Introduction The term ‘hepatitis’, deriving from Latin, simply means inflammation of the liver. This is analogous to a ‘sore’ in the skin, which is due to inflammation of the skin, the cause of which could be multiple and variable. In the case of the liver, alcohol, drugs and viruses are the common causes of inflammation of the liver. Hence, ‘viral hepatitis’ denotes a condition where inflammation of the liver is caused by certain specific viruses with affinity to the liver. Just like the influenza (and the parainfluenza) viruses that caused ‘flu’ tend to give trouble mainly to our respiratory system, hepatitis viruses cause trouble in our liver, giving rise to viral hepatitis. To date, scientists have identified at least 5 types of hepatitis viruses, namely hepatitis A, B, C, D and E viruses that cause hepatitis A, B, C, D and E, respectively. Whereas we can be infected by hepatitis A and E viruses by ingestion of contaminated food and drinks, hepatitis B, C and D viruses are transmitted via contaminated body fluids and blood. While the initial manifestation of the diseases is similar, there is also some difference in the outcome depending on the type and the timing of hepatitis virus infection that we have contracted with. Acute Viral Hepatitis Though particularly rare for hepatitis C virus, all hepatitis viruses can give rise to acute viral hepatitis. This is a condition that occurs upon recent exposure to the culprit virus. After a specific incubation period, which differs for various hepatitis viruses, the infected individual will then develop symptoms characteristics of hepatitis. Initially, the patient may experience flu-like symptoms, ranging from body-aches, transient fever, loss of appetite, nausea to mild vomiting. Chronic smokers may experience aversion for smoking. This will be followed by typical symptoms associated with jaundice, wherein the patient will notice darkening of the colour of his urine, yellow discoloration of the sclera of his eyes, and sometimes, lightening of the colour of his stools. If the patient sees a doctor at this time, specific blood tests can confirm the presence of inflammation of his liver, as well as identify the causative hepatitis virus. There is no specific treatment or drug for hepatitis caused by any of the hepatitis viruses. Most times, with adequate rest and nutrition, the patients will recover spontaneously. Meanwhile, the patient should be monitored by a doctor with regular blood tests to look out for the rare occurrence of liver failure, which happens in < 5 % of the patients. For the few unfortunate ones who develop liver failure, liver transplantation may be the only cure for them. In Singapore, hepatitis A and B account for the majority of the local incidences of acute hepatitis. While the infection may be acquired locally, people should be aware of hygiene during travel. Hepatitis E is common in the Indian subcontinent, it can also be found in certain Southeast and East Asian countries. Whereas it may be most commonly contracted by drinking contaminated water, hepatitis A is usually caused by ingestion of not-fully-cooked shellfish. On the other hand, hepatitis B, as well as hepatitis D is contracted mainly through unprotected sex and sharing of contaminated needles / instruments among intravenous drug abusers, during tattoo or acupuncture. The latter is also the route of transmission for hepatitis C. With screening carried out in the blood banks, contamination from transfusion of blood products is unlikely nowadays. Hence, it is important to avoid accepting commercial blood donors. Acute hepatitis caused by hepatitis A and E viruses usually recover without any long-term consequences. However, some of the patients who are infected by hepatitis B, C or D viruses may not be able to clear the viruses completely and develop chronic hepatitis virus infection, they are what were known as ‘carriers’ of certain hepatitis virus in the past. Chronic Viral Hepatitis For patients who have chronic viral hepatitis, the inflammation of the liver, which may be intermittent, can go on for decades. Expectedly, such repeated and prolonged insults to the liver then lead to irreversible damage to the liver. Structurally, there is scarring / hardening of the liver, accompanied by loss of liver function, giving rise to a condition known as liver cirrhosis with multitudes of clinical complications, including liver failure, necessitating liver transplantation, and liver cancer. Depending on the type of hepatitis virus, and the age at which the patient is exposed to the virus, the likelihood of developing a chronic (or prolonged) hepatitis virus infection differs. For those who are exposed to the hepatitis C virus, 80 % of them will be unable to get rid of the virus spontaneously, thus become hepatitis C “carriers” or, patients with chronic hepatitis C virus infection. For hepatitis B, the majority of patients (90%) who are exposed to hepatitis B virus for the first time in adulthood will be able to clear the virus completely after an episode of acute hepatitis B. However, the outcome is very different if the infection is acquired at the time of birth. The majority (90%) of newborns of mothers with chronic hepatitis B fail to clear the infection upon exposure to their mothers’ body fluid at birth and will then end up with chronic hepatitis B virus infection. The risk of this route of infection has been much reduced since the introduction of hepatitis B vaccination to the infants at the time of birth. Vaccination given at the time of birth confers protection to > 90% of these newborns against acquiring the infection from their mothers at birth. In Singapore, the commonest cause of chronic viral hepatitis is chronic hepatitis B. Chronic hepatitis C, which is relatively rare, is mainly confined among a small group of patients who have chronic kidney failure requiring haemodialysis. Hepatitis D, which can only exist in the presence of chronic hepatitis B, is even rarer. Patients with such condition should always see a doctor and seek treatment. Final Advice Nowadays, all newborns in Singapore are offered hepatitis B vaccination at birth. Catch-up hepatitis B vaccination programme is also implemented in secondary school level. For adults at risk, hepatitis A and B vaccine are provided by all primary health care givers in Singapore. It is important to screen for pre-existing chronic hepatitis B prior to hepatitis B vaccination. Persons involved in high-risk activities and profession who may have close contacts with patients with chronic hepatitis B should consider hepatitis B screening and vaccination. Patients with chronic hepatitis B and frequent travelers should consider hepatitis A vaccination. As for those who already have chronic hepatitis B or C, they should be seen regularly by their doctors who will carry out regular screening for complications of the disease, and consider treatment for them, when appropriate.