Global Alert and Response (GAR)

Hepatitis A


Hepatitis A - an introduction

- What?
- How?
- Who?
- Where?
- When?
- Why?

Hepatitis is a general term meaning inflammation of the liver and can be caused by a variety of different viruses such as hepatitis A, B, C, D and E. Since the development of jaundice is a characteristic feature of liver disease, a correct diagnosis can only be made by testing patients' sera for the presence of specific anti-viral antibodies.22, 40

Hepatitis A, one of the oldest diseases known to humankind, is a self-limited disease which results in fulminant hepatitis and death in only a small proportion of patients. However, it is a significant cause of morbidity and socio-economic losses in many parts of the world.18, 40

Transmission of HAV is typically by the faecal-oral route.18, 23, 39, 40

Infections occur early in life in areas where sanitation is poor and living conditions are crowded. With improved sanitation and hygiene, infections are delayed and consequently the number of persons susceptible to the disease increases. Under these conditions explosive epidemics can arise from faecal contamination of a single source.

Hepatitis A was formerly called Infectious hepatitis, Epidemic hepatitis, Epidemic jaundice, Catarrhal jaundice, Type A hepatitis, HA.18, 40

What causes the disease?
Hepatitis A is caused by infection with the hepatitis A virus (HAV), a nonenveloped, positive stranded RNA virus, first identified by electron microscopy in 1973, classified within the genus hepatovirus of the picornavirus family.18, 23

The virus interferes with the liver's functions while replicating in hepatocytes. The individual's immune system is then activated to produce a specific reaction to combat and possibly eradicate the infectious agent. As a consequence of pathological damage, the liver becomes inflamed.

How is HAV spread?
HAV is transmitted from person-to-person via the faecal-oral route.18, 23

As HAV is abundantly excreted in faeces, and can survive in the environment for prolonged periods of time, it is typically acquired by ingestion of faeces-contaminated food or water. Direct person-to-person spread is common under poor hygienic conditions.22

Occasionally, HAV is also acquired through sexual contact (anal-oral) and blood transfusions.22

Who is susceptible to infection?
People who have never contracted HAV and who are not vaccinated against hepatitis A, are at risk of infection.

The risk factors for HAV infection are related to resistance of HAV to the environment, poor sanitation in large areas of the world, and abundant HAV shedding in faeces.18

In areas where HAV is highly endemic, most HAV infections occur during early childhood.

Where is HAV a problem?
The virus is present worldwide, and the risk of infection is inversely proportional to levels of sanitation and personal hygiene.23

In developing countries with poor environmental hygienic conditions, nearly all children are infected with HAV before the age of 9. There is substantial underestimation of hepatitis A cases in these areas, because HAV infections for young children are mostly asymptomatic and therefore unrecognized.

As sanitation conditions improve, transmission shifts to older age groups and the incidence of symptomatic disease increases.

In most developed countries, endemic HAV transmission is unlikely.

Click here for: World distribution map

When is hepatitis A contagious?
In persons who develop clinically apparent hepatitis A, secretion of virus in stool at high titres begins one to three weeks prior to onset of illness, and may continue for several weeks at lower titres after jaundice occurs.21

Although the level of virus shedding does not correlate with the severity of liver disease, faeces are highly infectious and therefore extremely contagious during all of this period.

Why is there no treatment for the acute disease?
Hepatitis A is a viral disease, and as such, antibiotics are of no value in the treatment of the infection.

Antiviral agents, as well as corticosteroids, have no effect in the management of the acute disease.18

The administration of immune globulins (IG) may help preventing or improving the clinical manifestations of the disease if given within 2 weeks of infection, but it is of no help in the acute phase of hepatitis A.18, 39

Therapy can only be supportive and aimed at maintaining comfort and adequate nutritional balance.18

Complete recovery without therapy is generally the rule.18

 


World distribution map

From: Centers for Disease Control and Prevention (CDC), Atlanta, USA: 10 http://www.cdc.gov/ncidod/diseases/hepatitis/slideset/hep16.gif

Endemicity patterns (low, intermediate and high) of hepatitis A virus infection worldwide. (Note: this map generalizes available data and patterns may vary within countries).9


Worldwide endemicity of HAV infection

 

HAV endemicity

 

Regions by epidemiological pattern

 

Average age of patients (years)

 

Most likely mode of transmission

 

Very high

 

Africa, parts of South America, the Middle East and of south-east Asia

 

under 5

 

- person-to-person

- contaminated food and water

 

High

 

Brazil's Amazon basin, China and Latin America

 

5-14

 

- person-to-person

- outbreaks/ contaminated food or water

 

Intermediate

 

Southern and Eastern Europe, some regions of the Middle East

 

5-24

 

- person-to-person

- outbreaks/ contaminated food or water

 

Low

 

Australia, USA, Western Europe

 

5-40

 

- common source outbreaks

 

Very low

 

Northern Europe and Japan

 

over 20

 

- exposure during travel to high endemicity areas, uncommon source

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