Another African disease in Central Europa: Besnoitiosis of cattle. I. Light and electron microscopical study

Abstract

The paper reports the first detection of besnoitiosis of cattle in Germany. Just 2 years after the first appearance of the African Bluetongue disease (BTD) of cattle in Central Europe, another African agent of disease has arrived in Germany. While it was proven that the BTD virus was transmitted (after its first appearance) by endemic midges of the genus Culicoides (C. obsoletus, C. pulicaris), nothing is known, how the infectious stages of Besnoitia besnoiti-a member of the so-called cyst-forming coccidia-found their way to a herd in Southern Germany. The infected animals showed all characteristic clinical symptoms of besnoitiosis such as hyposclerodermia, hyperkeratosis, alopecia, and whitish tissue cysts in subcutaneous tissues as well as in the cornea. These cysts had diameters of up to 3 mm and consisted of a dense outer layer (=secondary cyst wall), which surrounded a host cell, that had been enormously enlarged by an inner parasitophorous vacuole containing thousands of 7-9 x 2 mum sized, banana-shaped cyst merozoites (=cystozoites, bradyzoites).Their fine structure was identical to that of published stages of B. besnoiti. During cyst development, the nucleus of the host cell had been hypertrophied and had apparently undergone several divisions, since many flattened, but very large nuclei were seen in light and electron microscopy. Thus, this study proves the arrival of another serious agent of disease of ruminants in Central Europe-a fact which is especially important, since in this species, there is neither information on the way of transmission from animal to animal nor exists concrete information on an efficacious therapy or on the modalities of its import into Germany.

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

“…Although the transmission cycle of B. tarandi is not fully understood, it is believed that it cycles through a predatorprey system with a carnivore as the definitive host (Dubey et al, 2004). However, wild ruminants and rodents should not be ruled out as potential reservoirs (Castillo et al, 2009;Mehlhorn et al, 2009). Biting or bloodsucking arthropods also may be important vectors of B. tarandi (Glover et al, 1990), but unlike bovine besnoitiosis (Bigalke, 1968), this has not been scientifically demonstrated.…”

Naturally Acquired Bovine Besnoitiosis

“…13,35,37 However, in light microscopic pictures, the ICW can be seen as a blue 37 or slightly eosinophilic layer. 35 Perhaps this layer was interpreted as artifact, occurring after processing of tissues for histological examination.…”

“…The collagenous nature of the OCW 13,35,37 resulted in a blue staining with Masson's trichrome stain and a red staining with orange-colored birefringence in polarized light in picrosirius red/Alcian blue stain, with the latter suggesting that the OCW is made up of collagen type I fibers.…”

Histopathologic and Ultrastructural Studies on Experimental Caprine Besnoitiosis

“…The present experimental study found skin thickening and hair loss to be features of the chronic phase, as previously reported in relation to various naturally occurring besnoitioses, 9,13,19 whereas resolution of the skin lesions was similar to that in some other Besnoitia infections. 16 The appearance of cysts at about 35 days after infection is somewhat earlier than that reported in native goats in Kenya, 21 with observation of Besnoitia cysts 56 and 60 days after bradyzoite inoculation. That experiment described cysts for a short period in some organs after infection but not the longer-term progressive changes in cysts and the associated tissue reactions during cyst degeneration, as shown in this study.…”