Attempts to transmit Trypanosoma cruzi by means of two species of ticks, Ornithodoros talaje and O. venezuelensis, were undertaken as follows :
Four lots of O. talaje were fed on guinea pigs infected with T. cruzi and subsequently fed on 15 clean guinea pigs. Two of these latter animals died too early for the results to be determined but the other 13 remained negative. Some of these ticks were later macerated and injected into 6 clean animals but this procedure also failed to produce any infection. These negative results would indicate that this species of tick does not commonly transmit T. cruzi by means of its bite and also that if the trypanosome undergoes any development in this tick the infection in the latter does not persist for a very long period.
Several lots of immature and adult O. venezuelensis were fed on guinea pigs infected with T. cruzi and later fed on 20 clean guinea pigs. Three of these latter animals were hosts either for one lot of the ticks on two occasions or for two or more lots. No results were obtained from these ticks feeding on the animals. Some of these ticks were later macerated and injected into 7 guinea pigs and each animal became positive after incubation periods of from fourteen to twenty-two days. These results tend to show that although T. cruzi may develop and persist in O. venezuelensis for a period of more than six months this tick does not usually transmit the infection to its hosts through feeding on them.
I wish to extend my thanks and appreciation to Mr. Joaquin Benavides and Mr. Joseph J. Romanchek, laboratory technicians, for the considerable amount of valuable assistance they gave me in the carrying out of these experiments.