310 



THE PIROPLASMASIDA 



range up to 15fi or even 27/1. Two types 

 are recognized: Macroschizonts, which 

 contain chromatin granules 0.4 to 1.9/i in 

 diameter and produce macromerozoites 

 2.0 to 2.5/1 in diameter; and microschi- 

 zonts, which contain chromatin granules 

 0.3 to 0.8 fi in diameter and produce mi- 

 cromerozoites 0. 7 to 1.0 /i in diameter. 



Life Cycle : The vectors of G. annu- 

 lala are Hyalu»i»ia delritum (syn. , H. 

 mai(relaniciuii) in North Africa and the 

 USSR, H. Irioicatum in parts of Africa, 

 H. dyuniedarii in Central Asia, H. ex- 

 cavalHDi (syn. , H. aimtuliciiui), H. turan- 

 iciDu (syn., //. rufipes glabmm) and H. 

 marginaliDii (syns. , H. savig)iyi, H. 

 aegypliuiit) in Asia Minor, and H. mar- 

 ginatum in India. Transmission is stage- 

 to-stage in all cases, and not thru the egg. 

 Ray's (1950) and Kornienko and Shmyreva's 

 (1944) claim of passage thru the egg has 

 been disproved by Delpy (1949) and Daubney 

 and Sami Said (1951). 



The life cycle of G. a)undata has been 

 studied in H. detritum by Sergent et al. 

 (1936). They admitted that they found no 

 stages which could be identified as macro- 

 gametes or microgametes and that they 

 saw nothing which could be recognized as 

 fertilization, but they nevertheless believed 

 that these must be present and called the 

 subsequent stage a zygote. According to 

 their account, the forms ingested by the 

 tick are gametocytes. These form gametes 

 in the tick's intestine, and the gametes in 

 turn give rise to zygotes. The zygotes 

 enter the intestinal epithelial cells, encyst, 

 and remain in the lumen of the intestine 

 for 6 to 8 months until after the nymphal 

 tick has hibernated and molted to the adult 

 stage. (//. detrition is a 2-host tick, with 

 the larva and nymph on one host and the 

 adult on the other. ) At this time they leave 

 the cyst and enter the salivary gland acini, 

 where they penetrate the gland cells and 

 turn into sporonts. These give rise to 

 sporoblasts in 3 or 4 days, and the sporo- 

 blasts in turn produce a multitude of sporo- 

 zoites which break out of the cells, enter 

 the salivary ducts and are injected into a 

 new host when the tick feeds. This life 

 cycle is similar to that described by Cow- 

 dry and Ham (1932) for T. parva, and is 

 subject to the same criticisms. 



Pathogenesis : Tropical gonderiosis 

 is similar to East Coast fever in most 

 respects. The mortality varies consid- 

 erably, from 10% in some areas to 90% 

 in others. It is about 20 to 40% in Algeria, 

 up to 90% in enzootic regions of the USSR 

 and 13 to 23% in indigenous calves in India. 



The incubation period following tick 

 transmission is 9 to 25 days, with a mean 

 of 15 days. The disease itself lasts 4 to 

 20 days, with a mean of 10 days. Per- 

 acute, acute, subacute, mild and chronic 

 forms have been described. The acute 

 form is the usual one. The first sign is 

 fever, the body temperature rising to 104 

 to 107° F. The fever is continuous or 

 intermittent, and persists for 5 to 20 days. 

 A few days after it begins, other signs 

 appear. These include inappetence, ces- 

 sation of rumination, drooling, serous 

 nasal discharge, lachrymation, rapid 

 heart beat, weakness, decreased milk 

 production and swelling of the superficial 

 lymph nodes and of the eyelids. Marked 

 anemia develops in a few days, and there 

 may be hemoglobinuria. Bilirubinemia 

 and bilirubinuria are always present. 

 Diarrhea appears, and the feces contain 

 blood and mucus. The conjunctiva is 

 icteric and may bear petechial hemor- 

 rhages. Affected animals become greatly 

 emaciated, and their erythrocyte count 

 may drop below 1 million per cu mm. 

 Death, if it comes, usually occurs 8 to 

 15 days after the onset. 



In the peracute form of the disease, 

 the animals may die in 3 or 4 days. In 

 the subacute form, the fever is usually 

 irregularly intermittent and lasts up to 10 

 or 15 days, after which the animals usually 

 recover; pregnant animals sometimes 

 abort. In the chronic form, intermittent 

 fever, inappetence, marked emaciation 

 and more or less anemia and icterus may 

 persist for 4 weeks or longer, but it may 

 take 2 months before the animals return 

 to normal; in some cases, the acute form 

 may suddenly supervene and the animals 

 may die in a day or two. In the mild form, 

 little is seen but mild fever, inappetence, 

 listlessness, slight digestive disturbances 

 and lachrymation lasting a few days. 

 There may be moderate anemia. 



