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.

Bimiracidial infections of Galba truncatula with Fasciola hepatica were carried out to determine the effect of food quality on the frequency of 1- and 2-sporocyst infections, to analyse its impact on the developmental patterns (normal, or abnormal) of redial generations, and to verify its consequences on cercarial production. These investigations were performed in snails reared at 20°C and provided with cos lettuce and commercial fish food (Tetraphyll®) as a food source until their death. Double-sporocyst infections with normal development of redial generations were recorded in 43.9% of infected snails (out of 296). Single-sporocyst infections were noted in the other snails, with normal development of generations in 53.7% and abnormal development (the first mother redia early degenerated) in 2.4%. Four successive redial generations were found in long-surviving snails (more than 90 days). In both 1- and 2-sporocyst infections, showing normal development of generations, the daughter rediae, which exited from the first mother redia (R2a rediae), constituted the greater group of free rediae and produced the highest percentages of cercariae (46.2–48.2%). However, the development of these rediae inside the snail body was slower in 2-sporocyst infections than in 1-sporocyst infections. The numbers of rediae noted in subsequent generations (R2b/R3a and R3b/R4a rediae) were similar, whatever the number of full-grown sporocysts. The number of shed cercariae recorded in the 1- and 2-sporocyst infections did not significantly differ. When long-surviving snails died, 19.8–20.7% of cercariae produced by free rediae (essentially by R2b/R3a and R3b/R4a rediae) were still present in their bodies. The increased frequency of 2-sporocyst infections demonstrated that food quality had a significant effect on the redial burden of F. hepatica developing inside G. truncatula.

The IgG3 antibody responses to carbohydrate epitopes were compared in BALB/c mice infected or immunized with six species of Trichinella: T. spiralis (T1), T. nativa (T2), T. britovi (T3), T6, T. nelsoni (T7), and T8. The dynamics of IgG3 responses and antigen recognition following infection or immunization were measured by ELISA and Western blot respectively, using glycosylated and deglycosylated larval crude extracts (LCE) prepared from homologous isolates. A high degree of protein glycosylation was found in all species and with similar profiles. Deglycosylation was completely achieved only in LCE from T1 and T6 isolates. The dynamics of IgG3 responses following infection or immunization significantly differed whereas the antigen recognition profiles appeared similar. Variations in the levels and antigen recognition patterns of IgG3 among the different species were apparent. The highest IgG3 levels were recorded in infections by the T8 isolate and the lowest in infections by the T6 isolate, whereas for immunization the highest IgG3 response was induced by T7 and the lowest by T8. Following antigen deglycosylation, the IgG3 responses were significantly reduced or abrogated and the recognition patterns markedly modified or suppressed in the different species of Trichinella.

Investigations undertaken on the monogeneans of amphibians in Nigeria have shown that host ecology has an influence on the distribution of these monogeneans. Amphibians from humid environments of the rainforest, a freshwater swamp and mangrove harboured no monogeneans, whereas those occurring in drier conditions in the savannah-mosaic and guinea savannah yielded five species of polystomatid parasites: Polystoma prudhoei from Bufo regularis, Polystoma galamensis from Rana galamensis, Eupolystoma alluaudi from Bufo regularis and Bufo maculatus, and two unidentified Polystoma species from Bufo regularis and Ptychadena oxyrynchus, respectively. Some of these monogeneans appear to have reproduction cycles which are synchronized with those of the hosts. The prevalence of E. alluaudi in Bufo spp. caught in New Bussa (68.4% in B. regularis and 82.3% in B. maculatus) were higher than those reported for this parasite in other locations in West Africa and for Eupolystoma anterorchis in Bufo pardalis from the Cape Flats of South Africa.

The ultrastructure of spermiogenesis and the mature spermatozoon in Catenotaenia pusilla (Cestoda: Catenotaeniidae) is described. Spermiogenesis is characterized by the presence of a single axoneme which grows on the outside of a cytoplasmic extension at an angle of 45°. Flagellar rotation and proximodistal fusion are produced in this process. The centrioles lack striated roots and an intercentriolar body. In the mature spermatozoon four different regions are described. The anterior extremity is capped by an apical cone and presents two helical crest-like bodies of unequal length. The axoneme, of the 9 + ‘1’ pattern of the Trepaxonemata, presents a periaxonemal sheath. The cortical microtubules form a spiral pattern at an angle of about 40° to the hypothetical spermatozoon axis. The nucleus is kidney- to horseshoe-shaped in cross section. Granules and proteinaceus walls are not observed in the spermatozoon of C. pusilla.

Over the past decades, various free-living animals (hosts) and their parasites have invaded recipient areas in which they had not previously occurred, thus gaining the status of aliens or exotics. In general this happened to a low extent for hundreds of years. With variable frequency, invasions have been followed by the dispersal and establishment of non-indigenous species, whether host or parasite. In the literature thus far, colonizations by both hosts and parasites have not been treated and reviewed together, although both are usually interwoven in various ways. As to those factors permitting invasive success and colonization strength, various hypotheses have been put forward depending on the scientific background of respective authors and on the conspicuousness of certain invasions. Researchers who have tried to analyse characteristic developmental patterns, the speed of dispersal or the degree of genetic divergence in populations of alien species have come to different conclusions. Among parasitologists, the applied aspects of parasite invasions, such as the negative effects on economically important hosts, have long been at the centre of interest. In this contribution, invasions by hosts as well as parasites are considered comparatively, revealing many similarities and a few differences. Two helminths, the liver fluke, Fasciola hepatica, of cattle and sheep and the swimbladder nematode, Anguillicola crassus, of eels are shown to be useful as model parasites for the study of animal invasions and environmental global change. Introductions of F. hepatica have been associated with imports of cattle or other grazing animals. In various target areas, susceptible lymnaeid snails serving as intermediate hosts were either naturally present and/or were introduced from the donor continent of the parasite (Europe) and/or from other regions which were not within the original range of the parasite, partly reflecting progressive stages of a global biota change. In several introduced areas, F. hepatica co-occurs with native or exotic populations of the congeneric F. gigantica, with thus far unknown implications. Over the fluke's extended range, in addition to domestic stock animals, wild native or naturalized mammals can also serve as final hosts. Indigenous and displaced populations of F. hepatica, however, have not yet been studied comparatively from an evolutionary perspective. A. crassus, from the Far East, has invaded three continents, without the previous naturalization of its natural host Anguilla japonica, by switching to the respective indigenous eel species. Local entomostrac crustaceans serve as susceptible intermediate hosts. The novel final hosts turned out to be naive in respect to the introduced nematode with far reaching consequences for the parasite's morphology (size), abundance and pathogenicity. Comparative infection experiments with Japanese and European eels yielded many differences in the hosts' immune defence, mirroring coevolution versus an abrupt host switch associated with the introduction of the helminth. In other associations of native hosts and invasive parasites, the elevated pathogenicity of the parasite seems to result from other deficiencies such as a lack of anti-parasitic behaviour of the naïve host compared to the donor host which displays distinct behavioural patterns, keeping the abundance of the parasite low. From the small amount of available literature, it can be concluded that the adaptation of certain populations of the novel host to the alien parasite takes several decades to a century or more. Summarizing all we know about hosts and parasites as aliens, tentative patterns and principles can be figured out, but individual case studies teach us that generalizations should be avoided.

Seasonal variation in a particular area may influence the occurrence of helminth infections and determining such fluctuations may help to maximize the beneficial effects of mass treatment. This study determined the seasonal variations in infection levels of Ascaris lumbricoides between March 2000 and June 2001 in two selected low-country plantations. Four hundred and seventy seven persons aged between 2 and 74 years (median 13) participated. Stools were tested using the Kato-Katz method and the prevalence and intensity of infection determined. All persons were treated with a single dose of mebendazole. Monthly follow-ups were undertaken with similar stool examinations and treatment given if found positive. Infection and re-infection rates were calculated each month. Rainfall and temperature were recorded each day. Total rainfall, number of wet-days and mean temperature was calculated for each month. The prevalence of Ascaris infection was 53.4% and 51.0% at Maliboda and Ayr estates respectively. Highest infection and re-infection rates at Maliboda (37.7%, 37.2%) occurred in June and at Ayr (13.3%, 25.9%) in October 2000 respectively. During the study period, the mean rainfall was 28.1 cm (range 7.4–63.9 cm) and mean temperature 27.6°C (range 22.1°–34.4°C). Significant correlations (P<0.05) were found between the re-infection rate and rainfall, temperature and the number of wet-days. Similar correlations were observed with the infection rate and temperature and the number of wet-days. Ascaris infections were found to correlate significantly only with the number of wet-days in a month (P<0.01). Thus, the number of wet-days appears to be a better indicator of Ascaris infections than total rainfall or mean temperature.

The epidemiology of Ancylostoma spp. was studied in the endangered Iberian lynx (Lynx pardinus) in the Doñana National Park, south-west Spain. Faecal samples were collected throughout a complete annual cycle (August 1997 to September 1998). The overall egg prevalence of Ancylostoma spp. was 57.8%. The pattern of abundance of Ancylostoma spp. eggs in faeces was overdispersed. Juvenile lynx demonstrated a statistically higher prevalence and abundance of Ancylostoma spp. than in adults. These levels of egg output (maximum 21195 epg), as previously reported in free ranging large felid cubs, could be close to disease involvement. The potential pathogenicity of hookworms and the influence of individual and ecological factors on hookworm transmission in the Iberian lynx from the Doñana National Park population are discussed.

Mucosal mast cells (MMC) play an important role in the immune response against selected species of intestinal nematode. The kinetics with which different strains of inbred mice resolve infection with Trichinella spiralis correlates with their ability to mount MMC responses in the intestinal mucosa. Homologues of MMC that express and constitutively secrete abundant amounts of the granule chymase, mouse mast cell protease-1 (mMCP-1), can be generated in vitro from bone marrow cultures supplemented with interleukins-3 and -9, stem cell factor and transforming growth factor-β1. Using the enhanced growth characteristics of these MMC homologues, a novel limiting dilution assay for mast cell precursor (MCp) frequency has been developed. The assay is highly specific, in that cultures containing mast cells are identified with mMCP-1 specific antibody, and almost three-fold more sensitive than previously published systems. MCp frequencies were compared in BALB/c and C57/BL10 strains of mice that, respectively, respond rapidly and slowly to infection with T. spiralis. MCp frequency (1/378 bone marrow cells) was significantly greater (P<0.05) in BALB/c than C57/BL10 mice (frequency: 1/751). Similarly the rate of growth of MMC homologues and the production of mMCP-1 was significantly (P<0.05) greater in BALB/c than in C57/BL10 bone marrow cultures.

It has previously been postulated that L-arginine emitted by penetrating Schistosoma mansoni cercariae serves as an intraspecific signal guiding other cercariae to the penetration site. It was suggested that penetrating in groups offers a selective advantage. If this hypothesis is correct and group penetration at one site on the host offers an advantage, it would follow that at such a site, successive groups of cercariae would be able to penetrate skin in either greater numbers or at a faster rate. This prediction was tested by the use of an in vitro model of cercarial penetration based on the Franz cell and using human skin. It was demonstrated that there was no increase in the percentage of cercariae able to penetrate the skin with subsequent exposures. Consequently, it seems unlikely that the release of L-arginine by cercariae during penetration could have evolved as a specific orientation system based on a selective advantage offered by group penetration.