Genotyping of Babesia bigemina from cattle from a non-endemic area (Switzerland).

In August 2002, bovine anaplasmosis and concurrent infections with Mycoplasma sp. and piroplasms were reported in a cattle herd in an alpine region of Switzerland. The piroplasms were identified by PCR/sequencing of part of the 18S rRNA gene as Babesia bigemina and Theileria of the buffeli/sergenti/orientalis-complex, which have never been diagnosed in Switzerland before. The B. bigemina isolate was genetically characterised at two loci and compared with isolates from Italy, Spain, Turkey, Kenya and Mexico. Analysis of the internal transcribed spacer 2 (ITS2) of the rRNA genes revealed high polymorphism not only among the isolates but even within the isolates, and the presence of two types of the ITS2 in every isolate was confirmed. A dendrogram based on ITS2 sequences showed that the Swiss isolate was most closely related to a Spanish isolate but no sequences of the isolate from Switzerland were identical to any of the other isolates. The isolate from Italy was not positioned in the same cluster as the Swiss and the Spanish isolate. This had been anticipated as the nearest known endemic area of B. bigemina in Central Italy. Sequence analysis of the rhoptry-associated protein-1c gene (rap1c) confirmed the similarity of the Swiss and Spanish isolate. Hence, our molecular analyses of the Swiss B. bigemina isolate did not unequivocally track its geographical origin and the way of introduction remains obscure.

[Piroplasms of ruminants in Switzerland and zoonotic significance of Babesia]. / Piroplasmen der Wiederkäuer in der Schweiz und zoonotische Bedeutung der Babesien.

Piroplasms are tick-transmitted blood parasites belonging to the genera Babesia and Theileria. In western and southern Switzerland, B. divergens, a small Babesia species, has been known for a long time as a parasite of cattle. Recent investigations have revealed the autochthonous occurrence of this parasite also in central and eastern Switzerland. On the occasion of an outbreak of anaplasmosis in the canton of Grisons, however, B. bigemina, a large Babesia species, and Theileria of the buffeli/sergenti/orientalis species complex were for the first time identified; the epidemiology of these two piroplasms in Switzerland remains unknown until now. The recent identification by genetic analyses of B. divergens in wild ruminants contradicts the hitherto postulated strict host specificity of this Babesia species for cattle. B. divergens as well as the closely related Babesia spp. genotype EU1 have in single cases also been identified in splenectomized humans. The rodent babesia B. microti which causes a human infection that is considered an "emerging tick-borne disease" in the U.S.A., is widespread in rodent populations in Switzerland, but seems to be of minor relevance as zoonotic pathogen here. Reasons for this could be differences in virulence of the parasites or in the transmission by the respective tick-vectors on the two continents.