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Hepatitis A is an infectious disease of the liver which, although not as severe as hepatitis B and C, affects a lot of people worldwide, and is considered one of the most frequent food-borne diseases.

Hepatitis A is a viral disease of the liver, caused by hepatitis virus A. This virus is spread by ingesting food or water contaminated with the feces of an infected person. Unlike some other types of liver diseases, this type of virus doesn't cause a chronic infection, although it can cause lead to discomfort, and, in rare cases, acute liver failure. 

Hepatitis A is a disease known around the globe, but some regions are affected more than others. Since it is transmitted via infected fecal matter, it is more common in parts of the world with poor hygiene, bad sanitation, or in cultures where open defecation is common. In western countries, the disease is usually spread via unwashed, imported food, or as a result of bad hygiene.

What causes hepatitis A?

Hepatitis A is caused by the hepatitis A virus. It is considered to be an ancient disease, tracing back to the earliest times our species started living in groups large enough for the virus to circulate between different individuals.

When a person ingests food or water contaminated with infected feces, the virus travels to the intestines. When it gets to the small intestines, it uses portal circulation (the blood vessel system connecting the intestines to the liver) to travel to the liver.

What exactly happens when it reaches the liver cells is yet to be determined (if we're talking about the molecular path of the virus entering the cell), but we do know that the host cell ingests it as if it were some food molecule, forming a membrane around it. This newly formed organelle tries to "eat" the particle, using enzymes, but the virus uses those enzymes to advance. The enzymes dissolve the protein envelope of the virus, freeing the nucleic acid of the virus. 

Once the viral RNA is free of the envelope, it starts replicating in the cytoplasm of the cell. At the end replication, the host cell dies, and a bunch of newly formed viruses exit the cell. Some go on to infect other cells, while others enter the bile, which carries them to the intestines, where the viruses are merged with feces and excreted from the organism.

It takes some time for the virus to cause damage to the tissue, so the period between infection and the emergence of the symptoms is between two and four weeks. The symptoms include:

  • Jaundice
  • Pain in the upper right quadrant of the abdomen
  • Diarrhea
  • Nausea
  • Loss of appetite
  • Dark colored urine

Besides the obvious way of becoming infected — eating unwashed food or drinking unsafe water — there are other ways of getting the disease too. Drug use can be a potential risk factor, especially for drugs which are taken by nose. Equipment used for sniffing, and surfaces used to prepare the drug may contain microscopic particles of infected fecal matter, which can cause the disease. Sexual intercourse with and infected person also poses a risk. 

How can we prevent hepatitis A?

First of all, there are different types of vaccines. Most of them are injected, while China even has a vaccine which is taken orally. What is common to all of these vaccines is that their success rate is nearly 100 percent, and almost all of the people who get the shot develop immunity against the disease within one month after administration. Even if you're not yet vaccinated, if you get a shot up to two weeks after potential infection, you can still be protected. 

Other means of prevention include improved sanitation and hygiene, and proper sewage disposal. You should be cautious if you travel to countries where the disease is more common. Eating raw, or undercooked fish or shellfish is a common way of getting infected. This should be noted, since there are some cultures where raw shellfish is sold as street food. The other way the disease spreads is by using unsafe water to make ice. The freezing temperature doesn't destroy the virus, at least not that quickly, and as the ice cube dissolves in your drink, the virus can enter your organism. 

There is no treatment for this type of hepatitis. The therapy is aimed towards reliving the discomfort this disease causes, and replacing the fluids and nutrients lost by vomiting and diarrhea. The illness usually lasts for several weeks, up to several months. This type of hepatitis doesn't cause a chronic, lifelong, disease.

In conclusion

Hepatitis A is a viral disease of the liver spread by food or water contaminated with infected feces. Although it is rarely deadly (in only 0,015 percent of cases), it can cause severe discomfort. Hepatitis A often presents in the form of an epidemic, and the recovery takes months, which can have a severe impact on the local economy too. The best way to stay safe is to get vaccinated, especially if you plan on traveling to a country with high a prevalence of the disease, and to always use safe water supply for drinking and washing your food.

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