In verruga the initial fever may continue for weeks, or even for months. It is very severe in many instances. Often it exhibits features like those of a malarial infection, including intermittency, profound anæmia, and sometimes enlargement of the spleen and liver. Very probably in such cases it is the outcome of a double infection— verruga attacking a malarial subject. Not infrequently in the endemic district a certain type of fever, believed to be verruga fever, proves fatal before the appearance of definite skin manifestations such as would justify a positive diagnosis. This was apparently the case with Carrion. The symptoms in his case closely resembled those of the very deadly fever referred to, which is known locally as Oroya fever.
In addition to the severity of the fever and rheumatic pains, the Peruvian disease is remarkable for the tendency to spontaneous hæmorrhage exhibited by the skin lesions. Apparently this peculiarity is attributable, like the hæmorrhages in the affection known as " mountain fever," to the diminished atmospheric pressure at great altitudes; for when the patients descend to the lower valleys, or to the sea-level, the tendency to bleeding ceases. Possibly the unusual vascularity of the swellings, which are sometimes permeated by a network of cavernous sinuses, also arises from the same circumstance.
In yaws we find no mention made of the occurrence of fungating granulomata in any situation but the skin. In verruga it would seem that the tumours may develop on mucous surfaces— in the œsophagus, the stomach, intestine, bladder, uterus, and vagina. Hence the dysphagia— a common symptom— and the occasional occurrence of hæmatemesis, melæna, hæmaturia, and bleeding from the vagina in this disease. Relapses both of the fever and of the eruption may occur.
Mortality.— The mortality ranges from 10 to 40 per cent, of those attacked. The risk is very much lessened on the appearance of the eruption.
Treatment.— Salvarsan seems to exert a specific influence, but its exact value has not been determined.
