Hepatitis A is an acute liver disease caused by the hepatitis A virus. It is considered to be the most favorable form of hepatitis as it cannot take a chronic course. The source of infection is a person with hepatitis A. He/she sheds the virus in feces, and then the virus - with water or food - gets into the body of other people. Doctors call this mechanism the fecal-oral contamination. More often, children may fall ill with hepatitis A through dirty hands. That is why this form of hepatitis is called "the disease of dirty hands". The spread of infection is associated with poor sanitation and crowding. Particularly high incidence of hepatitis A can be seen in developing countries. Infection occurs primarily through contaminated food and water. Direct contact with a patient as well as the use of the same dishes and a shared bathroom play an important role. The virus can persist on hands of a man for several hours and even longer on food at room temperature. A special feature of the virus of hepatitis A is that it is stable in the environment: at room temperature, it can be maintained for several weeks or months. The virus can also be transmitted through shellfish previously lived in water contaminated by sewage, or fruit and raw vegetables contaminated during processing. Heat treatment kills the virus of hepatitis A completely, but food can become contaminated after cooking. The virus can be spread among people because of the lack of skills of hygiene and close contact in areas with poor sanitation and overcrowding. This disease is common in all developing countries and rare in developed countries where skills of hygiene and vaccination control the spread of disease (Gallagher, 2005).
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Infection with the virus of hepatitis A descends from patients who are in the so-called "incubation period". The virus has already hit the body. It develops and multiplies in it, but clinical manifestations are not visible, and a person does not know that he/she is ill. Latent (asymptomatic) variants of the disease are possible, in which a patient is not isolated in the hospital, because a person does not know that he/she is sick and does not go to the doctor. At the same time, it is the source of the virus. These patients (with no visible forms of hepatitis A) have the greatest epidemiological significance. A number of such patients may be at 2-10 times higher than a number of patients with icteric forms (Gust & Feinstone, 1988).
Infection occurs through water and food, the so-called "contact-household" transmission of the disease. The water route of infection is of particular importance, providing the appearance of epidemic outbreaks of hepatitis A. "Blood contact" mechanism of transmission of hepatitis A is also possible. Susceptibility to hepatitis A is general. The most frequently disease is recorded in children older than 1 year (especially at the age of 3-12 years) and young persons. Seasonal increase of incidence in the summer-autumn period is peculiar to hepatitis A. Recurrence of hepatitis A is rare (Gust & Feinstone, 1988).
Risk of hepatitis A while traveling varies depending on the incidence of hepatitis A in the area, living conditions, hygiene when preparing food and duration of stay in the country. Risk when traveling in developed countries is very small. However, people traveling to rural areas of developing countries and having food and water with dubious hygiene are at risk. When traveling to countries where risk is greater, people should not try to drink water that may be contaminated (including ice in drinks). People should not eat raw shellfish, raw vegetables and fruit which were cooked in poor sanitary conditions. In cases hepatitis is suspected, a person should seek medical attention immediately. The physician must send the person to the hospital, where diagnosis will be accurate. Treatment of mild hepatitis A is primarily aimed at relieving symptoms. To avoid complications of liver injury, a person needs rest and confinement to bed. In 98% of cases, there is a full recovery (Gallagher, 2005).
In addition to hygienic precautions, vaccination remains the most effective approach to the prevention of hepatitis A. Vaccination against hepatitis A is recommended for all travelers to countries with moderate and high sickness rate (especially in developing countries). Immunoglobulin as a routine method for the prevention of hepatitis A is no longer recommended. Hepatitis A vaccine is available for adults and children over two years. Some people, especially children, may have asymptomatic hepatitis A, and so the disease cannot be properly diagnosed, and it remains unnoticed (Achord, 2002).
Hepatitis A is an acute cyclic infection characterized by a clear change of periods. After infection with the hepatitis A, the virus penetrates from the intestines into blood and from blood to the liver. The virus has a direct pathological effect on liver cells (hepatocytes). It causes inflammation and dysfunction. In future, the reproduction of the virus stops. Chronic forms of the infection happen very rarely. Hepatitis A is characterized by a variety of clinical manifestations. There are the following forms of severity of clinical manifestations: subclinical, erased, anicteric, icteric. According to the duration of flow, disease can be acute and protracted. According to the degree of severity, it can be mild, moderate and severe. Complications of the disease are relapses, exacerbations and biliary tract lesions. The incubation period of hepatitis A is an average from 21 to 28 days. Prodromal period lasts an average from 5 to 7 days. More often, the disease begins with rising of the body temperature to 38 - 40 °C during 1-3 days, catarrhal conditions, headache, loss of appetite, nausea, discomfort in the liver and stomach. After 2-4 days, urine changes its color, it acquires the color of beer or tea, sometimes diarrhea is possible. During this period, the liver and sometimes (10-20% of patients) spleen increase. Pressure on them is very sensitive. In order to establish an accurate diagnosis, biochemical examination of blood is produced. Then the height of the disease comes, which lasts from 2 to 3 weeks. As a rule, the occurrence of jaundice is accompanied by temperature abatement, reducing headaches and other manifestations of systemic toxicity, which is an important diagnostic feature of hepatitis A (Howard, Thomas, Stanley Lemon & Zuckerman, 2008).
In the development of jaundice phases of growth, the maximum development and decay are distinguished. The first takes oral mucosa (bridle, hard palate) and the sclera have icteric staining in the first place. In future, skin has icteric staining. The degree of jaundice usually corresponds to the degree of severity of disease and reaches "saffron" shade with severe forms of the disease. Mild form of the disease is characterized by mild intoxication and mild jaundice. Moderate form is accompanied by moderate intoxication. Severe form is characterized by severe intoxication, and signs of involvement of the central nervous system can be seen. Phase of fading occurs generally slower than the growth phase. It is characterized by the gradual disappearance of all symptoms of disease. With the disappearance of jaundice, a period of recovery begins, lasting from 1 to12 months. At this time, patients have normal appetite, autonomic disorders are faded, and a size of the liver and spleen is reduced. 5-10% of patients develop prolonged disease. It lasts up to several months. Typically, protracted form also ends with recovery of patients. The outcome of hepatitis A is usually favorable. Full recovery is seen in 90% of patients, there are residual effects in other cases. Mortality is less than 0, 04%. People who fully recovered from the disease develop antibodies to hepatitis A and lasting lifelong immunity is formed. Hepatitis A does not have a long heavy damaging effect on the liver. However, in rare cases, severe hepatic insufficiency can lead to coma and death. Most patients with acute hepatitis A fully recover from the infection (in contrast to hepatitis B and C, which cause chronic stable liver inflammation) (Thomas, Lemon & Zuckerman, 2008).
During examination, doctors record an increase of the liver and less often an increase of the spleen. For the diagnosis of hepatitis A, biochemical analyses of blood and urine are important. In this case, there is an increase of bilirubin and the so-called liver enzymes. Last fall into blood in the destruction of liver cells, and their concentration gives an indication about the degree of destruction of the liver tissue. Typically, hepatitis A level of these enzymes is increased in 8-10 times. The prognosis is favorable, and functions of the liver usually recover completely (Jonas, 2010).