Università di Bologna. DIPARTIMENTO DI SANITA' PUBBLICA VETERINARIA E PATOLOGIA ANIMALE VIA TOLARA DI SOPRA, 50 40064 OZZANO DELL'EMILIA (BOLOGNA) ITALIA
Abstract: The influence of host and parasite-related factors on the strongyle infection in 50 horses
coming from 6 European countries and slaughtered in Italy for meat production was investigated
using a multivariable modelling approach. The study was carried out by examining
adult helminths, faecal eggs (identified by culture to the third larval stage) and mucosal
larval stages of Cyathostominae. A modified Transmural Illumination technique (TMI) has
been performed and Cyathostominae empty mucosal cysts were also evaluated in order to
obtain further indications about small strongyles dynamic. All species found in this study
were previously reported in European horses. Major differences were detected comparing
Hungarian (#24) and Italian (#13) horses. Sex was confirmed as uninfluential, while
relations with host age were only partially consistent with the development of acquired
resistance. The analysis of both mucosal Cyathostominae larvae (more in Italy) and of the
percentage of empty cysts (higher in Hungary) along with lower large strongyle abundance
in Hungary allowed to hypothesise a wider use of anthelmintic treatments in Hungarian
horses compared to Italian ones. The results regarding adult Cyathostominae (no significant
differences nor regarding age or origin) suggested the important role of ecological
interactions between larval and adult stages in regulating small strongyle populations.
Abstract: The spatial distribution of large intestinal helminth parasites of 50 horses was studied. Both adult and mucosal larval stages were examined and counted within the ventral colon, dorsal colon and caecum. Thirty-three species of adult parasites were identified and their distribution in the three large intestinal regions reported, together with the localization of cyathostome encysted larvae and of empty mucosal cysts. In order to highlight interspecific interactions, both Spearman pairwise correlation (among all parasites) and multivariable negative binomial regression (among the most abundant parasites) were performed. Interactions among parasite species are very important from the ecological and parasitological point of view as they can modulate the abundance and the spatial distribution of parasites, as well as the composition of the infracommunity. The main results were: the selection of preferred sites of horse's large intestinal helminths has been confirmed; all statistically significant pairwise correlation coefficients (359 out of 666) were positive; the build up of multivariable regression models brought to light both negative and positive interactions; the most interesting competitive interactions have been observed between the most abundant and relatively large strongyle species: Strongylus edentatus and Strongylus vulgaris in the caecum and ventral colon. When S. edentatus is in the caecum, the favourite site of S. vulgaris, the latter decreases especially in the caecum. On the other hand, when S. edentatus is in the ventral colon, its favourite site, there is no negative relationship with S. vulgaris in the ventral colon and the positive correlation observed with bivariate analysis is maintained. The common belief that the horse large intestinal parasite community is isolationist, due to the absence of negative pairwise interaction, is therefore contradicted by the present study.
Abstract: Aim of the work. This paper presents a method to evaluate if competition is involved in determining the spatial niche of intestinal parasites.
Materials and methods. This method has been applied to the study of large intestinal helminths of 50 slaughtered horses. The whole study has recently been published (Stancampiano et al, 2010 Vet Parasitol doi:10.1016/j.vetpar.2010.01.031).
Results. Here we present the results regarding the relationship between two similar species, Strongylus vulgaris and Strongylus edentatus, found throughout the large intestine, but more abundant in the caecum and ventral colon respectively, according to the typical species composition of each intestinal region.
The role of ecological interactions on the spatial niche occupation, in particular the interspecific competition, is considered to be absent because of the absence of negative pairwise correlations between helminth species. In our opinion, the absence of these correlations does not demonstrate that competition is not occurring. Therefore, after a preliminary Spearmanâs test highligting positive pairwise correlations only, two negative binomial regressions were performed with S. vulgaris as dependent variable, in the caecum and ventral colon respectively, demostrating that the presence of S. vulgaris in a particular site is influenced by the presence of S. edentatus.
Conclusions. This kind of negative relations has never been highlighted before because the positive relation between the overall abundances of the two species, due to similar epidemiological frameworks, usually hides the ecological phenomenon of spatial competition avoiding its disclosure. This aspect was controlled in the model by the peculiar inclusion of the total number of S. vulgaris itself as independent variable.
Abstract: Aim of the work. The aim of this work was to develop a method for calculating the temporal dynamics parameters of gastrointestinal strongyles infection in a donkey population. In particular the force of infection, defined as the changement rate of the number of parasites, was estimated on the basis of quantitative coprological results.
Materials and methods. The research was conducted in an organic farm of donkeys in Salvarano di Quattro Castella (Reggio-Emilia) which is the largest donkeys farm in Europe housing a population of about 600 individuals. This population can be considered just like a free-living population primarily because of the animals are never treated with antihelminthic and because it is essentially an outdoor and closed-cycle farming. During the month of July 2009, 66 individual samples of faeces were collected from animals identified by microchip. A stratified sampling by age was performed in order to study the temporal dynamics of intestinal strongyles infection. Each specimen was examined using quali-quantitative coprological analysis and individual coprocoltures were performed for the strongyle eggs development up to the third larval stage (L3). The number of L3 belonging to different genera or species was compared to the number of strongyle EPG so as to estimate the number of L3/g both for small strongyles (Cyathostominae) and Strongylus vulgaris. In order to assess the progress of infections over time, the age of the donkeys was used as a proxy of the time of infection itself; therefore, the OLS regression model (linear or not) that best fits the observed data, so as to explain the relationship between the age of the donkeys and the quantity of larvae of parasites, was chosen. For the statistical analysis the software STATA 9.1 was used. For the study of the estimated functions and in particular for the calculation of the derivatives, the software Derive 6 was used.
Results. The dynamic of the infection over time (age of animals), both for small strongyles and S. vulgaris, fitted a logistic growth curve, whose study made it possible to estimate the force of infection of parasites and the maximum L3/g density reachable (carrying capacity K). The force of infection for small strongyles gets to a peak, equal to 3.3 L3/g month, at 5.3 months. The force of infection then decreases and becomes zero in 47 months, therefore the L3s remain stable after this time. In the case of S. vulgaris the force of infection was approximately equal to 0.22 L3/g month during the whole temporal range. The carrying capacity of the population of S. vulgaris is never reached, continuing to grow during the whole lifetime of the host.
Conclusions. This work has allowed to develop a method to calculate the force of infection and therefore to study the temporal dynamic of the major parasites of the donkey. It represents an important basis for models building, estimation of R0 and the realization of parasite control based on ecological data. Furthermore, the difference between the dynamic of small and large strongyles infections has been highlighted, showing that while the population of small strongyles attains its maximum level, the population of S. vulgaris never reaches its carrying potential. We want to point up that the true dynamic paramethers usually refers to the adult parasite population; nevertheless the force of infection estimated from coprological data represents a valid indicator of parasite dynamic, obtainable also in living animals and with a quite simple method.
Abstract: Abstract Anticoagulant poisoning is a common rodent
control method in urban areas, but rodents may exhibit
versatile feeding behavioural habits in varying environmental
conditions. This study has been conducted to
determine those environmental factors that could directly
influence bait consumption and which therefore may affect
an urban rodent control plan carried out with chemical
methods. In the city of Bologna (Italy), 2500 bait stations
have been monitored in various urban biotopes and the bait
consumption studied in relation to several environmental
factors, using both bivariate and multivariate analysis.
Results reveal that the rodent patch distribution triggers the
avoidance of baits placed outside of their home-range,
hence the importance on bait placement. The logistic
regression model confirms that vegetation, harbourage and
water supplies are important variables in determining bait
consumption, probably because they may spatially and
temporarily facilitate the agoraphobic rodent movement,
ensuring undisturbed bait consumption. The role of predators
(dogs and cats) and food competitors (synanthropic birds)
remains insignificant. However, bait eating invertebrates
may consume part of the bait. For a proper rodent control
plan the first real need is to minimize the alternative food
sources, which may compete with baits. Weather conditions
in which rodents could possibly pass unnoticed (fog and
rainfall) may encourage bait consumption, vice versa with a
cold climate. The considered environmental factors have
satisfactorily explained bait consumption, highlighting the
importance of human influence. The study of environmental
factors may be useful in categorizing several site-specific
conditions where rodent control efforts should be targeted,
enhancing any intervention by matching the correct and
specific strategy.
Abstract: The authors firstly provide a brief hystory of ecology and ecological approach to parasitology, with special reference to the italian situation where in 1992, the scientific italian society for wildlife diseases (SIEF: Società Italiana di Ecopatologia della Fauna) was founded. Thereafter, a review of papers published by italian authors regarding parasitology in wild mammals and birds is given, with special emphasys to the year and type of publication and to the use of an ecological approach. The authors conclude that, despite ecopathology was created in Italy by parasitologists, the role of ecology in the study of parasites still remain restricted to a limited number of research groups and host species and hope that in future an ecological approach, providing both an alternative point of view and additional instruments for the study of parasites, will be viewed as an opportunity without limiting it to a restricted group of host such as wildlife.
Abstract: Aim of the work. Due to the lack of data about donkey parasites, the aim of this work was to aquire direct informations about parasites of donkey, in order to highlight peculiar epidemiological patterns and possible differences with the horse. In addition, the availability of a large group of untreated equids made it possible to highlight parasitological features seldom investigated in horses.
Materials and methods. The research was performed in the organic donkey farm Montebaducco, in Salvarano di Quattro Castella (Reggio Emilia) which, housing a population of about 600 individuals, is the largest in Europe. It is an outdoor and closed-cycle farm, where the animals have never underwent antihelminthic treatments. The factory main activity is the milk production.
In July 2009, 72 faecal samples from microchip-identified donkeys were collected and data about animals were obtained.
Each specimen was examined using quali-quantitative coprological analysis and individual coprocoltures were performed to obtain the strongyle eggs development up to the third larval stage (L3). The percentage of L3s belonging to different genera or species was used to estimate the number of eggs belonging to the different genera or species identified after coproculture.
The relationship between parasitological results and sex (male and female), age (0-6 months, 6-24 months, 2-5 years, 5-10 years, more than 10 years), breeding category (foals with mare, mare with foals, pregnant mares, lactating mares, others), stable (five different farm areas) has been analyzed using the Pearsonâs ï£2 and the Kruskal-Wallis test for prevalence and quantitative data respectively, while the Spearman's rank correlation test was used to evaluate the correlation between quantitative variables. Significance was set at p<0.05.
Results. The coprological examination allowed to identify: strongyles (prevalence 93,83%; abundance 737,38 Eggs Per Gram); ascarids (18,05%; 32,78 EPG); pinworms (9,72%; 1,94 EPG); Trichuris sp. (1,39%; 0 EPG); Eimeria leuckarti (1,39%; 1,39 Oocysts PG).
L3s belonging to 8 distinct larval morphological groups were identified; they were grouped in small strongyles (93.1%, 659,1 Larvae Per Gram), Strongylus vulgaris (76.4%, 74.5 LPG), Strongylus edentatus (6.9%, 0.5 LPG), Triodontophorus sp. (18.1%, 2.6 LPG), Trichostrongylus sp. (12.5%, 1.1 LPG).
No significant difference emerged among donkeys relayed in different areas. About sex, differences emerged only for S. vulgaris that was significantly more prevalent and abundant in females.
Regarding age, ascarids were more prevalent and abundant in the younger age class (0-6 months); small strongyles were more prevalent and abundant in the older age classes, as well as S. vulgaris. The evidence of a significant positive correlation between strongyles and age, and of a negative correlation between ascarids and age has further confirmed these observations.
Finally, the analysis carried out among productive categories showed statistically significant differences in the prevalence of small strongyles and S. vulgaris, and in the abundance of small strongyles, S. vulgaris and Triodontophorus. In particular we have observed very low prevalences and abundances in foals and very high abundances of S. vulgaris in lactating mares.
Conclusions. This work confirms the dominance of small strongyles in the biotic community of equine parasites, even in the absence of treatments, emphasizing, conversely, a prevalence of S. vulgaris very far from the low prevalences usually reported also in donkeys (Wells D. et al, 1998, Vet Parasitol, 77: 163-177). It suggests that the decline of S. vulgaris accounted for in literature (Herd R., 1990, Comp Contin Educ Pract Vet, 12: 732-736) is probably not to be considered a fact.
In addition, some issues, never highlighted in horses before, emerged, such as the role of lactating mares in the epidemiology of S. vulgaris. Finally, while the importance of the very young age in the biology of ascarids is confirmed, the same proved untrue for small and large strongyles, that accumulate in older hosts. This latter epidemiological pattern, usually not reported in literature, has been probably revealed thanks to the peculiar breeding condition of the examined donkeys.
Abstract: Beef cattle heads (195 heads, 6 batches) imported for fattening from France to Italy were examined. Coprological qualitative and quantitative tests were performed, and the results analysed in relation to sex, breed, age, date of arrival, geographical origin (French department in which the animal was bred), and gathering centre (French department in which the animal was grouped with the others before travelling to Italy). The following parasites were identified: Eimeriidae (overall prevalence 60.5%); Strongyles (59%); Nematodirus spp. (14.3%); Trichuris spp. (4.1%); Capillaria spp. (2.0%); Paramphistomum spp. (27.6%); Dicrocoelium spp. (3.0%); Moniezia spp. (8.7%). All the observed parasites are widely reported in beef cattle either in Italy or in France. However, the seeming absence of Fasciola hepatica was unexpected, as well as the high prevalence of Paramphistomum spp. The variables that appeared to be more linked to parasite epidemiology were sex, altitude of the geographical origin and season.
Abstract: Host density is an important and widely accepted factor influencing microparasites epidemiology. In theory, host density would influence also macroparasite dynamic, although it would be achieved indirectly due to the presence of free-living infective stages of parasites. On this basis, it is expected that macroparasite abundance and prevalence would increase as host density increases, due to the higher probability for a new host to acquire infections from the environment. Nevertheless, some surveys indicate a negative relationship between host density and gastrointestinal helminth abundance in alpine chamois. On the basis of data collected from three different chamois populations, the Authors discuss the possibility that ecological factors different from host density should influence parasite biocoenosis dynamic, leading to the pattern observed in natural chamois-parasite systems.
Abstract: AIM: The aim of the study was to verify the occurrence of spatial competition among achanthocephalan parasites of cormorants. In particular we hypothesize that, as far as the number of parasites in individual host increases, the spatial range occupied in the intestine would increase and the concentration of parasites would remain stable or decrease.
METHODS: Achantocephalan from the intestine of 69 cormorans, shot for crop protection between September 2001 and March 2002 in the northern part of the River Po delta, were collected. The only acanthocephalan species previously identified in this cormorants population was Sowthwellina hispida (Dezfuli BS et al, 2002, Parasitology, 124: 537-544).
The intestinal length of each individual host was measured and, for each individual parasite (#1267), the point of attachment was assessed dividing the intestinal length in segments 1 cm long from the duodeno to the cloaca. In order to compare the localization of parasites among different host, the distance of each parasite from the duodeno was recoded as a percentage of the total intestinal length.
RESULTS: The overall spatial distribution of acanthocephalans is displayed in Figure 1. Figures 2 and 3 show the distribution in animal with less than 30 and more than 29 acanthocephalan respectively. The cut-off used to compare distribution in animal with âfewâ or âmanyâ parasites was chosen at the 29-30 level in order to obtain about the same number of parasites in each group (615 and 652 respectively). Due to the aggregated distribution of parasites in the host, the first group includes 57 cormorants while the second one 12.
All acanthocephalans were isolated in the distal half of the intestinal length.
CONCLUSIONS: As overall distribution (Fig. 1) suggests a bimodal pattern, with the most parasites distributed around the 80-90% of the intestinal length and a minor part around the 73-74%, we take into consideration the hypothesis that the acanthocephalans isolated belong to 2 different species, or that the distribution is dependant from the age or the sex of parasites. Taxonomic assessment is in progress, and the first hypothesis seems to be confirmed. In contrast with the supposition about spatial competition among parasites, the intestinal range occupied in animals with many acanthocephalans (Fig. 3) is narrower than the one occupied in animals with less than 30 acanthocephalan (Fig 2). In addition, Giniâs concentration index (Montanari A. et al, 2005, Statistica, Casa Editrice Ambrosiana, Milano, Italy) was 0.60 and 0.55 in group <30 and >29 respectively, showing, contrary to the previsions, an higher degree of concentration for parasites that belong to the more dense infracommunities. It is known that all acanthocephalans must move to some extent within their environment in order to mate, and in several acanthocephalan species immature individuals are positioned more anteriorly in the intestine than mature specimens (Crompton DWT, 1970, An ecological approach to acanthocephalan physiology, Cambridge University Press, UK). Probably the necessity to mate influences the spatial distribution of acanthocephalans in cormorants more than spatial competition.
Abstract: A three years survey on gastro-intestinal nematode egg output was carried out in four Alpine chamois herds (Rupicapra rupicapra rupicapra) from Belluno province (Italy). Data were analysed in order to detect the influence of cattle presence and chamois density on egg output, and to evaluate the stability of host-parasite relationship. As expected, variations related to the season were present, with the major peak of egg output observed in the summer. Results highlighted an unexpected inverse influence of host density on egg counts. The results are in relation to host-parasite relationship stability. Parasites seem to be able to self-regulate in the absence of parasite-induced host mortality. No effect due to cattle presence was detected.
Abstract: From 1987 to 1993, 89 wolves (Canis lupus) collected throughout the whole Italian range were examined for intestinal helminth parasites. Twelve species were found, including 5 nematodes (Uncinaria stenocephala, Toxocara canis, Ancylostoma caninum, Trichuris vulpis and Toxascaris leonina) and 7 cestodes (Echinococcus granulosus, Taenia hydatigena, T. multiceps, T. pisiformis, T. ovis, Mesocestoides lineatus and Dipylidium caninum). No significant differences were detected between sexes. T. canis showed higher prevalence and numbers in youngs, while E. granulosus and T. vulpis in adults. Interference between U. stenocephala and A. caninum was detected. Parasite biocenosis was stable in respect to geographical and ecological variables.
Abstract: A statistical approach highlighting interspecific competition for spatial niche between intestinal parasites is presented. Two similar nematode species, Strongylus vulgaris and Strongylus edentatus, collected throughout the large intestine of 50 horses but more abundant in the caecum and ventral colon respectively according to their typical location, were studied.
Ecological interspecific interactions are commonly considered to be absent because of the absence of negative pairwise correlations between helminth species abundances. However, the absence of these correlations does not demonstrate that competition is not occurring because similar epidemiology and biology could produce positive correlations and mask competitive interactions. Therefore, after a preliminary Spearmanâs test highligting positive pairwise correlations only between S. vulgaris and S. edentatus collected from different intestinal locations, two negative binomial regressions were performed with S. vulgaris as the dependent variable, (these appear in the caecum and ventral colon respectively), demonstrating that the presence of S. edentatus in the caecum influences the abundance of S. vulgaris both in the caecum and in ventral colon. This kind of negative relationship has never been highlighted before because the positive relationship between the overall abundances of the two species, due to similar epidemiological frameworks, usually hides the phenomenon of spatial competition. This aspect was controlled for in the present regression model by the inclusion of the total number of S. vulgaris itself as the independent variable.
Abstract: A deterministic model for the population dynamic of chamois and three species of gastrointestinal nematodes is proposed. The model considers the logistic growth of host population, exploitation and/or interference competition among different parasite populations and intraspecific competition between parasites individuals. In vertebrate-parasites systems, intraspecific competition is well known and is probably mediated by host immunity. The sensitivity of the parameter alpha (representing the parasite induced host mortality) and the comparison with field data suggest that intraspecific competition should play an important role in determining host and parasites abundances and in stabilizing chamois-parasites relationship.
