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MAY 19, 2000 VOL. 27 NO. 19 | SEARCH ASIAWEEK Lethal Letters Don't underestimate the hepatitis threat By WILLIAM LAI Consider the danger. The bug is deadly and 100 times more infectious than HIV. So it stands to reason that if there were an easy way to protect yourself against infection, you would take it straight away. Still, many people don't bother to make the effort. Partly that's because the disease springs from a confusing alphabet soup of related bugs. Hepatitis or inflammation of the liver is triggered by several types of viruses, which scientists have identified by letters. They began with A and B, and are now already up to G (see box). All the different forms produce debilitating symptoms such as nausea, vomiting, severe fatigue and jaundice. But the two big killers are types B and C. In fact, scientists say these bugs act like time-bombs: they damage genes in liver cells, but the lethal effects don't show up till much later when the organ starts losing its ability to perform vital functions such as purifying the blood, removing toxins from the body and making enzymes.
Of the two types, the hepatitis B virus or HBV poses the greatest health threat and most affects Chinese, Africans and Inuits. An estimated two billion people worldwide have been infected with the virus, 350 million of whom are carriers. And according to the World Health Organization, three-quarters of these chronic carriers live in Asia. The nations with the biggest infected populations: China and India. Some people suffering hepatitis B die within weeks; others recover and acquire lifelong immunity. Many, however, develop a chronic form of the disease in which they never rid themselves of the virus. Rather than directly kill liver cells, the bug continually replicates in the body and so activates cells in the immune system, which inflames the organ and inflicts irreparable damage. Often, the long-term result is cirrhosis or cancer of the liver. Meanwhile, the patient is liable to pass on the virus to more people. Like AIDS, hepatitis B is transmitted through body fluids such as blood. And people may be infected in the same ways: through transfusions, sharing contaminated syringes or toothbrushes or sexual contact. But while hepatitis B can be treated, it is also considerably more infectious than AIDS. More than 90% of carriers are infected by their mothers during birth. Children with HBV often pass on the bug to other kids too. Among the suspected avenues: cuts and scratches that come naturally to energetic youngsters. And children infected before they turn seven are more than twice as likely to become carriers than those who catch HBV when they are older. Yet an effective vaccine has been available since the early 1980s. It has a 95% success rate in preventing infection and even babies can safely be inoculated against hepatitis B. Indeed, it's the first vaccine against a major cancer. So why aren't more people lining up for a jab? Most of us still don't know enough about HBV and its possible consequences. More often than not, we tend to confuse it with type A, says Dr. Lai Ching-lung of the Queen Mary Hospital in Hong Kong. Less than half the people in the SAR, for example, can differentiate between types A and B, notes Lai, an authority on hepatitis. (Hepatitis A is usually transmitted through contaminated food, drinks and shellfish. Sufferers can also infect others through close contact and poor personal hygiene. But the virus does not lead to chronic disease, although it can occasionally be fatal.) For years, the standard treatment for chronic hepatitis B has been to administer alpha-interferon, a protein which suppresses virus replication while stimulating the immune response to HBV. But the therapy is far from satisfactory. For one thing, interferon isn't as effective for Asians as for Caucasians. Says Lai: "The most optimistic result is that about 20% of patients will respond to interferon compared with those with no treatment." Doctors have had more success with newer anti-viral drugs like lamivudine. Lai notes that the response rate to the medicine rises from about 20% in the first year of treatment to 60%-70% in the fourth year. The problem is patients develop resistance over time. Because people are the main reservoir of HBV, Dr. Chan Kin-ling of the Hong Kong College of Family Physicians argues that communities must be taught to reduce their chances of infecting others. Coupled with universal vaccination, he says, education is the only way to safeguard youngsters from the virus and its long-term health complications. About 10% of people in Hong Kong are carriers and every person who hasn't been inoculated risks infection, he says. (The SAR has provided free hepatitis vaccination for newborns since 1988 and countries such as Malaysia, South Korea and Thailand have made HBV jabs part of their immunization programs.) Attacks by the hepatitis C virus are just as disastrous on the body. Worse, there's no vaccine. And because most infected people don't show symptoms, as much as 90% of patients are not diagnosed till decades later. By the time, the effects of liver damage show up in medical tests, treatment may be too late. The hepatitis C bug mutates very quickly, which makes developing a vaccine more difficult. It also means some antibodies produced by infected individuals afford little protection, adds Lai. Fortunately, hepatitis C is a small problem in Asia: the incidence is below 0.5% for nations in the region. "Hepatitis C will remain uncommon because countries have been screening for the virus since the beginning of the 1990s," adds Lai. All the same, health administrators warn of resurgent viruses. Even hepatitis A, which has been declining in past years through improved public hygiene, may strike back. Only two years ago, Hong Kong officials were predicting a possible epidemic as fewer people have immunity against the A virus. With hepatitis, you've got to be familiar with all the alphabet. Write to Asiaweek at mail@web.asiaweek.com
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