ECHO-13 virus was first obtained from rectal and throat swabs collected in the Philippine Islands in 1953. Isolations were made from 10 apparently healthy children. Serologic evidence of infection was obtained in 11 other individuals.
ECHO-13 virus, although not neutralized at a 1:25 dilution by a single pool of American gamma globulin, has been isolated recently in two cities of the United States. Since it is neutralized by Japanese gamma globulin, it is probably also present in Japan. Apparently both complement-fixing and neutralizing antibodies do not remain elevated for long periods of time after infection.1,3 This limits the usefulness of serologic surveys in quantitative studies of the geographic distribution of ECHO-13 virus and the significance of absence of detectable antibody in gamma globulin as a qualitative test for absence of the virus in a population.
Two patients hospitalized with CNS disease, one of whom was paralyzed, showed a significant serologic response only to type 13 ECHO virus during the course of their illnesses. CNS pathology was observed in two inoculated monkeys. These data, which may be interpreted as presumptive evidence that ECHO-13 may produce CNS disease in man, are too limited and incomplete to permit any definite conclusions to be drawn at this time; but the increasing evidence that a number of the ECHO viruses and the enteroviruses as a group do possess the potential of producing CNS disease3, 4, 8-18 lends more weight to the probability that an occasional human CNS illness is attributable to ECHO-13 virus. Isolations and serological rises from a few children during outbreaks of diarrhea in Pittsburgh also do not lend themselves to interpretation since several other viral agents were isolated from the feces of other patients. This report therefore can serve only to point suspicion to ECHO-13 virus as a pathogenic agent. It shows what may be expected in terms of virus isolation and serological responses during infection, spread within a family, some of the limitations of serologic survey and summarizes what is known regarding geographic and seasonal distribution.