Some characteristics of poliovirus strains isolated in Uganda between 1966 and 1971.

Sixty-five poliovirus strains were investigated in genetic marker tests in order to obtain information on the characteristics of polioviruses circulating in Uganda where, owing to the insufficient use of live poliovirus vaccine, poliomyelitis remained a serious public health problem. Of the type 1 strains predominant in both epidemic and non-epidemic years, 29 were studied for their antigenic fine structure. Based on their intratypic character, these strains proved to represent six different antigenic variants. Three of these variants were predominant during certain periods; the first variant was present in 1966 and 1968, the second in 1967, and the third from 1969 to the end of observation period. Four strains from Kuwait and three from Ghana isolated in 1969 and 1970 showed an antigenic structure identical to that of the strains predominant in Uganda in these years. Some strains proved to be of vaccine origin. Twenty-nine type 1 and 24 type 2 strains showed a great variety of characteristics when studied in d, od, and rct/40 marker tests. There was no indication that the distribution of strains according to their in vitro markers would have been different in epidemic and non-epidemic years, or that any particular combination of markers would have been more common among strains isolated from paralytic patients than among those from non-paralytic patients. Nine of 12 type 3 strains had the rct/40(+) marker.