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Development and validation of a multiplex, real-time PCR assay for Babesia rossi and Babesia vogeli

Canine babesiosis is caused by tick-transmitted intraerythrocytic protozoan parasites occurring worldwide. In southern Africa, babesiosis is caused by Babesia rossi and B. vogeli and is one of the most common and important infectious diseases affecting dogs. There is no reliable, rapid and sensitive method for the detection of these parasites, especially when parasitaemia is low. The aim of this study was to develop a sensitive and specific multiplex TaqMan® MGB PCR assay for the diagnosis of canine babesiosis infections occurring in southern Africa, and to discriminate between Babesia rossi and B. vogeli. The fitness of purpose of the assay was to confirm diagnosis of suspect or clinical cases, and estimate prevalence of infection for research purposes. A total of 648 published sequences were used to design the assay. A set of group-specific canine Babesia spp. primers were designed to amplify a 117 nucleotide region of the 18S rRNA gene of all canine Babesia spp. Species-specific TaqMan® MGB probes were developed for B. rossi, B. vogeli, B. canis and B. gibsoni, but analytical validation was only performed for B. rossi and B. vogeli as a multiplex assay. The assay had a broad dynamic range and amplified B. rossi and B. vogeli efficiently (98.6% and 94.7% respectively). The assay was sensitive, with a 95% LOD of 10^-2.67% parasitized erythrocytes (PE) for B. rossi and 10^-2.03% PE for B. vogeli, and specific, with no cross reaction between B. rossi and B. vogeli and no detection of other haemoparasites that infect dogs, such as Ehrlichia canis and Anaplasma platys. Consistent repeatability within and between PCR runs was shown. This assay will be able to accurately and rapidly confirm babesiosis in canines and allow for treatment to be administered in the early stages of the disease, speeding up the recovery time in affected dogs.

First molecular detection of Babesia canis in dogs from Bosnia and Herzegovina

Babesia spp. are tick-transmitted protozoan haemoparasites of great economic, veterinary and medical impact worldwide. Herein we reported the very high prevalence of autochthonous babesiosis in symptomatic dogs from Bosnia and Herzegovina in the period from 2014 to 2016. Eighty dogs that did not leave the country were examined using parasitological and molecular analyses and babesiosis was diagnosed in 82.5% and 85.0% of them, respectively (p < 0.001). One species, Babesia canis was identified using molecular methodology (PCR and sequence analysis). Statistical analyses showed that epizootiological characteristics have no influence on the possibility of infection. Agglomerative hierarchical clustering (AHC) analyses used for comparing the symptoms and clinical signs of infection in dogs pointed out that a high degree of anemia, followed by thrombocytopenia (89%), lethargy (100%), loss of appetite (95%), fever (66%) and icterus (61%) was dominant. In addition, results of the statistical analysis performed showed that more dogs with no data of tick prophylaxis (70%) were found Babesia infected. Those results point to further intensified epizootic surveys in the territory of Bosnia and Herzegovina.

Molecular evidence of natural infection with Babesia canis canis in Croatia

The aim of the present study was to detect and characterise the species and subspecies of Babesia spp. that cause canine babesiosis in Croatia. Twenty-eight dogs with typical signs of babesiosis (lethargy, anorexia, fever, dark urine and thrombocytopenia) were included in this study. Their blood smears showed the presence of Babesia canis . The results showed the detection of one subspecies, namely Babesia canis canis using PCR, and subsequent sequence analysis demonstrated portions of the nss rRNA gene in 27 out of 28 samples. Sequence analysis of the isolates showed 100% identity in 11 samples, 99.7% identity (one nucleotide difference) in 11 samples and 99.4% identity (two nucleotides difference) in 5 samples with B. canis canis . The results of this study confirm the presence of B. canis canis in infected dogs in Croatia and demonstrate a slightly new genetic variant of Babesia subspecies.