To check for hepatitis E virus, the saliva test does almost as well as the routine blood test. It also requires less logistics.
- Globally, 20 million people are infected with hepatitis E every year.
- 56,000 cases are fatal.
- Women are particularly exposed to complications: 30% of deaths after infection, against 1% in the general population.
- Hepatitis E most often manifests as acute inflammation of the liver. The rare fulminant forms threaten the survival of the patient.
A simple saliva sample will soon be enough to detect hepatitis E. This is the promise of the School of Public Health at Johns Hopkins University (United States). Its researchers are behind a saliva test that identifies the virus. According to their first study, published in the Journal of Immunological Methods, this system is almost as effective as the classic blood test.
The saliva test developed in the United States relies on a different system from those which analyze blood samples. In both cases, antigens can detect the antibodies associated with the viral infection. But instead of being attached to a solid surface, they are attached to fluorescent microbeads.
A test in Bangladesh
This increased circulation allows, on paper, to encounter more antibodies in a liquid like saliva. It still had to be confirmed in practice. To do this, the scientists collaborated with doctors from a center in Dhaka (Bangladesh), often called upon for hepatitis E.
141 patients provided blood and saliva samples. Among them, 76 were seen for symptoms suggestive of hepatitis E. The others had been referred to the establishment for other reasons. The body fluids of all of these participants were examined with both a blood test, using the ELISA method, and the saliva test.
At the end of the experiments, the effectiveness of the two approaches is very similar. The ELISA technique detected 50 past hepatitis E infections and 17 current cases. Within the asymptomatic group, 28 past infections were also reported. The saliva test does almost as well. He only makes mistakes on two past infections and four ongoing infections.
Inadequate sanitary facilities
If the results are confirmed, a real alternative to blood tests is emerging. Because currently, only two methods can diagnose an infection with the hepatitis E virus: a blood test or a test of feces – which looks for genetic material.
But these approaches pose a problem in countries where access to health care is difficult. This is precisely the case in the areas most affected by hepatitis E. India, Pakistan, Nepal, Bangladesh and certain regions of Africa concentrate the majority of diagnoses.
The first cause of the cases lies in the poor implementation of sanitary facilities. Poorly – if not – isolated from the drinking water system, soiled by contaminated faeces. While most of the time the infection resolves spontaneously, 56,000 deaths occur each year. Women are particularly vulnerable, since the death rate is 30%.
Less logistics
Rapid detection of hepatitis E cases is therefore essential. However, “the surveillance of epidemics and the reduction of the rates of contamination by hepatitis E are limited by the obstacles which arise in the diagnosis”, underlines Christopher Heaney, last author of the study. Proposing a simplified device could remove some of the limits.
Unlike the blood test, its saliva alternative does not require personnel trained in the handling of biological fluids, protection of samples against heat or the tools necessary for the disposal of used syringes. Enough to considerably simplify logistics. It remains to develop a device simple enough for deployment in the field.
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