822 THE FLAGELLATA 



8. Trypanosoma cruzi. 1 



Schizotrypanum cruzi. 



When engaged upon an anti-malarial campaign in the State of Minas Geraes 

 in Brazil in 1909 Chagas encountered a large biting insect known to the 

 inhabitants as Barbeiro. This insect which belongs to the Reduviidce (Con- 

 orrhinus megistus) is about an inch or more long and lives in cracks in the walls 

 or ceilings of human dwellings from which it only emerges in the darkness. 

 Chagas dissected some of these bugs and found crithidial-like flagellates in 

 the hind gut. A number were sent to Cruz who fed them upon a small striped 

 monkey (Callithrix penicillata). Three to four weeks later trypanosomes of 

 unusual appearance were found in the monkey's blood. Chagas' attention 

 was now drawn to a disease affecting chiefly children of which the symptoms 

 were extreme anaemia, enlargement of the superficial lymphatic glands, 

 oedema, enlargement of the spleen and functional disturbances especially of 

 the nervous system with frequent occurrence of actual imbecility. 2 In the 

 peripheral blood of one of these cases Chagas found a trypanosome which was 

 identical with that seen in laboratory animals infected with Conorrhinus 

 megistus. 



Experimental inoculation. Monkeys (Callithrix), dogs, rabbits, and guinea- 

 pigs are all susceptible to infection ; Callithrix and guinea-pigs being more 

 susceptible than dogs and rabbits. The disease can be reproduced either by 

 inoculation or by allowing infected bugs to feed upon the animal. 



Guinea-pigs die in 5 to 10 days. In the majority of cases the trypanosome 

 is not found in the peripheral blood but in the lungs. 



In inoculated monkeys (Callithrix) trypanosomes appear in the blood in 

 about a week. The animals survive six weeks or so. 



Morphology. Staining reactions. For staining blood films Chagas used 

 Giemsa's solution or Rosenbusch's stain. 



Rosenbusctis stain. Fix the films whether spread with blood or with the water 

 of condensation from blood-agar tubes before they are quite dry in Schaudinn's 

 perchloride solution in the cold. Wash in 50 per cent, alcohol then in water. Treat 

 for at least 1 hour and a half in 3 '5-5 per cent, iron alum. Stain for 5 minutes or 

 more in the following solution : 



1 per cent, solution of hsematoxylin in 96 per cent, alcohol. 

 Saturated aqueous solution of carbonate of lithium. 



Add the latter to the former until a wine colour is obtained. 



Differentiate with a very dilute solution of iron alum (this operation must be 

 watched under the microscope). Wash, dehydrate and mount in balsam. 



In the peripheral blood. In the peripheral blood the parasite may be 

 within the red cells, partly within the red cells, merely attached to the red 

 cells by the blepharoplast or may be free in the plasma. The parasites exhibit 

 a sexual dimorphism. The so-called male parasites are relatively slender, have 

 an elongated nucleus, a strikingly large blepharoplast and often exhibit a 

 second mass of chromatin in front of the nucleus. The so-called female 

 parasites are somewhat short and squat, the blepharoplast is situated termin- 

 ally or very near the end and the nucleus consists of a loose mass of chro- 

 matin. These appearances are very similar alike in man, monkeys and guinea- 

 pigs. 



In the lungs. Multiplication does not take place in the circulating blood. 

 In the lungs certain multiplication forms are seen which Chagas regards as 



1 This section has been added. 



2 The symptoms, and especially the dropsy and nervous symptoms which precede 

 death, are so like the symptoms of ankylostomiasis that the disease is known locally 

 as Opilacao and Canguarythe names given to ankylostomiasis. 



