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      Dynamics of infestation of tracers lambs by gastrointestinal helminths under a traditional management system in the North of Tunisia Translated title: Dynamique d’infestation d’agneaux traceurs par les strongles digestifs dans des conditions d’élevage traditionnel au Nord de la Tunisie

      1 ,   1 , * , 1

      Parasite

      EDP Sciences

      helminths, sheep, epidemiology, Tunisia, helminthes, mouton, épidémiologie, Tunisie

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          Abstract

          The authors present a survey of gastrointestinal helminths of sheep on permanent pastures in the extreme north region of Tunisia (Mediterranean climate). Dynamic infestation of animals has been monitored by using batches of three tracer lambs introduced each two months during 2004 and 2005. These lambs were kept in the pens of veterinary school of Sidi Thabet (Tunisia) during three months and then necropsied. Faecal and blood samples were took from tracer lambs each two months during the whole period, and from animal flock only during 2004. The main helminth genera encountered were Trichostrongylus spp., Teladorsagia spp., Strongyloides papillosus and Anoplocephalidea; occasionaly were found Nematodirus, Oesophagostomum, Chabertia, Cooperia, Trichuris and Paramphistomum. The egg count of the ewes and lambs in the flock showed two peaks. For both ewes and lambs there is a gradual increase from January with a peak in May-June. This first peak is considered to be due to acquisition of infective larvae during the rainy and cold season, as evident from the worm burdens of tracer lambs. The second peak was exclusively observed in ewes during late autumn-early winter (November-December); it has two origins: infestation by third larvae stage and the periparturient rise. The worm burdens of tracer lambs showed that there was a gradual accumulation of nematodes from September- October, reaching a peak in March-April; a very low or naught infection is reported during the dry period (July-August). Infection by Anoplocephalidea was higher during the dry season. This study is primordial for a comprehensive control programme implementation against gastrointestinal helminths.

          Translated abstract

          Les auteurs présentent une étude quantitative et qualitative des helminthes gastro-intestinaux des ovins dans le nord de la Tunisie (climat méditerranéen). La dynamique d’infestation des animaux a été contrôlée en utilisant des lots de trois agneaux traceurs introduits tous les deux mois durant une période qui s’est étalée sur deux années, 2004 et 2005. Après leur retrait du pâturage, les agneaux traceurs ont été gardés à l’École vétérinaire de Sidi Thabet (Tunisie) durant trois mois, puis autopsiés. Des échantillons de matière fécale et de sang ont été pris sur des agneaux traceurs à chaque période de pâture et aussi sur des animaux d’un troupeau de la région d’étude durant l’année 2004. Les principaux helminthes rencontrés étaient Trichostrongylus spp., Teladorsagia spp., Strongyloides papillosus et Anoplocephalidea, et occasionnellement ont été trouvés Nematodirus, Oesophagostomum, Chabertia, Cooperia, Trichuris et Paramphistomum. Le décompte des oeufs par gramme chez les brebis et les agneaux dans le troupeau a montré deux pics. Pour les deux types d’animaux, il y a une augmentation graduelle à partir de janvier, avec un pic en mai-juin. Ce premier pic est considéré comme lié à l’acquisition des larves infestantes durant la saison pluvieuse et froide de l’année, comme en témoigne la charge parasitaire des agneaux traceurs. Le second pic a été exclusivement observé chez les brebis en fin d’automne-début d’hiver (novembre-décembre) ; il a deux origines : l’infestation par les L3 automnales et l’augmentation du nombre d’oeufs de nématodes émis par les femelles autour de la mise bas. La charge parasitaire chez les agneaux traceurs a montré qu’il y avait une accumulation progressive des nématodes à partir de septembre-octobre, atteignant un maximum en mars-avril, alors qu’une infestation très faible ou nulle est signalée durant la période sèche de l’année (juillet-août). L’infestation par des Anoplocephalidea était plus élevée pendant la saison sèche. Cette étude était nécessaire pour la mise en oeuvre d’un programme de contrôle efficace des helminthes gastro-intestinaux.

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          Most cited references 31

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          High prevalence of Echinococcus multilocularis in urban red foxes (Vulpes vulpes) and voles (Arvicola terrestris) in the city of Zürich, Switzerland.

          Over a period of 26 months from January 1996 to February 1998, 388 foxes from the city of Zürich, Switzerland, were examined for intestinal infections with Echinococcus multilocularis and other helminths. The prevalence of E. multilocularis in foxes sampled during winter increased significantly from 47% in the urban to 67% in the adjacent recreational area, whereas prevalence rates of other helminths were similar in both areas. Seasonal differences in the prevalence of E. multilocularis were only found in urban subadult male foxes which were significantly less frequently infected in summer than in winter. The distribution of the Echinococcus biomass, as expressed by worm numbers per fox was overdispersed in 133 infected foxes randomly sampled in winter. Ten of these foxes (8%) were infected with more than 10,000 specimens and carried 72% of the total biomass of E. multilocularis (398,653 worms). Prevalences did not differ significantly in these foxes in regard to age and sex but worm burdens were significantly higher in subadult foxes as compared with adult foxes. In voles (Arvicola terrestris) trapped in a city park of Zürich, E. multilocularis metacestodes were identified by morphological examination and by PCR. The prevalence was 20% among 60 rodents in 1997 and 9% among 75 rodents in 1998. Protoscoleces occurred in 2 of the cases from 1997. The possible risk for human infection is discussed with respect to the established urban E. multilocularis cycle.
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            Improving the assessment of the economic impact of parasitic diseases and of their control in production animals.

            This paper reviews the ways in which the economic impact of parasitic diseases of production animals have been evaluated. It then discusses the shortfalls of such studies, as well as the opportunities for improving the quality of economic impact assessments and their value to decision makers in the future. The paper first identifies the impacts that are specific to parasitic diseases. It then goes on to review the abundant literature on estimating the total costs of diseases. The authors argue that this approach severely limits the opportunity for economic assessments to aid decisions in disease control and research. The paper then reviews the literature on studies of avoidable costs, before discussing ways in which economic impact assessments can be enhanced. These issues include greater emphasis on incorporating the lost productivity potential caused by parasitic diseases, greater emphasis on valuing actual rather than intended control measures, and greater emphasis on quantifying the productivity effects at the societal level, particularly in the developing world.
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              Fasciola hepatica and Paramphistomum daubneyi: changes in prevalences of natural infections in cattle and in Lymnaea truncatula from central France over the past 12 years.

              A retrospective study was carried out over a 10- to 12-year period to analyse the changes in prevalences of natural fasciolosis and paramphistomosis among cattle and snails in central France, and to determine the causes which had induced these changes. The prevalences of natural fasciolosis in cattle increased from 1990 to 1993 (13.6% to 25.2%) and diminished afterwards up to 1999 (at 12.6%). Those of natural paramphistomosis showed a progressive increase between 1990 and 1999 (from 5.2 to 44.7%). The prevalences of natural infections and the numbers of free rediae counted in the snails (Lymnaea truncatula) infected with F. hepatica did not show any significant variations over time. By contrast, the prevalences of natural paramphistomosis in snails significantly increased from 1989 to 1996 and remained afterwards in the same range of values (3.7-5.3%), while the number of free rediae significantly increased up to 2000 (from a mean of 6.5 to 13.8 rediae per infected snail, respectively). Three hypotheses may explain the increase of paramphistomosis in cattle and snails: a better quality of diagnosis for the detection of P. daubneyi eggs in veterinary analysis laboratories, the use of specific molecules in the treatment of cattle fasciolosis since 1993, and the lack of an effective treatment up to now against cattle paramphistomosis. Since the objective of most farmers in central France is to obtain the highest antiparasitic efficiency with a single treatment of cattle per year, it is reasonable to assume that the prevalence of bovine paramphistomosis will continue to increase in the future.
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                Author and article information

                Journal
                Parasite
                Parasite
                parasite
                Parasite
                EDP Sciences
                1252-607X
                1776-1042
                November 2012
                15 November 2012
                : 19
                : 4 ( publisher-idID: parasite/2012/04 )
                : 407-415
                Affiliations
                [1 ] Laboratoire de Parasitologie, École Nationale de Médecine Vétérinaire 2020 Sidi Thabet , Université de La Manouba Tunisie
                Author notes
                [* ]Correspondence: Mohamed Gharbi. Tel.: 216 71 552 200/281 – Fax: 216 71 552 441. E-mail: gharbim2000@ 123456yahoo.fr
                Article
                parasite2012194p407 10.1051/parasite/2012194407
                10.1051/parasite/2012194407
                3671457
                23193526
                © PRINCEPS Editions, Paris, 2012

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                Page count
                Figures: 3, Tables: 2, Equations: 0, References: 57, Pages: 9
                Categories
                Original Contribution

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