TRYPANOSOMIASIS 219 



monest in Africa, because of the prevalence of the 

 tsetse fly in whose body the protozoa are transmitted. 

 The bite of these flies becomes infective for the well 

 three days after biting the affected, and continues 

 so for about four or five weeks. These pests bite 

 during the daytime, so that protection and screening 

 of houses is insufficient usually to guard against dis- 

 ease. Of course the infected persons as well as the 

 healthy must be protected from insects. Inasmuch 

 as it is thought that some species of trypanosomas in 

 the blood of the lower animals are infective for man, 

 strict quarantine is placed on animals within countries 

 where this disease exists, and upon exported specimens. 



When the protozoa come into the blood they are 

 carried throughout the body and lodge chiefly in the 

 lymph glands, an enlargement of which is an early 

 sign of infection. When the disease is well settled 

 we see progressive anemia, weakness, and sleepiness, 

 whence comes the name u sleeping sickness." The 

 end comes from profound anemia and prostration. 

 Pains and dropsical collections are common. The 

 disease lasts a varying time. The early stages are 

 slow, but w T hen the great depression begins it usually 

 progresses rapidly to a fatal end. The changes pro- 

 duced are those of obstruction to the lymphatic system 

 and low-grade chronic inflammations. The micro- 

 organisms are_ present in the blood, all organs, including 

 the lymph glands, and the cerebrospinal fluid. From 

 all these places they may be recovered in making a 

 diagnosis. 



Trypanosomas are irregular, elongated, twisted 

 bodies with a large nucleus variously placed, and a 



