Hepatitis is a severe disease of the liver. Damage to the liver can be self-inflicted from drugs or alcohol, or can be caused by viruses. Hepatitis E is one of the 5 main types of hepatitis known to be caused by a virus. 

Symptoms of hepatitis E can overlap with many other diseases of the liver. Luckily, there are many different ways to distinguish hepatitis E from other liver diseases. By documenting common findings from hepatitis E patients, clinicians can diagnose individuals much faster. 

Overview of hepatitis E

Hepatitis refers to inflammation caused to the liver tissue (hepatic tissue) from an illness or self-inflicted methods. Hepatitis E is one of the 5 types of hepatitis caused by a specific virus. The hepatitis E virus can spread through contaminated waters; the incidence of hepatitis E cases is highest in countries with poor sanitation and low access to clean water, with approximately 20 million people being infected each year. It is usually young adults (aged 15-40) who become infected with Hepatitis E, but for pregnant or immunocompromised individuals, an initial infection could become a chronic infection.¹

The incidence of Hepatitis E is rising in middle-to-high income areas, thought to be from specific strains of the virus that spread between animals. These zoonotic strains of the virus can spread through raw or undercooked meats, and have contributed to infection ‘’hotspots’’ in previously unaffected areas, putting more individuals at risk of being infected with Hepatitis E.² Therefore, it is important to identify and diagnose viral hepatitis quickly to prevent any outbreaks, and identify the source of the virus to prevent more people from becoming infected. 

Symptoms of hepatitis E 

Following infection, you may not present with symptoms. Asymptomatic individuals may not know they are infected, and their immune systems may remove the virus from their bodies with ease. 

In symptomatic cases, individuals infected with Hepatitis E may present with a range of symptoms including:

• Jaundice, or the appearance of skin (and sometimes the whites of the eyes) looking yellow 
• Abdominal pain on the upper right of the abdomen, nausea or vomiting, or a general feeling of sickness, mild fever

Ways to identify liver damage

For those who do not present with physical symptoms, a range of tests can be performed to help identify or eliminate the liver as the source of the health problems. This can be done through liver function tests or imaging technology.

What are liver function tests?

Liver function tests are a series of blood tests used by clinicians to assess the working function of the liver. They can be used to identify areas of liver damage based on elevations of key enzymes needed for detoxification purposes in the liver. Common liver tests and their abbreviations include:

AST 

Aspartate transaminase (AST) is an enzyme needed to break down certain proteins. This enzyme is usually present inside cells; therefore, if levels of AST are elevated in the blood, this can indicate cell damage. AST is found in many parts of the body, not just the liver; therefore, AST alone should not be used to determine liver damage.

ALT 

Alanine aminotransferase (ALT) is another enzyme needed to break down certain proteins. Unlike AST, ALT is found in high amounts in the liver cells. Therefore, elevated ALT levels in the blood can more specifically indicate liver tissue damage. 

Bilirubin 

Bilirubin is the waste product created when our body breaks down red blood cells. One of the functions of the liver is to take this bilirubin and remove it from our body in the form of bile. Bile is an important component of digestion and helps our digestive system function normally. If there is elevated bilirubin in our blood, this indicates that our liver is not working as it should be and that there is an underlying problem. Becoming jaundiced is one physical indication of having excess bilirubin. Pale stools and dark urine can also be linked to the pigment of bilirubin. 

What are liver imaging tests?

As well as blood tests, imaging tools can be used to accurately identify the areas of liver damage. These tools can be helpful in combination with blood tests to better inform clinicians on the state of your liver and can help direct them to the appropriate treatments. Examples of imaging tools used include:

CT scans 

A computerised tomography (CT) scan uses X-rays and special computer technology to create cross-sectional images of the body. CT scans create much more detailed images than singular X-ray images, so they are far more advantageous to use in a medical setting. CT scans can provide images of both soft and hard tissues of the body, and are useful in both bone and blood vessels. A CT scan can be used to identify evidence of fatty liver tissue, and if any of the ducts of the gallbladder are blocked, which could contribute to the onset of jaundice. 

MRI scans 

A magnetic resonance imaging (MRI) scan uses a strong magnetic field and radio waves to create high-resolution images of soft tissues. MRI has some advantages compared to  CT scans, namely not delivering high doses of radiation to the individual, and being able to generate higher quality images that can provide more detail about the health of the liver. MRI scans are particularly useful in identifying liver tumours, and liver-specific image contrast agents can be used to identify small damage to the liver. ³

Ultrasound 

Ultrasounds work by using sound waves to create images of our internal organs. When the sound waves reach an internal organ, the waves can bounce and echo, which is then transformed into an electrical current. This can be used to generate an image or a sonogram, which can be interpreted in real time. Whilst ultrasound can create 2D images, like those used during pregnancy check-ups, 3D ultrasound images can be created too. Ultrasound images are far more practical than CT or MRI imaging techniques as it is non-invasive, cheap, and free from radiation. A specific branch of ultrasound called elastography can be used to assess the stiffness of the liver tissue. This information can be used to assess if patients have liver fibrosis, a hardening of liver tissue following liver damage and an indicator of more serious liver disease.

These imaging tools have become very important to help with the diagnosis of liver disease for patients and ensure they receive the appropriate treatment. 

How does hepatitis E affect imaging and liver function test results?

Elevations of ALT, AST and bilirubin are common laboratory findings in those infected with hepatitis E. Levels of these biomarkers can remain high for 6 weeks post-infection.⁴ However, these laboratory findings can overlap with other forms of hepatitis and abnormalities of the liver. Therefore, imaging results can help form a clearer understanding of the specific diagnosis for the patient.

CT and MRI scans can show swelling of liver tissue, indicating inflammation has taken place following hepatitis infection. Ultrasound can show high echo intensity areas if the liver is very fatty. In cases of late-stage severe hepatitis, fluid can appear in images as black, flat structures and is indicative of severe liver damage.⁵ Imaging tools can also be used to identify blockages to duct systems, and can help to pinpoint the cause of jaundice in patients. If the hepatitis E virus has damaged too much liver tissue, cells can die, and this dead tissue can be seen as low-density tissue, appearing dark on CT scans. 

Summary

Hepatitis E is a severe disease that commonly affects people in low-sanitation areas. Whilst some people who become infected do show no symptoms, other infected individuals may become very ill and uncomfortable during the infection period. By understanding how hepatitis E affects liver tests and imaging results, such information can be used by clinicians to help you receive the correct treatment.