Those traveling to areas where hepatitis A is prevalent should seek protection with two new hepatitis A vaccines that became available this year and last.
In the past, those traveling to areas where hepatitis A was present were protected by a shot of immune globulin (formerly called immune serum globulin or gamma globulin), which confers immediate, if short-lived, immunity, said Dr. Victor Kovner, a Studio City internist who focuses on travel medicine. But in late June, a major manufacturer of intramuscular immune globulin--until last year, the standard hepatitis A preventive--voluntarily withdrew its supplies from the market after a new FDA test found fragments of hepatitis C virus in samples. Already in short supply, immune globulin is expected to become more difficult to find.
But travelers who need protection from the viral disease hepatitis A, present in many developing countries, can choose between Vaqta, which was approved by the Food and Drug Administration earlier this year, and Havrix, which was approved last year.
Unless departing at the last minute, travelers are now advised by the Centers for Disease Control and Prevention to take either of the two new vaccines to protect themselves against hepatitis A.
The disease is common in Africa, Asia (excluding Japan), the Mediterranean, Eastern Europe, the Middle East, Central and South America and Mexico. (For updated information, call the CDC International Traveler's Hotline,  332-4559.)
Experts say the new vaccines, which promise long-term effectiveness, are a significant advance over immune globulin, which is concentrated hepatitis A antibodies derived from human blood plasma. A single 2-milliliter dose of immune globulin only provides protection for about three months. Though manufacturers can't yet pinpoint how long the new vaccines are effective, studies so far suggest they may last several years.
Travelers who elect to take the new vaccines, however, must plan ahead. The initial dose of both is best administered at least two weeks before travel, according to the manufacturers, and, according to the CDC, the vaccine produces immunity four weeks after the first dose in almost all people.
A disease that attacks the liver, hepatitis A is not usually life-threatening, but can be accompanied by debilitating symptoms such as fatigue, fever, muscle and joint aches, nausea, vomiting and pain in the liver area. Jaundice is also common. Some require a year for full recovery.
Transmission usually occurs via the fecal-oral route, most often from close person-to-person contact such as that between an infant and a parent, according to the CDC. The virus can also be acquired by eating contaminated food or drinking contaminated water or ice cubes because the virus can remain active for long periods.
During outbreaks, those at increased risk include children in day-care centers, men who have sex with men and those who inject recreational drugs, according to the CDC. The incubation period varies from 15 to 50 days, but averages 28.
The disease is most common in developing countries. In the United States each year, 138,000 people become infected, according to a CDC spokeswoman, and 100 die from hepatitis A.
Both vaccines are made from inactivated hepatitis A virus and work by stimulating the body's defense mechanism, just as a natural infection would, but without causing the actual infection. Effectiveness of the vaccines ranges from 94% to 100%, according to spokesmen for the manufacturers, SmithKline Beecham and Merck Vaccine Division.
Cost of the two vaccines is also similar. In an informal poll of Southern California physicians, a single dose of either was about $75, with some physicians adding on an office visit fee. They said they see little difference in the protection provided by the two products.
Both vaccines require an initial dose and a booster for adults. One formula of Havrix requires two initial doses and a booster for children. Side effects can include soreness at the injection site and a headache. The new vaccines are not recommended for children under 2, who are advised by the CDC to use immune globulin.
Already in short supply because of increased demand by the military, immune globulin will probably be difficult to find at least until the end of the year.
In late June, Centeon in King of Prussia, Pa., voluntarily withdrew all its intramuscular immune globulin supplies, marketed under the Armour Pharmaceutical label, said Arlene Santhouse, a spokeswoman for the company. Some of the lots evaluated by the FDA with a new, more sensitive test were found to contain hepatitis C (another form of hepatitis) virus fragments, she said.
If Centeon had not voluntarily withdrawn the supplies, the FDA could have stepped in, she said. But in a letter to manufacturers, an official from the U.S. Department of Health and Human Services said that finding virus fragments does not mean the product is infectious. There have been instances of hepatitis C transmission via intravenous immune globulin, according to the department, but "immune globulin preparations for intramuscular administration [such as that used by travelers] have not been implicated in the transmission of hepatitis C virus."
"We are currently working on a new version," said Santhouse, who expects it to be available by year's end. The newer immune globulin, she said, will be pasteurized to inactivate any hepatitis C virus present.
Even with the new vaccines, she and others said, immune globulin will still be useful for small children and last-minute travelers. It can also be administered to those who did not take the vaccine and are then exposed.
The Healthy Traveler appears the second and fourth week of every month.