Introduction 

Hepatitis E virus (HEV) is a non‑enveloped, single‑stranded RNA virus predominantly transmitted via the fecal-oral route, especially through contaminated water and food. In many low- and middle-income countries, limited access to safe water, inadequate sanitation, and poor hygiene practices fuel widespread HEV outbreaks. Worldwide estimates suggest around 20 million new infections each year, resulting in millions of cases and approximately 40,000-70,000 deaths.⁷ Pregnant women, particularly in the third trimester, face elevated fatality risks as high as 20-50% in some epidemics,¹ making prevention a critical public health priority.

As no widely available antiviral therapy exists, effective control of HEV outbreaks hinges on hygiene, sanitation, and safe water interventions, collectively referred to as WASH (Water, Sanitation, and Hygiene).³

Transmission mechanisms of hepatitis e

Waterborne spread

In HEV genotype 1 or 2 endemic regions (e.g, parts of Africa and South Asia), contamination of drinking-water systems due to sewage leakages, inadequate treatment, or flooding frequently triggers large outbreaks.¹² In Dar Sila, eastern Chad, a large epidemic affecting thousands was tied to contaminated groundwater and poor water treatment practices.⁵

Overcrowding and sanitation failures

Overcrowded conditions, open defecation, and lack of proper sewage disposal elevate HEV transmission. These factors allow fecal pathogens to enter community water systems, especially during rainy seasons or in temporary settlements.¹²

Secondary and zoonotic transmission

While person‑to‑person transmission is rare in HEV genotype 1 outbreaks, certain household settings have documented possible secondary spread. Additionally, genotypes 3 and 4 in high‑income countries can move from animals (especially pigs) to humans via undercooked pork or wild game meat.¹¹ Still, in endemic regions, waterborne exposure remains dominant.

Key hygiene and sanitation interventions

Safe water supply and treatment

Ensuring the availability of treated, chlorinated drinking water is essential. During the 2016-17 outbreak in Am Timan, Chad, humanitarian actors implemented community chlorination and hygiene kit distribution. However, only 43% of households maintained adequate residual chlorine (≥0.2 mg/L), underscoring the need for proper water handling and storage education.⁶

The World Health Organization recommends a residual free chlorine level of ≥ 0.5 mg/L for 30 minutes to inactivate enteric viruses, including HEV.¹² Boiling, filtration, and proper container hygiene provide additional barriers in situations where chlorination is incomplete.

Improved sanitation

Isolation of human waste using functioning latrines or sewer systems reduces environmental contamination. Shared or poorly maintained latrines, or open defecation, significantly elevate outbreak risk.⁶ Refugee-camp outbreaks in Niger and Chad have repeatedly been linked to unsanitary latrine conditions in displaced settings.⁴

Hand hygiene with soap

Handwashing using soap and water is highly effective in removing fecal residues that could contain viral particles. In the Chad outbreak, households that reported constantly washing hands before meals had a lower risk of HEV infection (OR ≈ 0.33), though borderline significant.² Alcohol‑based sanitizers are not effective against non‑enveloped viruses such as HEV, so soap use remains vital.⁸

Food hygiene practices

Handling food safely is another critical measure. Contamination of produce or meats via polluted water or unhygienic practices can transmit HEV, particularly in regions where zoonotic genotypes circulate. Thorough cooking (≥ 70 °C) and clean food-handling facilities help reduce infection risk.¹¹

Real‑world evidence from outbreak responses

Chad, 2016-2017 (Am timan outbreak)

In this urban outbreak, MSF-led responses involved water chlorination, distribution of hygiene kits, and hygiene education. Despite high coverage (99% of households received kits), only 43% maintained safe chlorine levels. Households that refilled water containers promptly and used secure wells had higher rates of safe water storage.^6,9

Risk analyses showed that larger households and those with more children were more vulnerable to HEV infection. Cases were less likely to report consistent handwashing before meals (OR ~0.33), suggesting behavior change is crucial.²

Niger, 2017 (Diffa region displaced persons camps)

A major HEV outbreak in refugee camps was attributed to poor-quality drinking water, inadequate latrine infrastructure, and low hygiene standards. Out of nearly 1,917 suspected cases, 736 (≈ 38%) were confirmed via PCR or ELISA; mortality was 1.9%, with nearly 45% of fatalities occurring in pregnant women.⁴

Eastern chad (Dar sila), 2004-2008

As reported, repeated HEV outbreaks occurred in this region over several years under conditions of inadequate water treatment and sanitation. Water supplies frequently exhibited fecal coliform contamination, signaling ongoing environmental transmission potential.⁵

Why WASH interventions succeed in controlling HEV

Breaking the transmission chain: WASH measures directly prevent HEV contamination of water and food by interrupting fecal-oral pathways.

Cost-effective and rapid: Provision of chlorination, soap, latrines, and health messaging can begin within days, far faster than vaccine deployment.³

Community scalability: Simple behavior-change interventions (handwashing, container cleaning, safe latrine use) can be taught across communities, including literacy-light and culturally-tailored messaging.

Protection for vulnerable groups: Interventions especially benefit pregnant women and children in crowded settings, who face the highest risk of severe outcomes.⁸

Planning for effective implementation

Community engagement & behavior change communication

Success depends on engaging local leaders, using appropriate media (posters, radio, interpersonal outreach), and tailoring messages around key times: after defecation, before cooking/eating, before handling infants, and during water collection.

Infrastructure monitoring and maintenance

Chlorine residuals at water points should be periodically tested. Faulty pipelines, flooded latrines, or broken pumps must be addressed swiftly to avoid recontamination. Regular sweep teams and surveillance systems can help identify risks early.

Emergency preparedness and response

Preparedness plans should include prepositioned hygiene kits, chlorine tablets, latrine supplies, and pre-trained WASH response teams. These enable rapid scale-up when outbreaks strike. Integration with vaccination strategies (where available) should also be in place.

Vaccination: A complement

An effective HEV vaccine (Hecolin/HEV 239) is licensed and used in China. WHO supports its use during outbreaks in high-risk groups, particularly pregnant women, but only as a complement, not a substitute, for robust WASH interventions.¹

Limitations and challenges

Infrastructure gaps: In remote, conflict-affected, or flood-prone areas, building and maintaining a clean water supply and sanitation facilities can be difficult.

Cultural norms: Reluctance towards latrine use, misconceptions about hygiene, or poor adoption of soap use may limit effectiveness.

Resource constraints: Continuous monitoring, procurement of hygiene materials, and sustained health promotion require logistical and funding support.

Population density and displacement: High-density camps, informal settlements, and frequent population moves complicate maintaining hygiene standards.^4,6

Summary

Hygiene and sanitation are the most effective first-line defenses against HEV outbreaks in endemic regions. Access to safe water, proper faecal disposal, consistent hand hygiene, and food safety practices directly disrupt HEV transmission. These interventions are low-cost, community-driven, and rapidly deployable, critical in protecting high-risk populations, including pregnant women and residents of high-density settings.

Vaccination offers additional protection where available, but cannot replace WASH. Health systems, governments, and humanitarian agencies should prioritise robust hygiene and sanitation programs as foundational outbreak prevention and response strategies.