Parasites of red blood cells: Babesia and Mycoplasma (Proceedings)
• Protozoal disease (genus: Babesia) of dogs and cats where merozoites (piroplasms) infect RBCs• Degree of illness is usually dependent on the severity and rate of anemia development.
• Anemia mainly as a result of immune mediated hemolysis but also due to direct piroplasm damage to RBCs.
• Infection (by tick transmission, transplacental, blood transfusion, or, in the case of B. gibsoni, by bite wounds presumably by blood from infected dog entering a bite wound.) followed by 2 week incubation period during which piroplasms infect and multiply in RBCs, resulting in RBC damage mainly from immune mediated processes but also direct RBC lysis.
• In the case of Rhipicephalus sanguineus tick, larvae, adults and nymphs can all transmit infection; ticks need to be attached for several days; in ticks, the parasite reproduces by sexual reproduction; ticks can be infected by eating a blood meal or by transovarial means.
• Large (4 – 7 µm): B. canis distributed worldwide; 3 sub-species based on biologic, genetic and geographic distribution:
o B. canis vogeli – USA, Africa, Asia, Australia. Transmitted by R. sanguineus ticks, so disease found in southeastern, southern states, and California.
o B. canis rossi - Africa (most virulent sub-species)
o B. canis canis – Europe, areas of Asia
o Small (2 – 5 µm): several genetically distinct sub-species:
o B. gibsoni – world-wide distribution (especially Asia) including the USA.
o B. conradae – (California – genetically distinct from B. gibsoni) – infects only dogs and only reported in California.
o B. microti-like – Spain, but recently reported in a Pit Bull terrier dog from Mississippi (unknown if this is a local case or imported).
o Theileria annae – (Spanish dog piroplasm). Reported in Spain and Europe.
• Small (2 – 5 µm) – B. felis reported in Africa.
• History of tick attachment.
• History of recent dog bite wound may be a risk for B. gibsoni infection.
• Any age or breed of dog can be infected.
• Severity of disease – depends on the strain of the organism, and the age and breed of the animal.
• B. canis infections - more prevalent in Greyhounds (USA).
• B. gibsoni infections - more prevalent in American Pit Bull, Staffordshire, and Tosa Inu breeds.