An experiment was carried out to investigate the anthelmintic activity of papaya latex (Carica papaya) against natural infection of Ascaris suum in pigs. Sixteen naturally infected pigs were, on the basis of faecal egg counts and body weight, allocated into four groups, each of four pigs. Three groups (groups B, C, and D) were given papaya latex per os at dose levels of 2, 4, and 8 g of papaya latex per kg body weight, respectively. The fourth group (group A) served as a non-treated control. Results of post mortem counts on day 7 post treatment revealed worm count reductions of 39.5, 80.1 and 100% in groups B, C, and D, respectively. Some of the pigs receiving the highest dose of the latex showed mild diarrhoea on the day following treatment. Otherwise, no clinical or pathological changes were observed in the treated animals. The possible future use of this traditional herbal medicine for livestock and humans is discussed.

The relatively small literature on mitochondrial DNA (mtDNA) diversity in nematode species is summarized here. Nematodes show a wide range of overall genetic diversities and population genetic structures. Species-wide levels of diversity correlate strongly with the breeding system and other life cycle features that control effective population size. Obligate outcrossers that parasitize mobile vertebrate hosts are the most diverse, species having hermaphroditic stages are less so, and species having asexual reproductive stages appear even less diverse. Nevertheless, these conclusions are preliminary because there exist so few data on DNA diversity in nematodes. What is needed are more comparative studies using similar sampling designs and the same DNA markers, including nuclear loci and further work with mtDNA

In Turkana, Kenya, a prevalence of hydatidosis of nearly 10% has been recorded among the pastoralists yet their livestock have a much lower prevalence of the disease. The present study investigated the release from dogs and subsequent survival of Echinococcus eggs in Turkana huts, water-holes and in the semi-arid environment. The results were compared with the survival of eggs of Taenia hydatigena and T. saginata. The study was repeated under the cooler and moister conditons found in Maasailand where livestock have a greater incidence of hydatid disease than in Turkana but where the incidence in man is ten times lower. The average number of Echinococcus eggs per proglottid is 823. Nine percent of these remain in proglottids 15 minutes after release from a dog and the released eggs lose their viability in less than two, 48 and 300 hours in the sun, huts and water in Turkana respectively; the major influencing factor being temperature. The greater survival of eggs in the houses, coupled with the fact that dogs congregate for most of the day in the small houses facilitating a close man:dog contact, provide ideal conditions for the trasmission of the parasite to man. The hostile environmental conditions and lack of contact between dogs and livestock contributes to the lower infection rate in livestock. Conversely in Maasailand, Echinococcus eggs survive in the environment for longer than three weeks and in addition, dogs are used for herding. This partly explains the higher infection rate among Maasai livestock but the low human infection rate remains arcane and requires further study. The rapid mortality of the majority of Echinococcus eggs in Turkana suggests that control measures aimed at dog control and a decreased man:dog contact should have a profound effect on the incidence of the disease in an area intrinsically unsuitable for the parasites' survival.

A large number of planorbid snails are now commonly transported by man mainly through the aquatic plant trade. However, only a restricted number of species establish viable populations in a new habitat and a more restricted number spread. Only five planorbid species can be ranked in this last category and can be considered as pests because of their role in the transmission of parasites to humans or domestic animals: Biomphalaria glabrata, B. straminea, B. tenagophila, B. pfeifferi and Indoplanorbis exustus. The neotropical B. glabrata, B. straminea and B. tenagophila have proven their capacity to invade another continent sometimes creating new transmission foci. The African B. pfeifferi and the Indian I. exustus have also expanded their distribution area with long-distance dispersal. Other planorbid species, i.e. Helisoma duryi, Amerianna carinata and Gyraulus spp. have been able to establish viable populations, but not to spread, presumably because they are limited to specific habitats or/and display poor competitive abilities.

The development of the reproductive system of O. circumcincta is described and the developmental cycle divided into phases. It is suggested that these defined phases can be used to give an accurate profile of a worm population. The population of worms found in the experimentally infected lambs is defined in terms of these phases, linear measurements and, in the mature female worms, the presence or absence of the vulval flap.

1. This paper describes the life-history of Limnaea truncatula under laboratory conditions.

2. Under controlled conditions sexual maturity may be reached in 28 days and egg laying continues for the greater part of the snail's life.

3. Under good environmental conditions each snail may lay as many as 60 eggs in a single day and a total of more than 3,000 in a life approximately a year.

4. Egg laying occurs during every month and at temperatures as low as 10°C. to 11°C. The incubation period of the egg is related to the atmospheric temperature.

5. The longevity of the snail is likely to be related to its rate of growth and to environmental conditions including periods of drought.

6. The snail remains fully active at temperatures as low at 1.5°C.Sustained temperatures much above 20°C. are unfavourable, temperaturesabove 25°C. proving markedly deleterious.

Extraintestinal nematodes of the red fox (Vulpes vulpes) are a wide group of parasites that infect wild and domestic carnivores and occasionally humans. Nematodes in the cardiopulmonary system, stomach, urinary apparatus and muscle tissue of 165 red foxes (Vulpes vulpes) from north-west Italy (Liguria and Piedmont) were investigated between 2009 and 2012. Of the cardiopulmonary nematodes, a high prevalence of Angiostrongylus vasorum and Eucoleus aerophilus (syn. Capillaria aerophila) was found, 78.2% and 41.8% respectively; Crenosoma vulpis (15.8%) and Filaroides spp. (4.8%) were also found. Spirocerca lupi (23.5%), Aonchotheca putorii (syn. Capillaria putorii) (8.6%) and Physaloptera spp. (2.5%) were detected in the stomach and Pearsonema plica (syn. Capillaria plica) (56.8%) in the bladder. Eucoleus boehmi (syn. Capillaria boehmi) was also detected in the nasal cavities of one of the two foxes examined. A coprological examination revealed eggs of E. aerophilus, A. putorii, S. lupi, Physaloptera spp. and eggs of intestinal parasites. Filarial worms were absent in all the 165 animals examined, nor was there evidence of Trichinella spp. in any of the foxes. The foxes were found to host a high prevalence of many species of extraintestinal nematodes. The prevalence of A. vasorum in foxes found in the present study is among the highest in Europe. In addition, to the best of our knowledge, E. boehmi and Filaroides spp. have never been reported before in this host in Italy.

Neorickettsia (formerly Ehrlichia) risticii, the agent of Potomac horse fever (PHF), has been recently detected in trematode stages found in the secretions of freshwater snails and in aquatic insects. Insectivores, such as bats and birds, may serve as the definitive host of the trematode vector. To determine the definitive helminth vector, five bats (Myotis yumanensis) and three swallows (Hirundo rustica, Tachycineta bicolor) were collected from a PHF endemic location in northern California. Bats and swallows were dissected and their major organs examined for trematodes and for N. risticii DNA using a nested polymerase chain reaction (PCR) assay. Adult digenetic trematodes, Acanthatrium sp. and/or Lecithodendrium sp., were recovered from the gastrointestinal tract of all bats and from one swallow. The intestine of three bats, the spleen of two bats and one swallow as well as the liver of one swallow tested PCR positive for N. risticii. From a total of seven pools of identical digenetic trematodes collected from single hosts, two pools of Acanthatrium sp. and one pool of Lecithodendrium sp. tested PCR positive. The results of this investigation provide preliminary evidence that at least two trematodes in the family Lecithodendriidae are vectors of N. risticii. The data also suggest that bats and swallows not only act as a host for trematodes but also as a possible natural reservoir for N. risticii.

The value of tongue and meat inspection as diagnostic tools for porcine cysticercosis was assessed in 65 Zambian village pigs by comparing the results with carcass dissections. In addition, the intensity of infections, distribution and viability of cysts in infected pigs were measured. Five pigs (7.7%) were positive on tongue examination, while routine meat inspection showed 12 (18.5%) positives. However, carcass dissections detected cysticerci in 31 (47.7%) pigs. The range in number of cysticerci was 1 to 14,662 per carcass. Cysticerci were distributed throughout the carcass with the highest concentration in the heart, tongue and hind legs. In one animal 13 viable cysts were detected only in the brain. Fourteen pigs had more than 100 viable cysts, six between 2 and 100, and four had single cyst infections. Seven animals harboured only calcified cysts. These findings demonstrate the serious shortcomings of routine detection methods for porcine cysticercosis. While the specificity of tongue palpation and meat inspection was 100%, these tests failed to detect the infection in 83.9% and 61.3% of infected pigs, respectively.

A total of 298 slugs belonging to four species, Arion lusitanicus, A. ater, A. ater rufus and Limax maximus, were collected from six different localities within a radius of 30 km from Copenhagen and examined for naturally acquired Angiostrongylus vasorum infection. Overall, 28 slugs (9%) were infected, but the prevalence varied among the studied localities: Rude Forest (26%), West Amager Forest (18%), Jaegersborg Forest and Deer Park (8%), Frederiksberg Park (4%), Assistens Cemetery Park (0%) and Frederiksberg Botanical Garden (0%). Only third-stage larvae (L3) were recovered from the slugs, in numbers ranging from 1 to 392 per slug. Overall 82% of the infected slugs harboured fewer than 10 larvae and only 14% harboured over 100 larvae.

The effect of three phenols (ellagic, gentisic and gallic acids) from the axlewood tree Anogeissus leiocarpus on Onchocerca ochengi and drug-resistant strains of Caenorhabditis elegans, a model organism for research on nematode parasites, is investigated. Worms were incubated in different concentrations of phenols and their survival was monitored after 48 h. Among the three acids, ellagic acid strongly affected the survival of O. ochengi microfilariae, O. ochengi adults, a wild-type C. elegans and anthelmintic-resistant strains of C. elegans, namely albendazole (CB3474), levamisole (CB211, ZZ16) and ivermectin (VC722, DA1316), with LC50 values ranging from 0.03 mm to 0.96 mm. These results indicate that the binding of ellagic acid in the worm differs from that of resistant strains of C. elegans. The efficacy of both gallic and gentisic acids was not significantly changed in resistant strains of C. elegans treated with levamisole (ZZ16, LC50= 9.98 mm, with gallic acid), albendazole (CB3474, LC50= 7.81 mm, with gentisic acid) and ivermectin (DA1316, LC50= 10.62 mm, with gentisic acid). The efficacy of these three pure compounds is in accordance with the use of A. leiocarpus from its locality of origin. The in vivo toxicity data reveal that the thresholds are up to 200 times higher than the determined LC50 values. Thus, ellagic acid could be a potential option for the treatment of nematode infections, even in cases of drug resistance towards established anthelmintic drugs.

The influence of temperature and humidity on the survival and development of Toxocara canis eggs in an in vitro model system was investigated. Two soil samples were inoculated with T. canis eggs and maintained at 3% and 50% humidity and temperatures of 19–24°C. Nine soil samples were inoculated with T. canis eggs of which three samples were kept at 4°C with humidities at 3%, 15%, and 30%; three were maintained at 21°C and three more were incubated at 34°C, and at the same three humidity levels. Samples were monitored every 7 days for a total of 2 months, for the presence and development of eggs. With increasing temperature, the number of eggs undergoing development increased (P<0.01); the number of deformed eggs decreased, the number of infective eggs increased (P<0.01), and egg maturation was accelerated. A decrease in the survival of infective eggs occurred at 34°C. An increase in humidity produced a rise in the number of developed eggs at all three temperatures (P<0.01). This study suggests that elevated temperatures accelerated the development as well as the degradation of eggs of T. canis, whereas the range in humidity was directly correlated with egg development.

1. At least twenty-two species of filarial worms are known to develop in mosquitoes. Filarial larvae of non-human origin must often be present in mosquitoes dissected during filariasis surveys yet the larvae seen are commonly assumed to be of human origin.

2. On Pate island off the Kenya coast where bancroftian filariasis is prevalent, several distinct species of infective larvae were found in mosquitoes both in the houses and in the bush. Seven species of filarial worms were found in the local animals and a collection of known infective larvae was made by feeding mosquitoes on these different infections. A study of the material in this “reference collection” showed that many of the larvae in “wild” mosquitoes could be identified with confidence.

3. A technique has been developed for the dissection of preserved and stained mosquitoes; this method has many advantages and can be used in routine filariasis surveys.

4. The characters which were most useful in differentiating the infective larvae were: the length; the position of the anus; and the shape of the caudal extremity. Eight species of infective larvae were available for study, these are described and illustrated: W. bancrofti, W. malayi, W. pahangi, W. patei, D. corynodes, D. repens, D. immitis and S. equina. The literature dealing with a further fourteen species is reviewed.

5. A simple key has been produced to help identify the species of infective larvae found in mosquitoes.

6. On the Kenya coast W. bancrofti infective larvae have been found only in C. fatigans, A. gambiae and A. funestus. Infective larvae of animal origin which might easily be mistaken for those of W. bancrofti have been found in Ae. pembaensis, Ae. aegypti, M. uniformis and M. africanus.

7. Formulae for transmission indices based on infection rates in insect vectors are of little value unless there is confidence in specific identification.

8. A study of the infective larvae in Simulium neavei from an onchocerciasis area in Uganda has shown that not all the larvae are of human origin. A closer examination of the morphology of infective larvae in the vectors of filarial parasites of man in other areas will almost certainly show that the interpretation of infection rates may be complicated by the presence of infections of nonhuman origin.

9. Feeding experiments were carried out with Aedes pembaensis and Ac. aegypti on a donkey infected with Setaria equina; both of these mosquitoes proved to be suitable vectors of this filarial worm.

Outbred LACA mice were administered low (100 ova), medium (1000 ova), high (3000 ova) and trickle (4×250 ova) doses of Toxocara canis ova and the effect of infection was examined with respect to the number of larvae recovered from the brain and their behaviour. Recovery of larvae from the brain was generally low with the % recovery expressed in terms of the total dose administered being highest for the 3000 dose (6.1%) and 1000 dose (6%), followed by the 100 (4.4%) and trickle (3.5%) doses. The variation in larval recoveries was large between individual mice receiving similar doses. The level of infection in the brain was lower in mice receiving a multiple as opposed to an equivalent single dose of ova. Mice were then divided into three larval intensity groupings based upon the number of larvae recovered from their brain. The ranges for the groups were as follows: low intensity group, 0–15 larvae; moderate intensity group, 27–55 larvae; high intensity group, 66–557 larvae. Three behavioural tests were carried out on control and infected mice. Exploration and response to novelty was examined using a ‘T’ maze and learning was investigated by means of a water-finding task. Anxiety was measured using an elevated plus maze apparatus. Infected mice were less explorative and less responsive to novelty in the ‘T’ maze and this was particularly pronounced for the heavily infected mice. In the elevated plus maze, infected mice displayed reduced levels of anxiety to aversive and exposed areas of the maze, particularly in the case of the moderate and high intensity mice. There was evidence for impaired learning ability in the water task apparatus for moderate and high intensity mice. In general, the effects of infection on behaviour were more pronounced in the moderate and high intensity groups compared to the low intensity group.

Anisakid nematodes belonging to the Anisakis simplex complex are highly prevalent in several fish species off the coast of Portugal and are an important zoonotic problem in the Iberian Peninsula. Two reproductively isolated sibling species of the Anisakis simplex complex were identified from Pleuronectiformes inhabiting the Portuguese coast using restriction fragment length polymorphism (RFLP). Recombinant genotypes corresponding to presumptive Anisakis simplex sensu stricto and Anisakis pegreffii hybrids were also detected by this technique, as well as the species Anisakis typica. Although 25 species of Pleuronectiformes were investigated, Anisakis spp. larvae were only found in seven: Arnoglossus imperialis, Arnoglossus laterna, Lepidorhombus boscii, Citharus linguatula, Platichthys flesus, Dicologlossa cuneata and Solea senegalensis. The occurrence of hybrids in relatively sedentary fishes such as the Pleuronectiformes suggests that the Portuguese coast may constitute an area of hybridization and, therefore, is of particular interest for the study of the process of hybridization and speciation for these anisakids.

A consistent and reproducible method is described for isolating pure populations of microfilariae of Litomosoides carinii, Brugia pahangi, B. malayi and Dipetalonema viteae, free of cells, from blood, by density gradient centrifugation on Percoll in 0.25M sucrose. The recovery of the microfilariae was 85 to 97%.

Under conditions of pollution both host and parasite are susceptible to the pathogenic effects of toxicants, which in turn may result in detrimental changes to their immunological and physiological processes. Digenetic trematodes, which encompass species of both medical and economic importance, possess complex life cycles and are common parasites of both vertebrates and molluscs. The combined stress induced by pollution and parasitism influences the physiology of the host which can have implications not only on host survival but also on the functional biology of resident parasite populations. The present paper reviews the effects of pollutants on the immunology and physiology in both vertebrate and molluscan host–trematode systems and the implications for parasite transmission.

In the present paper, recent results obtained on the use of different distributions observed in larval species of Anisakis, genetically identified by means of allozyme markers, for stock characterization of demersal (Merluccius merluccius), small (Trachurus trachurus) and large pelagic (Xiphias gladius) finfish species in European waters, are reviewed and discussed. Several species of Anisakis were identified in the three fish hosts: A. simplex (s.s.), A. physeteris, A. typica, A. ziphidarum,A. pegreffii, A. brevispiculata and A. paggiae. Canonical discriminant analysis performed on all the samples of the three fish species collected in areas comprising their geographical range, according to the different species of Anisakis identified, showed distinct fish populations in European waters. In all the three fish hosts, the pattern of distribution of Anisakis larvae allowed discrimination of Mediterranean stocks from Atlantic stocks. In the case of swordfish, the possible existence of a southern Atlantic stock separated from a northern one is also suggested. Congruence and discordance with the population genetic data inferred from allozyme markers on the same samples of the three fish species are also discussed.

1. 8515 specimens of the common periwinkle, Littorina littorea (L.), from four localities on the North Yorkshire coast were examined for larval Digenea during 1966 and 1907. Four species were found, namely Cryptocotyle lingua (Creplin, 1825), Himasthla leptosoma (Creplin, 1829), Cercaria lebouri Stunkard, 1932 and Cercaria A, the incidence of infection with which correlated with the presence of sea bird and wader final hosts.

2. 5878 of all L. littorea examined were from one locality of relatively high incidence of infection where there were seasonal changes in incidence, being greatest during the autumn and early winter and least during the summer. The incidence of infection was higher in larger than in smaller periwinkles except in infections with an unidentified species, named Cercaria A, where the incidence declined sharply in L. littorea above 25 mm shell length. The ecology of the infections is discussed.

Seven geographically varied isolates of Strongyloides ratti were cloned. Each clone was examined for the degree of homogonic development of the free-living generation and by enzyme electrophoresis. Considerable variation was found between the clones in the degree of development that was homogonic. In Contrast, the clones were indistinguishable by enzyme electrophoresis.