To the Editor.
—I have read with great interest the report by Wannamaker which appeared in the September issue of the American Journal of Diseases of Children (124:352-358, 1972). In this article, the author emphasized the importance of developing new reliable methods for recognition of streptococcal infections, mainly for estimating the risk of complications. An accurate diagnosis cannot be made by other than laboratory means, since the clinical manifestations are not specific. Unfortunately the throat culture and the other laboratory procedures, although essential for the diagnosis, are of unsatisfactory predictive value.Recently a simple cytochemical method, based on the decreasing myeloperoxidase (MPO) activity of peripheral blood leukocytes, has been proposed as a diagnostic aid for detection of streptococcal diseases in the acute phase.1,2 Two hundred thirty blood samples from healthy subjects and patients with acute bacterial and viral diseases, and 42 from patients with streptococcal infections recognized by laboratory