Blastocystosis - Epidemiology

Epidemiology

Like other protozoal infections, the prevalence of Blastocystis infection varies depending on the area investigated and the population selected. A number of different species groups of Blastocystis infect humans, with some being reported to cause disease while others do not. To date surveys have not distinguished between different types of Blastocystis in humans so the significance of findings may be difficult to evaluate. Developing countries have been reported to have higher incidences, however recent studies suggest that symptomatic infection with Blastocystis may be prevalent in certain areas of industrialized countries as well:

• A nation-wide study conducted by the CDC using data reported from 1987 found the prevalence Blastocystis infection in the United States to be 2.6%. The study indicated that Western states, such as California, reported a higher prevalence.

• A 2000 study by a private laboratory of stool samples from 48 states in the United States identified a prevalence of 23%. The study was conducted by a laboratory in Arizona and emphasized Western states which have previously been found to have higher rates of Blastocystis infection.

• A Canadian study of samples received in 2005 identified Blastocystis as the most prevalent protozoal infection identified.

• A study in Pakistan identified Blastocystis infection in 7% of the general population and 46% of patients with irritable bowel syndrome. The study used stool culture for identification.