238 Arthropods as Essential Hosts of Pathogenic Protozoa 



showed that the so-called Brill's disease, studied especially in New 

 York City, is identical with the typhus fever of Mexico and of 

 Europe. 



The conditions under which the disease occurs and under which 

 it spreads most rapidly are such as to suggest that it is carried .by 

 some parasitic insect. On epidemiological grounds the insects most 

 open to suspicion are the lice, bed-bugs and fleas. 



In 1909, Nicolle, Comte and Conseil, succeeded in transmitting 

 typhus fever from infected to healthy monkeys by means of the 

 body louse (Pediculus corporis). Independently of this work, 

 Anderson and Goldberger had undertaken work along this line in 

 Mexico, and in 1910 reported two attempts to transmit the disease 

 to monkeys by means of body lice. The first experiment resulted 

 negatively, but the second resulted in a slight rise in temperature, 

 and in view of later results it seems that this was due to infection 

 with typhus. 



Shortly after, Ricketts and Wilder (1910) succeeded in transmitt- 

 ing the disease to the monkey by the bite of body lice in two experi- 

 ments, the lice in one instance deriving their infection from a man 

 and in another from the monkey. Another monkey was infected 

 by typhus through the introduction of the feces and abdominal 

 contents of infested lice into small incisions. Experiments with 

 fleas and bed-bugs resulted negatively. 



Subsequently, Goldberger and Anderson (19126) indicated that 

 the head louse (Pediculus humanus) as well, may become infected 

 with typhus. In an attempt to transmit typhus fever (Mexican 

 virus) from man to monkey by subcutaneous injection of a saline 

 suspension of crushed head lice, the monkeys developed a typical 

 febrile reaction with subsequent resistance to an inoculation of 

 virulent typhus (Mexican) blood. In one of the three experiments 

 to transmit the disease from man to monkey by means of the bite 

 of the head louse, the animal bitten by the presumably infected head 

 lice proved resistant to two successive immunity tests with viru- 

 lent typhus blood. 



In 1910, Ricketts and Wilder reported an experiment undertaken 

 with a view to determining whether the young of infected lice were 

 themselves infected. Young lice were reared to maturity on the 

 bodies of typhus patients, so that if the eggs were susceptible to 

 infection at any stage of their development, they would have every 

 opportunity of being infected within the ovary. The eggs of these 

 infected lice were obtained, they were incubated, and the young lice 



