Biological properties of the pathogen
The pathogen is a small, non-enveloped RNA virus characterized by high stability in the external environment. It remains viable when frozen for years, withstands room temperature in a dried state for several weeks, and is resistant to acids and fat solvents (ether, chloroform).
To inactivate the virus, boiling (more than 5 minutes), autoclaving, ultraviolet exposure (1 minute), or chemical disinfectants (e.g., 70% ethanol) are used. In the human body, the virus replicates exclusively in hepatocytes. Unlike many other viruses, it does not destroy the cell directly. New viral particles are excreted into the bile ducts while the hepatocyte remains viable and can function for up to one year.
Epidemiological profile
The disease is a strict anthroponosis—humans are the sole source of infection. Patients with mild, anicteric, and latent forms pose the greatest threat regarding spread due to the absence of overt symptoms.
Routes of transmission:
- Waterborne (dominant mechanism).
- Foodborne and contact-household (especially in children's groups).
- Atypical (sexual, parenteral via blood transfusion during the incubation period).
The peak of contagiosity occurs in the last third of the incubation period, the entire pre-icteric period, and the first days of jaundice. With the appearance of icterus, contagiosity drops sharply. The disease exhibits summer-autumn seasonality and cyclic surges every 3–5 or 7–20 years. Susceptibility to the infection is universal, but children aged 3–12 and young adults under 29 are most commonly affected.
Pathogenesis and lesion morphology
The pathological process develops cyclically. Following enteral penetration, the virus initially localizes in the intestinal lymphoid tissue, after which it enters the liver via the bloodstream (viremia). Enterohepatic circulation develops: the virus is excreted with bile into the intestine, from where part of it is eliminated in the feces and part is reabsorbed.
The main mechanism of liver damage is immune-mediated. CD8+ lymphocytes and macrophages (via antibody-dependent cellular cytotoxicity) destroy infected hepatocytes. This leads to the release of intracellular enzymes into the blood (increased ALT and AST) and the development of intoxication.
Pathomorphologically, the liver shows acute mesenchymal inflammation and focal or zonal necrosis (predominantly in the periportal zone). However, massive parenchymal destruction does not occur, and most hepatocytes remain intact.
Clinical periods of the overt form
The classic icteric form occurs in only 10–20% of infected individuals and proceeds in several stages:
- Pre-icteric period (about 1 week). Characterized by an acute onset, pronounced intoxication (fever, dyspepsia, asthenia), and hepatomegaly. Jaundice is not yet present, but a spike in transaminases is already detected in the blood.
- Transition phase. At the peak of intoxication, urine darkens and stool becomes light.
- Icteric period (1–2 weeks). Jaundice appears sequentially: mucous membranes, sclera, then skin. Paradoxical sign: with the onset of jaundice, intoxication rapidly subsides. Predominantly direct bilirubin rises in the blood (usually up to 100 µmol/L), and the cytolytic syndrome is pronounced.
- Convalescence (from several weeks to months). Biochemical parameters normalize and clinical symptoms regress.
Forms, severity, and outcomes
In 70–80% of cases, the infection runs a mild, anicteric, or asymptomatic (inapparent) course, which is particularly characteristic of children. Moderately severe courses occur in 20–25% of patients. Severe (2–3%) and fulminant forms develop rarely, primarily in individuals with a burdened background (elderly patients, those with liver pathology).
Outcome variants:
- Complete recovery (most frequent).
- Prolonged convalescence (recovery lasts 3–6 months with persistent asthenia and fermentemia).
- Relapsing course.
Chronification of the process is completely uncharacteristic of this virus. Following the infection, persistent lifelong immunity is formed, the marker of which is IgG class antibodies.
Briefly: answers to topical questions
What family and genus does the hepatitis E pathogen belong to?
The hepatitis E pathogen belongs to the family Hepeviridae and the genus Hepevirus. It is a non-enveloped RNA-containing virus with a single-stranded genome structure. Morphologically, the virion size is 32–34 nm. This pathogen causes an acute infectious disease with primary liver damage, transmitted predominantly via the fecal-oral mechanism.
Which patient groups are at high risk for a fulminant course of hepatitis E?
Pregnant women are at high risk for a fulminant course of viral hepatitis E. The highest probability of a severe course progressing to a fulminant form is characteristic of patients in the third trimester of pregnancy, as well as the first week of the postpartum period (puerperium). During this period, the incidence of acute liver failure increases to 20–40%. This condition poses a direct threat of maternal and fetal mortality, and complications often include massive bleeding against the background of thrombohemorrhagic syndrome.
What specific serological markers are used to confirm the acute phase of hepatitis E?
To confirm the acute phase of an infection caused by the hepatitis E virus, the detection of early specific antibodies is used. The main serological method is enzyme-linked immunosorbent assay (ELISA), aimed at detecting the following markers:
- anti-HEV IgM — acute phase antibodies, which are detected in blood serum starting from the 5th–10th day of the disease and can circulate for up to 24 weeks.
It should be noted that these antibodies can sometimes disappear rapidly, leading to false-negative results. For final verification, the molecular biological method (PCR) for detecting HEV RNA can also be used.
To remember the dynamics of the icteric period, keep the "jaundice paradox" in mind: the liver turns yellow — the patient turns brighter (intoxication drops sharply, well-being improves).
Class and exam questions
The virus does not have a direct cytopathic effect. New virions are simply excreted from the cytoplasm into the bile, leaving the hepatocyte viable. Cell destruction occurs later due to the body's own immune system.
The virus does not have a direct cytopathic effect. New virions are excreted from the cytoplasm into the bile, leaving the cell intact. The death of infected hepatocytes is caused by an attack by the body's own immune system (CD8+ lymphocytes).
During which period is the patient most dangerous to others?
Maximum contagiosity is observed at the end of the incubation period and in the pre-icteric period. As soon as the patient develops jaundice, virus excretion decreases sharply, and contagiosity drops.
Is breastfeeding permitted with this hepatitis?
Yes, breastfeeding is not contraindicated at any stage of the disease, as the virus is not excreted in breast milk.
What else to study on this topic
- Cholestatic variant of the course of viral hepatitis
- Specific laboratory diagnostics (anti-HAV IgM and IgG)
- Hemogram changes and biochemical syndromes
- Differential diagnosis of icteric forms
- Pathogenetic mechanisms of the anicteric form
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