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摘要
An outbreak of bovine besnoitiosis in Germany; pathomorphological, ultrastructural and molecular-biological investigations
Introduction
Bovine besnoitiosis is caused by Besnoitia besnoiti, an obligate intracellular apicomplexan protozoan parasite, which has been reported from different countries of Africa and Asia as well as from France, Spain, and Portugal. The disease is of high economic importance. This paper reports on the first outbreak of bovine besnoitiosis in Germany.
Case report
A 3.4 year-old Charolais cow with unusual skin lesions was admitted to the Clinic for Ruminants of the Ludwig-Maximilians-University in Munich. The animal came from a cow-calf-operation with 214 animals. The skin lesions were distributed mostly all over the body, and consisted of multifocal hypotrichosis, alopecia, lichenification, erythema, and seborrhea. Because of a poor prognosis, the animal was euthanized.
Post mortem examination of the animal revealed a marked generalised hyperplasia of peripheral lymph nodes and a severe generalised thickening of the skin (up to 2 cm). Cutaneous changes were most evident around the eyes and at the muzzle, teats and extremities. Additionally, multiple disseminated miliary nodules were present bilaterally in the mucosal membranes of the conchae and the vestibulum vaginae. Skin biopsies were taken from further 53 cattle of the same livestock with suspicion of dermal lesions. For histopathological examination and transmission electron microscopy tissue samples were routinely fixed, embedded, and stained according to standard protocols.
Histopathologic findings revealed characteristic cysts of Besnoitia spp. in the skin of the muzzle, eye lids, neck, thorax, teats, tail, extremities and the pelvic region as well as in several organs e.g. conchae, tendons, tonsils, eye lids, septum nasale, vestibulum vaginae and in synovial membranes.
The cysts were approximately 250 to 300 pm in diameter, circular in cross section, and were surrounded by a moderate to severe chronic granulomatous inflammation. The cyst wall (up to 20 pm) was composed of a prominent outer hyaline layer, a middle layer consisting of a multinucleated host cell, and a thin inner membrane which enclosed the parasitophorous vacuole. The vacuole contained numerous fusiform bradyzoites measuring from 7 x 2 pm to 8 x 2 pm. Transmission electron microscopy of Besnoitia besnoiti bradyzoites revealed typical apicomplexan structures like a conoid, polar ring, 22 microtubules and several rhoptries. The diagnosis was confirmed by serological examination and the species Besnoitia besnoiti was identified by polymerase chain reaction.
Discussion
The pathogenesis, life cycle, and route of infection of B. besnoiti are poorly understood. The presented case indicates that besnoitiosis crossed a further frontier. It is actually unclear, if the disease has been spread within Germany. Due to an increasing awareness of besnoitiosis in Germany, further cases will possibly be detected in future.
- 出版日期2010
