Specialist laboratories may achieve detection using cell culture and complex extraction methods, but techniques currently available are not suitable for routine application and recovery rates remain poor. Methods currently used for routine detection of SRSVs in faeces are based on electron microscopy. In order to achieve detection at least one million virus particles per gram of faeces need to be present, and so only faecal samples obtained within 48 hours of the onset of symptoms are suitable for examination for SRSVs. A recently developed PCR test is more sensitive than electron microscopy and is able to detect SRSV in vomitus and in faeces up to 7 days after onset of symptoms. Detection of Hepatitis A virus in faeces by electron microscopy is usually not possible, because by the time jaundice occurs the peak of excretion of virus particles has passed.
Diagnosis is based on detection of specific IgM and IgG antibodies in the blood serum or saliva.
They are highly resistant to chilling, freezing, preservatives and ionising radiation. Hepatitis A virus is rapidly destroyed by heating at temperatures above 85 deg C and it is likely that SRSVs are also inactivated at this temperature. Inactivation of viruses occurs at temperatures above 65 deg C at a rate proportional to the temperature but also depends upon the composition of the medium. They are also resistant to alcohol and high sugar concentrations. They should not return to work until at least 48 hours after cessation of symptoms.