Saliva test offers easier, cheaper diagnoses of liver disease

A newly developed "oral fluid" test could offer an easier, less expensive alternative for diagnosing liver disease and may eventually help develop treatment, researchers say.

Hepatitis E virus (HEV) causes liver disease that infects an estimated 20 million people worldwide each year and kills more than 56,000.

Hepatitis E is not as well known as the other viruses that cause hepatitis, an acute or chronic inflammation of liver tissue, said lead author Christopher D. Heaney, PhD, associate professor at Johns Hopkins Bloomberg School of Public Health in the US.

Currently, the only way to test for both recent and past hepatitis E is through a blood or stool test.

However, the new saliva test is simple and accurate and does not require specially trained personnel for collection, the need to protect samples from heat, and sanitary disposal of needles -- factors essential in a blood test, and affect timely diagnosis, Heaney said.

The new saliva test uses a different platform in which antigens are attached to fluorescent beads, which can circulate more easily through a liquid, potentially encountering more antibodies to a disease if they are present in saliva. 

It also allows for testing of a number of different antigen targets within the same saliva sample, thus one could test for multiple different infections in a single saliva sample, the researchers said, in the paper published in the Journal of Immunological Methods. 

The findings also showed that the saliva test scored high as far as sensitivity and specificity -- important indicators of a test's accuracy -- as well as nearly matched the performance of the blood test widely used to assess recent or past HEV infections.

For past infection, sensitivity and specificity for the saliva test were 98.7 per cent and 98.4 per cent respectively, while for recent infection, sensitivity and specificity were 89.5 per cent and 98.3 per cent respectively.