GAME ANIMALS TO DISEASE IN AFRICA 13 
(ii) The trypanosome proved of inconstant virulence in the 
experimental animals. It was most virulent for 
mice, much less so for rabbits, cats, and monkeys. 
Transmission to rats was successful only in a few 
cases. Guinea-pigs were refractory. In dogs the 
parasites only of the first passage produced a fatal 
infection. 
(iii) Some of the experimental animals resisted infection, 
and were immune to later infections. 
In 1909 Leo Frobenius presented to the Zoological Gardens 
at Hamburg four ponies said to be immune to tsetse. Try- 
panosomes were found in one. Attempts to infect mice, rats, 
and guinea-pigs were unsuccessful. (It will be remembered 
that in the case of the pony from Togo the trypanosome was 
most virulent for mice. — R. B. W.) A dog was infected and 
died, and from its blood mice and rabbits became infected, but 
rats and guinea-pigs did not. A cat and a monkey which 
became infected recovered and are said to have become immune. 
The pony showed no signs of illness. (See 4 Sleeping Sickness 
Bulletin,’ No. 29, pp. 324-325.) 
There appears to be some evidence that Trypanosoma 
brucei or pecandi occurs in dogs in the Sudan as a natural 
infection (‘ Sleeping Sickness Bulletin,’ No. 33, p. 31). 
Trypanosoma brucei has also been made to infect certain birds, 
goose, kestrel, fowl (‘Sleeping Sickness Bulletin,’ No. 25, 
pp. 87-89). 
From the above summary it will be seen at once how very 
important domestic animals are in Africa as possible reservoirs 
of trypanosomes. 
It is also interesting to remember that trypanosomiasis, 
both human and of domestic animals, is not confined to 
Africa. 
The human trypanosomiasis of Brazil was discovered by 
Dr. Carlos Chagas when organising measures against malaria. 
The parasite Schizotrypanum cruzi is transmitted to human 
beings by a biting insect ( Conorrhinus megistus), which resembles 
the common bed bug in habits. It is also pathogenic for guinea 
pigs, rabbits, dogs, and monkeys. (See ‘ Sleeping Sickness 
Bulletin,’ Vol. 2, No. 16, p. 117.) 
