Relatively few species of zoonotic parasites have been recorded in humans in Papua New Guinea. A greater number of potentially zoonotic species, mostly nematodes, occur in animals but are yet to be reported from humans. Protozoa is the best represented group of those infecting man, with Giardia duodenalis, Cryptosporidium parvum, Cyclospora cayetanesis, Toxoplasma gondii, Sarcocystis spp., Entamoeba polecki, Balantidium coli and, possibly, Blastocystis hominis. The only zoonotic helminths infecting humans include the trematode Paragonimus westermani, the cestodes Hymenolepis nana, H. diminuta and the sparganum larva of Spirometra erinacea, and the nematodes Trichinella papuae and Angiostrongylus cantonensis and, possibly, Ascaris suum. Other groups represented are Acanthocephala (Macracanthorhynchus hirudinaceus)), insects (Chrysomya bezziana, Cimex sp., Ctenocephalides spp.), and mites (Leptotrombidium spp. and, possibly Sarcoptes scabiei, and Demodex sp.). One leech (Phytobdella lineata) may also be considered as being zoonotic. The paucity of zoonotic parasite species can be attributed to long historical isolation of the island of New Guinea and its people, and the absence until recent times of large placental mammals other than pig and dog. Some zoonotic helminths have entered the country with recent importation of domestic animals, in spite of quarantine regulations, and a few more (two cestodes, one nematode and one tick) are poised to enter from neighbouring countries, given the opportunity. Improvement in water supplies, human hygiene and sanitation would reduce the prevalence of many of these parasites, and thorough cooking of meat would lessen the risk of infection by some others.

Genetic variability of the ovine parasite Haemonchus contortus from the Alpine area was investigated using mitochondrial DNA (nd4 gene), internal transcribed spacers 1 and 2 and microsatellites, in order to assess whether cross-transmission between domestic and wild ruminants occurs. The dataset was composed of 78 individual adult male H. contortus collected from chamois (Rupicapra r. rupicapra), roe deer (Capreolus capreolus), alpine ibex (Capra ibex ibex), domestic goat (Capra hircus) and sheep (Ovis aries) from different alpine areas. The data obtained show low host specificity and high genetic variation within H. contortus populations. The analyses indicate the presence of two mitochondrial haplotype clusters among host species and the absence of cryptic parasite species, confirming H. contortus as a generalist nematode and suggesting that parasite transmission between populations of domestic and wild ruminants normally occurs.

The use of parasites as biological tags in population studies of marine fish in the south-western Atlantic has proved to be a successful tool for discriminating stocks for all species to which it has been applied, namely: Scomber japonicus, Engraulis anchoita, Merluccius hubbsi and Cynoscion guatucupa, the latter studied on a broader geographic scale, including samples from Uruguayan and Brazilian waters. The distribution patterns of marine parasites are determined mainly by temperature–salinity profiles and by their association with specific masses of water. Analyses of distribution patterns of some parasite species in relation to gradients in environmental (oceanographic) conditions showed that latitudinal gradients in parasite distribution are common in the study area, and are probably directly related to water temperature. Indeed, temperature, which is a good predictor of latitudinal gradients of richness and diversity of species, shows a latitudinal pattern in south-western Atlantic coasts, decreasing southwards, due to the influence of subtropical and subantarctic marine currents flowing along the edge of the continental slope. This pattern also determines the distribution of zooplankton, with a characteristic specific composition in different water masses. The gradient in the distribution of parasites determines differential compositions of their communities at different latitudes, which makes possible the identification of different stocks of their fish hosts. Other features of the host–parasite systems contributing to the success of the parasitological method are: (1) parasites identified as good biological tags (i.e. anisakids) are widely distributed in the local fauna; (2) many of these species show low specificity and use paratenic hosts; and (3) the structure of parasite communities are, to a certain degree, predictable in time and space.

Sixty-eight red foxes were collected from the metropolitan area of Copenhagen and examined for helminth infections. Standard faecal flotations for intestinal parasites gave the following results: Strongyle eggs (75.0%), Capillaria eggs (36.8%), Toxocara eggs (23.5%), Taenia eggs (1.5%), and coccidia oocysts (2.9%). Gastrointestinal helminths were collected from 21 of the 68 foxes with the following specimens found: Uncinaria stenocephala (85.7%), Toxocara canis (81.0%), Taenia spp. (38.1%), Mesocestoides lineatus (23.8%) and Polymorphus spp. (9.5%). Faeces of 39 foxes were examined by the Baermann method for larvae of cardiopulmonary worms with 20 foxes (51.3%) being infected. Fourteen foxes (35.9%) were infected with Angiostrongylus vasorum, 11 (28.2%) were infected with Crenosoma vulpis, and 5 foxes (12.8%) were infected with both species. Muscle digestion of diaphragms from the 68 foxes indicated that none harboured larvae of Trichinella spiralis.

Schistosoma haematobium and S. bovis are widespread schistosome species causing human and cattle schistosomiasis, respectively, in Africa. The sympatric occurrence of these two species and their ability to infect the same Bulinus intermediate snail hosts necessitates precise methods of identification of the larval stages. A rapid diagnostic ‘mulitplex’ one-step polymerase chain reaction protocol (RD-PCR) was developed using cytochrome oxidase subunit 1 (COX1) mitochondrial DNA (mtDNA) to discriminate between S. haematobium and S. bovis. A single forward primer and two species-specific reverse primers were used to produce a polymerase chain reaction (PCR) fragment of 306 bp and 543 bp for S. bovis and S. haematobium, respectively. Serial dilutions were carried out on various lifecycle stages and species combinations to test the sensitivity and specificity of the primers. This RD-PCR proved highly sensitive, detecting a single larval stage and as little as 0.78 ng of genomic DNA (gDNA) from an adult schistosome, providing a cost-effective, rapid and robust molecular tool for high-throughput screening of S. haematobium and S. bovis populations. In areas where human and cattle schistosomiasis overlap and are transmitted in close proximity, this mitochondrial assay will be a valuable identification tool for epidemiological studies, especially when used in conjunction with other nuclear diagnostic markers.

The details of the post-embryonic development of Echinorhynchus truttae in the intermediate host, Gammarus pulex, and the final host, Salmo truttae, are described.

The cystacanths of this species are sexually mature and are formed about 82 days after infection at room temperature, ca. 17°C.

Copulation takes place in the definitive host soon after the worms enter the pyloric region of the intestine. About 10 weeks after infection, mature eggs are passed out with the faeces of fish.

1. Observations on Fasciola hepatica in Limnaea truncatula under laboratory conditions showed that the cercariae did not emerge at temperatures below 9°C. Above 9°C. emergence proceeded indiscriminately up to the limit of experimental observation (26°C).

2. Experience showed that emergence occurred in the light or in darkness while changes in the hydrogen-ion concentration of the water containing the snails (within the range 5.5 to 8.5) had no effect on emergence. There was some evidence that an increase of carbondioxide in the water slowed but did not inhibit emergence but depletion of oxygen had no apparent effect.

3. In the laboratory, emergence could be induced by removing snails from dry habitats and immersing them in water or by removing snails from watery habitats and placing them in fresh water. We were unable to determine the exact physical.or chemical factors acting as a stimulus under such conditions.

This paper describes some hitherto unrecorded aspects of trematode development in a molluscan host.

It is shown that the rate of development of Fasciola hepatica in its host Limnaea truncatula is influenced not only by temperature but by the amount of food assimilated by the snail and by the number of rediae which are in competition within a single host.

The most rapid development of the parasite will occur in hosts which have access to ample supplies of food and in which moderate numbers of rediae become established. At laboratory temperatures, infection with a single miracidium rarely leads to the establishment of more than 40 rediae, a number which is apparently adjusted to the economy of the host, since it allows development at a maximum rate.

1. The recovery of nearly 400 specimens of Fasciola hepatica from experimental infections of the mouse, representing 20 stages covering the period from the first day of infection to maturity at 37 days, has made possible for the first time a study of growth and maturation. Flukes have reached the bile duct on the 32nd day of infection, and in two instances reached this final location on the 29th and 24th days.

The use of worm egg counts for observational and experimental purposes in naturally infested sheep has become very popular since Whitlock and Gordon (1989) introduced the simple and efficient McMaster slide technique. When using a dilution technique such as this, the accuracy of the count increases as more eggs are counted. In order to count more eggs when using the McMaster slide it is usually more convenient, in practice, to take more samples (i.e. count more cells) than to alter the dilution. It is therefore desirable to know the optimum number of samples which should be counted for each sheep when comparing the counts of naturally infested sheep. The usefulness of sampling on one or more days is another problem concerning experiments of this nature.

Serology (ELISA and immunoblot) using native glycoproteins, affinity purified glycoproteins, and a recombinant antigen is known to be highly specific to Taenia solium cysticercosis in humans and pigs. These techniques were applied for dogs in the highly endemic area of cysticercosis in Papua (Irian Jaya), Indonesia. Analysis of dog sera by both ELISA and immunoblot revealed 7 of 64 dogs were highly positive. Examination of two sero-positive dogs revealed cysticerci of T. solium in the brain and heart of these dogs. Mitochondrial DNA analysis confirmed that they were the same as T. solium previously confirmed from pigs and biopsies from local people from Irian Jaya. It is suggested that the life cycle of T. solium may be completed not only between humans and pigs but also between humans and dogs.

Cystic echinococcosis (CE) caused by Echinococcus granulosus sensu lato (s.l.) is a significant zoonosis, especially in developing countries of the Middle East, with many studies focusing on CE genotypes in Iran. We performed a systematic review to determine the exact status of E. granulosus genotypes in the country. We explored English (Pubmed, Scopus, ISI Web of Science and Science Direct) and Persian (Magiran, Iran Medex and Scientific Information Database) databases along with Google Scholar. Our review included 73 studies published prior to the end of 2015. In total, 2952 animal (intermediate and definitive) hosts were examined, and the prevalent genotypes comprised G1 (92.75%) and G6 (4.53%) in sheep, cattle, camels, goats and buffaloes; G3 (2.43%) in five herbivore hosts and dogs; G7 (0.2%) in sheep and goats; and G2 (0.06%) in dogs. G1 was mostly dominant in West Azerbaijan, whereas G3 and G6 were identified most frequently in the provinces of Isfahan and Fars, respectively. Regarding human CE infection, 340 cases were reported from Iran, with the identified genotypes G1 (n = 320), G6 (n = 13) and G3 (n = 7). Most CE-infected humans originated from Isfahan province (168 cases), whereas the lowest number of infected persons was noted in Kerman province (two cases). The information obtained from this systematic review is central to better understanding the biological and epidemiological characteristics of E. granulosus s.l. genotypes in Iran, leading to more comprehensive control strategies.

Among Biomphalaria glabrata/Schistosoma mansoni snail–trematode combinations, it appears that some parasites succeed whilst others fail to infect snails. Snails that become infected are termed susceptible hosts. Those which are not infected are traditionally determined as ‘resistant’. Here the concept of B. glabrata resistance to S. mansoni is re-examined in the light of additional observations. It is suggested that, in B. glabrata/S. mansoni, compatibility is tested independently for each individual miracidium and host, and that the success or failure of an infection does not depend on the snail susceptibility/resistance status, but on the ‘matched’ or ‘mismatched’ status of the host and parasite phenotypes.

Knowledge of the morphological phenotypes of the liver fluke Fasciola hepatica (Trematoda: Digenea) is analysed. The influence of parasite age on its dimensions, the adult fluke growth model, variation in a biometric variable versus time, and variation in a biometric variable versus another biometric variable (allometric model) are revised. The most useful allometric model appears to be (y2m]#x2212;y2)/y2=c [(y1m−y1)/y1]b, where y1=body area or body length, y2=one of the measurements analysed, y1m, y2m=maximum values towards which y1 and y2, respectively, tend, and c, b=constants. A method based on material standardization, the measurement proposal and allometric analysis is detailed. A computer image analysis system (CIAS), which includes a colour video-camera connected to a stereomicroscope (for adult studies) and a microscope (for egg studies), facilitates the processing of digital imaging. Examples of its application for the analysis of the influence of different factors on the liver fluke phenotype are shown using material from the Northern Bolivian Altiplano, where human and domestic animal fascioliasis is caused by F. hepatica only. Comparisons between the development of livestock fluke populations from highlands and lowlands are discussed and the relationships between host species and liver fluke morphometric patterns is analysed.

Six transformation techniques ((i) incubation of cercariae in isotonic; medium; (ii) penetration of isolated skin; (iii) stimulation with crude egg lecithin; (iy) mechanical disruption by passage through a syringe and 21 gauge needle; (v) by whorling of cercariae with a vortex mixer; (vi) syringe transformation followed by incubation) were evaluated. The organisms produced were assessed for infectivity for mice by 6 different routes of infection (percutaneous, intradermal, subcutaneous, intra-peritoneal, intravenous and intramuscular). At perfusion the largest numbers of adult worms were recovered from mice injected intramuscularly with organisms produced by the syringe technique and control mice given cercariae percutaneously. The peak for migration of schistosomula (following syringe transformation and intramuscular injection) through the lungs and the appearance of adult worms in the mesenteries was shown to be similar to cercariae administered percutaneously.

Biological control of parasitic nematodes of domestic animals can be achieved by feeding host animals chlamydospores of the nematode-trapping fungus Duddingtonia flagrans. In the host faeces, D. flagrans develop traps that may catch nematode larvae. In experiments on agar, D. flagrans had a growth rate between 15 and 60 mm/week at temperatures between 20 and 30°C. The presence of nematodes induces the fungus to produce traps. The rate of trap formation in D. flagrans has an optimum at 30°C, producing 700–800 traps/cm2/2 days, when induced by 20 nematodes/cm2 on agar. Approaching 10 and 35°C the ability to produce traps is gradually reduced. The response of chlamydospore production on agar to changes in temperature is the same as that for trap formation. On agar, at 10, 20 and 30°C D. flagrans loses its trap inducibility after 2–3 weeks. During the ageing process, increasing numbers of chlamydospores are produced up to a certain limit. The time for reaching maximum chlamydospore concentration coincided with the time for loss of induction potential. The implications of these results in relation to biological control in faeces are discussed.

Initial clinical trials using Trichuris suis eggs (TSO) in autoimmune diseases such as inflammatory bowel disease, revealed a striking suppressive effect on the autoimmune response. Here, we analysed the effect of TSO therapy on the course of multiple sclerosis (MS), as a Th1/Th17-associated autoimmune disease. Different immunological parameters in four patients with secondary progressive MS were surveyed during a 6-month therapy with TSO, focusing on the modulation of T-cell Th1–Th2 balance as well as on the innate immune response. We are able to show a slight downregulation of the Th1-associated cytokine pattern, especially relevant in interleukin (IL)-2 (P < 0.05 after 2 months of therapy), with a temporary increase of Th2-associated cytokines such as IL-4. Furthermore, mild eosinophily and changes in CD4+ and CD8+T cells and natural killer (NK) CD56 bright cell numbers were observed. The findings observed in this group of patients suggest that TSO therapy has a moderate immunomodulatory impact in MS.

Irradiated cercariae, irradiated schistosomula, or hcterologous infections were used to vaccinate sheep against Schistosoma mattheei infection. In the first experiment four doses of I04 S. mattheei cercariae irradiated at 6Kr were administered to sheep by percutaneous infection at 4 week intervals. This induced a 74% reduction in a challenge infection compared to control sheep while only 13% protection was achieved in a third group of sheep immunised with normal cercariae of the heterologous parasite S. mansoni. No significant differences were seen in histopathology of the liver of any of the sheep but the pathological changes were more severe in the large and small intestines of sheep vaccinated with the heterologous parasite. In the second experiment with irradiated cercariae only one or two immunising exposures were used. The degree of protection in the adult worm load (9–11%) was not significant and no significant differences were noticed in the pathology of the vaccinated and control animals. In the third experiment four doses of irradiated organisms were used to vaccinate five groups of sheep: 3Kr or 6Kr cercariae were administered by percutaneous infection; 6Kr skin-transformed scbistosomula were administered by intramuscular injection; the same 6Kr skin-transformed schistosomula were given by intravenous injection and 6Kr syringe transformed schistosomula were administered by intramuscular injection. The degree of protection (determined as the reduction in worm burden) achieved by these different procedures was respectively 72%, 61%, 77%, 56% and 78%. These results indicate the possibility of making a live vaccine against ovine schistosomiasis and show that effective immunisation is not dependent on the presence of a mature worm infection or on cercarial penetration of the skin by the immunising infection.

1. The number and duration of free-living and parasitic stages of N. dubius has been determined.

2. The results have been discussed in relation to previous accounts of the life cycle, and some of the discrepancies explained.