Hepatitis A is a viral and highly contagious liver infection caused by the hepatitis A virus. Hepatitis A virus is spread primarily by the fecal-oral route. Hepatitis A virus transmission can occur by consuming food prepared by an infected person, drinking contaminated water, having close personal contact with a person who has the disease.

Risk factors that may increase the possibility of having hepatitis A include, travel internationally, providing care in a nursing home center, using illegal drugs, and Sexual intercourse with an infected person. Signs and symptoms of hepatitis A, include abdominal pain or discomfort, Jaundice, nausea, and vomiting. Number of research that exploring the pathogenesis of hepatitis A infections has been remarkably decreased after the discovery of hepatitis A vaccine.

Diagnostic steps to investigate hepatitis A may include, reviewing the medical history, performing a physical examination, and blood tests. There is no available cure or antiviral for hepatitis A. The human body is able eventually to get rid of the infection on its own. Coping techniques to cope with hepatitis A include plenty of rest and using of painkillers.

To prevent hepatitis A, some measures can be suggested, including vaccination, good personal hygiene, and adopting safety precautions when visiting other countries. The most cases of hepatitis A will recover within two months and there will be no long-term complications.

Hepatitis A is a viral and highly contagious liver infection caused by the hepatitis A virus. Hepatitis A infection does not cause chronic liver disease and is rarely fatal. Hepatitis A, hepatitis B, and hepatitis C are caused by different viruses, spread in different ways, and require different interventions. Hepatitis A is the least serious and mildest of these liver infections.

Hepatitis A virus (HAV) is classified in the genus Hepatovirus within the family Picornaviridae, and it is characterized as a small, nonenveloped hepatotropic virus.

6 different genotypes (I to VI) of hepatitis A have been investigated in the literature. The human genotypes are I, II and III, the other genotypes (IV, V, and VI) are simian genotypes. Genotypes I to III are further subdivided into distinct groups (A and B).The most frequently reported genotype among humans is genotype I. Although more investigations are required, some studies indicate severe clinical manifestations coincide with some of these genotypes.

Hepatitis A is caused by a virus and spread primarily by the fecal-oral route. Hepatitis A virus transmission can occur by:

• Consuming food prepared by an infected person who did not wash his / her hands after using the bathroom or who washed them in contaminated water.Also, the infection may transmit by eating shellfish that live in contaminated water.
• Drinking contaminated water or eating food washed in contaminated water including ice cubes.
• Having close personal contact with a person who has the disease, such as through sex or by providing care for an infected person.
• Having close contact with an object that came into a contact with stool of an infected person.

It is important to mention that a baby cannot get hepatitis A by breastfeeding. Moreover, hugging or sitting next to an infected person does not transmit the virus to a healthy person; also, coughing or sneezing does not spread the virus.

There are several risk factors that may increase the possibility of contracting the virus, include:

• Travel internationally, especially to Asia, South or Central America, Africa and the Middle East.
• Providing care in a nursing home center or working in a childcare center.
• Providing care for someone who infected with the disease.
• Using illegal drugs, including drugs that are not injected.
• Having a clotting-factor disorder, such as hemophilia.
• Involving in a health care, food, or sewage industry.
• Being a man who has sex with other men (MSM).
• Sexual intercourse with an infected person.
• Having HIV.
• Being in jail.
• IV drug use.

Since the development of hepatitis A vaccine almost 2 decades ago, the motivation to conduct research exploring the pathogenesis of hepatitis A infections and how the infection is cleared from the liver has been decreased.

Hepatitis A is transmitted by fecal-oral route and replicates in the liver. The replication of the virus depends on hepatocyte uptake. After the uptake occurs, the viral RNA is uncoated and host ribosomes bind to make up polysomes. Soon after that, the viral proteins can then be synthesized by copying of viral genome by a viral RNA polymerase.

Hepatitis A virus can reach the blood and, is excreted by the biliary system into the faces 10-12 days after the infection. Hepatitis A virus’s concentration is quite high in faces than it is in the serum. However, a significant decline in hepatitis A virus excretion 7-10 days after onset of symptoms has been observed. By the third week of illness, the majority of infected persons no longer excrete virus in the feces.

Hepatitis B shares a number of features with hepatitis A, such as being positive-strand RNA virus, along with other features that relate to replication mechanisms include the production of double-stranded RNA and potent induction of innate immune responses during the replication of the genomes by cytoplasmic membrane-bound replicase complexes. Moreover, both viruses use similar disruption strategies against the early innate immune responses.

Symptoms of hepatitis A may not appear in many people who are infected with the disease.Signs and symptoms of hepatitis A may include:

• Abdominal pain or discomfort, especially in the area occupied by the liver,
• Flu-like symptoms, such as fever and headaches,
• Jaundice (yellowish eyes and skin),
• Tiredness and malaise,
• Gray- or clay-colored stools,
• Nausea and vomiting,
• dark yellow urine,
• Loss of appetite,
• Joint pain.

In general, symptoms of hepatitis A tend to be milder in children. The severity of hepatitis A symptoms increases as age advances.

Physicians are usually examining symptoms and recommending blood tests to diagnose the disease. Diagnostic steps to investigate hepatitis A may include:

• Reviewing the medical history: This may involve asking questions that relate to immunization and travel history.
• Physical examination: Physician may perform a physical examination to detect liver enlargement or tenderness.
• Blood tests: A physician or nurse may draw a blood sample from the patient and send it to the laboratory. Blood tests may show:
• Increased level of immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies to hepatitis A.
• Increased level of liver enzymes (liver function tests), particularly transaminase enzyme levels.

Additional tests may be suggested to detect hepatitis A virus RNA, such as RT-PCR (reverse transcriptase polymerase chain reaction).

There is no available cure or antiviral for hepatitis A. The human body is able eventually to get rid of the infection on its own. Coping techniques that may help infected persons with hepatitis A may include:

• Plenty of Rest:  Infecting with hepatitis A can promote feelings of tiredness and sickness. It is advisable to maintain a cool, well-ventilated environment, wear loose clothing, and avoid hot showers to reduce any itching.A physician may also recommend taking days off from work or school and avoiding sexual intercourse until at least a week after jaundice or other symptoms started.
• Coping with nausea: Nausea can cause loss of appetite sometimes and make it difficult to eat. Eating smaller, lighter meals can help reduce nausea and vomiting. Eating more high-calorie foods can be suggested for those who need to get enough calories. For example, drink fruit juice or milk rather than water.
• Using painkillers: Medications such as paracetamol or ibuprofen can be suggested for aches and pains, but it is important to consult a physician before using any kind of medications because some patients should take lower doses than normal or completely avoid certain medications for a period of time.
• Reduce the strain on the liver: Avoiding alcohol is an essential step to reduce the strain on the liver. Alcohol, acetaminophen (ex: Tylenol), and certain other medicines, vitamins, and supplements can cause more damage to the liver.

It is rare to see any complications caused by hepatitis A and it is improbable to cause a long-term liver damage, and it does not progress to be chronic.

Most cases of hepatitis A show full recovery within two months without developing permanent liver damage.

Some of the preventive measures concerning hepatitis A include:

• Vaccination: Vaccination is the best way to prevent hepatitis A. Hepatitis A vaccine is recommended for :

1. Travelers to certain countries
2. All children age 12 months or older
3. People at high risk for infection with the virus.

The hepatitis A vaccine is given in two doses. The second dose should be given 6 to 12 months after the first shot. Taking both shots is important to provide full protection against the virus.

• Immunoglobulin: Short-term protection (lasting three to six months) can be provided by injecting antibodies called immunoglobulin. Immunoglobulin must be administered within two weeks of exposure to the hepatitis A virus to provide maximum protection, and it is mostly given to those who remain in close contact with infected persons.
• Safety precautions when traveling: Some of the advices that can be given to those who travel to regions where hepatitis A outbreaks occur, include:

1. Wash all fresh fruits and vegetables
2. Avoid raw or undercooked meat and fish
3. Drink bottled water and use it when brushing your teeth
4. Avoid drinking beverages of unknown purity, with or without ice

• Good personal hygiene: Special attention should be given to hand washing, especially after using the bathroom or changing a diaper and before preparing food or eating.

The most cases of hepatitis A recover within two months and there will be no long-term complications. The patient normally develops life-long immunity against the virus and the virus does not remain in the body after the infection is gone.

In some cases, symptoms may appear and disappear for up to 6 months before eventually go away and the risk of death is so low, but, the risk remains higher among people who suffer from long-term liver disease and among older adults.

• According to World Health Organization (WHO) publications, hepatitis A virus (HAV) affects 120 million people annually worldwide.
• The following is hepatitis A – related information mentioned in a study published in World Journal of Hepatology:

• In Africa, the available information in regard to hepatitis A infection is limited. However, available data shows endemicity rates in most of the African countries, with the exception of subpopulations in some countries, such as white people in South Africa.
• In Asia, hepatitis A seroprevalence rates vary considerably among countries.Low endemicity areas include Japan and Taiwan where decreasing of hepatitis A prevalence has been reported in the last years.
• Countries including Korea, Indonesia, Thailand, Sri Lanka and Malaysia are considered moderate endemicity countries and incidence rates are decreasing gradually, at least in urban areas.
• In several Latin America countries, such as the Central and the Caribbean areas, the endemicity patterns continue to be high.

• According to Eurosurveillance journal, the notification rate in the European Union / European Economic Area has fallen between 1997 and 2011, from 10.0 to 2.5 per 100,000 population. In addition, from 2005 to 2012, the reported proportion of cases infected abroad ranged from 49 to 80% in Sweden and was estimated at 37% in Germany and 36% in France in the same time period.
• According to Centers for Disease Control and Prevention (CDC) publications, in 2010, a total of 1,670 cases of acute hepatitis A were reported in the USA. The overall incidence rate for 2010 was 0.5 cases per 100,000 population.
• According to the Australian Department of Health, in recent years, notifications and hospitalizations reports related to hepatitis A have been decreased with a downward trend. However, A very large outbreak of hepatitis A occurred in New South Wales in 1997, the outbreak associated with the consumption of raw oysters at that time, also, a large outbreak associated with semi-dried tomatoes occurred during 2009.