Triploid, parthenogenetic forms of the lungfluke, Paragonimus westermani, occur in Japan, Korea and China. The origin(s) of triploidy has been debated over the years. Sequences of two regions in the mitochondrial DNA, i.e. partial lrRNA (16S), and a portion of the non-coding region, were obtained from natural populations of P. westermani. All triploid individuals (Japan, Korea, China) and a single tetraploid individual (China) had identical sequences in the 16S region studied. Some sequence variation was observed among diploids, with those from Taiwan being distinct from the remainder. Both neighbour joining and parsimony trees using the 16S region placed diploid individuals from southwestern Japan close to the triploids and the tetraploid. The fragment amplified from the mitochondrial non-coding region showed dimorphism. One form (type A) consisted of 239bp comprising two identical tracts of 70bp separated by a tract of 93bp. The second form (Type B) consisted of only a single 70bp tract. All diploid individuals from Taiwan, China and Korea possessed type A, while those from Japan were polymorphic; individuals from Oita and Hyogo had type B, those from Chiba had type A, but both types were found in Mie. On the other hand, all of the triploid individuals and two tetraploid individuals possessed type B. Both the form present in the non-coding region and the 16S sequence suggest an affinity between a south-eastern group of diploid populations in Japan and the triploid form. A possible mechanism responsible for the origin of the triploid is discussed.

The effect of ageing of adults of Echinostoma friedi (Trematoda: Echinostomatidae) on the infectivity of miracidia yielded was analysed. Miracidia were obtained after hatching of eggs obtained from adult worms of E. friedi collected weekly during the course of experimental infections in golden hamsters. Miracidial infectivity, measured in terms of percentage of infection in Lymnaea peregra, was significantly influenced by the age of the adult worms from which the miracidia were derived. Infective miracidia only were obtained from adult worms in the age range from 4 to 9 weeks post-infection. Infectivity was maximal in those miracidia derived from adults collected 8 and 9 weeks post-infection. The results suggest that adult worms producing viable eggs require additional maturation to be able to yield eggs containing infective miracidia.

A unique human case of alveolar echinococcosis was described in 1979 from the Klatovy district of the Czech Republic. However, there were no previous epidemiological studies in this area focusing on detection of the source of infection – Echinococcus multilocularis adults producing eggs. During the period June 1997 to April 1999, 29 out of a total of 46 (63.3%) red foxes (Vulpes vulpes) in the Klatovy district and one of four foxes (25.0%) in the Pilsen South district were found to be infected with adult worms of E. multilocularis. No E. multilocularis adults were found in other animals from the Klatovy district (i.e. three specimens of Martes martes, two Martes foina, one Mustela erminea, two Meles meles and one Felis catus f. domestica). An examination of faecal samples from 55 dogs (Canis familiaris) from the Klatovy district resulted in the detection of E. multilocularis DNA in one (1.8%) sample. The present results support the possibility that human alveolar echinococcosis previously described in the Czech Republic had the character of an autochthonous infection. There are also indications of a potential risk of infection to humans.

Host responses to primary infections with Heligmosomoides polygyrus were studied in fast responding FVB mice (H-2q). Pathological changes in the intestinal mucosa, mesenteric lymph nodes and spleen were examined. Features of the fast response were typical: low effectiveness of infection and limiting of parasite survival and egg production, with worm expulsion occurring about 60 days post-infection. The intestinal inflammatory response involved infiltration by different cells into the intestinal mucosa and granulomata formation. As is typical for intestinal nematode infection enteropathy, decreased villus:crypt ratio and hyperplasia of goblet and Paneth cells were also present. Reactions of the intestinal mucosa, mesenteric lymph nodes and spleen increased over time post-infection and after worm expulsion. Enteropathy may help worm expulsion by creating an unfavourable environment for H. polygyrus. The implications of these findings and the potential role of intestinal intraepithelial lymphocytes in the pathogenesis of generated lesions are discussed.

This article presents a short simulation active-learning exercise that can be used in political science undergraduate and postgraduate environmental politics courses to introduce and teach the subject of environmental activism. The exercise, which asks students to role play as determined environmental activists, draws on an analytical framework from Diani and Donati (1999) that provides a typology of nonpartisan political organizations. This “learning through typology” allows students to prioritize critical analysis while engaging with the subject matter in a creative and enjoyable way. The article provides the full process of the exercise, from the grounding in the framework and provision of contextual examples, to the running of the simulation, and finally to the presentation of students’ work and a group debriefing session. This exercise therefore adds to the growing use of simulations and active learning in the increasingly prominent field of environmental politics.

Rapid freezing and substitution with fixative prior to scanning electron microscopy was used to demonstrate the pattern of beat and recovery of the cilia of free swimming miracidia of Fasciola hepatica. There were stages of dexioplectic metachronal co-ordination and the power stroke was approximately 15° anticlockwise from the anterior–posterior axis. Around the circumference of the body of the miracidia there were approximately 12 metachronal waves of power and recovery. Free-swimming cercariae were recorded by time-lapse photography and, after conventional fixation, by scanning electron microscopy. Cercarial tail-beats were to the posterior of the body in the lateral plane at a rate of 8 Hz. The tail has paired lateral ridges positioned to act as leading edges. There is an array of 32 sensory papillae on the mid-ventral surface of the tail. The tegument of the most distal part of the tail is described: it is free of sensory endings and the surface shows a spiral pattern.

The in vitro effects of ethanol and aqueous extracts of the medicinal plant Cardiospermum halicacabum on adult worms and microfilariae of Brugia pahangi were investigated. With or without the plant extracts in culture medium, the motility of adult worms, microfilariae and microfilarial release from female worms were monitored daily. After 7 days of culture, viability or tissue damage of adult worms was assessed using the MTT assay. At > 500 μg ml-1, the aqueous extract significantly reduced motility of adult females after 24 h of exposure and adult males after 3 days. The aqueous extract, at > 500 μg ml-1, also significantly reduced microfilarial release from female worms, starting on day 2. The reduction in the motility of adult worms and the pattern of microfilarial release from female worms were concentration and time dependent. The MTT assay results revealed that adult worms cultured in the presence of aqueous extracts at > 500 μg ml-1 were damaged. However, the aqueous extract did not affect the motility of microfilariae with the exception of those in higher concentration extracts. Higher concentrations of ethanol extracts (2 mg ml-1) inhibited both the motility of adult worms and the release of microfilariae from females. Little effect of ethanol extracts was detected by the MTT assay, as only slight damage was caused to worms exposed only to the highest concentration (2 mg ml-1). However, ethanol extract at 500 μg ml-1 rapidly reduced the motility of microfilariae on day 2. The present study revealed that an aqueous extract of C. halicacabum has mild but definite direct macrofilaricidal action on B. pahangi.

Quantities of trace elements including copper, zinc, cobalt, manganese and iron were investigated in the liver tissue of rats at the acute or chronic stages of fascioliasis following treatment with zinc-copper hydroxochloride mixed crystals. Oral dosing (with food) of zinc–copper mixed crystals to healthy rats increased zinc and copper levels in the liver and decreased the iron content compared with controls. Manganese and cobalt levels did not change significantly. Significant reductions in all trace elements except manganese occurred in the liver of rats with acute or chronic fascioliasis. Manganese levels were slightly increased in rats at the acute stage and slightly decreased in rats at the chronic stage of fascioliasis. The application of mixed zinc–copper crystals at the acute or chronic stages of fascioliasis lead to a restoration of zinc and copper levels and a slight reduction in the iron levels in liver tissue of rats. The beneficial effects of applied salts were more apparent in rats chronically infected with Fasciola hepatica.

The parasitic fauna of two fish species, namely gill-netted samples of 652 Oreochromis leucostictus and 448 Tilapia zillii from Lake Naivasha and Oloidien Bay was investigated during the period from the end of October 1995 to September 1996. Five larval helminth parasites were recovered including the nematode, Contracaecum sp., the acanthocephalan Polyacanthorhynchus kenyensis, the digenetic trematode, Clinostomum sp. and two cestodes, Amirthalingamia sp. and Cyclustera sp. Both prevalence and intensity of the infection of these helminths increased in larger sized fish, whereas male fish were more heavily infected than females. No seasonality in infection level were observed. The health status of both fish species remained unaffected, although O. leucostictus from Oloidien Bay which harboured heavy infections of Contracaecum exhibited stuntedness and the lack of fatty deposits around the digestive caecum.

The lung fluke, Paragonimus westermani (Kerbert, 1878), is widely distributed in Asia, and exhibits much variation in its biological properties. Previous phylogenetic studies using DNA sequences have demonstrated that samples from north-east Asia form a tight group distinct from samples from south Asia (Philippines, Thailand, Malaysia). Among countries from the latter region, considerable molecular diversity was observed. This was investigated further using additional DNA sequences (partial mitochondrial cytochrome c oxidase subunit 1 (COI) and the second internal transcribed spacer of the nuclear ribosomal gene repeat (ITS2)) from additional samples of P. westermani. Phylogenies inferred from these again found three or four groups within P. westermani, depending on the method of analysis. Populations of P. westermani from north-east Asia use snail hosts of the family Pleuroceridae and differ in other biological properties from populations in south Asia (that use snail hosts of the family Thiaridae). It is considered that the populations we sampled can be divided into two species, one in north-east Asia and the other in south Asia.

In Great Britain free-living common pheasants Phasianus colchicus are often managed at high densities owing to their popularity as a quarry species. They are prone to infection by a range of parasite species including Heterakis gallinarum, Capillaria spp. and Syngamus trachea. In 1995 the efficacy of an indirect anthelmintic technique for controlling parasitic worm burdens of pheasants was determined in a pilot study on a shooting estate in the south of England. Between 2000 and 2003 a large-scale field experiment was conducted on nine estates in eastern England to determine the effect of the technique on parasite burden and pheasant breeding success. In the absence of anthelmintic treatment worm burdens increased rapidly through March and April, whereas birds given anthelmintic-treated grain had lower worm burdens during the same period. The breeding success of pheasants was significantly higher on plots provided with anthelmintic treatment, although no long-term increases in population densities were observed. The burdens of the most common parasite H. gallinarum were significantly lower in pheasants from treatment plots six weeks after the anthelmintic treatment had ceased, but spring treatment did not influence parasite burden in the following winter.

This research offers an adaptive model-based methodology for autonomous control of 3-RRR spherical parallel manipulator (RSPM) based on a novel modeling framework. RSPM is an overconstrained parallel mechanism that has a variety of applications in medical procedures such as ankle rehabilitation because of its precision and accuracy. However, obtaining a complete explicit dynamic model of these mechanisms for tracking purposes has been a problematic challenge due to their inherent singularities, coupling effects of the limbs, and redundant constraints imposed by the intermediate joints. This paper presents a novel algorithm to obtain the analytical kinematic solutions of RSPMs based on the closed-loop vector method, which includes constraint analysis. By incorporating constrained kinematics into the dynamic model, a comprehensive explicit dynamic solution of the non-overconstrained version 3-RCC of RSPM is developed in task space, based on screw theory and the linear homogeneous property of algebraic equations on the manipulator twist. Based on the proposed computational framework, a robust self-tuning backstepping control (STBC) strategy is applied to the robot to overcome the effect of external disturbances and time-varying uncertainties. Furthermore, an observer-based compensation (OBC) method is presented for dealing with the nonlinear hysteresis loops of the ankle during trajectory tracking purposes. The closed-loop stability of the whole system including STBC and OBC is theoretically performed by Lyapunov methods. The proposed methodologies are validated by realistic co-simulations in different scenarios. For instant, in the presence of external disturbances, the maximum tracking error norm of STBC is 37.5% less than the sliding mode approach.

The validity and reliability of haematuria when used as screening criteria in community diagnosis of urinary schistosomiasis is presented. Between May and July, 1998, 1173 persons were screened for haematuria and examined for the presence of eggs of Schistosoma haematobium in their urine from all participating households in the Ozitem area of Bende Local Government Area, Abia State, Nigeria. Haematuria showed a sensitivity rate of 41.0% and specificity of 82.0% when used to identify cases of urinary schistosomiasis. Some factors that influenced the validity of haematuria as a diagnostic criterion are discussed. The use of haematuria amongst subjects in the first twenty years of their life is recommended.

Although Toxocara canis, an important pathogen of ocular disease, tends to migrate to the eye, the precise migratory route has yet to be determined experimentally. Mongolian gerbils, Meriones unguiculatus, known as a useful animal model for human toxocariasis, were used to investigate the migration route toward the eyes. Infective larvae of T. canis were directly inoculated into the intracranial region. Haemorrhagic lesions or larvae were observed in 56.3% of cases. Histopathologically, a larva was observed in the optic nerve of gerbils 6 days after inoculation, and two larvae were found in the optic chiasma in the gerbils having a haemorrhage in the retina 9 days after inoculation. These results indicate that T. canis migrates from the brain to the eye through the optic nerve. Considering these data and previous studies showing that the ocular changes appear as early as 3 days of infection in the oral-administrated gerbils, there are two phases in the migration to the retina: a haematogenous early phase and an optic nerve route late phase.

Gastrointestinal helminths were collected from pademelons of the genus Thylogale (Marsupialia: Macropodidae) in eastern Australia and Papua New Guinea. Examined were 12 Thylogale stigmatica stigmatica and 13 T. s. wilcoxi, the latter subdivided into eight specimens from the northern limit of their distribution and five from southern areas, all from eastern Queensland, Australia, one T. s. oriomo from Papua New Guinea and ten T. thetis from southeastern Queensland and northern New South Wales, Australia. Six species of cestodes and 40 species of nematodes were found. The helminth community of T. s. stigmatica was similar to that found in northern specimens of T. s. wilcoxi, while differences from the helminth community present in southern T. s. wilcoxi could be accounted for by parasites acquired from sympatric T. thetis. Thylogale thetis harboured a community of helminths distinct from but related to that in T. stigmatica. The evidence suggests that all subspecies of T. stigmatica examined share a common helminth community, but that in areas of sympatry, T. stigmatica and T. thetis share some of their parasites.

During the summer and autumn of 1994, 1995 and 1996, 406 juvenile herring caught off the Swedish west coast were examined for parasites. Amongst those found was the digenean Pseudobacciger harengulae, which represents new host and locality records for this parasite. Pseudobacciger harengulae has been reported from several species of clupeiformes, mostly from tropical and temperate regions of the Atlantic, Pacific and Indian Oceans. The morphology of P. harengulae is described and compared with earlier descriptions of P. harengulae and P. manteri. The possible relationships between P. harengulae and P. manteri are discussed and the validity of the P. manteri is questioned. Most of the specimens (75%) of P. harengulae were found in the pyloric caeca and the remainder (25%) in the intestine.

Levels of parasitism and the dynamics of helminth systems is subject to the impact of environmental conditions such that we may expect long term increases in temperature will increase the force of infection and the parasite's basic reproduction number, R0. We postulate that an increase in the force of infection will only lead to an increase in mean intensity of adults when adult parasite mortality is not determined by acquired immunity. Preliminary examination of long term trends of parasites of rabbits and grouse confirm these predictions. Parasite development rate increases with temperature and while laboratory studies indicate this is linear some recent studies indicate that this may be non-linear and would have an important impact on R0. Warming would also reduce the selective pressure for the development of arrestment and this would increase R0 so that in systems like the grouse and Trichostrongylus tenuis this would increase the instability and lead to larger disease outbreaks. Extreme climatic events that act across populations appear important in synchronizing transmission and disease outbreaks, so it is speculated that climate disruption will lead to increased frequency and intensity of disease outbreaks in parasite populations not regulated by acquired immunity.

Almost everyone believes that freedom from deprivation should have significant weight in specifying what justice between generations requires. Some theorists hold that it should always trump other distributive concerns. Other theorists hold that it should have some but not lexical priority. I argue instead that freedom from deprivation should have lexical priority in some cases, yet weighted priority in others. More specifically, I defend semi-strong sufficientarianism. This view posits a deprivation threshold at which people are free from deprivation, and an affluence threshold at which people can live an affluent life, even though their lives may be even further improved beyond that point. I argue that freedom from deprivation in one generation lexically outweighs providing affluence in another generation; in all other cases, freedom from deprivation does not have lexical priority.