I570 



VERRUGA PERUVIANA 



due to a parasitic protozoon, and, indeed, there is no doubt about 

 the truth of this with regard to syphilis and with regard to rabies, 

 and it is quite possible that verruga peruviana will some day be 

 found to be of protozoan origin, thus confirming Raymondi's striking 

 conjecture. 



The study of the distribution of the disease in the various pro- 

 vinces of Peru, as detailed above, with the aid of a large-scale map, 

 will impress the reader with the similarity to the distribution of 

 Rocky Mountain fever, and will lead him to the conclusion that the 

 setiological cause must in some way be associated with some blood- 

 sucking animal, perhaps an arachnid; and, indeed, this is supported 

 by a fact well known— that the persons most prone to the infection 

 are those who work in the fields. Such ideas must, however, be 

 taken as mere suggestions, as at present there is no direct evidence 

 in favour of them. Very minute bacillary-like rods, thicker in the 

 middle than at the ends and variable in number, have been described 

 in the red cells by Barton, Gastiaburu, Rabagliati, and Biffi. They 

 become scanty after the eruption, and disappear during convales- 

 cence. Similar bodies have been seen by De Vecchi, Bassett-Smith, 

 and Martin Mayer. De Vecchi considers them to be products of 

 degeneration. 



Strong, Tyzzer, Brues, Sellards, and Gastiaburu's experiments 

 would point to the virus being a filterable one, and inoculable in 

 monkeys. Inoculated in the testes of the dog and rabbit it induces 

 characteristic changes. As already stated, these authors believe 

 that the disease is not connected with Oroya fever, which, according 

 to them, is due to Bartonella bacilliformis (p. 502), and is not inocul- 

 able infmonkeys. 



Age, sex, and race appear to have no influence, though it has been 

 asserted that the coloured races have a partial immunity, which 

 is due to mild attacks at a very early age, as nearly every inhabitant 

 in the towns of the endemic areas acquires verruga, and if reinfected 

 has only a very mild attack, for, as a rule, an attack confers a 

 lasting immunity. Strangers visiting an endemic area are attacked 

 almost at once with the disease in its gravest form. The disease 

 may be acquired by travelling through an endemic area, but there 

 is much more risk of infection if a night is spent therein, and if the 

 endemic zone is quitted before sunset the risk of infection is greatly 

 diminished. Another important point is that newly-born infants 

 may acc^uire the disease. Cole has made some inoculation experi- 

 ments in monkeys with a certain degree of success. 



Pathology. — As the causation is unknown, the account of the 

 pathology must be limited to very few remarks. There has been 

 great doubt as to whether verruga can be transmitted to animals by 

 inoculation, though Odriozola related that he inoculated a bitch with 

 the blood from verruga lesions obtained from a post-mortem, with 

 the result that the animal developed a typical skin eruption, and 

 eventually died. The disease is said to occur naturally among 

 animals — e.g., horses, mules, asses, dogs, and fowls — ^but especially 

 among quadrupeds, although Monge states that no one has definitely 



