There is a general lack of information on the occurrence of specific non-O157 STEC serotypes in persons with HUS and diarrhoea, by population and in relation to other enteric pathogens. Surveillance Surveillance for isolates of non-O157 STEC and surveillance for cases of HUS provide complementary data. Surveillance for HUS is easier and more complete because patients are hospitalized and the diagnosis of HUS does not depend on stool culture. With regard to isolates of non-O157 STEC, a basic amount of laboratory information needs to be collected in order to maximize the isolates' usefulness for surveillance purposes.
Most countries now rely on the latter.
The only area where non-O157 STEC have been isolated less frequently than O157 in recent studies of diarrhoea is North America, where they are isolated about half as frequently as O157. In any given location, however, non-O157 STEC may be either one of the most frequently isolated pathogens from diarrhoeal stools or one of the least frequently isolated. Among the over 200 non-O157 STEC serotypes, those in serogroups O26, O103, O111 and O145 are most commonly isolated from humans and are clearly recognized as human pathogens. Thus, at present, the most important non-O157 STEC serogroups, from an epidemiologic perspective, are O26, O103, O111 and O145. Table 1 shows the non-O157 STEC serotypes that have been isolated from humans.