Hepatitis B is the most common strain here and can cause liver cancer. APRIL CHONG reports
One in 35 adults here is a hepatitis B carrier. This works out to 2,860 in 100,000 people.
However, many do not know they carry the virus. This is because the condition often has no noticeable symptoms.
More than 90 per cent of hepatitis B cases are transmitted from mother to child during birth, said Dr Tan Hui Hui, consultant at Singapore General Hospital’s gastroenterology and hepatology department.Many people are unaware that they are carriers and find out only when they have a blood test done, she added.
However, if they do not find out about their condition and if the virus remains in the body for more than six months, the condition becomes chronic. This can lead to liver cirrhosis and cancer years later.
If the infection is less than six months old, it is called acute hepatitis.
Carriers can unknowingly infect others through blood and body fluids, such as during sexual contact. Those who get infected by carriers make up the remaining hepatitis B cases.
However, most people who are infected in adulthood are able to fight off the disease without any help within months.
On the contrary, the majority of children who contract the virus through birth will not be able to fight off the infection and will carry the virus for life.
There is a vaccine available for hepatitis B.
Although hepatitis B is the most prevalent strain in Singapore, other types of the virus can be found here too.
Hepatitis A and E are largely transmitted through contaminated water.
This could happen when a person eats tainted shellfish harvested from water that has been contaminated with the viruses.
The hepatitis A and E viruses cause acute infection but are seldom fatal and infected people usually build immunity against any subsequent attacks.
There is no specific treatment for these acute infections and the diseases have to run their course, which can last up to six months.
A vaccine is available for hepatitis A, one has been developed for hepatitis E but it is not commercially available yet.
Hepatitis C, which can lead to liver cirrhosis, is usually passed through bodily fluids.
Often associated with shared needle use, unchecked blood transfusions and non-sterile medical procedures, it is the leading cause of liver disease in countries such as the United States and China.
Here, one in 100 to 200 people are carriers.
Unlike hepatitis B, there is no vaccination for hepatitis C. Those who had blood transfusions before screening for hepatitis C was established in the 1990s are at risk and the infection is asymptomatic until liver damage sets in years later.
Treatment for hepatitis C is similar to hepatitis B. There is no complete cure for those whose bodies cannot fight the hepatitis C virus but antivirals and protein interferons can be used to prevent viral replication.
Hepatitis D and G, both transmitted through blood, are not usually found here and hepatitis F has been delisted because of insufficient proof that it causes disease.
Hepatitis B, though the most common here, is unfortunately hard to detect in young patients who largely get the disease during birth.
Their immune system tolerates the virus and they do not suffer from liver inflammation like older patients, said Dr Yap Chin Kong, a liver disease specialist at Mount Elizabeth Medical Centre.
However, as the young carriers reach their 20s, their immune system starts fighting the virus and this causes liver inflammation.
If the patient’s body does not win this fight, prolonged inflammation can occur, leading to liver damage and cirrhosis, said Dr Yap.
Hepatitis B vaccination was introduced in the national immunisation programme in 1987, with children offered the three-course jabs over six months. They are, however, not compulsory by law.
The number of hepatitis B cases has been falling since. The incidence of acute hepatitis B has dropped from 243 cases (9.5 per 100,000 people) in 1985 to 87 cases (1.7 per 100,000 people) in 2008.
During the same period, the reported number of cases in children went from 10 to none.
These days, babies of mothers found to be carriers of hepatitis B are given immunoglobulins and vaccinations to ward off the infection.
The threat remains for the middle-aged and older folk, who did not have the benefit of early screening and vaccination.
The jabs do not work if one is already infected, said Dr Tan. Also, people who had blood transfusions before the mid-1980s are at risk because blood screening methods for hepatitis B were not as established then.
Liver cancer, of which hepatitis B infection is a major cause here, shows no symptoms in the early stages. One way of prevention is to get the hepatitis B vaccination early.
Adults at risk – such as those who have family members with hepatitis B, have many sex partners or are immigrants from endemic areas – should get a blood screen.
About 95 per cent of people who take the set of three injections will develop an immune response.
However, whether the jabs have worked can only be determined by a blood test, said Dr Yap. The protection is believed to last for life, he added.
The 7 strains of hepatitis
A&E These are transmitted through contaminated water but rarely fatal. A vaccine is available for hepatitis A. A person is usually able to fight off these viruses without help. A small number of people may suffer serious liver damage.
B More than 90 per cent of cases are transmitted from mother to child during birth. It can lead to liver cirrhosis and cancer. Vaccination is available and antivirals are used to prevent the virus from replicating.
C It is passed through bodily fluids. There is no vaccination available. Antivirals can prevent viral replication.
D&G Transmitted through blood but not found here. Hepatitis G is found in countries like the United States and Germany. Hepatits D is rare in developed countries and is found in places like sub-Saharan Africa.
F Delisted because there is insufficient proof that it causes disease. Some studies have even failed to proof its existence.