Addressing hepatitis A, E transmission ‘crucial’ to prevent outbreaks, improve standards
Hepatitis A and hepatitis E are viral infections that primarily affect the liver and are transmitted through the fecal-oral route.
These infections are spread through contaminated food, water or direct contact with an infected person, making them a significant concern in settings where hygiene practices are compromised. These viruses become a significant public health issue, particularly in areas with poor sanitation, limited access to clean water and overcrowded living conditions.
Road ‘can be rough’ for some with HAV
Although we traditionally consider these to be infections limited to third world locations where exposure to contaminated food and water is more common, there have been recent HAV outbreaks recorded in the U.S., primarily caused by person-to-person transmission among people who use drugs and those experiencing homelessness.
Starting in 2016, the CDC tracked multiple outbreaks of HAV in several states, which led to an awareness campaign encouraging vaccination in vulnerable populations. Although there has been a 43% decrease in incidence from 2020 to 2021, HAV cases still remain four times higher than in 2015.
HAV is a vaccine-preventable infection, reminding us that we need to be proactive and vaccinate populations at risk. We also need to consider acute HAV as an explanation when an individual presents with symptoms such as fever, fatigue, abdominal pain, nausea, vomiting, diarrhea, joint pains or jaundice, or exhibit concerning blood work including elevated alanine aminotransferase, aspartate aminotransferase and bilirubin.
Although HAV does not result in a chronic infection, it can be debilitating in some people and has a mortality rate of approximately 0.1%, which means that although most people fully recover, the road to feeling good can be rough and every once in a while, someone dies. Older adults with chronic liver disease or those who are immunocompromised are at higher risk for liver failure, whereas children often lack symptoms but can surreptitiously transmit the infection to those around them.
In the U.S., the CDC advocates for vaccination in high-risk groups such as those who inject drugs or are experiencing homelessness, men who have sex with men and those who have recently been in jail or prison. The CDC also advocates for vaccination among people with liver diseases like cirrhosis, hepatitis B or hepatitis C, as they are at higher risk for developing serious complications from HAV infection during outbreaks.
HEV infection ‘not the same’ globally
Like HAV, HEV is an infection that is common in areas with poor sanitation. Although it is not considered a common cause for acute hepatitis in the U.S., a study using serologic tests collected by the National Health and Nutrition Examination Survey in two periods of time — 1988 to 1994 and 2009 to 2016 — found that HEV exposure was present in 21% and 6% of the U.S. general population, respectively.
However, HEV infection is not the same everywhere. Two different epidemiological scenarios have been described: transmission from contaminated drinking water, which is typical in tropical and subtropical regions and linked to HEV genotypes 1 and 2 (HEV-1, HEV-2), and zoonotic transmission of HEV genotypes 3 and 4 (HEV-3, HEV-4), often linked to ingestion of pork meat in resource-rich nations.
HEV-1 and HEV-2 present as acute or subclinical infection, whereas HEV-3 and HEV-4 are often asymptomatic but can lead to chronic infection in immunosuppressed individuals.
Although a study looking at HEV antibodies in Americans could not determine exposure, many cases of HEV in the U.S. involve people who have traveled to locations where HEV is common.
HEV is especially dangerous during pregnancy, as it can lead to acute liver failure and fetal complications such as miscarriage, stillbirth and premature birth. This is primarily described with HEV-1 in India, where infection can occur in epidemics.
Although vaccination is not available in most countries, there are several vaccine candidates being evaluated.
Increase awareness to minimize morbidity, mortality
Both HAV and HEV typically cause acute illness that resolves on its own, but they can also lead to severe complications, especially in vulnerable groups such as pregnant women and individuals with weakened immune systems.
Despite being preventable through vaccination and improved hygiene practices, these infections remain prevalent in many parts of the world. Understanding and addressing the transmission routes of these viruses is crucial for preventing outbreaks, improving global health standards and ensuring that vulnerable populations are protected from preventable diseases.
This month’s Healio Gastroenterology Exclusive addresses the presentation, prevention and management of HAV and HEV. With increased awareness, the morbidity and mortality of these infectious viruses can be minimized.
References:
- Clinical overview of hepatitis A. https://www.cdc.gov/hepatitis-a/hcp/clinical-overview/index.html. Accessed Feb. 26, 2025.
- Hepatitis A outbreak linked to person-to-person contact. https://www.cdc.gov/hepatitis/outbreaks/ongoing-hepatitis-a/index.html. Accessed Feb. 26, 2025.
- Hepatitis E basics. https://www.cdc.gov/hepatitis-e/about/index.html. Accessed Feb. 26, 2025.
- Pisano MB, et al. PLoS One. 2022:doi:10.1371/journal.pone.0272809.
For more information:
Nancy S. Reau, MD, FAASLD, AGAF, is the Richard B. Capps Chair of Hepatology, associate director of solid organ transplantation and section chief of hepatology at Rush University. She can be reached at nancy_reau@rush.edu.
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