Presentation on theme: "MONITORING BESNOITIA TARANDI IN BARREN GROUND CARIBOU (RANGIFER TARANDUS) RECOMMENDED TISSUE FOR SAMPLING AND DIAGNOSTIC TECHNIQUE Julie Ducrocq, 1 Stéphane."— Presentation transcript:
MONITORING BESNOITIA TARANDI IN BARREN GROUND CARIBOU (RANGIFER TARANDUS) RECOMMENDED TISSUE FOR SAMPLING AND DIAGNOSTIC TECHNIQUE Julie Ducrocq, 1 Stéphane Lair, 1 Guy Beauchamp, 1 and Susan Kutz 2 1 Centre québécois sur la santé des animaux sauvages / Canadian Cooperative Wildlife Health Centre. Faculté de médecine vétérinaire, Université de Montréal, St. Hyacinthe, Québec, Canada. 2 Faculty of veterinary medicine, University of Calgary, Calgary, Alberta, Canada. The odds of B. tarandi infection (n=311) (Fig. 1) are : 51% higher for the rostrum compared to the conjunctiva (p<0.0001); 59% higher in the metatarsus compared to the conjunctiva (p <0.0001); Not significantly different between the metatarsus and the rostrum; 42% lower in the thigh compared to the rostrum (p<0.0001); 45% lower in the thigh compared to the metatarsus (p<0.0001). B. tarandi intensity of infection (n=83) (Fig. 2) is: 40% higher in the metatarsus compared to the rostrum (p=0.002); 122% higher in the rostrum compared to the conjunctiva (p<0.0001); 216% higher in the metatarsus compared to the conjunctiva (p<0.0001); 54% lower in the thigh and the metatarsus (p<0.0001); BESNOITIA TARANDI B. tarandi is a parasite known to be present in barren ground caribou populations; Transmission cycle; It is thought that carnivores and arthropods are, respectively, definitive hosts and vectors of this parasite; Thickening, ulceration and secondary infections of the skin, as well as alopecia (loss of hair) are the most commonly observed signs in infected caribou; Microscopically, B. tarandi cysts are often found around blood vessels and in tissues rich in fibroblasts; Affected structures are the dermis (skin), subcutaneous fascias, tendons and associated sheaths, periosteum, muscular fascias, lungs and testicules; Visual observation of B. tarandi cysts (0-5 to 1mm whitish, round and elevated structures) on the conjunctiva has been suggested as a way to assess if this parasite is present. METHODOLOGY In collaboration with the CircumArctic Rangifer Monitoring and Assessment Network, sections of tissues from the conjunctiva and from the skin covering the rostrum, the metatarsus and the thigh from 311 harvested caribou were sampled and analyzed; The presence of B. tarandi cysts was determined by histological examination of each section and Intensity of infection was calculated as the number of cysts per mm 2 ; Multivariate logistic regression models were used to evaluate the variation between sampled tissues in regards to the presence of B. tarandi cysts; Sampled tissues were considered as a repeated measure; Prevalence was logit transformed and Intensity of infection was analyzed using a negative binomial model; The natural logarithm of the area sampled (mm 2 ) was used as an offset; The following parameters were included in this model: Geographical location: North American (NA) western (Bathurst, Bluenose West, Porcupine and Southampton Island) (n= 156) and eastern (Leaf River and George River) (n=155) herds; Gender: male (n=87) vs. female (n=224); Age class: adult (n=267) vs. calf (n=44). Results of the visual observation were compared to the overall status of each animal for B. tarandi as determined by the microscopic examination; Data were available for 95 caribou from the NA western herds and 152 caribou from the NA eastern herds; Sensitivity, specificity, positive and negative predicted values were calculated by geographical location. DISCUSSION Visual observation of tissues as a diagnostic test Sensitivity values for the visual evaluation of sampled tissues were low (Figure 3); Intensity of infection was shown to be higher in the Eastern herds and therefore more likely to be detected visually; Visual observation of tissues did not yield satisfying results compared to histological diagnosis. Histological analysis Diagnosis of B. tarandi infection in Rangifer tarandus by histology should be preferred; Since B. tarandi cysts are more likely to be found in skin sections from the metatarsus and rostrum, these locations should be sampled; Since variation in densities of B. tarandi cysts exists, comparison between animals should be made using the same sampling location. ACKNOWLEDGEMENT OF CARMA NETWORK COLLABORATORS Joëlle Taillon and Steeve Côté (Université Laval, Québec); Vincent Brodeur, Stéphane Rivard, Lyna Lambert, Andrée-Anne Tremblay and Denis Vandal (Ministère des Ressources naturelles et de la Faune, Québec); Manon Simard, Peter May, Sandy Suppa and Bill Doidge (Nunavik Research Center, Kuujjuak); Brett Elkin, Bruno Croft, Jan Adamczewski, Marsha Branigan, Alasdair Veitch, Richard Popko, Jennifer Bailey, Judy Williams, Fred Manderville, Allicia Kelly, Ernie Campbell, J.P. Rabesca, Lawrence Catholique (Government of the Northwest Territories); Christine Cuyler and her people from the Greenland Institute of Natural Resources. Mitch Campbell from the Nunavut Government and Jane Harms from the University of Saskatchewan; Dorothy Cooley and Martin Kienzler from the Government of Yukon; Pat Curry, Nathan DeBruyn, Dean Brown, Ryan Brook from the University of Calgary; We also would like to acknowledge the following hunters for their participation in community hunter-harvest caribou sampling: Merry Jonas, Henry and Charlie Tobac, Wilbert Kochan, Jared Lafferty, Alvin Orlias, George Oudzi, Angus Shae and Sharon Pierrot from the Northwest Territories and Danis Ohaituk, Tommy Elijassiapik, Aliva Epoo, Epoo Kusudluak, Johnny Naluktuk, Johnny Bobby, Juani Elijassiapik and Thomas Baron from Nunavik. RECOMMENDATION: MICROSCOPIC EXAMINATIONS OF THE SKIN FROM THE ANTERIOR ASPECT OF THE MID-METATARSUS PROVIDE A RELIABLE INDEX OF PREVALENCE AND INTENSITY OF INFECTION WITH B. TARANDI. Ulceration of the scrotum Presence of B. tarandi cysts on the conjunctiva OBJECTIVES OF THE STUDY Identify the best tissue to sample for the diagnostic B. tarandi in caribou. Evaluate the sensitivity and the specificity of visual observations compared to microscopic examination. Figure 2. B. tarandi intensity of infection by sampled sites (whiskers = SD) Leaf River herd caribou, Nunavik, Québec, Canada Inuit hunter training in collaboration with the Nunavik Research Center Leaf River herd field collection (Fall 2007) Hind leg collection Histological slide preparation B. tarandi cysts in the metatarsus Density of infection in the superficial dermis with ImageTool Laboratory data collectionMetatarsus skin sampling B. tarandi cysts on the periosteum of metatarsus bones RESULTS OF MULTIVARIATE LOGISTIC MODELS RESULTS OF VISUAL OBSERVATION OF TISSUES Negative predicted value Positive predicted value SpecificitySensitivity WHEHWHEHWHEHWHEHTissues Thigh Metatarsus Rostrum Conjunctiva Figure 3. The ability of visual evaluation of tissues to detect B. tarandi infected caribou by geographical locations. EH: North American Eastern herds WH: North American Western herds Figure 1. Proportion of sampled sites with B. tarandi parasitic cysts (whiskers = SD).