THE HEMOFLAGELLATES 



55 



the parasite may cause an acute, fatal 

 disease resulting in death in about 10 weeks, 

 or a chronic condition with recovery in 

 about a year, or a mild, almost asympto- 

 matic condition (Hornby, 1949). The dis- 

 ease is similar in sheep, goats, camels 

 and horses. Swine are more resistant. 



The signs of trypanosomosis due to 

 this species are similar to those caused 

 by other trypanosomes, except that the 

 central nervous system is not affected. 



Fiennes (1953) described the lesions 

 observed in untreated T. coiigolense in- 

 fections of cattle. The lymph nodes are 

 edematous, the liver is congested, the 

 marrow of the long bones is largely des- 

 troyed, and there are hemorrhages in the 

 heart muscle and renal medulla. In cattle 

 treated with antrycide or dimidium, the 

 lesions are more chronic. The spleen is 

 enlarged, the liver is swollen and some- 

 times fibrous, the lymph nodes are hyper- 

 trophied, edematous and somewhat fibro- 

 tic, the kidneys show chronic degenera- 

 tion, the hemolymph tissue is hyperplas- 

 tic, and the marrow of the long bones is 

 largely destroyed. 



Fiennes (1950), described a cryptic 

 form of trypanosomiasis in cattle, usually 

 following drug prophylaxis or unsuccessful 

 drug therapy, in which severe lesions 

 occur in the heart. These lesions were 

 associated with degenerate or lysed try- 

 panosomes, but some normal forms were 

 also present. This is probably similar to 

 the condition described by Curasson (1943) 

 and Reichenow (1952), in which masses of 

 degenerating trypanosomes plug the capil- 

 laries. 



Diagnosis : This disease can be diag- 

 nosed by detection of the parasites in blood 

 smears. Repeated examinations may be 

 necessary in chronic cases. Inoculation 

 of rats or guinea pigs may give positive 

 results when blood examinations are neg- 

 ative. 



Cultivation: Same as for T. brucei. 



T. vivax until after World War II. Several 

 drugs have been introduced since then, and 

 active research is still going on. The gen- 

 eral pattern has been similar. Each new 

 drug was introduced with glowing accounts 

 of its effectiveness, later its limitations 

 were discovered, and it was either dropped 

 or assumed its place in the trypanocidal 

 armamentarium while the search passed 

 on to a new field. The review articles 

 listed under treatment of T. brucei may be 

 consulted for further information, but 

 progress is being made so rapidly that both 

 they and some of the recommendations be- 

 low may soon be out of date. 



Ethidium is the most effective and 

 safest of several phenanthridinium deriv- 

 atives which have been used. Cattle are 

 treated by intramuscular injection of 

 1 mg/kg ethidium bromide or chloride. 

 The tiypanosomes disappear from the 

 blood within 2 days. The earlier phenan- 

 thridinium compounds caused photosen- 

 sitization and liver damage, but Ethidium 

 apparently does not. 



Antrycide methyl sulfate is also effec- 

 tive against T. coiigolense. Cattle are 

 treated with a single subcutaneous injection 

 of 4. 5 to 5.0 mg/kg, while 3 to 5 mg/kg is 

 used in horses and dogs. Antrycide causes 

 a painful local reaction when given subcu- 

 taneously, and may sometimes also cause 

 increased salivation, sweating and tremors. 

 In addition, there are a number of reports 

 of drug-fastness developing to antrycide. 



The diamidine, Berenil, has been used 

 with success in preliminary experiments, 

 but has yet to be completely evaluated. The 

 dosage for cattle is about 2 mg/kg subcu- 

 taneously or intramuscularly. 



The above recommendations deal with 

 curative treatment. A great deal of work 

 has also been done on chemical prophylaxis 

 of trypanosomosis. The idea here is to 

 inject drugs in relatively insoluble form so 

 that they will be released slowly over a 

 long period of time and will protect animals 

 for months. 



Treatment : No effective treatment 

 was known for either T. coiigolense or 



Antrycide chloride, which is much less 

 soluble than antrycide methyl sulfate, is 



