Hepatitis E: Description, Causes and Risk Factors:
Hepatitis E, like hepatitis C, is a positive-strand RNA virus that appears to be unique agent, and has not been conclusively identified as belong to any known virus family, though it does share characteristics with the Calicivirus family. Analysis of this virus RNA shows that the virus forms a genetically distinct group that is closer to rubella virus than to members of Caliciviridae family.
There are many genotypes of HEV (hepatitis E virus). The major geographic distributions are genotype 1 in Asia and Africa, genotype 2 in Mexico and Africa, genotype 3 in developed countries, and genotype 4 in Asia. Genotypes 1 and 2 circulate in humans while genotypes 3 and 4 are generally zoonotic diseases.
Most replications of the hepatitis E virus ultimately occur in the liver, and virus particles are present in the bile and feces of the infected person from late incubation of the virus to the first week of illness.
The incubation of this virus in humans ranges from three to nine weeks.
Historically, researches thought widespread infection of HEV (hepatitis E virus) was found only in India, Central Asia, parts of Africa and in Mexico. According to CDC, currently 40% of acute viral hepatitis infection in India results for HEV infection. The largest recorded outbreak of this occurred in Xinjing, China with more than 119,000 document cases.
Hepatitis E viruses were also found in breast milk, but there are no known documented cases of break milk transmitting the virus to infants.
A study lead by NIH (National Institute of Health) suggests that hepatitis E viruses are common among wild rats in the US. Researchers are now examining any potential connection between animals and HEV infection in humans.
Researchers also identified a strain of HEV in pigs and swine that is very similar to that strain that causes disease in humans. However, there is no evidence of that pig virus causes disease in human or pigs.
Other major reservoirs of HEV antibodies include lambs, cattle, and chickens.
Transmission of the hepatitis E virus generally happens when someone drinks water that is contaminated with the fecal matter—even just microscopic traces—of an infected person. Major outbreaks typically happen in regions of the world where sanitation is poor.
Few cases of this have resulted from person-to-person contact, and there is no evidence that the virus can be spread through sexual activity. Transmission through blood is also rare.
Recent studies have suggested that hepatitis E is likely a zoonotic infection transmitted from domestic pigs and other wild animal species; pig contact does not explain all endemic cases in the United States. Shellfish may be a source of exposure.
Symptoms may include:
Nausea and vomiting.
There can also be a signs of elevated bilirubin in the blood and urine, mild increase in alkaline phosphatase, and bile duct enzyme.
When infected the body's immune first releases IgM (immunoglobulin M) to combat a foreign substance or antigen. In this case of virus, the concentration of IgM antibodies quickly decline after three to six months of the onset of an HEV infection. As a result, the quantity of IgM antibodies in blood helps doctor diagnose the stage of an infection.
IgG (immunoglobulin G) antibodies are also releases to fight the virus. This type of antibody, which is the most abundant, can cross the walls of the blood vessels to fight viruses. Hepatitis E IgG antibodies have been shown to persist for two to 13 years after the onset of an infection.
Diagnosis of hepatitis E in people depends on finding hepatitis E specific antibodies in their blood and hepatitis E RNA in either blood or stool. In addition, hepatitis E is acute or symptomatic there can be increase in liver enzymes including alanine aminotransferase, -glutamyl transpeptidase (GGT), which indicate liver inflammation or damage.
To diagnose hepatitis E in a patient, doctors measures the quantity of IgM HEV antibodies or significant increase in IgG antibodies in patient's blood.
No treatment currently exists for hepatitis E - the only treatment available addresses the symptoms, not the disease. No antiviral therapy has been proven to be effective against this virus in controlled laboratory experiments.
In milder cases, healthcare providers usually prescribe rest, plenty of fluids, and a nutritious diet. While the body fights hepatitis E, a person should avoid any medicines—over-the-counter or prescribed—that could damage the liver. Sufferers should also avoid alcohol during the recovery period, as alcohol may also damage the liver.
Preliminary studies in cells cultures suggest ribavirin and interferon alpha may inhabit hepatitis E virus replication.
Currently, there is no vaccine that prevents hepatitis E. Not even immunoglobulin prepared from plasma collected from hepatitis E infected people is effective in preventing the disease.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.