Common Name

Hepatitis A has been known as Infectious Jaundice since 1912 due to its ability to be easily transmitted within households or through closely knit communities. Perhaps it is most frequently known in Ireland as the Yellow Jaundice which perhaps signifies the fact that the yellow discolouration may be very severe!

Geographical Distribution

The disease occurs throughout the world and it is certainly well reported in Ireland. Nevertheless, with the improvements in personal and public hygiene the disease now only tends to occur in small epidemics throughout our country. In the developing parts of our world, where faecal contamination of food and water supplies are a common occurrence, many of the population will be exposed to the disease while they are children. In these regions the disease remains endemic and tourists will be at significant risk.

Causative Agent

Hepatitis A (HAV) is caused by a small unenveloped symmetrical RNA virus which measures approximately 27nm. Due to its very small size the virus can easily transfer through normal water filtration systems. The virus invades into liver cells and is excreted in bile and faeces.

Transmission

The disease is mainly transmitted through the oro-faecal route (contaminated fingers, food and water consumption) but sexual transmission is also well reported. The virus is only present in the blood for a very brief time so transmission through blood transfusion or needle stick exposure is very rare. The virus may be present for a transient time in saliva and so could, in theory, be coughed from person to person. This would be rare and by far the most common means of transmission is through the drinking of contaminated water or the consumption of contaminated foods. Without much doubt undercooked bivalve shellfish constitute the greatest single hazard for travellers to many of the tropical regions of the world. If the local population excretes the virus in their faecal material – and this is disposed of into the sea close to shell fish beds – then there is a distinct probability that these shell fish will filter the water and concentrate this contaminated faecal material. Bivalve shell fish are generally undercooked (steamed for 45 seconds etc.) and thus full sterilisation cannot occur. So while travellers insist on eating what amounts to raw faeces it is hardly surprising that the transmission of HAV occurs with such regularity!

Age Profile

The disease can affect all ages. In those living in developed countries there is a tendency for adults to be affected while in the tropics the disease mainly occurs among children.

Incubation & Disease Cycle

Following an incubation period, which is usually between 25 to 30 days, the individual presents with diffuse ‘flu like symptoms. This prodromal period can be very confusing as there are usually no localising signs or symptoms. The patient may be diagnosed as influenza and treated symptomatically until they return to the surgery a few days later looking like a lemon and lime cordial. At that stage the diagnosis may be fairly straightforward and blood can be drawn for confirmation. If, however, the examining doctor maintains a heightened degree of awareness then the initial consultation (during the pre jaundice phase) may reveal a significant history of exposure, some tenderness in right upper quadrant of the abdomen and perhaps a history dark looking urine. Under these circumstances laboratory examination of the urine and blood may reveal the diagnosis and so potential spread of the disease may be limited. Other typical signs and symptoms include anorexia, fatigue, vomiting, abdominal discomfort, fever, muscle aches and, occasionally, arthritis has been reported. In children, especially under 5 years of age, the disease may present with an non-jaundiced pattern. That is the jaundice may be absent or very mild. These children may just become anorexic for a week or so and somewhat lethargic. Again the diagnosis may be very difficult to consider.

Mortality

In the majority of cases Hepatitis A is a non-life threatening condition. The majority of adults remain lethargic and off work for one to two months and feel under par for up to six months. (Many complain bitterly about having to stay off alcohol for up to 18 months – worse than the disease itself!). In adults over 40 years of age there is a reported 2% mortality from fulminant hepatitis. In children the disease is usually mild and often, in those under 5, they remain asymptomatic. However a proportion of these children can go on to develop significant disease and may require liver transplantation.

Diagnosis

Confirmation is usually made on finding anti-HAV IgM in the serum though it is theoretically possible to also find the virus in faecal samples very early in the disease. Anti-HAV IgG may be found within 1 to 2 weeks and this remains detectable for many years conferring long term immunity to the individual. Liver function tests including serum bilirubin, asparate aminotransferase and alanine aminotransferase are elevated.

Treatment

There is no well recognised treatment for this viral disease and the majority of patients will recover with supportive therapy. In patients with fulminant disease liver transplantation will need to be considered.

Protection

Care with food and water hygiene are paramount in protecting the individual traveller. Active and Passive protection can also be offered to those without their own immunity. Fig 1(on a separate sheet) gives a possible plan of action which could be used is assessing which vaccine to give to international travellers who have a risk of contracting Hepatitis A while abroad. Routine blood screening for anti-HAV IgG may not be worthwhile in those under 40 years of age with no history of jaundice.

Passive Immunity

Since 1943 hyperimmune serum has been used to protect against HAV. Pooled gammaglobulin is usually administered a few days before travel and provides very adequate protection for a number of months depending on the dosage given. This is a blood product formed from pooled serum and thus fears have been expressed about its safety with regard to the transmission of other viral diseases (HIV,HBV, HCV etc.). Statements from the World Health Organisation and the Center for Disease Control in Atlanta have confirmed their opinion that prepared intramuscular gammaglobulin is safe and there is no evidence that viral transmission could occur. There are more recent concerns about nvCJD which is linked with Mad Cow Disease (BSE) and has a very long incubation period.

Active Immunity

Since 1992 in Ireland we have access to active immunisation for HAV in the form of Havrix. More recently we have Vaqta which is another similar product. These synthetically made materials have been shown to be safe and effective in providing long term protection against Hepatitis A. Generally one single vaccine provides protection within 2 to 4 weeks which last for approximately 6 months to 1 year. A single booster dose at that time maintains the protection for at least a further 10 years.

Summary

Unprotected travellers are at significant risk of Hepatitis A during their time abroad. The accepted figures vary from 1:300 to 1:500 for those travelling to the tropics for a 2 week vacation. The disease is serious in that those affected are frequently off work for up to 2 months. For the self employed this could spell financial disaster. Travellers should avoid under cooked shellfish meals and take special care with their food and water consumption. Vaccination cover (either passive or active) should be offered to all travellers to regions outside Western Europe, North America and Australia/New Zealand