Clinical, pathological, and laboratory diagnoses of diseases of harbour porpoises (Phocoena phocoena), live stranded on the Dutch and adjacent coasts from 2003 to 2016.

Harbour porpoises (Phocoena phocoena) in the North Sea live in an environment heavily impacted by humans, the consequences of which are a concern for their health. Autopsies carried out on stranded harbour porpoises provide an opportunity to assess health problems in this species. We performed 61 autopsies on live-stranded harbour porpoises, which died following admission to a rehabilitation centre between 2003 and 2016. The animals had stranded on the Dutch (n = 52) and adjacent coasts of Belgium (n = 2) and Germany (n = 7). We assigned probable causes for stranding based on clinical and pathological criteria. Cause of stranding was associated in the majority of cases with pathologies in multiple organs (n = 29) compared to animals with pathologies in a single organ (n = 18). Our results show that the three most probable causes of stranding were pneumonia (n = 35), separation of calves from their mother (n = 10), and aspergillosis (n = 9). Pneumonia as a consequence of pulmonary nematode infection occurred in 19 animals. Pneumonia was significantly associated with infection with Pseudalius inflexus, Halocercus sp., and Torynurus convolutus but not with Stenurus minor infection. Half of the bacterial pneumonias (6/12) could not be associated with nematode infection. Conclusions from this study are that aspergillosis is an important probable cause for stranding, while parasitic infection is not a necessary prerequisite for bacterial pneumonia, and approximately half of the animals (29/61) probably stranded due to multiple causes. An important implication of the observed high prevalence of aspergillosis is that these harbour porpoises suffered from reduced immunocompetence.

Role of Crassicauda sp. in natural mortality of pantropical spotted dolphins Stenella attenuata: a reassessment.

Evaluating the effect of parasites on population size is essential for designing management and conservation plans of wild animal populations. Although knowledge in this area is scarce in cetaceans, current evidence suggests that species of the nematode genus Crassicauda may play an important regulatory role in some populations. In the present study, a semiparametric regression technique was applied to a previously published dataset to re-examine the role of Crassicauda sp. in natural mortality of pantropical spotted dolphins Stenella attenuata. The resulting model indicated parasite-induced mortality at ages between 6.5 and 9 yr and at roughly 12 yr. The maximum mortality estimates obtained could represent 2 to 4% of natural mortality in dolphins 6 to 8 yr old. This estimate is substantially smaller than previously published values, but in contrast with previous research, our model provides clear statistical evidence for parasite-induced mortality because the bootstrapped 95% confidence intervals of the estimated mortality rates excluded the 0 value. We also evaluated, through simulations, how potential sampling biases of infected dolphins could overestimate parasite-induced mortality. Small differences in sampling selectivity between infected and uninfected animals could substantially reduce the mortality estimates. However, the simulated models also supported the notion of statistically significant mortality in juvenile dolphins. Given that dolphins older than 16 yr were poorly represented in the dataset, further research is needed to establish whether Crassicauda sp. causes meaningful mortality for population dynamics among adult individuals.

Conflict and diarrheal and related diseases: a global analysis.

The purpose of this study was to determine the association between deaths owing to terrorism, civil war and one-sided violence from 1994-2000 and disability-adjusted life years (DALYs) attributable to diarrheal and related diseases, schistosomiasis, trachoma and the nematode infections (DSTN diseases) in 2002 among World Health Organization Member States. Deaths resulting from terrorism, civil war and one-sided violence were significantly related to DSTN DALYs across the majority of sex-age subgroups of the populace, after controlling for baseline levels of improved water/sanitation and a variety of economic measures: overall, a 1.0% increase in deaths owing to terrorism and related violence was associated with an increase of 0.16% in DALYs lost to DSTN diseases. Associations were greatest among 0-to-4-year olds. The results of the present study suggest that DSTN disease control efforts should target conflict-affected populations with particular attention to young children who suffer disproportionately from DSTN diseases in these settings. In view of the evidence that terrorism and related violence may influence DSTN DALYs in the longer term, control strategies should move beyond immediate responses to decrease the incidence and severity of DSTN diseases to seek solutions through bolstering health systems infrastructure development among conflict-affected populations.

The lethal and sub-lethal consequences of entomopathogenic nematode infestation and exposure for adult pine weevils, Hylobius abietis (Coleoptera: Curculionidae).

Entomopathogenic nematodes (EPN) frequently kill their host within 1-2 days, and interest in EPN focuses mainly on their lethality. However, insects may take longer to die, or may fail to die despite being infected, but little is known about the effects of EPN infection on insects, other than death. Here we investigate both lethal and sub-lethal effects of infection by two EPN species, Steinernema carpocapsae and Heterorhabditis downesi, on adults of the large pine weevil, Hylobius abietis. Following 12h nematode-weevil contact in peat, S. carpocapsae killed a significantly higher proportion of weevils (87-93%) than H. downesi (43-57%) at all concentrations tested. Less than 10% of weevils were dead within 2 days, and weevils continued to die for up to 10 days after exposure (LT(50) of 3 days or more). In a separate experiment, live weevils dissected 6 days after a 24h exposure to nematodes on filter paper harbored encapsulated and dead nematodes, showing that weevils could defend themselves against infection. Some live weevils also harbored live nematodes 6 days after they had been removed from the nematode infested medium. Feeding by weevils was not affected by infection with, or exposure to, either species of EPN. We discuss these results in relation to the use of EPN in biological control against H. abietis.

Re-establishment of nematode infra-community and host survivorship in wild Soay sheep following anthelmintic treatment.

Compared to mainland Britain, where there has been decades of anthelmintic use, the natural host-parasite relationship of the wild Soay sheep on the remote archipelago of St. Kilda has remained undisturbed. Small-scale anthelmintic bolus experiments on the island have previously shown that the removal of gastrointestinal nematodes can improve over-winter survival of young and male sheep in high host density years. This study, in which two-year-old sheep were treated, is the first to examine patterns of re-establishment of different nematode species in sheep following treatment and also investigates which species are likely to affect host survival. The experiment showed that, although all sheep were equally likely to die, host sex and weight influenced temporal survivorship in that females and heavier sheep tended to survive longer. Examination of the nematodes that had re-infected males six months after administration of an anthelmintic bolus showed that, compared to controls, the diversity of species was lower. Of the nine nematode species, there were fewer Trichostrongylus axei and Trichostrongylus vitrinus nematodes in treated sheep. In control sheep there were more T. axei and T. vitrinus nematodes in males than females. In addition there was an association between host over winter weight loss and the intensity of T. vitrinus. The fact that this species had higher numbers in males than females and was associated with over-winter weight loss implies it could have an important role in host mortality in high-density years.

Livestock disease threats associated with intensification of pastoral dairy farming.

This paper provides an overview of the changes in the pasture-based dairy systems of New Zealand and Australia that may influence the health of cattle. There are relatively few available data that can be used to quantify the effects of increased intensification of milk production on the health of cattle. There is evidence that increased production increases the risk of mastitis and culling for udder health. Increased risks of mastitis with treatment with somatotropin support these findings; however, the risk of mastitis may decrease with increased milking frequency. Larger herds with greater stocking density should increase the risk for infectious disease, but evidence to support this contention is sparse. Very intensive grazing patterns associated with higher grass yields achieved using better cultivars and greater use of fertilisers favour nematode parasites. There is some evidence of anthelmintic resistance in both nematodes and liver fluke. Veterinarians will need to be aware of the potential for these to reduce the productivity of cattle. There have been benefits of improved nutrition on the efficiency of energy use for dairy production. Diseases such as bloat and ketosis appear to be of lower prevalence. It also appears that mineral nutrition of pasture-fed cattle is being better addressed, with gains in the control of milk fever, hypomagnesaemia and trace-element deficiencies. However, acidosis is a condition with a high point prevalence in pasture-based dairy systems where cows are fed supplements; one study in Australia found a point prevalence of approximately 11% of cows with acidosis. There is evidence from this study that the neutral detergent fibre (NDF) in pasture-based diets may need to be higher than 30% of the diet to maintain rumen stability. Laminitis and acidosis are different conditions with a similar pathogenesis, specifically highly fermentable diets. The prevalence of lameness was 28% in herds in Australia, suggesting that this condition must be a focus for preventive medical approaches, including the design of laneways, feed pads and dairies.

Fatal gastrointestinal parasitism in goats: 31 cases (2001-2006).

OBJECTIVE: To evaluate signalment, history, clinical and pathologic findings, and seasonal weather patterns in association with fatal gastrointestinal parasitism in goats. DESIGN: Retrospective case series. ANIMALS: 152 goats that were > 1 day of age. PROCEDURES: Characteristics including age and counts of coccidia oocysts and trichostrongyle ova (eggs) per gram of feces (EPG) in goats that died because of gastrointestinal parasitism and goats that died because of other causes were compared. Weather data and annual incidence of caprine fatal gastrointestinal parasitism were investigated. RESULTS: Death was attributed to gastrointestinal parasitism in 31 of 152 (20%) goats (median age, 5 months; range, 1 month to 7 years); deaths were attributed to coccidiosis (n = 7 goats; median age, 4 months; median EPG, 2,225), trichostrongylosis (6 goats; median age, 1.25 years; median EPG, 3,700), or dual infection (18 goats; median age, 6.7 months; median EPG, 8,088 coccidia and 5,475 trichostrongyles). Sudden onset of weakness or death was a common historical finding; diarrhea was evident in 15 goats. Common postmortem findings in these goats included cachexia, tissue pallor, poorly formed feces, and mesenteric lymphadenomegaly. Wet weather in spring and summer was associated with increased annual incidence of fatal gastrointestinal parasitism in goats. CONCLUSIONS AND CLINICAL RELEVANCE: Gastrointestinal parasitism is an important cause of death in goats. Clinical signs may not develop until just prior to death, and diagnosis is achieved via parasitologic evaluation of feces and necropsy. Seasonal weather patterns should be considered on an annual basis when designing parasite control programs for goats.

Gastrointestinal nematode species burdens and host mortality in a feral sheep population.

Every few years a large proportion of the feral sheep on Hirta, St Kilda die due to food shortage. The effects of malnutrition are exacerbated by gastrointestinal nematodes. As found in sheep flocks in mainland Britain, Teladorsagia circumcincta has long been considered the predominant and most pathogenic nematode species in all age classes of Soay sheep. Previous research indicated that intensity of this species showed a negative association with host age and comprised 75% of the entire gastrointestinal burden. Here we present new data that show Trichostrongylus axei and Trichostrongylus vitrinus to be the predominant worm pathogens in young Soay sheep. In the present study, Trichostrongylus spp. burdens declined with host age whereas T. circumcincta actually increased in burden over the first few age classes. Also, male hosts had significantly higher burdens of Trichostrongylus spp. than females, with this genus making up a higher proportion of the strongyle egg producing community in male hosts than female hosts. These new findings raise questions concerning our previous interpretation of the main nematode species contributing to strongyle egg count in the population, and the contrasting infection patterns of these nematode species in unmanaged St Kilda Soay sheep compared with domestic sheep in mainland Britain.

Mortality in Laysan ducks (Anas laysanensis) by emaciation complicated by Echinuria uncinata on Laysan Island, Hawaii, 1993.

In November 1993, unusual mortality occurred among endangered Laysan ducks on Laysan Island, one of the remote refugia of the Northwestern Hawaiian Islands National Wildlife Refuge (USA). Ten live ducks were emaciated, and blood samples documented anemia, heterophilia, and eosinophilia. Pathology in 13 duck carcasses revealed emaciation, marked thickening of the proventricular wall, abundant mucus, and nodules in the gastrointestinal tract. Histology revealed granulomata associated with nematodes in the proventriculus, small intestines, and body walls of nine of 10 ducks examined on histology. We suspect that low rainfall and low food abundance that year contributed to enhanced pathogenicity of parasite infection, either through increased exposure or decreased host resistance. Because the Laysan duck is found only on Laysan island and is critically endangered, translocation of this species to other islands is being considered. Given that we have not seen pathology associated with Echinuria spp. in native waterfowl on other Hawaiian Islands and given the parasite's potential to cause significant lesions in Laysan ducks, it will be important to prevent the translocation of Echinuria spp.

Internal parasites of free-ranging guanacos from Patagonia.

In the winter of 2000, a greater than 80% reduction in the guanaco population located in Cabo Dos Bahi;as Wildlife Reserve, Chubut, Argentina, was evident due to massive mortality attributed to starvation. Twelve guanacos were necropsied and samples were analyzed at the Parasitology Laboratory of Facultad de Ciencias Veterinarias, Universidad Nacional del Litoral. Fecal analysis revealed developmental stages of Nematodirus sp., Marshallagia sp., Trichuris sp. and Eimeria spp. Histopathological analysis showed the presence of Sarcocystis sp. in muscle and fascia cysts. Other parasites recovered included Dictyocaulus filaria, Trichuris tenuis and Moniezia expansa. Of these, D. filaria and M. expansa possibly reflect interactions with domestic sheep. This is the first time that T. tenuis has been reported in guanacos.

Parasitic infections in live freshwater tropical fishes imported to Korea.

We examined 15 species of ornamental tropical fishes originating from Southeast Asia to determine the cause of losses among 8 fish farms in Korea. A total of 351 individuals belonging to 5 different families (1 species of Characidae, 6 of Cichlidae, 3 of Cyprinidae, 1 of Heleostomatidae, and 4 of Poecilidae) were collected for the purpose of detecting metazoan and protozoan parasites. Parasites were fixed and stained using routine methods, and identified. We found 3 ciliates, 2 monogeneans, 1 nematode, and 1 copepod from 7 host species. Of these, Ichthyophthirius multifiliis was the most common parasite in our study, and together with Trichodina sp., caused mass mortality of Sumatra barb Puntius tetrazona at 1 farm. We also found Camallanus cotti and Tetrahymena corlissi from guppies Poecilia reticulata, both for the first time in Korea. Farmers consider these 2 pathogens to be the most serious ones in Korea. Gussevia asota from oscar Astronotus ocellatus, and Gyrodactylus bullatarudis from platy Xiphophorus maculatus were also found in Korea for the first time. We believe that appropriate quarantine practices for tropical ornamental fishes should be introduced because the failure to require and implement quarantines has already resulted in the accidental introduction of exotic parasites to fish farms, and because these parasites can cause further economic losses if they become established in the wild.

Evaluation of the association of parasitism with mortality of wild European rabbits Oryctolagus cuniculus (L.) in southwestern Australia.

Abundances of the parasitic nematodes Trichostrongylus retortaeformis and Passalurus ambiguus, and 8 Eimeria species were estimated by fecal egg and oocyst output in 12 discrete free-ranging populations of wild rabbits (Oryctolagus cuniculus) in southwestern Australia. Comparisons of parasite egg and oocyst counts were made between those rabbits known to have survived at least 2 mo after fecal samples were collected and those rabbits that did not survive. There were significant negative relationships between parasite egg and oocyst counts and survival when all age groups and collection periods were pooled for several species of coccidia and for T. retortaeformis. However, when the same comparisons were made within rabbit age groups and within collection periods, there were very few significant differences even where sample sizes were quite large. The differences indicated by the pooled analysis for coccidia were most likely due to an uneven host age distribution with respect to survival, combined with an uneven distribution of the oocyst counts with rabbit age. The result for T. retortaeformis was similarly affected but by a seasonal pattern. Parasitism by nematodes and coccidia did not appear to be an important mortality factor in these rabbit populations, at least at the range of host densities we examined. This suggests that other factors must have been responsible for the observed pattern of density-dependent regulation in these rabbits.

[Economic losses in pheasant breeding evoked with endoparasites]. / Ekonomiczne straty w hodowli bazantów wywolane pasozytami wewnetrznymi.

Parasitical invasions constitute a serious veterinary-economic problem in pheasant breeding. The studies were carried out between 1995-1997 in a big breeding centre situated in the Middle Pomerania region, where the basic flock amounted to 1000-1200 bird individuals. The aim of the study was to determine a condition of the pheasants' affliction with nematodes, reasons for the invasion and possibilities of a decrease in the losses thus brought about. In the subsequent years, the flock affliction reached the following proportions: 40% in 1995, 42% in 1996, and 68% in 1997. Between 1995 and 1996, the findings revealed eggs of the nematode Capillaria sp (C. anatis and C. phasianina) in their faeces, with less frequent cases of Trichostrongylus tenuis, Heterakis isolonche and Syngamus trachea. Between 1995-1996 40% deaths in the afflicted flock were brought about by Syngamus trachea whilst in 1997 syngamosis resulted in 80% deaths among the afflicted birds. To determine reasons for the confirmed nematode invasion in the studied period during which all the requirements were fulfilled in the pheasant breeding, conclusions were drawn on the basis of the study. Also, preventive measures were suggested to stop any further appearance of syngamosis or losses due to other endoparasites, as those in 1997.

Effect of strategic gastrointestinal nematode control on fertility and mortality of N'Dama cattle in The Gambia.

A large-scale longitudinal study was undertaken to investigate the effects of a strategic treatment of gastrointestinal nematodes on the mortality and fertility of N'Dama cattle under village conditions. Initially, 1046 animals from 26 private N'Dama cattle herds, were monitored from October 1989 to December 1994. Each herd was stratified by age and the animals were randomly allocated to two groups with a similar average age. One group received a single anthelmintic treatment of fenbendazole (Panacur, 7.5 mg/kg BW, Hoechst Veterinä AG) in October 1989, whereas the other group remained untreated. In July 1990, the herds were subdivided into two different treatment schemes. In the herds of scheme 1, the treated animals (Treatment group I) were treated once (in August), whereas in the herds of scheme 2, the treated animals (Treatment group II) were treated twice (in July and September). The same treatment schedule was used in the subsequent rainy seasons until December 1994. One group in every herd of both schemes served as control (Treatment group 0) and received no anthelmintic treatment throughout the study. The average annual cumulative incidence mortality between 0-1 year was more than two times higher in treated animals compared to their controls (21% against 7.5%). No differences were found in older age categories. Survival analysis confirmed differences in mortality from 0-1 year, but were not significant in proportional hazard models. The 25% quantiles of age at first calving was used to quantify differences between twice treated animals (50.2 months) and its controls (58.3 months) which represents a decrease of 8 months in twice treated animals. Annual calving rates of twice treated animals were 52.2% compared to 43.6% in the control group (P < 0.001), which is an increase of 8.6% to the control rate. Possible causes of increased mortality in 0-1 year old treated calves are discussed. We can conclude that in the present epidemiological situation and the given parasite spectrum, gastro-intestinal nematodes mainly affect host fertility. Strategic control of gastro-intestinal nematodes is thus recommended for young heifers up to their age of first calving provided the overall financial analysis of the intervention is beneficial.

Effect of decreased oxygen content on eels (Anguilla anguilla) infected by Anguillicola crassus (Nematoda: Dracunculoidea).

The survival chances of eels with Anguillicola crassus infection of varying intensity and with varying pathological changes were studied in an experimental system devoid of fresh oxygen supply. Eels most severely affected by anguillicolosis died first, while those with less expressed pathological lesions tolerated sublethal oxygen levels for a longer time. Findings were similar at 20-21 degrees C and at 27-28 degrees C; at 27-28 degrees C, however, the fish required a higher oxygen content to survive. The experiments demonstrate that Anguillicola infections substantially impair the eels' natural resistance and, under unfavourable environmental conditions, may lead to their death.

The role of nematode parasites in Soay sheep (Ovis aries L.) mortality during a population crash.

In early 1989, two-thirds of the Soay sheep population on St Kilda died over 12 weeks. Post-mortem examinations revealed emaciated carcasses and considerable nematode burdens, with protein-energy malnutrition as the probable cause of death. Haematological and blood biochemical changes in the sheep, as well as fecundity of gastrointestinal nematodes, suggested the hosts were immunosuppressed. In parallel, laboratory experiments in which Soay sheep on a high plane of nutrition were artificially infected with Ostertagia circumcincta, showed no clinical signs or mortality when supporting worm burdens similar to those recorded in dead sheep on St Kilda. Anthelmintic treatment of a group of animals increased daily survival rates in ewes and male lambs, although treated animals became re-infected as the 'crash' progressed. It is suggested that parasites contribute to mortality in malnourished hosts, exacerbating the effects of food shortage.

Disease conditions affecting common seals (Phoca vitulina) around the Scottish mainland, September-November 1988.

Common seal populations around the Scottish coast were less severly devastated by phocine distemper than those on the Continent. Nevertheless, over a 4-month period, 59 common seals were examined postmortem. The macroscopic and histopathological lesions are described. Forty-two per cent of these seals were considered to be suffering from phocine distemper. Serology on 29 of the 59 seals was undertaken and the results are discussed in relation to the histopathological findings. Bordetella bronchiseptica proved to be an important secondary invader in phocine distemper virus infected seals. Verminous pneumonia was shown to be a frequent problem, particularly in juveniles.

Use of confidence ellipses to detect effects of parasites on the growth of yellow perch, Perca flavescens.

Determining the causes of mortality in populations of fish is inherently difficult. To simplify the determination of whether parasite-induced mortality occurs, parasitologists have relied on 3 types of subjective analyses of graphs. Peaked host age-parasite intensity curves concomitant with a decrease in the degree of dispersion (measured by variance-to-mean ratio) of parasites in older age-classes of fishes, a slope of less than 2.0 for a log-log graph of variance versus mean intensity of infection, and differences between truncated and nontruncated forms of a theoretical frequency distribution for the parasite are considered indicators of parasite-induced mortality in fishes. The nematode Raphidascaris acus causes significant parasite-induced mortality in natural populations of yellow perch (Perca flavescens) in Dauphin Lake, Manitoba, Canada. Using this fish-parasite system we present a comparison of some of the graphical techniques used by parasitologists to detect parasite-induced mortality and show how confidence ellipses based on the parameters beta 0 and beta 1 of a linear model for growth of yellow perch (weight = beta 0 + beta 1 x age) can be used to compare many growth curves simultaneously. When plotted in a bivariate fashion (beta 0 vs. beta 1), vertical displacement of confidence ellipses along the ordinate (beta 1) are due to sublethal effects on growth of fishes in response to parasites, whereas lateral shifts along the abscissa (beta 0) are suggestive of parasite-induced mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Mortality of fallow deer (Dama dama) experimentally-infected with meningeal worm, Parelaphostrongylus tenuis.

Six fallow deer (Dama dama) fawns died after receiving 25 to 150 infective larvae of Parelaphostrongylus tenuis. Fawns given higher doses usually died sooner (6 to 23 days) than those given lower doses (54 to 67 days). Early deaths were associated with severe acute peritonitis resulting from perforation of the intestinal wall; later deaths were associated with paralysis and inability to rise. Numerous adult P. tenuis were found within neural tissues of the brain and spinal cord in the three fawns with paralysis. One white-tailed deer (Odocoileus virginianus) exposed to infective larvae from the same source survived infection without exhibiting clinical signs and began passing larvae in feces 88 days post-exposure. At the doses used in this study, meningeal worm caused fatal infections in fallow deer. Results are compared to published observations of fallow deer naturally-infected with P. tenuis.