An echovirus (previously written ECHO, or enteric cytopathic human orphan) is a type of enterovirus. There are several different serotypes of echovirus known to infect humans.
In the United States, ARUP Laboratories and Cambridge Biomedical offer a serum microneutralization assay that is designed to measure the concentration of serum antibodies to five serotypes of the virus; 6, 7, 9, 11, and 30. This specific assay has been shown to be sensitive for detection of chronic infections in ME patients. A persistent fourfold or greater rise in antibody titer is often found in these patients, which is not often found in healthy controls.
A complement fixation assay for echovirus serotypes is available in the United States from LabCorp and Quest Diagnostics, however this specific type of assay has not been found to be sensitive for the chronic infections found in ME patients.