Comparison of Gross Visual and Microscopic Assessment of Four Anatomic Sites to Monitor Besnoitia Tarandi in Barren-Ground Caribou (Rangifer Tarandus)

Abstract

ABSTRACT:The objective of this study was to establish a standardized protocol to monitor Besnoitia tarandi prevalence and intensity in barren-ground caribou (Rangifer tarandus) herds by: 1) calculating the relative sensitivity and specificity of the gross visual assessment of four anatomical sites compared with microscopic evaluation, and 2) determining which of four anatomical sampling sites was the most sensitive for detecting B. tarandi cysts by microscopy. Sampled tissues consisted of the conjunctiva of the left eye and skin sections from the rostrum, metatarsus, and thigh from 312 harvested caribou. Diagnosis of infection with B. tarandi was based on observation of at least one cyst by microscopic examination. For each tissue, the maximal density of cysts (number of B. tarandi cysts/mm 2 in the section examined) was calculated for a measured area consisting of the dermis extending from the epidermis of the skin to the base of the hair follicles and adnexal structures. For the conjunctiva, the entire submucosa was evaluated. Gross visual evaluation markedly underestimated B. tarandi prevalence in caribou with a relative sensitivity ranging from 0.29 in the conjunctiva to 0.13 in the skin section from the thigh, whereas relative specificities ranged from 0.98 to 1.00. The metatarsus and rostrum skin sections had the highest probabilities of cyst detection of all four anatomical sampling sites. The metatarsus harbored significantly higher densities of B. tarandi cysts than the rostrum, thigh, or conjunctiva. In conclusion, microscopic evaluation of a skin section from the anterior aspect of the mid-third portion of the metatarsal region could be used as a standardized comparative indicator of density of B. tarandi infection in Rangifer.

Chronic bovine besnoitiosis: Intra-organ parasite distribution, parasite loads and parasite-associated lesions in subclinical cases

“…The classical sites of grossly visible tissue cysts in infected cows have been reported to be the skin/subcutis, scleral conjunctiva, vaginal mucosa (in particular the vestibulum vaginae), and the upper respiratory tract (Pols, 1960;McCully et al, 1966;Nobel et al, 1981;Majzoub et al, 2010;Rostaher et al, 2010;Manuali et al, 2011;Gentile et al, 2012;Schares et al, 2011). The same predilection sites have been reported for the closely related Besnoitia species B. bennetti (Ness et al, 2012) and B. tarandi (Ducrocq et al, 2012). Our six assessed cows had cleared, or at least considerably reduced in number, the once visible tissue cysts in the scleral conjunctiva.…”

Variables Associated With Besnoitia Tarandi Prevalence and Cyst Density in Barren-Ground Caribou (Rangifer Tarandus) Populations

“…Samples were obtained from animals harvested from two migratory barren-ground caribou populations in Northern Qué bec and Labrador, the Riviè re-aux-Feuilles and the Riviè re-George herds (Table 1), with the use of a standardized protocol established for B. tarandi (Ducrocq et al, 2012) A full-thickness section of skin of at least 2 cm 2 taken from the anterior aspect of the mid-third portion of the metatarsus region from each caribou was fixed in 10% neutral-buffered formalin solution either fresh or after one cycle of freezing and thawing. Fixed tissue was embedded in paraffin wax and sagittal sections were cut (4 mm thick) and stained with hematoxylin, phloxine, and saffron (Luna, 1968).…”

“…Observed prevalence (%) was the percentage of caribou sampled in which at least one B. tarandi cyst in the metatarsal skin section was detected. For each positive metatarsal skin section, maximal cyst density (number of cysts/mm 2 in the superficial dermis) was calculated according to Ducrocq et al (2012).…”

Standardized monitoring of Rangifer health during International Polar Year

“…(cysticerci in skeletal or cardiac muscle; omas, 1996), Hypoderma tarandi (scars or bot larvae on underside of skin; Cuyler et al, 2012), Cephenemya trompe (larval bots in the pharynx, examined once head was removed; Cuyler et al, 2012), Besnoitia tarandi (cysts in metatarsal skin and bulbar conjunctiva; Ducrocq et al, 2012), and any other abnormalities were also recorded on the eld datasheet. e lungs and heart were examined grossly for parasites, and the gastrocnemius and/or the cranial crural muscles [referred to elsewhere as 'peroneus' (Allaye Chan-McLeod et al, 1995); Fig.…”