There are a number of viruses than can infect the liver, and produce hepatitis. Some specifically target the liver: hepatits A (HAV), hepatitis B (HBV), hepatitis C (HCV), hepatitis D (HDV) and hepatitis E (HEV). Other viruses in the course of a general infection, can also affect the liver, the most common being mononucleosis (Ebstein Barr virus), cytomegalovirus (CMV), measles, AIDS, Ebola and others.
The most frequent and important, , are the hepatitis A, hepatitis B and hepatitis C, which will be reviewed.
This is the most common form of hepatitis worldwide, causing a 30 % of hepatitis in western countries, the figure being probably higher in underdeveloped countries. HAV is an RNA virus, belonging to a family called Picornavirus.
The infection is transmitted by the ingestion of water and food contaminated by feces, and occasionally large scale outbreaks can occur. The period of greatest infectivity when one can transmit the infection is in the 2 week period before the onset of clinical illness; fecal shedding of the virus continues for 2 or 3 weeks after that.
One can experience very mild forms of the disease without symptoms, so that it goes undiagnosed, but typically in children, adolescents and young adults fever, abdominal pain, nausea, general aches and pains are common, and they become yellow in the skin, with dark urines. Very rarely there is a severe form called fulminant hepatic failure, with liver transplantation being the only option to death.
Diagnosis is suggested by the physician finding abnormal liver function tests, and can be confirmed by an anti.HAV antibody. Most cases resolve favourably in 4 to 6 weeks, with no specific treatment. Besides rest and a light diet, sanitary precautions such as frequent hand washing and individualized eating implements are recommended. There is no chronic form of this particular virus.
Vaccination is effective, and should be administered 4 weeks before traveling to an endemic area. It is also recommended for people at high risk of exposure. For people already exposed and not vaccinated, there is an antiserum (a specific immunoglobulin) which provides protection for 3 to 5 months, according to the dose used.
Hepatitis B is a liver infection caused by the hepatitis B virus (HBV). There are more than 350.000.000 chronically infected people worldwide, and in Argentina the prevalence of this infection is estimated at 2% of the population.
Initially, though many cases have no symptoms at all, it can be confused with a mild ‘flu-like condition, and some patients can become yellow (jaundiced) for a short period, with dark colored urine. Frequently it is only detected through a routine blood test, either for a check-up or screening of blood donors.
The virus is transmitted from an infected person through sexual relations, through their blood or secretions, or from a mother to her baby at birth. Most people (about a 90%), recover completely in the first 6 months after the initial infection, without lasting consequences. A small number go on to develop a chronic liver infection, which can progress to cirrhosis (extensive liver scarring), liver cancer or liver failure. The younger the patient, the higher the probability of chronic infection.
Once detected, other tests such as sonography (ecography) or a liver biopsy may be necessary to determine accurately the stage of the illness, as in early stages there are efficient antiviral drugs to be used.
There is a clear group of situations which puts people at risk to develop the infection:
Vaccination is very effective in preventing this infection, and is now used routinely in new born babies, in infants and adolescents, and should be used in all persons who are included in the high risk group mentioned above.
This is a global health problem, with approximately 200 million chronic carriers worldwide, and most countries report an average of 2 % of the population as infected with this virus. It is also an RNA virus, belonging to the Flaviviridae family. It is estimated that in the United States 4 million people have been infected by the virus, and 8.000 to 10.000 people die each year from HCV-related chronic liver injury.
The known modes of transmission are from infected blood transfusions, injection drug use and needlestick injury. It can also be transmitted sexually, and from mother to offspring at birth. Risk factors for this infection include a history of multiple sex partners, multiple blood transfusions, injection drug use, hemodyalisis, and occupational exposure to blood and blood-derived products. Other factors may include tattooing, body piercing, sharing razors or sharing straws for intranasal cocaine. A history of military service has also been mentioned.
The acute stage of the infection can be completely silent, especially in children and young adults, though frequently symptoms similar to those of Hepatitis A can be experienced. It is estimated that a 15 % of infected persons heal spontaneously, whilst an 85 % go on to have chronic hepatitis. In this form, it can also go unnoticed for 15 or 20 years, the only symptom being fatigue in some people. It is frequently diagnosed when in a routine checkup the liver enzymes are found to be slightly elevated in a blood test, and subsequent specific testing using antibodies against Hepatitis C can confirm the presence of this usually silent condition. This test becomes positive after 8 weeks of infection, this rather long window of negativity being a risk when considering blood donors. Fortunately it can now be detected as early as 1 to 2 weeks with a test called PCR, where viral concentrations can be measured, being useful both for diagnosis and for following the results of treatment.
Fortunately, treatment is now available for both the acute and the chronic forms, with a drug called interferon, with a high rate of viral clearance. In the latter form, another medicine called ribavirin is added. According to certain characteristics of the C virus, the treatment should last 6 or 12 months. In cases of treatment failure, there are 2 new groups of drugs which show promising results. Unlike Hepatitis A and B, no vaccine has yet been developed for this illness.
The British Hospital has a team of 4 Hepatologists, led by Dr. Luis Colombato, who is Chief of the Gastroenterology Department and well known locally and internationally for his work in this field. They are all active both in clinical work as in research in illnesses related to the liver. They are also active in hæmodynamic studies involving the circulation of the liver.
Should you need more information, you can write to the Hepatitis Group at the British Hospital, at email@example.com, or phone them at 4309-6807.
Dr. John Emery, MD.