Studies on Macaca mulatta infected with Rocky Mountain spotted fever.

Abstract : Acid-base alterations and changes in other selected serum constituents (free fatty acids, triglycerides, cholesterol, copper, cortisol, alpha sub 1-acid glycoprotein, haptoglobin and albumin) were measured during a study in 16 male rhesus monkeys to determine the median lethal dose (LD50) of Rocky Mountain spotted fever (RMSF) rickettsiae. The LD50 in monkeys of the yolk-sac-grown seed stock was 10 to the 1.35th power plaque-forming units. Blood samples were taken from unanesthetized monkeys conditioned to repeated handling. Arterial pH increased and pCO2 decreased in monkeys during the febrile period. Free fatty acids, triglycerides, copper, cortisol, alpha sub 1-acid glycoprotein and haptoglobin increased, whereas albumin decreased during the disease. No significant changes were observed in arterial pO2. Cholesterol remained unchanged. The increase in arterial pH and decrease in pCO2 indicated that respiratory alkalosis was present in monkeys acutely infected with Rickettsia rickettsii.