First report of Cytauxzoon sp. infection in Germany: organism description and molecular confirmation in a domestic cat

Cytauxzoonosis is described as an emerging tick-borne disease of domestic and wild felids caused by protozoans of the genus Cytauxzoon. While in the Americas the condition is described as a fatal disease, in Europe, reports on the clinical expression of the infection are scarce. This study describes the first case of Cytauxzoon sp. infection in Germany, in a domestic cat. A 6-year-old male domestic cat living in Saarlouis (Saarland) was presented with anorexia, lethargy and weight loss. The cat had an outdoor lifestyle and had not travelled abroad. Serum clinical chemistry analysis revealed azotaemia with markedly increased symmetric dimethylarginine, hypercreatinemia, hyperphosphatemia and hypoalbuminemia. Moreover, a mild non-regenerative anaemia was present. Approximately 1 year prior to these findings, the domestic cat was diagnosed with a feline immunodeficiency virus (FIV) infection. These results pointed toward a decreased glomerular filtration rate, presumably as a result of kidney dysfunction. Round to oval signet ring–shaped intraerythrocytic organisms, morphologically suggestive for a piroplasm, were revealed during blood smear evaluation with a degree of parasitaemia of 33.0%. PCR analyses and sequencing of a region of the 18S rRNA gene confirmed the presence of a Cytauxzoon sp. infection, with 99–100% nucleotide sequence identity with previously published Cytauxzoon sp. isolates. As this is the first molecularly confirmed Cytauxzoon sp. infection in a domestic cat in Germany, these findings suggest that cytauxzoonosis should be considered as a differential diagnosis in cases of anaemia in outdoor domestic cats, particularly in areas where wild felid populations are present.