Hepatitis A Virus (HAV) is a single-stranded RNA virus from the Picornavirus family. It is enclosed in a 20-sided (icosahedral) shell resembling the poliovirus molecule.
HAV was originally known by several other names: infectious hepatitis, epidemic hepatitis, acute cattarrhal jaundice, and acute epidemic hepatitis.
First isolated by Purcell in 1973, the Hepatitis A virus was classified in the genus Enterovirus, but further studies showed that it did not belong there and was reclassified to its own category of Hepatovirus.
HAV first replicates in the epithelial cells of the intestines. The virus then moves into the bloodstream and is transported to the liver, where it replicates again, causing the classic symptom of jaundice. Large numbers of the virus particles are then shed into the bile duct, where they reenter the intestines to be excreted in the feces.
Since HAV is most often spread via the fecal/oral route, proper handwashing is imperative to prevent its spread to foods. HAV is rarely transmitted via blood transfusions or contaminated needles, but it can be contracted after eating shellfish caught in contaminated waters.
HAV can infect both humans and other primates, but provides lifelong immunity after the initial illness. The incubation period is, on average, about a month, with it being as short as two weeks and as long as two months and is directly related to how much of the virus entered the body at one time.
Symptoms of HAV infection start out like the flu, but the difference develops a short time later when the signs of liver inflammation appear in the form of yellowish skin and whites of the eyes. By that time, the patient is already starting to feel better. The greatest danger of infection comes during the peak period of incubation when the person is still unaware of any illness. This is the 2-week period between exposure and the onset of jaundice. By the time that jaundice appears, the virus has begun to weaken, but the person can still remain infectious for up to 10 days longer. With proper rest and diet, symptoms usually dissipate within 2-6 weeks without any further treatment. High temperatures of 85°C (185°F) and bleach will kill the virus.
Most frequently, HAV affects children and young adults, and usually stems from poor sanitary practices and overcrowded conditions. Normally, it is a mild acute illness that begin with ‘flu-like’ complaints and tender lymph nodes, especially in the neck. There can also be a mild cough and diarrhea (sometimes clay-colored stools) with upper abdominal pain. This is followed by jaundice, fever, dark urine, loss of appetite, and general weakness. In rare instances, however, there can be a lengthy illness of up to 6 months or a relapse during the year following the first onset. On the rare occasion, death can result from fulminate liver failure (occurring suddenly and with great intensity).
Those who know they have been exposed to the virus within the previous two weeks are given a gamma globulin or antibody injection. Once symptoms begin, the gamma globulin is not effective, however. Treatment for HAV is generally nothing more than rest. It is very important that the liver receives this rest as much as possible in order for it to heal itself and speed recovery. In cases of fulminate liver failure, transplantation is the only recourse.
Some reports indicate that the use of choline can be effective against HAV and HBV. The use of probiotics and a healthy vegetarian diet are also advocated, since meat causes an extra strain on the liver as it breaks down the proteins. Anything that builds the immune system will be of benefit in thwarting the development of viral hepatitis in the first place.
Immune globulin (IG) is prepared from a pool of blood plasma collected from many different people with immunity. IG is then put through a process called ‘cold ethanol fractionation’ producing the final product. It has been tested negative for HBV surface antigen, for HIV, and for the antibody to HCV. The process by which it is made will automatically kill the HIV.
If IG is given within two weeks of exposure, it is about 85% effective in preventing the disease. The vaccine does not interfere with most other vaccines, but it will interfere with such live, attenuated vaccines as those for measles, mumps, rubella, and varicella (chicken pox).
Individuals who have had Hepatitis A disease or who have completed the series of Hepatitis A vaccinations have lifetime immunity and do not require IG.
A frequently asked question concerns the difference between IG and the Hepatitis A vaccine. IG is manufactured from antibodies of a large pool of donated human plasma. It is a passive form of protection because the body of the person receiving IG does not react to the IG, but simply circulates it, giving instant, but short term, protection lasting but a few months. Then the protection disappears.
A vaccine or immunization is an active form of protection, stimulating the recipient’s immune system to build its own antibodies. The immune system then retains the pattern so that more antibodies can be manufactured in the future. Immunity response to a vaccine may last several months to a lifetime.