While the parasites are present in great numbers in severe cases they may be very scarce in mild forms of the disease.
Very striking is the rapidly developing anaemia which frequently shows a red cell count of less than a million within a few days. Normoblasts are quite numerous and fulminating cases show numerous megaloblasts.
Polychromatophilia and poikilocytosis are noted.
In the red cells we have the picture of a rapidly developing pernicious anaemia The color index is above 1.
The leucocytes number about 20,000 of which 60 to 70% are neutrophiles. Immature neutrophiles, as the metamyelocyte, are very common.
Prophylaxis and Treatment
The transmitting agent not being known we are in the dark as to prevention. Evidence points to some arthropod biting at night as the incidence of the disease decreased when those working in the Oroya fever zone were compelled to leave the valleys before sundown. The treatment is largely one of nursing although some have reported favorably from the intravenous administration of salvarsan.
VERRUGA PERUVIANA
General Considerations
Verruga peruviana is an infectious eruptive disease, caused by an unidentified virus, lasting two or three months, and characterized by successive eruptions exhibiting two types of lesion,—the miliary and the nodular,—both of which show a pronounced tendency to ulceration and haemorrhage. The eruption of verruga somewhat resembles that of yaws and it was at one time suggested that verruga was simply yaws as influenced by high altitude. Strong and his colleagues found that they could infect rabbits intratesticularly and that lesions resembling those of man could be produced in dogs and monkeys by cutaneous and subcutaneous inoculations. The virus has been transmitted from monkey to monkey. The monkey is not as susceptible to the virus as man and the rabbit and dog less so. Inoculation of the monkey is not followed by a generalized eruption. The Wassermann reaction was negative. In extracts from the granulomatous lesions they found a very active haemolysin. It will be remembered that animals are not susceptible to Oroya fever blood inoculations.