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

摘要

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 × 2 μm 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.