Failure of yellow fever immunization to produce a catabolic response in individuals fully adapted to a protein-sparing modified fast.

In previous studies, patients consuming a protein-sparing modified fast (PSMF) did not develop the expected increase in nitrogen excretion following incidental infectious illness. To assess the catabolic response with a controlled infection in such patients, 17-D yellow fever vaccine was administered to four young obese adults after 3 weeks of this hypocaloric regimen (PSMF), essentially carbohydrate-free and providing 1.5 g protein/kg ideal body weight. Average daily nitrogen excretion from the third week of the PSMF was compared to values from the week following immunization. Contrary to the experience with malnourished children being nutritionally rehabilitated or young adults fed an adequate calorie, low (0.1 g/kg body weight) protein diet, neither urinary nitrogen excretion nor nitrogen balance was significantly affected in the study group. In three of the four subjects in the group, average nitrogen balance was positive in the week pre-and post-yellow fever immunization. In individuals fully adapted to a PSMF the metabolic consequences of mild infection on nitrogen metabolism were reduced. This may be because the usual catabolic hormones, glucocorticoid and glucagon, which are elicited by infection fail to increase nitrogen excretion in fasting or whenever dietary carbohydrate is excluded.