THE PIROPLASMASIDA 



301 



diameter. They generally contain a vac- 

 uole. Multiple infections of the erythro- 

 cytes are common. In addition, masses 

 of 30 to 100 "merozoites" have been des- 

 cribed for Raiigelia vitalii (a synonym of 

 B. caiiis) in the endothelial cells of the 

 lungs and kidneys. However, these were 

 much more likely agglomerations of or- 

 ganisms in the small blood vessels. 



Life Cycle : The life cycle has been 

 described above (p. 287). The vectors 

 are Rltipiceplialus scaigiiineus thruout the 

 world, Dermacentor marginalus (syn. , 

 D. reticulati(s), D. pictiis and I>. veiiiis- 

 tus in Europe, D. pictiis and Hyalomina 

 margiiiatum in the USSR, and Hae)na- 

 pliysalis leaclii in South Africa. Trans- 

 mission takes place thru the egg in all but 

 D. pictiis, and stage-to-stage in this spe- 

 cies, R. sanguineus and H. leaclii. 



Pathogenesis : The severity of in- 

 fections with B. canis varies considerably 

 with the strain. In some localities it is a 

 comparatively mild disease, while in 

 others it may be highly pathogenic. Both 

 young and old dogs are susceptible. In 

 countries where the disease is endemic, 

 the indigenous dogs usually become in- 

 fected while young and do not suffer such 

 a severe disease, while the mortality is 

 high among imported dogs. 



The incubation period is 10 to 21 days 

 in naturally infected dogs. The first sign 

 of disease in acute cases is fever. This 

 is quickly followed by marked anemia, 

 with icterus, inappetence, marked thirst, 

 weakness, prostration and often death. 

 Hemoglobinuria is sometimes but not 

 usually present. 



In chronic cases the fever is not high 

 and seldom lasts more than a few days 

 and there is little icterus. Anemia is 

 severe, and the dogs are listless and be- 

 come very weak and emaciated. 



Canine babesiosis is protean in its 

 manifestations, and may take on many 

 different clinical forms. Involvement of 

 the circulatory system may produce edema, 

 purpura and ascites; there may be stoma- 

 titis and gastritis; and involvement of the 

 respiratory system causes catarrh and 



dyspnea. Keratitis and iritis are seen if 

 the eyes are affected, and myositis and 

 rheumatic signs if the muscles are in- 

 volved. 



Central nervous system involvement 

 causes locomotor disturbances, paresis, 

 epileptiform fits, etc. (Malherbe and 

 Parkin, 1951; Malherbe, 1956). A cere- 

 bral form of the disease was described by 

 Purchase (1947) in which parasites were 

 rare in the blood but abundant in the brain 

 capillaries. This tendency to clog the 

 capillaries is common to many species of 

 Babesia. In cerebral babesiosis the signs 

 may be confused with those of rabies. 



In South America, the disease is 

 called nambiuvu, meaning "bloody ears" 

 in the Guarani language. As the name 

 suggests, it is a hemorrhagic disease. 

 There is bleeding from the edges of the 

 ears and from the muzzle, particularly 

 in young dogs in summer. There are also 

 internal hemorrhages. 



The spleen is enlarged, with dark red, 

 soft pulp and prominent splenic corpuscles. 

 The liver is enlarged and yellow, with 

 pathological changes ranging from conges- 

 tion to centrilobular necrosis (Gilles, 

 Maegraith and Andrews, 1953). The heart 

 is pale and yellowish. The kidneys are 

 yellowish, and show considerable nephro- 

 sis or nephritis histologically. The mus- 

 cles are pale and yellow, and the fat and 

 mucous membranes may be yellowish. 

 There may be a variable amount of fluid 

 in the pleural, pericardial and peritoneal 

 cavities. Small hemorrhages are some- 

 times present on the heart, pleura, bron- 

 chi and intestines. There is less icterus 

 in chronic than in acute cases. 



Immunity : Recovered animals re- 

 main infected in a state of premunition. 

 This persists for life if they are kept in 

 an endemic area, but the parasites die 

 out in a year or more in the absence of 

 reinfection. 



Diagnosis : In endemic areas, symp- 

 toms of fever, anemia, and icterus, with 

 or without hemoglobinuria, are suggestive 

 of canine babesiosis. The diagnosis can 

 ordinarily be confirmed by finding the 



