In the letter world of hepatitis, B and C are most well known as causing severe and potentially fatal liver injury. But what about hepatitis A virus (HAV)? HAV is one of the world’s most common viral infections, and even though a vaccine given to school age children helps to limit the occurrence of the disease, it is the cause of more than half of the reported cases of viral hepatitis in the United States, and it has significant morbidity.
Hepatitis A is an RNA viral infection shed in the stool and usually spread by food contaminated with fecal matter. It can also be contracted from contaminated water, through personal contact with others infected with the disease, spread in day care centers from child to child, and even through sexual contact. Since hepatitis A has a very long incubation period (approximately 28 days from exposure to the onset of symptoms), it is often hard to trace back to a particular source. More than one-half of the cases never have a specific, identifiable risk factor found.
Onset of the disease is quite dramatic, with fever, nausea, vomiting, diarrhea and jaundice (yellow skin). Headache, weight loss, dark urine and abdominal pain develop as the liver is affected. Symptoms are generally more intense with age, and younger children are less affected than older individuals. Hepatitis A is most contagious two weeks before and one week after symptoms begin, and recurrences are not uncommon.
It is generally not possible to differentiate the individual types of hepatitis from their clinical presentation alone. Even viral infections, drugs, toxins and bacterial and parasitic infections may present with similar pictures. Diagnosis is made by the detection of serum immunoglobulin M (IgM) anti-HAV antibodies. The test is available in most clinical laboratories. Sometimes administration of the hepatitis A vaccine can cause a false positive result, so it’s an important question to ask when the disease seems mild but the testing comes up positive.
Thankfully, hepatitis A is a self-limiting infection in most cases—complications are generally most severe after age 50. One in six affected people may have a relapse, but unlike other forms of hepatitis such as B and C, there is no chronic state. Inflammation of blood vessels, anemia, kidney failure and pancreatitis can occur during the acute phase. There is no treatment for the virus except supportive care, and most all cases subside, even those with relapse. Older individuals should be watched more carefully for complications, and children should not return to school until fever and jaundice have subsided.
The CDC has authorized a vaccine for children, who get a series of immunizations between the age of one and two. Those traveling into areas where hepatitis A is common should receive the vaccine as well. An immunoglobulin that gives passive immunity for up to three months may also be coadministered in adults.
Almost all cases of recovered hepatitis A can be issued at best rates without any problem. Those who have had a recurrence or in whom liver function tests remain abnormal must be fully evaluated, as the more dangerous hepatitis B and C may coexist, or other liver problems and inflammations may cause separate mortality and morbidity and require ongoing treatment.
