Hepatitis E: transmission, pregnancy and treatment

Hepatitis E is inflammation of the liver caused by the hepatitis E virus (HEV). In the vast majority of people it is an acute, self-limiting infection, meaning it clears on its own within a few weeks and leaves no lasting damage. The two situations that call for special attention are pregnancy, especially the third trimester, and people with a weakened immune system, in whom the infection can become chronic.

It is the most common cause of acute viral hepatitis worldwide. It spreads through the digestive route: in developing countries mainly through water contaminated with feces, and in developed countries mainly through eating undercooked pork or game meat. This article answers how it is transmitted, why it is dangerous in pregnancy, how it is diagnosed and when it needs treatment.

How is hepatitis E transmitted?

HEV is shed in the stool and enters the body through the mouth. There are several genotypes of the virus with different transmission patterns:

• Genotypes 1 and 2: found in areas with poor drinking-water quality in Asia, Africa and parts of Central America. They spread through contaminated water and cause outbreaks, often after rains or floods. They infect only humans.
• Genotypes 3 and 4: predominate in Europe, North America, Chile and other developed countries. They are a zoonotic infection, meaning one transmitted from animals. The main reservoir is the pig, along with wild boar and deer. Infection occurs from eating undercooked pork or game meat or raw cured products. These genotypes rarely spread from person to person.

HEV can also be transmitted through blood transfusions, which has led several countries to screen donors. Mother-to-child transmission during pregnancy is possible with genotype 1 and can cause severe hepatitis in the newborn.

What symptoms does it cause?

The incubation period is 2 to 8 weeks. When symptoms appear, they are those of any acute hepatitis and cannot be distinguished from hepatitis A:

• Jaundice (yellowing of the skin and eyes) and dark urine.
• Fatigue, loss of appetite, nausea and pain in the right upper abdomen.
• Low-grade fever and, at times, joint pain.

Many infections, especially with genotypes 3 and 4, run their course without symptoms or with complaints so mild they go unnoticed. HEV can also cause manifestations outside the liver, particularly neurological ones such as Guillain-Barre syndrome and other neuropathies.

Why is it dangerous in pregnancy?

This is the most important feature of hepatitis E. In pregnant women infected with genotype 1, especially in the third trimester, the disease can progress to acute liver failure (fulminant hepatitis), with a mortality that in some series reaches 20 to 25%. It also raises the risk of miscarriage, premature birth and death of the newborn.

This risk is concentrated in the regions where genotypes 1 and 2 circulate. With genotypes 3 and 4, typical of Chile and developed countries, the same severe behavior during pregnancy has not been observed.

When does it become chronic?

In a person with a normal immune system, hepatitis E always resolves. Chronic infection, with the virus replicating for months or years, occurs almost exclusively in immunocompromised people and with genotypes 3 and 4. The groups at greatest risk are:

• Organ transplant recipients on immunosuppressive drugs.
• People with advanced HIV infection.
• Patients on chemotherapy or treatments that weaken the immune system.

If left untreated, chronic hepatitis E can cause fibrosis and progress to cirrhosis within a few years, so in these patients it is worth detecting and treating early.

How is it diagnosed?

Suspicion arises from acute hepatitis with elevated liver enzymes (ALT and AST) and bilirubin, once more common causes have been ruled out. The diagnosis is confirmed with blood tests:

• Anti-HEV IgM antibodies: indicate a recent or ongoing infection.
• Anti-HEV IgG antibodies: appear later and reflect past contact with the virus. They can persist for many years.
• HEV RNA in blood or stool: detects the virus directly. It is the key test when chronic infection is suspected or in immunocompromised people, in whom antibodies may be unreliable.

What is the treatment?

In most cases no specific treatment is needed. Acute hepatitis E is managed with rest, good hydration and monitoring, avoiding alcohol and medications that overload the liver. The infection resolves on its own.

Drug treatment is reserved for two situations:

• Chronic hepatitis in immunocompromised people: the first step, when possible, is to reduce immunosuppression, which in many cases lets the body clear the virus on its own. If that is not enough, ribavirin is used for at least three months; in a landmark study it achieved sustained clearance of the virus in about 78% of transplant recipients.
• Acute liver failure: cases of fulminant hepatitis require hospitalization and, in the most severe ones, liver transplant is considered.

Can it be prevented?

Prevention is the main defense. When traveling to endemic areas, it is best to drink bottled or boiled water and avoid raw foods. In all settings, it is important to cook pork, wild boar and deer thoroughly, since heat inactivates the virus.

A recombinant vaccine against hepatitis E (Hecolin) exists and, in a large clinical trial in China, showed high efficacy and good tolerability. So far, however, it is only registered and available in China, so it is not part of vaccination programs in Chile or most countries.

See also

• Hepatitis A
• What is hepatitis?
• Types of hepatitis
• Jaundice
• Liver transplant