CANINE BABESIOSIS IN SOUTH-AFRICA - MORE THAN ONE DISEASE - DOES THISSERVE AS A MODEL FOR FALCIPARUM-MALARIA

South African canine babesiosis is caused by the virulent Babesia cani s rossi. In recent years, this common disease has been detected in 12% of dogs presented at the outpatients' division of the University of P retoria's (Onderstepoort) Veterinary Academic Hospital, and 31% of the affected dogs have been hospitalized as seriously ill. Of these hospi talized cases, 50% had severe anaemia at presentation, 32% had moderat e anaemia and 18% were non-anaemic (often polycythaemic), frequently w ith central-nervous-system signs or multiple organ failure. A retrospe ctive survey of 662 hospitalized cases revealed that the haematology, clinical biochemistry and patient profile (signalment) of the severely anaemic dogs were distinct from those of the non-anaemic, indicating that the babesiosis in these two groups of dogs should be viewed as tw o different diseases in terms of the postulated, underlying, 'pathomec hanisms'. The severely anaemic dogs exhibited hypoxic hepatic disease and an increase in serum urea without a concomitant increase in creati nine), seldom had profound electrolyte imbalances and tended to have a much more profound leucocytosis, consisting of a left-shifted inflamm atory leucogram, with higher numbers of circulating metamyelocytes, ly mphocytosis and monocytosis. In contrast, the non-anaemic dogs exhibit ed severe azotaemia (which could be of renal or pre-renal origin) and often showed a marked electrolyte disturbance (reflecting acid-base ab normalities) and a very mild leycocyte response; such dogs often prese nted as leucopenic, many being lymphocytopenic. These results indicate that the severely anaemic dogs had developed haemolytic disease (poss ibly immune-mediated), whereas the non-anaemic dogs had developed an a cute and overwhelming inflammatory response. The mean age of the non-a naemic dogs (2.66 years) was less than the dogs in the 'severe anaemia group' (0.83 years). Dogs belonging to the traditional fighting breed s (bull terriers, pit bull terriers and Staffordshire bull terriers) w ere noticeably over-represented in the non-survivors of the acute infl ammatory response group, possibly indicating an underlying genetic bas is for the different presentations. It is evident that the inflammator y-response disease presentation, which is similar to complicated falci parum malaria in humans, may serve as an animal model for that disease .