Babesiosis due to the canine Babesia microti-like small piroplasm in dogs - first report from Portugal and possible vertical transmission

Parasitemia with small piroplasms was detected by microscopy in two dogs. All three dogs were positive by PCR and the Babesia microti-like small piroplasm (syn. Theileria annae) was identified by DNA sequencing. These are the first confirmed cases of babesiosis caused by the B. microti-like piroplasm both in dogs from Portugal and in dogs suspected of clinical piroplasmosis outside of Spain.Although the bitch and the male had visited neighboring Galicia (northwestern Spain), where the disease is endemic, incursion of this piroplasm into northern Portugal is evident and infection of the non-traveled pup was due to either vertical transmission or autochthonous tick infection.Species of protozoa from the Babesia and Theileria genera (order Piroplasmida) infect dogs in many parts of the world and cause important diseases known as babesiosis or piroplasmosis [1]. The etiological agents are transmitted by ixodid tick vectors [2], although transmission via blood transfusion [3] and the placenta [4] have been reported for some babesial species and dog to dog transmission of B. gibsoni by dog bites is strongly supported by epidemiological evidence [5-8]. Canine babesiosis may range from being sub-clinical to severe and fatal, depending on the virulence of the pathogen species or strain [9] and also on the susceptibility of the individual host as related to its age, immune status and concurrent infection or illness [1,10]. Lethargy, anorexia, pale mucous membranes, hyperthermia, hemoglobinuria, splenomegaly, hemolytic anemia and thrombocytopenia are clinical manifestations frequently described in dogs suffering from piroplasmosis [11,12].The size of their pear-shaped intraerythrocytic stages (piroplasms) has traditionally been used for the identification of Babesia species in dogs: large forms of Babesia canis (3-5 μm) and small Babesia gibsoni (0.5-2.5 μm). Additional criteria, especially molecular techniques, have further differentiated several "large" or "small" agents of