[The ecology of ticks, tick-borne diseases and biological tick control in Baden-Württemberg]. / Ökologie von Zecken als Überträger von Krankheitserregern in Baden-Württemberg und biologische Zeckenbekämpfung.

Ticks and tick-borne diseases are of great significance for the health of humans and animals. However, the factors influencing their distribution and dynamics are inadequately known. In a project financed by the Baden-Württemberg Ministry of the Environment, Climate and Energy Industry, as part of the program BWPLUS, interdisciplinary specialists work together to determine the influence of weather, (micro)climate, habitat, land use, human activities, and the population dynamics of host animals on the distribution and abundance of ticks and the diseases that they transmit in Baden-Württemberg. The project comprises four modules: the large-scale distribution of ticks in Baden-Württemberg (module 1), detailed studies of host-tick-pathogen interaction in relation to the microclimate (module 2), and the spatial occurrence of important tick-borne pathogens (module 3). The fourth module involves the comprehensive analysis and synthesis of all data in order to determine the relative importance of the factors studied and to develop a risk model. Recently, intensive investigations into tick control have been undertaken using various entomopathogenic fungi and nematodes as well as a parasitoid wasp. Our aim was to determine whether these natural enemies could be used to effectively reduce the number of free-living ticks.

First evidence of Babesia gibsoni (Asian genotype) in dogs in Western Europe.

Canine babesiosis in Europe is generally caused by Babesia canis canis and Babesia canis rossi. Here we describe the first two autochthonous cases of Babesia gibsoni (Asian genotype) infection in Germany. Two American pit bull terriers showed clinical and hematologic signs consistent with babesiosis. Polymerase chain reaction (PCR) analysis of the 18S rDNA of blood samples revealed 486 bp fragments. The sequences were 100% identical to each other and 100% identical to Babesia gibsoni (Asian genotype). These results represent the first genetic evidence of Babesia gibsoni (Asian genotype) parasites in dogs in Western Europe.

[Importance of PCR for the diagnostics of canine babesiosis]. / Bedeutung der PCR in der Diagnostik der caninen Babesiose.

Clinical standards to confirm babesiosis in dogs include the direct identification of the infectious agent in blood smears and serological assays for Babesia canis-specific antibodies. Here, we demonstrate in seven cases (with data on anamnesis, clinics, laboratory diagnostics, and therapeutic outcomes) that a new diagnostic procedure is required. This is the molecular-genetic identification of babesia by real time PCR allowing an unequivocal identification of the infectious agents. Indeed, all seven patients presenting severe clinical symptoms were PCR-positive, but only two of them had specific antibodies and showed babesia in their bloodstream. Six of the dogs appeared to have acquired babesiosis while travelling abroad, and one in the Swiss canton of Schaffhausen.

Staphylococcus aureus food-poisoning outbreak associated with the consumption of ice-cream.

In April 2013, a food poisoning outbreak caused by staphylococcal enterotoxins (SEs) in ice-cream occurred in Freiburg, Germany, among the 31 participants of a christening party. Of the 13 cases, seven were hospitalized or obtained ambulatory treatment. Different types of ice-cream, which was freshly produced at the hotel where the party took place, were found to contain SE and high amounts of coagulase positive staphylococci. Enterotoxigenic Staphylococcus aureus strains isolated from ice-cream and human cases were of the same spa-type (t127), harboured the sea gene and displayed identical phenotypic resistance-, Fourier transform infrared spectroscopy- (FT-IR) and microarray-profiles. Despite the strong microbiological and epidemiological evidence of ice-cream being the incriminated food vehicle of the outbreak, a common source of S. aureus from the ice-cream could not be deduced. As none of the employees carried the outbreak strain, either the equipment used for the production of the ice-cream or a contaminated ingredient is the most likely introduction source.

Neotrombicula autumnalis (Acari, Trombiculidae) as a vector for Borrelia burgdorferi sensu lato?

Larvae of the trombiculid mite Neotrombicula autumnalis were collected at 18 sites in and around Bonn, Germany, to be screened for infection with Borrelia burgdorferi s.l. by means of PCR. Questing larvae numbering 1380 were derived from the vegetation and 634 feeding ones were removed from 100 trapped micromammals including voles, mice, shrews and hedgehogs. In a laboratory infection experiment, a further 305 host-seeking larvae from the field were transferred onto Borrelia-positive mice and gerbils, and examined for spirochete infection at various intervals after repletion. In three cases borrelial DNA could be amplified from the mites: (1) from a larva feeding on a wild-caught greater white-toothed shrew (Crocidura russula), (2) from a pool of four larvae feeding on a B. garinii-positive laboratory mouse, and (3) from a nymph that had fed on a B. afzelii-positive laboratory gerbil as a larva. In the first case, borrelial species determination by DNA hybridization of the PCR product was only possible with a B. burgdorferi complex-specific probe but not with a species-specific one. In the second case, probing showed the same borrelial genospecies (B. garinii) as the laboratory host had been infected with. In the latter case, however, DNA hybridization demonstrated B. valaisiana while the laboratory host had been infected with B. afzelii. Subsequent DNA sequencing confirmed much higher similarity of the PCR product to B. valaisiana than to B. afzelii indicating an infection of the mite prior to feeding on the laboratory host. The negligible percentage of positive mites found in this study suggests that either the uptake of borrelial cells by feeding trombiculids is an extremely rare event or that ingested spirochetes are rapidly digested. On the other hand, the results imply a possible transstadial and transovarial transmission of borreliae once they are established in their trombiculid host. However, unless the transmission of borreliae to a given host is demonstrated, a final statement on the vector competence of trombiculid mites is not possible.