How is hepatitis A transmitted from person to person, what is the source of the infection?

1. Hepatitis A: general characteristics
2. How is hepatitis A transmitted
3. What is the source of hepatitis A infection?
4. How to protect yourself from hepatitis A infection
5. Useful video
6. Conclusion

Hepatitis A, Botkin's disease “Jaundice” is all the names of the same viral disease. The prevalence of infection is higher than it is customary to think about it.

Every year, up to 1.5 million cases of infection are registered in the world - and this is a far from complete picture, since often the disease is asymptomatic, without recourse to medical care. Children aged 3-10 years are most susceptible to a virus called hepatitis A. How is this infectious disease transmitted?

Hepatitis A: general characteristics

Like other viruses combined into the hepatitis group, variant A infects liver cells.

The hepatitis A virus is transmitted by infiltrating the body in the following ways:

• through the oral mucosa;
• through the pharyngeal mucosa;
• through the mucosa of the small intestine.

After that, the virus spreads through the bloodstream throughout the body, settling in the liver.

If the hepatitis A virus is transmitted through the upper respiratory tract, an infected person develops an inflammatory process in the pharynx, accompanied by catarrhal symptoms, coughing.

In the case of penetration through the gastrointestinal tract, the virus causes inflammation of the intestinal mucosa: typical dyspeptic symptoms (abdominal pain, nausea, vomiting, diarrhea, etc.) appear.

With both methods of infection in humans, the body temperature rises. In general, symptoms at the initial stage do not differ from typical symptoms of ARVI (in the first case) and enterovirus infections (in the second case).

Incubation and dozheltushny periods can last up to 4 weeks, and sometimes more. The stage of active replication of the virus in the liver cells lasts about 1 week. The source of hepatitis A, viral particles, is excreted from the liver to bile and removed from the body of the patient with a stool.

During the donor period, hepatitis A is transmitted most actively to patients by the environment: the maximum amount of virus is excreted - 100000000 virions in 1 ml of excrement.

The icteric period can last from several days to several weeks. At this time, the amount of viral particles released by the patient begins to decline, and at 3-4 weeks it is no longer determined by laboratory methods.

The epidemiological risk of hepatitis A is that often the disease may not manifest itself with any symptoms. There is evidence that children in 90% of cases suffer from jaundice of an asymptomatic type. For this reason, the source of infection in hepatitis A is often child care.

In adults, the number of asymptomatic cases of disease is less, but the rate can also reach a high value and reach up to 50%. Moreover, in 70% of cases the disease develops without the icteric stage. From here You can find out more information about the blood test for hepatitis A.

How is hepatitis A transmitted

As was shown in the previous paragraph, the transmission path of hepatitis A consists of two components:

• the alimentary pathway (the virus enters the body with food, "through the mouth");
• fecal tract (virus enters the environment with feces).

The main source of hepatitis A infection is water from decentralized water supply facilities (wells, springs, lakes). The virus enters the water with sewage in the absence of centralized sewage and purification process.

The epidemiological situation due to Botkin's disease is constantly monitored. To this end, not only the number of infections is taken into account, but also sampling of drinking water from facilities with decentralized water supply, as well as from sewage wastewater, through which hepatitis A is transmitted.

According to the available open data for 1999, antigens of viral hepatitis A were found in 9.6% of water samples and 6.4% of samples taken from sewage, which indicates the constant presence of the virus in the environment.

Hepatitis A is transmitted during locally emerging epidemics not only in African and Asian countries, but also in prosperous and economically developed regions. For example, in a study conducted in the United States, it was shown that more than 30% of its participants have antibodies to hepatitis A, which indicates a previous infection (in most cases, secretive).

A separate group in the high-risk zone are children. If adults, in contact with a sick person, become infected in no more than 20% of cases, then in the pediatric group, hepatitis A is transmitted in 80% of cases.

That is, out of 100 children (among unvaccinated and not previously ill with jaundice) who have contacted the patient, for example, in a kindergarten or school, up to 80 people fall ill. You can read more about hepatitis A vaccine in this article .

Increased risk in children is associated with features of children's behavior and a natural disregard for personal hygiene measures. Touching the mouth with unwashed hands or eating unwashed thermally unprocessed food, contact of the mucous membrane of the mouth with surrounding objects (toys, pencils and other stationery, etc.) all contribute to the fact that hepatitis A is transmitted to the child.

What is the source of hepatitis A infection?

Botkin's virus is quite stable in the environment.

Table. The stability of the virus A in the sources under certain environmental conditions.

Sources and environmental conditions Preservation period with the possibility of transmission to humans min or more When boiling for up to 5 minutes With ultraviolet irradiation up to 1 minute In rooms and household items for up to several weeks In the external environment at a temperature of 0 ... + 10 degrees C up to several months At negative temperatures up to several years
The stability of the virus contributes to its trouble-free migration from wastewater to drinking water sources (at a positive ambient temperature) and preservation on household items.

Summarize what is the source of infection with hepatitis A:

• natural water sources located near the place of residence of people (lakes, wells, springs);
• unwashed hands;
• unwashed vegetables, fruits, berries;
• insufficiently cooked seafood, in particular mussels, shrimp, which are traditionally subjected to minor heat treatment (in case they were caught in waters that are in contact with wastewater);
• public toilets (door handles, taps, flushing system elements, etc.).

More often outbreaks of infection are due to polluted water. In this case, this water does not necessarily drink. Hepatitis A is transmitted, for example, while swimming in an infected lake.

How to protect yourself from hepatitis A infection

To reduce the likelihood of infection with hepatitis A, the paths of infection of which are now obvious to the reader, you should follow the basic rules:

• boil non-chlorinated water thoroughly;
• not to swim, not to swim in the water basins, located near the settlements of people who are not equipped with centralized sewers;
• wash your hands with soap after using the toilet;
• wash with soap and water before eating;
• wash with soap thermally uncooked food (vegetables, fruits, berries);
• heat fish and seafood for at least 5 minutes;
• Do not touch your lips or mouth with your fingers or objects (eg, a pencil, pen).

Useful video

How to reduce the risk of jaundice (Hepatitis A) is described in the following video:

Conclusion

1. Like other diseases with a similar mechanism of distribution - dysentery, cholera, typhoid fever - hepatitis A is transmitted in groups and societies with a low level of general sanitary conditions and individual hygiene.
2. Increasing the general sanitary culture in adults and instilling hygiene standards in children help protect themselves and others from hepatitis A infection even in epidemiologically unfavorable regions and during outbreaks of the disease.