IN A COUNTRY as large as the US, with so many different geographical areas and socioeconomic groups, it is probably unwise to give a prevalence figure of Entamoeba histolytica for the general population. However, since the prevalence rate has been frequently cited to be 10 to 20%, it is well to state that it is more likely around 5%. Although it is possible that the incidence of E histolytica is declining in the US, this lower appraisal of the prevalence results from accepting the so-called small race E histolytica as a separate species ( Entamoeba hartmanni ) and from considering primarily survey results of the general public.1
E histolytica has been found throughout the US wherever careful examinations have been performed, but the rates vary from place to place and even from group to group within the same general locality. For example, on Indian reservations in five different states the prevalence rate was found to range from 1.5% to 33%2 and in the vicinity of Little Rock, Ark, it ranged from 1% to 6% in four separate yet fairly close communities.3 Therefore, for a given community or population group, it is not satisfactory to assume a particular prevalence rate until a careful survey has been performed.
Brooke MM. Epidemiology of Amebiasis in the US. JAMA. 1964;188(6):519–521. doi:10.1001/jama.1964.03060320041009
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