Our approach has two limitations. First, we assume that
all diarrhoea patients with stool specimens containing ipaH are
infected with Shigella species. It seems unlikely that ipaH at
this site is derived from organisms other than Shigella species,
but the presence of Shigella could indicate colonization and not
infection. Studies using the same laboratory methods failed to
detect ipaH in healthy volunteers from Bangkok (O. Sethabutr et
al., unpublished data, 2003) which makes colonization without