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Global heating may spread hepatitis E

July 27, 2022

Hepatitis E is one of the least understood forms of the disease. For Hepatitis Day 2022, DW looks at why it affects the world's most vulnerable people.

Person walks with cattle in a flooded area of Bangladesh
Hepatitis E is common in countries like Bangladesh, where proper sanitation infrastructure is lacking and major flood events happen regularlyImage: Rashed Mortaza/DW

For people in rich industrialized countries like the US or Germany, our understanding of hepatitis is often confined to hepatitis B and C, which are usually spread through sex.

But for the billions of people living in parts of the world without proper sanitation, waterborne strains of hepatitis, such as hepatitis A and E, are much more common.

These forms of hepatitis — and hepatitis E especially — are largely transferred through water contaminated with fecal matter. Experts predict their spread will increase in the coming years as the climate continues to heat.

How hepatitis E spreads

Hepatitis E is most common in south and east Asia. In India, cases increase during monsoon months, which usually last from June to September. But hepatitis E is also a threat in some African countries.

Outbreaks typically happen in developing countries because of water contamination, when there is a shortage of water or an excess of water, such as after a flood, in areas with faulty sanitation.

"When you have a flood, the flood water can go into the sewers. And then when the floodwaters recede, you have sewage contamination. So, of course that water is contaminated with feces. That's a prime way to have transmission of hepatitis E," said Ayodele Majekodunmi, a researcher at the University of Ghana who has studied the spread of hepatitis E in sub-Saharan Africa.

But Majekodunmi added that hepatitis E can also spread in drought-like conditions.

"During dry weather, if the river recedes, you now have more concentrated water sources. Instead of everyone being able to take water from a flowing river, there are only a few pools left, and everyone is using those water sources. So, they get contaminated more easily," said Majekodunmi.

When a person becomes ill with hepatitis E, they will first show nonspecific symptoms, like a mild fever, reduced appetite, fatigue, nausea and vomiting.

Eventually, that person will likely develop jaundice — a yellowing of the eyes, skin and mucous membranes — which lasts anywhere from two to eight weeks. Almost all patients recover. 

Drought in Iraq
Hepatitis E outbreaks can occur after floods but also in drought areas when water sources become scarceImage: ASAAD NIAZI/AFP/Getty Images

More studies needed into the effects of climate change on waterborne illnesses

Researchers expect that flooding events will increase due to global warming.

But it is too early to definitively say whether climate change is already playing a role in the spread of hepatitis E, according to Rakesh Aggarwal, a professor in gastroenterology and medical sciences in Puducherry, India.

Aggarwal said studies still need to examine how increased global temperatures may or may not be causing an increase in hepatitis cases.

In fact, Aggarwal said that hepatitis E cases may have declined in the past 10-15 years in places like India and other countries, where the illness is endemic, but where people are getting better access to good sanitation facilities.

This isn't only the case for hepatitis E, but many waterborne illnesses across the world.

"They have declined because we are doing many things [to improve water supply]," said Aggarwal. "Would they have declined faster if climate change was not occurring? We can't say."

Hepatitis E infection rates may be higher than we know 

Some 20 million people are infected with hepatitis E globally each year. Those infections tend to lead to about 3.3 million symptomatic cases.

In 2015, the disease caused around 44,000 deaths. Although the death rate for young, healthy people is very low, it spikes to around 20% among pregnant women.

These rates are low in comparison with hepatitis B and C, which together caused over a million deaths in 2019, according to data from the World Health Organization (WHO).

But Ayodele Majekodunmi thinks infection rates could be much higher.

Through her research on the prominence of hepatitis E in sub-Saharan Africa, Majekodunmi found that in parts of Ghana, where no such survey had yet been done, the virus was endemic.

We need standardized hepatitis detection kits

Majekodunmi said that the global medical and pharmaceutical community pays little attention to hepatitis E, possibly because of its low spread in the developed world and relatively low mortality rate.

"Some diseases are simply considered more important, or 'sexier' than others," said Majekodunmi. "The big three are traditionally malaria, tuberculosis and HIV. If you work with any three of those, getting money for your research isn't a problem, but we have another group of diseases which disproportionately affect the poorest of the poor wherever they are found. And these tend to be waterborne diseases."

A small child walks through a refugee camp
Hepatitis E often spreads in places that lack sanitation and clean water, such as in refugee campsImage: Abdulnasser Alseddik/picture-alliance/AA

There is currently no "gold standard" kit for hepatitis E detection. That makes it more difficult for researchers and public health agencies in different countries to compare their results and understand how prevalent the virus is globally, said Majekodunmi.

Majekodunmi would like to see hepatitis E added to the WHO's list of neglected tropical diseases, which, she said, would stimulate funding into research surrounding the virus's ubiquity, origins and solutions to combat it.

People in poor living conditions still most at risk 

"Middle class people tend not to get hepatitis E, whether that's a middle class person in Germany or a middle class person in Nigeria," Majekodunmi said.

The disease is largely present in areas where living conditions are lowest, such as refugee camps, areas undergoing humanitarian crises and places vulnerable to catastrophic climate events.

"If everybody had access to good sanitation," Majekodunmi said, "the [number of infections with waterborne] diseases would plummet overnight."

Edited by: Zulfikar Abbany

Clare Roth
Clare Roth Editor and reporter focusing on science and migration