The effect of dietary cobalt from three different sources on uninfected and Ascaridia galli-infected Hisex chickens, has been studied. The chicken diet was supplemented with 0.06 Co2+ kg-1 food either in the form of two glycine–cobalt compounds or mixed zinc–cobalt basic salt. An excess of dietary cobalt in small doses increases the gain of body weight and decreases host mortality. A greater bioefficiency of cobalt was established in infected chickens. A mathematical model has been used to provide a quantitative interpretation of the observed results. The model solutions of the kinetics of worm numbers and body weight are in a good agreement with experimental data. The model is valid for different degrees of A. galli infections and for treatment with different trace elements. The value of the kinetic parameter, regarded as a phenomenological constant of the host immune response, depends on the degree of infection.

Electrorotation is a non-invasive technique that is capable of detecting changes in the morphology and physicochemical properties of microorganisms. The first detailed electrorotation study of the egg (ovum) of a parasitic nematode, namely Ascaris suum is described to show that electrorotation can rapidly differentiate between fertilized and non-fertilized eggs. Support for this conclusion is by optical microscopy of egg morphology, and also from modelling of the electrorotational response. Modelling was used to determine differences in the dielectric properties of the unfertilized and fertilized eggs, and also to investigate specific differences in the spectra of fertilized eggs only, potentially reflecting embryogenesis. The potential of electrorotation as an investigative tool is shown, as undamaged eggs can be subjected to further non-destructive and destructive techniques, which could provide further insight into parasite biology and epidemiology.

Natural infection by intestinal nematodes was assessed in Santa Ines and Ile de France sheep breeds, over a five-month grazing period, with emphasis on the development of the immune response in lambs under two anthelmintic treatment regimens. Nineteen Santa Ines and 19 Ile de France male lambs were allocated into two treatment groups: animals under suppressive treatment with anthelmintics; and animals under targeted selective treatment (TST). The nematodes Trichostrongylus colubriformis and Strongyloides papillosus showed the highest infection intensity in the TST animals in both breeds. Parasite-specific immunoglobulin G levels were significantly higher and more rapidly induced in Santa Ines lambs. Additionally, these lambs had higher levels of parasite-specific immunoglobulin A in intestinal mucus. Animals under TST had higher means of mast cells and globule leukocytes in the intestinal mucosa due to longer and greater parasite challenge in comparison with the suppressive group. A breed effect (P < 0.05) was recorded for mast cells, with Santa Ines lambs presenting the highest counts. Although Santa Ines lambs had lower intestinal nematode counts than Ile de France lambs, they had shown a large variation in T. colubriformis burden, with most of them presenting a marked worm burden, despite showing an earlier and more intense immune response to intestinal nematode infection.

Dawestrema cycloancistrium is the main ectoparasite causing mortality in fingerlings of pirarucu (Arapaima gigas) in Amazonian aquaculture. Very little is known about the D. cycloancistrium reproductive index and appropriate methods of collecting eggs for investigation. This study aimed to determine the oviposition rate of D. cycloancistrium. To achieve this aim, two egg quantification methods were tested: the estimative method (ME) and the total counting method (MT). Compared with the MT, the ME overestimated the number of eggs counted, which were 2943.5 ± 2840.6 and 1041.5 ± 533 eggs, and the oviposition rate, which was 80.1 ± 58.7 and 31.4 ± 16.4 eggs/parasite/day, for ME and MT, respectively. These results show that for studies quantifying D. cycloancistrium eggs, the total eggs in the sample must be counted, as the estimates made using subsamples are not representative. Using the MT, the oviposition rate for D. cycloancistrium was determined to be 31.4 ± 16.4 eggs per adult parasite per day. The present study demonstrates the egg production capacity of a monogenean species parasite of A. gigas, providing basic biological data for D. cycloancistrium.

The biodiversity and composition of endoparasites in fish obtained from the Antarctic and subantarctic zones are compared in this study. Several fish were collected in the summer from Antarctica (King George Island) and the Southern Pacific coast (Strait of Magellan and Almirante Montt Gulf). This database was complemented with published information on fish endoparasite communities from both zones, with specimens of fish sample size n ≥ 15. Thus, 31 fish species were analysed in this study, which altogether had 79 parasite species. Diversity indices were calculated for the parasite community of each fish species. Then they were compared between the Antarctic and subantarctic zones. Parasite species composition and host specificity (as the number of fish species used by a parasite species) were also analysed and compared between zones. The diversity indices and the abundance of parasites were significantly higher in the Antarctic than the subantarctic fish. Few parasite species (7.6%) were shared between fish from both zones, showing significant differences in parasite composition. Antarctic parasites were less host-specific than subantarctic parasites, which allowed the coexistence of several parasite species in the fish. The high parasite abundance in Antarctic fish could trigger sympatric speciation in certain parasitic lineages or the exploitation of new resources, resulting in more parasite species than those in subantarctic environments. The high abundance of Antarctic parasites implies different methods and rates of transmission than those of subantarctic parasites. In addition, more alternative fish hosts were used by the Antarctic than subantarctic parasites. This altogether indicates that host–parasite interaction dynamics significantly differ between the Antarctic and subantarctic systems.

The effect of flubendazole orally administered at 10 mg/kg/day for 5 consecutive days (the 11th, 20th or 40th post-infection) on the number of first-stage larvae (L1) of Angiostrongylus cantonensis released in the faeces of rats each infected with 40 third-stage larvae was determined. Faecal examination for 5 months, the period from medication to dissection of rats, showed that L1 release ceased in all the rats of medicated groups by about 1 week after the termination of dosing and resumed 1–2 months later in 86% of the rats which were dissected at the end of experiments with the recovery of adult worms of both sexes. Throughout the period of 5 months, about 2–4×104 L1/gram of fresh faeces was recorded in non-medicated control groups. There was a 38–79% reduction in adult worms at the dissection. Microscopic examination of the uteri of the remaining adult worms and lung tissues of rats confirmed no normal egg production in the adult worms from rats of medicated groups, except the rats with the resumption of faecal L1 release.

Ostertagia trifurcata was first described by Ransom (1907) from sheep and goats in United States. It has since been reported from various other countries and appears to have a world wide distribution. This species is recorded from India for the first time, in the present paper.

In Great Britain, O. trifurcata was first recorded by Boulenger (1914) but his record seems to have been overlooked by Travassos (1987). It has also been reported from sheep and goats in different parts of Great Britain by Morgan (1925), Jones (1926) and Oldham and Morgan (1984). All these workers report the occurrence of this species in association with Ostertagia circumcincta. Elsewhere, the association of O. circumcincta and O. trifurcata has been reported by Tetley (1984) from New Zealand, Ransom (1911) from United States, Gebauer (1982) from Germany and Saquenet (1946) from Algeria. In my collection from India (Kangra District), O. trifurcata,is present in small numbers together with O. circumcincta which is always the predominant species. In a collection of helminths from Cyprus in the London School of Hygiene and Tropical Medicine a few O. trifurcata were found in association with a large number of O. circumcincta.

The development of the larvae of Breinlia booliati a new filarial parasite of the forest rat Rattus sabanus in Aedes togoi is described. Complete larval development to the infective stage occurred in the fat body of the head, the thorax, and especially the abdomen of the mosquito. The first moult occurs at 7 days and the second at 11 days. As the larvae grow very rapidly in length, the parts of the parasitized fat body cells which harbour the developing larvae take on a syncytial appearance. By the 11th day, the larvae move out from the fat body into the haemocoele. The infective forms are found in the proboscis at the 12th day after the infecting blood meal.

When carrying out hatching experiments it would frequently be an advantage to have a quantitative measure of the activity of the root excretion used and search was accordingly made for a stable substance which could be made to a solution of constant known strength and which could be used as the basis for the comparison of the activity of different samples of root excretion. Hurst (Hurst 1937) records that tyrosine in dilute solution, lysine in the form of its picrate as well as picric acid at ·01% concentration caused active hatching to occur and experiments using the above single cyst technique were conducted to investigate these claims. The results with the former two substances were disappointing but dilute picric acid solutions were found to be very active. Since it is hoped to publish a further paper in which the effects of picric acid will be considered quantitatively and in detail it is not proposed to publish data in this article but concentration experiments showed that picric acid is most active at ·02—·01% concentrations, the solutions being made up in distilled water. Several experiments were conducted in which picric acid in these concentrations was compared with water and with root excretion; in all cases picric acid hatches were significantly greater than water hatches although picric acid was not generally as active as root excretion taken from vigorously growing plants.

Human gnathostomiasis is a food-borne zoonosis caused by a tissue nematode of the genus Gnathostoma. The disease is highly endemic in Asia, including Thailand. The freshwater swamp eel (Monopterus albus), the second intermediate host of the gnathostome nematode, has an important role in transmitting the infection in Thailand. Surveys on the infective larvae of Gnathostoma spinigerum based on morphological features in freshwater swamp eels have been performed continuously and reported in Thailand. However, there is still limited molecular data on intra-species variations of the parasite. In this study, a total of 19 third-stage larvae of morphologically identified G. spinigerum were collected from 437 liver samples of freshwater swamp eels purchased from a large wholesale market in Bangkok, Thailand. Molecular characterization based on mitochondrial cytochrome c oxidase subunit I (COI) sequences was performed to elucidate their genetic variations and phylogenetic relationship. Among the 19 infective larvae recovered from these eels, 16 were sequenced successfully. Phylogenetic analyses inferred from the partial COI gene showed the presence of three distinct COI haplotypes. Our findings confirm the presence of G. spinigerum as the main species in Thailand.

(1) Rats and mice are specific hosts to N. brasiliensis.

(2) The life span of the parasite may reach up to 100 days in the rat but is much shorter in other experimental animals.

(3) Chickens do not become infected with this parasite.

(4) It was found that the route of migration of this parasite inside the body to the lungs was via the lymph system and not via the blood in all experimental animals.

(5) The larvae, after application to the skin, reach the lymph glands draining the site of infection, not before 12 hours ; and they reach the lungs at 18 hours after exposure to infection.

The occurrence of Ankylostomes resembling human hookworms in the domestic pig has been the subject of several recent papers, the most noteworthy being the contributions of Ackert and Payne (1922 and 1923) and Gordon (1922 and 1923).

Paractinolaimus sahandi n. sp., found in wet soil samples collected from the rhizosphere of grasses of Sahand Mountains, Iran, is described. This new species is characterized by its long body (3.5–4.7 mm), high a value (74.5–88.5), anterior location of posterior subventral nuclei, occupying 62.5–68.0% of glandularium distance, the presence of 1–4 pre- and 1–3 post-vulval papillae and numerous tiny, not innervated papillae in front and behind the vulva in the outer layer of cuticle; common functional males in the population, with 62.5–81.3 μm long spicules and 15–17 ventromedian supplements. The new species, which is the only one in the genus showing the advulval cuticular tiny papillae and is unusually slender, is compared to four species of Paractinolaimus, namely P. macrolaimus, P. longidrilus, P. spanithelus and P. rafiqi. The ribosomal 18S rDNA (1246 bp sequenced) and 28S rDNA D2/D3 region (844 bp sequenced) of P. sahandi n. sp. were sequenced for molecular characterization. Sequences of the 18S and 28S D2/D3 of P. sahandi n. sp. have distinct differences from those of the only sequenced P. macrolaimus, with 6 bp differences in 18S and 38 bp differences and five gaps in 28S. This is the first report of the occurrence of members of Actinolaimidae in Iran.

The present study records the occurrence of major lipid fractions and their fatty acids in a digenetic trematode parasite Paramphistomum cervi, and the rumen fluid and liver of the goat (Capra hircus). The amount of neutral lipids (NL), glycolipids (GL) and phospholipids (PL) of goat liver, rumen fluid and of the parasite shows that the rumen fluid is rich in NL, which is also in maximum quantity in the parasite, while the liver is rich in PL followed by NL. The number of fatty acids of total lipids (TL), NL and PL is greater in the parasite than those of the liver and rumen fluid. The number of fatty acids of GL is higher in the liver than in the parasite and the rumen fluid. Comparison of unsaturated fatty acid (UFA), C18 total and C18 UFA of TL, NL, GL and PL of the liver, rumen fluid and the parasite shows that the amount of C18 UFA is higher in P. cervi in all the lipid fractions, except for GL, than in the rumen fluid and the liver. The results reveal that P. cervi absorbs a greater number of fatty acids than its host.

Canine echinococcosis is caused by the adult tapeworm of Echinococcus granulosus. As intermediate hosts, humans and livestock become infected following ingestion of eggs that are passed in the faeces of dogs. Mature eggs develop into hydatid cysts in different organs, leading to hydatid disease, which is a serious public health problem. In the present study, we investigated the proportion of mature eggs of E. granulosus in 140 dogs from three regions of Tunisia. The results showed the predominance of immature E. granulosus eggs in infected dogs and the occurrence of a small proportion of oncospheres. The ability of immature eggs to infect humans and livestock is discussed.

Laboratory rats were infected by intra-peritoneal injection with the metacestodes of Taenia crassiceps. A soluble extract was prepared from the metacestodes removed from the peritoneal cavity of the rats. Doublediffusion, immuno-electrophoresis and fluorescent labelled antibody staining techniques were used. The extract tested against rabbit anti-normal rat serum was found to contain an antigen common to both the host and the parasite.

Experiments involving cattle, horses, pigs and fowls are presented which are considered to give evidence that thiabendazole is highly active against the Strongyle parasites but not so active against the ascarid parasites of the digestive tract of these animals. The strongyles of cattle can be controlled with a dose of 75–100 mg./kg. and those of horses with as little as 25 mg./kg. In pigs 100 mg./kg. was very active against Oesophagostomum dentatum but this dose level was of poor efficiency against Ascaris lumbricoides. A high dose of 500 mg./kg. appeared to be necessary to control Ascaridia galli in the fowl.

Three species of genus Bychowskyella Akhmerov (1952), i.e. B. fossilisi Majumdar & Agarwal, 1989, B. tchangi Gusev, 1976 and B. wallagonia (Jain, 1959a) Gusev, 1961, were found to parasitize the gill filaments of siluriform fish in India. This redescription based on light microscopic examination of B. fossilisi, B. tchangi and B. wallagonia provides detailed taxonomic data for these species. We also amplified the 18S ribosomal RNA gene to evaluate the phylogenetic relationships of these three species. The morphological and genetic profiles confirmed the validation and taxonomical relationships of the above-mentioned species belonging to the genus Bychowskyella.

Marine limpets, Notoacmea scapha, were collected from an intertidal mud flat in Otago Harbour, New Zealand, and examined for infection with larval trematodes. Three separate species of trematode (opecoelid sp. A, Acanthoparyphium sp. A and Curtuteria australis) were identified from the limpets, based on molecular evidence. This is the first report of these three trematodes in limpets, indicating that the latter are physiologically suitable second-intermediate hosts. However, based on ecological information on the diet of the parasites' definitive hosts, we conclude that the limpet N. scapha does not contribute to the transmission of any of the trematodes. Instead, it acts as a sink for cercariae that fail to locate appropriate second-intermediate hosts.

Aminopeptidase-like activities in crude whole body extracts of the free-living nematode Caenorhabditis elegans and the plant parasitic soybean cyst nematode Heterodera glycines were examined. General characteristics including pH optima, heat lability, and inactivation of enzyme by organic solvent were the same for the two species. All developmental stages of H. glycines exhibited activity. In older females, activity was present primarily in the eggs. Affinity for the substrate L-alanine-4-nitroanilide was the same regardless of the stage examined, and was similar for the two species (Km=2.3±0.3 mM FOR C. ELEGANS AND 2.9±0.2 Mm for H. glycines). Nearly all (>95%) of C. elegans aminopeptidase-like activity was present in the soluble fraction of the extract, while H. glycines activity was distributed between the soluble and membrane fractions. Specific activities of the soluble enzymes were highest in C. elegans and H. glycines juveniles. The C. elegans enzyme was susceptible to a number of aminopeptidase inhibitors, particularly to amastatin and leuhistin, each of which inhibited aminopeptidase-like activity more than 90% at 90 μm. In H. glycines, aminopeptidase-like activity was inhibited 39% by amastatin at 900 μm. The apparent molecular weight of the soluble C. elegans enzyme is 70–80 kDa. Some activity in H. glycines is present in the 70–80 kDa range, but most activity (80–90%) is associated with a very high molecular weight (>240 kDa) component.