Prevalence and Incidence of Entamoeba histolytica
Outbreaks of Entamoeba histolytica:
The most dramatic incident in the USA was the Chicago World's Fair outbreak in 1933 caused by contaminated drinking water; defective plumbing permitted sewage to contaminate the drinking water. There were 1,000 cases (with 58 deaths). In recent times, food handlers are suspected of causing many scattered infections, but there has been no single large outbreak.
MMWR 34(9):1985: In October 1983, the Los Angeles County (California) Department of Health Services was notified by a local medical laboratory of a large increase in the laboratory's diagnoses of intestinal amebiasis (Entamoeba histolytica infection). Thirty-eight cases were identified from August to October. The laboratory staff estimated that, before August, they had diagnosed approximately one E. histolytica infection per month. A preliminary investigation failed to identify a common source of the infection. Morbidity and Mortality Weekly Reports For more information on recent outbreaks see the CDC.
(Source: FDA Bad Bug Book)
About prevalence and incidence statistics:
The term 'prevalence' of Entamoeba histolytica usually refers to the estimated population
of people who are managing Entamoeba histolytica at any given time.
The term 'incidence' of Entamoeba histolytica refers to the annual diagnosis rate,
or the number of new cases of Entamoeba histolytica diagnosed each year.
Hence, these two statistics types can differ:
a short-lived disease like flu can have high annual incidence but low prevalence,
but a life-long disease like diabetes has a low annual incidence but high prevalence.
For more information see about prevalence and incidence statistics.