Do Hepatitis A Antibodies Indicate Infectivity?

by Ben Best

[References to HARRISON'S are to the book HARRISON'S PRINCIPLES OF INTERNAL MEDICINE (14th Edition, 1998)]

Hepatitis simply means inflammation of the liver -- usually caused by a virus, but sometimes by a toxin. Because the symptom (liver inflammation) is common to all hepatitis manifestations people often assume that the causative agent is the same. But the alphabetically-named viral agents (A, B, C, D and E) are all distinct entities. Hepatitis A virus, for example, consists of a 7,500 base-pair linear strand of RNA which is spread by fecal shedding, whereas hepatitis B virus is a circular 3,200 base-pair strand of DNA which is most highly infectious in blood and, to a lesser extent, in semen.

Testing positive for Hepatitis A Virus (HAV) antibodies is very different from testing positive for Human Immunodeficiency Virus (HIV) antibodies of AIDS. In an immune system disease such as HIV, antibodies cannot destroy the virus. In viral diseases not affecting the immune system, antibodies generally do destroy the virus. For most people, antibodies in the blood against a virus means that the immune system has fought or is fighting the virus. If the virus has been defeated, the disease is gone, even though antibodies remain. (Of course a person in an acute phase of an infectious disease has antibodies and is infective.)

Some relevant quotes from HARRISON'S:

"This agent [Hepatitis A] is transmitted almost exclusively by the fecal-oral route."

"Following acute illness, anti-HAV of the IgG class [Immunoglobulin G, ie, antibody G] remains detectable indefinitely, and patients with serum anti-HAV are immune to reinfection."

"No HAV carrier state has been identified after acute type A  Hepatitis."

"Despite persistence of virus in the liver,viral shedding in feces, viremia, and infectivity diminish rapidly once jaundice becomes apparent."

World Prevalence of anti-HAV Antibodies

There is an excellent series of papers on Hepatitis A in the beginning of THE JOURNAL OF INFECTIOUS DISEASES 1995, Supplement 1 (Volume 171). The lead article on epidemiology gives good statistics on the prevalence of anti-HAV antibodies in different countries and age-groups. A graph on page S6 shows a virtual 100% incidence of the disease by age 10 in Asia & Africa. In Europe & the USA there is a 50% incidence by age 30 and a 90% incidence by age 50. [A report from the CDC shows incidence in the USA to be highest in states closest to Mexico.]

Body Fluid HAV Infectivity Titers

Another excellent graph on page S20 shows Hepatitis A titers in feces to be 10,000 times greater than that in blood, which is again 100 times greater than saliva titers and 1,000 times greater than titers in urine & semen -- reinforcing the assertion that transmission is almost always due to fecal contamination.

Virologic Events in HAV Infection

For the great majority of patients, fecal HAV drops permanently to zero within a month-and-a-half. Viremia up to a year is extremely rare. The Immunoglobulin G antibodies (IgG anti-HAV) typically peak at 4 months with such a slow decline that immunity is essentially unlimited.

Concerning delayed infectivity HARRISON'S, states "A small proportion of patients with Hepatitis A experience relapsing Hepatitis weeks to months after apparent recovery from acute Hepatitis. Relapses are characterized by recurrence of symptoms ... Rarely, liver test abnormalities persist for many months, even up to a year. Even when these complications occur, Hepatitis remains self-limited and does not progress to chronic liver disease."

An article in ANNALS OF INTERNAL MEDICINE 106:221-226 (1987) which reported 6.6% of 256 patients experiencing a relapse between 30-90 days after the primary episode -- with Hepatitis A virus present in stools during the relapse period. A similar article on page S15 of the previously-mentioned JOURNAL OF INFECTIOUS DISEASES found an 11.9% incidence of relapse in 59 patients 4-7 weeks after the first peak -- accompanied by the reappearance of symptoms.

A good short summary of the basic facts concerning Hepatitis A can be found on the website of the Centers for Disease Control (CDC) -- a very authoritative and up-to-date source of information on infectious diseases in the United States:

           www.cdc.gov/ncidod/diseases/Hepatitis/a/fact.htm

These symptoms might be common for any flu. Transmission is strongly identified with stools. Evidence of sexual transmission is usually most strongly associated with anal activities with persons in the acute stage.

HARRISON'S states "Virtually all previously healthy patients with Hepatitis A recover completely from their illness with no clinical sequelae." But the disease can be, in rare cases, fatal. A March 2000 report on HepNet:

           www.hepnet.com/hepa.html

states that of the 200,000 Americans infected with Hepatitis A yearly, approximately 100 die. Since the severity of illness increases with age I suspect that these are mostly elderly people and/or people with other serious health problems. Nonetheless, up to 22% of adult patients require hospitalization. Since the severity of the illness increases with age, vaccination for adults can be a good idea. Vaccination provides about 20 years of immunity -- not as good as antibodies from previous infection.

Hepatitis A & E infection are by fecal-oral transmission and Hepatitis C is almost entirely spread by transfusion or needle-sharing. Immunization against Hepatitis B is a requirement for entering massage school in Canada, but there is no such requirement for Hepatitis A. There has never been a case of transmission of any form of Hepatitis through professional massage in Canada.

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