. This study demonstrates that only infected nymphal ticks can support the complete development of the filarial worm. Infected larval ticks are not suitable intermediate hosts, nor are infected adults. Development depends on some stage-specific property of the vector, and the maturation to the infective stage is stimulated during the course of the nymphal-adult moult.

Female ICR mice, 6–8 weeks old, were exposed to 100 metacercarial cysts/host of Echinostoma trivolvis to determine the effects of this cyst dosage on worm infectivity, distribution, growth and acetabular attachment in the host small intestine, Of 42 exposed mice, 22 were infected 4 to 17 days postinfection (PI) with a mean worm recovery of 11 to 41%. Mean body area of worms increased from about 0.4 mm2 on day 4 PI to about 2.0 mm2 by day 9 PI. No consistent pattern of worm growth was seen beyond day 9. Distribution data showed that worms were found mainly in the anterior part of the small intestines on day 4 PI and then more posteriorly up to day 8 PI. Worm distribution patterns were quite variable beyond day 11 PI. Scanning electron microscopy showed that the acetabulum left a distinct ‘fingerprint’ or acetabular plug on the intestinal mucosa of the host. The ‘fingerprint’ was temporary and disappeared within 1 min after worms were removed from the intestines.

To study the distribution of Lymnaea truncatula in the Porma river basin (León, NW Spain) and its helminth fauna, malacological samplings were carried out at 66 points in the basin and the presence of these molluscs was detected in 31. To trace the dynamics of this mollusc population and the prevalence and intensity of its infection by trematodes, malacological samplings were made at fortnightly intervals over two years at five locations, situated in the upper and middle regions of the river Porma basin. To confirm the identity of the larval stages found in the molluscs, second intermediate and/or definitive hosts, depending on the trematode species, were experimentally infected to complete the life cycles. Two different species of Plagiorchiidae and one of Notocotylidae were identified. The infection prevalence of Plagiorchis elegans for the 6291 specimens of L. truncatula examined was 2.8% and infection was observed in snails collected in 7 of the 31 sample localities. This parasite was found in all months of the year, with the highest prevalence observed in July and October. When the corrected frequency values were considered, a slightly positive relationship was observed between the infection prevalence and the latter months. The highest percentages of snails harbouring immature sporocysts were detected in March and June–July, while the highest percentages with sporocysts containing mature cercariae were observed in spring and at the end of summer–autumn, and cercarial shedding in the latter. Of the 6291 L. truncatula examined 0.3% were infected by sporocysts of Opisthioglyphe ranae. The infection was detected in only one locality, in four months of the year, with the highest prevalence in May. Notocotylus neyrai was found in 2.6% of the 6291 mollusc specimens checked and was collected from 12 of the 31 localities. The highest prevalence was observed in October, April and July and the corrected frequency values reveal a positive relationship between the infection prevalence and those three months. The highest percentage of molluscs harbouring rediae of N. neyrai with germinal mass was found in April and September–October. On the other hand, rediae with mature cercariae were present in almost every month, but we only observed cercarial shedding in October and March. The L. truncatula infection prevalence by P. elegans, O. ranae and N. neyrai increased with the size of the molluscs. Double infection was only observed in four snails: one harboured O. ranae and N. neyrai and three F. hepatica and P. elegans.

A total of nine playground sites in Dublin city and county were surveyed from which 228 samples were removed. Of these samples, 15% were positive for Toxocara canis ova and a mean egg density of 1.4 ova/100 g was calculated. Two types of playground sites were identified and that the level of toxocaral contamination was found to be greater in ‘neighbourhood playgrounds’ than in ‘adventure playgrounds’. There was no significant difference in the number of positive samples taken from sites both inside and outside these playgrounds. No evidence of Toxocara cati ova was found. Only one sample was positive for Toxascaris leonina ova. Over 50% of the T. canis ova identified were infective. The findings in this study suggest that the sample's moisture content contributes to the long term survival of infective Toxocara ova in the environment. A recovery rate of 69.8% was achieved with a modified version of the flotation method.

The miracidium of Transversotrema patialense (Digenea: Transversotrematidae) has 21 epidermal cells arranged in four tiers with an epidermal formula of 6, 9, 4, 2. The penetration gland is large, conspicuous, contains a posterior globular part with 6 prominent nuclei and opens out through 6 pores arranged in two lateral groups at the tip of the apical papilla. The miracidium lacks lateral papillae, possesses a well developed subepithelium, a pair of flame cells and a germ ball.

The cephalic end of the type species of pharyngodonid genera Travnema and Cosmoxynemoides, T. travnema Pereira, 1938 and C. aguirrei Travassos, 1949, parasites of Brazilian freshwater fishes, was studied by scanning electron microscopy. The mouth aperture of Travnema was found to be circular, surrounded by four cephalic papillae and two lateral amphids and the cuticle of the cephalic end had a conspicuous dense sculpture. On the other hand, the mouth aperture of Cosmoxynemoides was triangular, surrounded by three lip-like elevations covering the whole surface of the relatively flat cephalic extremity, each with two inner lobes separated one from another by a short groove; the lip-like elevations bore four medium-sized, kidney-shaped cephalic papillae and two minute amphids (two papillae on the dorsal elevation and one papilla and one amphid on each of two ventrolateral elevations); the cuticle of the cephalic end was smooth. Both species were noted for the absence of oral lamellae and the presence of lateral alae. Both genera are listed in the family Pharyngodonidae but Travnema (and also Hakynema), due to its morphological peculiarities, is considered to represent a distinct subfamily Travnematinae within the Pharyngodonidae. The finding of both T. travnema and C. aguirrei in the characid fish Astyanax bimaculatus lacustris represents new host records.

The karyotypes of Vampirolepis nana, Hymenolepis diminuta and Vampirolepis erinacei (Cestoda: Cyclophyllidea) have been described. The number of chromosomes in the diploid cell of the studied taxa was 2n = 12. The absolute and the relative lengths of the chromosomes of V. nana and H. diminuta were measured. The chromosomes had similar metric values. In the karyotypes of V. nana and H. diminuta there were ten one-arm chromosomes and.one two-arm chromosome (the third in length in the karyotype of V. nana and the first in length in the karyotype of H. diminuta). The chromosomes in the karyotype of V. erinacei had one arm which was proved by the terminal localization of the constitutive heterochromatin. The examined species differed in the morphology of some chromosomes in the karyotypes.

Blood samples from 50 dogs with episodic weakness and 50 clinically normal dogs, all belonging to hunting breeds, were examined for microfilariae using the modified Knott's method. The prevalence of microfilaraemia in dogs belonging to the episodic weakness group was 10% for Dirofilaria immitis, 30% for Dirolfilaria repens and 8% for Acanthocheilonema reconditum. In the clinically normal group, the figures were 14% for Dirofilaria repens and 4% for Acanthocheilonema reconditum. The overall percentage of dogs with microfilaraemia in the episodic weakness group was 44 and that of the clinically normal group 16, with a statistically significant difference (P<0.01). The prevalence of microfilaraemia due to the nonpathogenic filarial species (Dirofilaria repens, Acanthocheilonema reconditum) was 34% and 16% for the episodic weakness group and the clinically normal dogs, respectively, with no significant difference.

Analysis of Giemsa-stained mitotic metaphase plates of Microsomacanthus spasskii and M. spiralibursata (Cestoda: Hymenolepididae) revealed the diploid chromosome numbers for both species to be 2n=6. The karyotypes are remarkably similar in general morphology; they both consist of three pairs of metacentric or meta-submetacentric chromosomes graded in size from 4.3 to 7.0 μm. Slight interspecific differences exist in the position of the centromere of chromosomes of the pair 3. Based on existing chromosome data the possible pathways of the karyotypic evolution within the family Hymenolepididae are discussed.

Compressed organ autoradiography has been utilized to study the migration of the homogonic strain of Strongyloides ratti from the site of skin penetration to the gut. This transit is characterized by rapid disappearance of parasites from the cutaneous site of infection, followed by vascular dispersal throughout all organs investigated. For the first time, parasite migration in both naive and previously sensitized hosts is compared; the principal stations of migration are the same in the two groups although there is a quantitative difference in accumulation of parasites with time in these stations. Parasite attrition occurs in both groups of animals; however, in naive rats it is not manifest until day 20–25 post challenge, whereas in sensitized rats immune elimination occurs as early as 48 h post challenge.