In Reply.—We agree with Drs Rosales and Kjolhede that fever may be the cause of reduced serum retinol concentrations during acute measles, and that this reduction may result from RBP acting as a negative acute-phase reactant. As we stated, our study "cannot establish whether low vitamin A levels cause or result from severe measles." This does not mean, however, that reduced retinol does not, in turn, increase the severity of illness in children with measles and other infections. Three controlled studies of vitamin A therapy in measles,1-3 as well as our observation that vitamin A levels are low in children with measles, support the hypothesis that measles may reduce vitamin A levels (eg, via fever and inflammation), and that these reduced levels may, in turn, increase severity of illness. As Rosales and Kjolhede note, we did not find more diarrhea or pneumonia in children with low retinol levels; however, since