Babesia canis (B. canis subsp. canis, B. canis subsp. vogeli, B. canis subsp. rossi): Microscopic exam; Molecular diagnosis (PCR).
Babesia canis is a protozoan parasite of dogs, but they have also recorded isolated cases in humans. The disease is considered endemic in Europe, South Africa, Asia and America.
There are three subtypes of Babesia canis: Babesia canis canis, Babesia canis and Babesia canis rossi vogeli. These strains differ in virulence, geographic location and the tick vector, but are identical in appearance. The most pathogenic type, Babesia canis rossi, is endemic in South Africa. Babesia canis canis is located in Europe and some countries in Asia and is considered intermediate in pathogenicity. The less pathogenic and most common form in the US vogeli is Babesia canis.
The life cycle of this organism involves an intermediate host where it matures, usually ticks, which transmit the infection during feeding releasing sporozoites into the bloodstream of the dog. This transmission requires two to three days. Known vectors include Rhipicephalus sanguineus, Haemaphysalis bispinosa and H. longicornis. However, the disease can be transmitted through the exchange of needles for vaccinations, surgical material, blood or through direct contamination induced lesions in dog fighting. Babesia canis develops in erythrocytes of the host, which can be visualized as pyriform bilobed organisms that often occur in pairs and are approximately 4-5 .mu.m in length. Inside the red cell, the body Babesia canis is released from its outer coating and begins to divide, acquiring a new form called merozoite could be ingested by a new tick during feeding. After ingestion by ticks, Babesia canis sexual reproduction begins (gamogony), resulting in numerous sporozoites that accumulate in the salivary glands of ticks.
Clinical signs include lethargy, weakness, vomiting, fever, pale mucous membranes and dark colored urine. In addition, the disease can cause severe hemolytic anemia and thrombocytopenia life - threatening in young dogs. Also, other symptoms including neurological and respiratory signs may occur. In some dogs, clinical signs can be mild or unapparent, so it may be subclinical carriers, especially for Babesia canis vogeli. Although acute infection is associated with severe anemia and thrombocytopenia, many dogs survive the acute phase and become chronic carriers of the infection.