TRANSMISSION OF OROYA FEVER 181 



it is simply looked upon as possibly belonging to a group of micro- 

 organisms intermediate, as perhaps are the spirochsetes, between 

 Bacteria and Protozoa, but with a decided leaning toward the 

 latter. 



Transmission. — The method of transmission of Oroya fever 

 is still in doubt, but it seems practically certain that some ar- 

 thropod acts as a transmitting agent. All the other parasites 

 of the group to which Bartonella belongs are transmitted by ticks, 

 but there is apparently no tick having habits compatible with the 

 occurrence of the disease. The Harvard expedition attempted 

 to obtain the development of Bartonella in a mosquito, Pha- 

 langomyia dehilis, which is common in the infected zones, but 

 without success. That the transmitting agent is a nocturnal 

 blood-sucker of very limited distribution but abundant within 

 its range is strongly indicated by the limitations of the disease 

 and by the fact that in many cases a single night in the infected 

 zone is sufficient for contracting it, whereas there is apparently 

 no danger a short distance from the infected zone, or within it 

 in the daytime. According to Townsend, who spent two years 

 investigating verruga (which he considers identical with Oroya 

 fever) the only arthropod which fulfills all the conditions is a 

 sandfly, Phlebotomus verrucarum, which is a very abundant 

 nocturnal blood-sucker apparently limited in its distribution to 

 the verruga zones. Townsend attempted experiments with the 

 transmission of the disease through the agency of this insect but 

 his results have not been generally accepted. Whether or not 

 Phlebotomus is instrumental in transmitting Oroya fever is a 

 matter which will have to be proved by further research but the 

 circumstantial evidence against the insect is strong. 



As pointed out by Townsend, the portions of Peru which are 

 haunted by Oroya fever and verruga have one of the most perfect 

 and healthful climates in the world and they would be ideal for 

 sanatoriums and resorts were it not for these diseases. It is to 

 be hoped that the diseases may soon be more thoroughly worked 

 out and gotten under control. However, if Phlebotomus is in- 

 strumental in the transmission of either, the hope of eradicating 

 them in the near future is slight, judging by the difficulties which 

 have been experienced in Mediterranean countries in controlling 

 these minute rock-breeding insects. 



