Hepatitis E
Hepatitis E is a liver inflammation caused by the hepatitis E virus (HEV), a positive-sense, single-stranded, nonenveloped RNA virus. It primarily spreads through the faecal-oral route, similar to hepatitis A.
HEV affects millions globally, with 28 million cases reported in 2013. It is one of five known human hepatitis viruses: A, B, C, D, and E.
Signs and Symptoms
Acute Infection
The incubation period for hepatitis E averages 40 days, ranging from 2 to 8 weeks. Symptoms include jaundice, fatigue, and nausea, though many infections are asymptomatic.
Symptoms coincide with elevated hepatic aminotransferase levels. Viral RNA is detectable in stool and blood during the incubation period, and serum IgM and IgG antibodies against HEV appear just before clinical symptoms.
Recovery is marked by virus clearance from blood and the persistence of IgG antibodies.
Chronic Infection
In immunocompromised individuals, such as those with solid organ transplants, hepatitis E can cause a chronic infection. This may lead to severe outcomes like fulminant liver failure or liver cirrhosis.
Other Organs
HEV can also affect other organs, leading to conditions such as acute pancreatitis, neurological complications (e.g., Guillain-Barré syndrome), glomerulonephritis, and severe thrombocytopenia.
Infection in Pregnancy
Pregnant women, particularly in the third trimester, face a more severe course of infection, with mortality rates of 20-25% in some outbreaks. Complications include preterm delivery, abortion, stillbirth, and neonatal death.
Virology
HEV belongs to the family Hepeviridae and genus Orthohepevirus. There are eight genotypes, with genotypes 1 and 2 restricted to humans and often causing large outbreaks in developing countries.
Genotypes 3 and 4 infect both humans and animals and are responsible for sporadic cases in both developing and industrialised nations.
Transmission
Hepatitis E primarily spreads through contaminated water, especially following heavy rainfall or flooding. Direct person-to-person transmission is uncommon.
Genotypes 3 and 4 can be transmitted zoonotically through contact with animals or consumption of undercooked meat. Domestic pigs and wild animals like deer are common reservoirs.
Diagnosis
Diagnosis relies on blood tests detecting HEV RNA or IgM antibodies. The viraemic window for detecting HEV RNA is about three weeks after symptoms begin.
In immunocompromised individuals, both IgM antibodies and HEV RNA tests are used to confirm infection.
Prevention
Sanitation
Proper sanitation, including treatment and disposal of human waste, safe water supplies, and good personal hygiene, is very important. Cooking meat at 71°C for five minutes kills the virus.
Vaccines
A recombinant vaccine, HEV 239, is approved for use in China but not in other countries. It has shown efficacy in preventing hepatitis E in trials.
Treatment
No specific antiviral drugs are established for hepatitis E. Ribavirin may be effective in treating chronic hepatitis E in immunocompromised patients.
Reducing immunosuppressive therapy can help clear the virus in transplant recipients.
Epidemiology
Hepatitis E causes about 20 million infections annually, leading to around three million acute illnesses and 44,000 deaths in 2015. Pregnant women are particularly at risk of severe complications.
Outbreaks are common in regions with poor sanitation, such as parts of Asia, Africa, and Central America. Increasing cases are reported in developed countries.
Recent outbreaks have occurred in Uganda, South Sudan, Nepal, and Namibia, highlighting the global health challenge posed by hepatitis E.
Self-assessment MCQs (single best answer)
What is the primary mode of transmission for hepatitis E virus (HEV)?
Which genotype of hepatitis E virus is most commonly associated with chronic infection in immunocompromised individuals?
Which population is at the highest risk of severe outcomes from hepatitis E infection?
What is the most common method for diagnosing an acute hepatitis E infection?
Which of the following is NOT a known complication of chronic hepatitis E infection?
What preventive measure is most important in controlling the spread of hepatitis E?
Which animal is considered a significant reservoir for genotypes 3 and 4 of the hepatitis E virus?
What is the recommended cooking temperature and duration to inactivate the hepatitis E virus in meat?
What is a common neurological complication associated with hepatitis E infection?
What percentage of acute hepatitis E infections are symptomatic?
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