To the Editor.—The case report, "Paralytic Poliomyelitis in an Unimmunized Child: Apparent Result of a Vaccine-Derived Poliovirus" by Cesario and others (Amer J Dis Child118:895, 1969) is a careful report of clinical and laboratory studies with factual material with which no one could disagree.
A 5-year-old child developed clinical polio, was found to have type 2 in his stool, and antibodies rose against the strain. Quite acceptably the patient had type 2 poliomyelitis.
Laboratory tests showed that the isolate, by way of Wecker and temperature markers, was a "vaccine-like" strain. His sister also harbored a fecal infection which was type 2 but showed marks of an "intermediate strain (which)... was possibly a vaccine derived strain." One may justifiably conclude that with intimate household exposure the virus isolates were identical even though they had different marker characteristics; it is unlikely that the type 2 viruses were simultaneously acquired