High genetic diversity of Babesia canis (Piana & Galli‐Valerio, 1895) in a recent local outbreak in Berlin/ Brandenburg, Germany

Abstract

Canine babesiosis caused by Babesia canis (Piana & Galli-Valerio, 1895) is emerging in new regions in Europe since its vector Dermacentor reticulatus (Fabricius, 1794) is expanding its geographic range. In the Berlin/Brandenburg area in northeast Germany, D. reticulatus is highly abundant but in the past only one autochthonous B. canis infection was reported. Since 2015, autochthonous cases were occasionally diagnosed but numbers increased since autumn 2019. The aim of the study was to genotype autochthonous canine Babesia spp. infections from Berlin/Brandenburg.Between 04/2015 and 01/2022, 46 dogs with acute babesiosis were presented to the small animal clinic (one dog was infected twice resulting in 47 samples). There were 32 dogs that had never left Berlin/Brandenburg and 14 others that had not left the region in the 6 weeks prior to disease onset. PCRs targeting the 18S rRNA and the Bc28.1 merozoite surface antigen were positive in 47 and 42 samples, respectively. Sequencing of cloned PCR products identified all samples as B. canis with 17 18S rRNA and 12 Bc28.1 haplotypes. Based on network analysis for 18S rRNA sequences and a previously described polymorphic dinucleotide, samples were assigned to two distinct clusters. One contained 31 and the other 16 samples. Using network analysis, the Bc28.1 haplotypes could also be separated into two clusters differing by at least five polymorphisms. Analyses of sequences from multiple clones indicated the presence of up to five 18S rRNA and eight Bc28.1 haplotypes and thus high parasite variability in an individual host. The genetic diversity could suggest that the parasites in the region have multiple origins, but diversity in individual dogs and dog populations from endemic regions is unknown. The suitability of both markers for genotyping is questionable due to potential intragenomic diversity for the rRNA and high intergenomic variability for the Bc28.1 marker.

Autochthonous Babesia canis infections in 49 dogs in Germany

“…Polymerase chain reaction testing for detection of the 18S rRNA gene of piroplasm was positive in all dogs, and sequencing showed 99.47 to 100% identity with other sequences of B. canis from GenBank (Accession number ON152329‐ON152375). 16 Seventeen different genotypes were identified, with all cases from 2015 attributable to a single genotype.…”

Update and prognosis of Dermacentor distribution in Germany: Nationwide occurrence of Dermacentor reticulatus

“…In contrast to D. marginatus, D. reticulatus was collected throughout the winter months (December to February), confirming winter activity of this tick species. The seasonal pattern of D. reticulatus activity in Germany is paralleled by the occurrence of autochthonous canine babesiosis cases, which have become particularly frequent as of 2019 ( 12 , 13 ), emphasizing the need of year-round tick-protection.…”

“…Further studies on increasing endemisation of Babesia canis , e.g., by pathogen screening in Dermacentor ticks, are highly desirable, as are studies to unravel the role of D. reticulatus as a driver of TBEV spread in Germany. Given the currently reported increasing numbers of autochthonous canine babesiosis cases ( 12 , 13 ) in conjunction with the nationwide D. reticulatus occurrence and its activity during winter or the colder months, which complements that of Ixodes ricinus , a year-round tick protection of especially dogs all over Germany is strongly recommended. Furthermore, dogs entering Germany should be screened for B. canis infection to prevent establishment of further transmission foci due to importation of the pathogen.…”

“…This tick species plays an important role in veterinary medicine due to its vector function for Babesia canis , the piroplasmid parasite responsible for potentially fatal babesiosis in dogs ( 11 ). An increase in canine babesiosis cases has indeed been observed, e.g., in Poland, the United Kingdom and Germany, and linked to the expanded distribution of D. reticulatus ( 3 , 12 – 14 ). Furthermore, local D. reticulatus populations in the Netherlands have recently been incriminated in autochthonous transmission of Babesia caballi and Theileria equi , the causative agents of equine piroplasmosis ( 8 ).…”

Genetic Diversity of Babesia canis Strains in Dogs in Lithuania

“…B. canis genotypes 18S rRNA-A (GA nucleotides) and 18S rRNA-B (AG nucleotides) occur in European countries at different rates of prevalence [ 17 , 26 ]. In the previous studies conducted in Lithuania, the 18S rRNA-A genotype was identified in 50% and 34.2% of B. canis sequences originating from D. reticulatus ticks and dogs, respectively [ 7 , 15 ].…”