Hepatitis A Strikes Hardest in Older Individuals

FOR IMMEDIATE USE April 2, 1997
Contact: Donna Cary; 215-652-5558

Judi Kroeger; 610-821-1299; [email protected]

HEPATITIS A STRIKES HARDEST IN OLDER INDIVIDUALS

West Point, Pa., April 2, 1997 -- Even in areas where hepatitis A is common, Americans tend to underestimate its risks, according to a Gallup survey. The survey was commissioned by Merck & Co., Inc. The company makes a vaccine indicated for hepatitis A.

According to the Federal Centers for Disease Control and Prevention (CDC), hepatitis A is the seventh most commonly reported infectious disease in the U.S. It ranks sixth among the top ten causes of foodborne disease and remains a major public health problem. It is spread by the fecal-oral route.

Gallup surveyed more than 1500 adults in Memphis, Tenn., where an outbreak has been ongoing, and in Los Angeles, Ca., a major city in the state with the highest number of reported cases of the disease in 1995 and 1996. Respondents included the general public, restaurant owners or managers, and daycare operators whose facilities care for diapered children. Most survey respondents think HAV affects all age groups in the same way or that children are made sicker by the disease.

In fact, the reverse is true. Hepatitis A is often without symptoms in young children and strikes hardest in older individuals, putting about 20 percent of those with reported cases between the ages of 15 and 39 and more than 30 percent of those over 40 in the hospital every year.

While food-related transmission of hepatitis A is a relatively small percentage of reported cases (5 to 7 percent), it is important because of its potential to spread the disease widely within a community. Daycare facilities with very young children and infants also have figured prominently in the spread of the disease.

"Children may have no symptoms, so their disease is not suspected. But, they spread hepatitis A to susceptible siblings, parents, playmates and daycare workers," said Harry Keyserling, M.D., Associate Professor of Pediatrics at Emory University School of Medicine, Atlanta, Georgia, and a leading authority on hepatitis A. "In addition, about 45 percent of individuals who become infected don't know how -- or where -- they contracted the disease. However, nearly half of them have youngsters at home under the age of five."

Food-related outbreaks in the U.S. have been linked to salads, sandwiches, raspberries, lettuce and other uncooked foods handled or prepared by an infected individual incubating the disease. Now, imported frozen strawberries may be the culprit.

"While foodservice and daycare environments that care for children in diapers are not the only sources of hepatitis A, they are among those with the greatest potential to spread the disease among susceptible populations," Dr. Keyserling said. "We need to do a better job of educating parents and others who care for small children, the general public, and those in at-risk groups about disease prevention through personal hygiene and vaccination. This is particularly important when you realize that about 50 percent of all adults in the U.S. are susceptible to hepatitis A because they have never contracted the disease."

Hepatitis A Background

An estimated 143,000 individuals in the U.S. are stricken with hepatitis A each year, nearly half of whom are not considered part of recognized high risk groups. Of these, about 100 individuals die each year. At particular risk for more serious consequences are those older than 50 years of age.

"There is no cure for hepatitis A and no treatment except bedrest," said Dr. Keyserling. Of the adults who contract it, most recover over a several week period, but as many as 20 percent may experience a relapse that leaves them ill for up to six months. They lose, on average, 27 days from work or school. Annual direct and indirect costs associated with hepatitis A, for which there is no cure, were approximately $200 million in the U.S. during 1987.

A Hardy Virus

The hepatitis A virus is hardy and spreads readily. Unlike many other viruses, it can survive for a month or more at room temperature on kitchen countertops, children's toys and other surfaces, and is maintained indefinitely in frozen foods and ice. Foods must be heated above 85oC (185oF) for one minute to inactivate it. Its persistence in the environment contributes to its ability to infect large numbers of susceptible individuals who then transmit the virus to others before they themselves develop symptoms. "This disease is hard to track," said Dr. Keyserling. "Its incubation period ranges from 15 to 50 days, with the virus being shed in the feces of infected individuals for up to two weeks before they even suspect they are sick. It spreads readily when susceptible individuals ingest virus-contaminated food or water."

Symptoms, which occur suddenly, include fatigue, nausea, vomiting, jaundice and abdominal pain.

An Old Problem, A New Solution

Reports of what is now known to be hepatitis A date back to 400 B.C. The virus has afflicted armies in every conflict in the past century and is believed to have played a role in Napoleon's defeat. It has, however, now perhaps met its own Waterloo with the introduction of vaccines that offer pre-exposure protection to those who have never had the disease.

The hepatitis A vaccine, VaqtaÆ (Hepatitis A Vaccine, Inactivated), produced by Merck & Co., Inc. was 100 percent effective in a landmark clinical trial in children in the U.S. after a single primary dose. It is indicated for individuals older than two years of age. Side effects from the Merck vaccine were comparable to placebo in clinical trials.

"The most common adverse effect in clinical trials was tenderness at the site of injection," Dr. Keyserling reported. "Of course with more widespread use of hepatitis A vaccines, we may see additional adverse events. Nonetheless, those at risk for contracting or spreading the disease should consider vaccination." Vaccines should not be administered to those allergic to any of the components of the vaccine.

Merck & Co., Inc. is a worldwide leasters at home under the age of five." Food-related outbreaks in the U.S. have been linked to salads, sandwiches, raspberries, lettuce and other uncooked foods handled or prepared by an infected individual incubating the disease. Now, imported frozen strawberries may be the culprit.

"While foodservice and daycare environments that care for children in diapers are not the only sources of hepatitis A, they are among those with the greatest potential to spread the disease among susceptse see full prescribing information, attached.