Hepatitis is common in travelers to areas outside North America, Northern Europe, and Australia, and may result in an unpleasant prolonged illness. All travelers should understand how the different types of hepatitis are spread.
Professor Arie J. Zuckerman is Director of the Department of Medical Microbiology at the London School of Hygiene and Tropical Medicine, and of the WHO Collaborating Centre for Reference and Research on Viral Hepatitis.
Viral hepatitis is common throughout the world and is a major public health problem. At least six different viruses are capable of causing the infection, and the illnesses associated with each (which are all very similar) are as follows:
- Hepatitis A, also known in the past as infectious hepatitis or epidemic jaundice
- Epidemic non-A hepatitis
- Hepatitis B, also known in the past as serum hepatitis
- Hepatitis D, (Delta hepatitis)
- Non-A, non-B hepatitis, which is caused by several different viruses, (although, by definition, not by the viruses responsible for hepatitis A and B).
The viruses responsible for hepatitis A and hepatitis B have been ‘characterized’, i.e. a great deal is known about their size, structure, and biology. Sensitive laboratory tests are available for detecting components of the viruses (viral antigens) and immune products against the viruses (antibodies) in the blood or tissues of people who have been infected with these viruses—and hence a diagnosis of infection can be made with precision.
The viruses responsible for non-A, non-B hepatitis has not, on the other hand, been fully characterized, and specific laboratory tests are not available for detecting them. The diagnosis of non-A, non-B hepatitis is thus made (as the name implies) in cases of hepatitis where hepatitis A, hepatitis B, hepatitis D, and other viruses are known to cause liver damage have been excluded.
The illness seen in all forms of hepatitis is similar and results from acute inflammation of the liver. It is frequently heralded by symptoms such as fever, chills, headache, fatigue, generalized weakness, and aches and pains. A few days later, there is often loss of appetite, nausea, vomiting, right upper abdominal pain or tenderness, followed closely by dark urine, light-colored feces, and jaundice of the skin or the sclerae (outer coating of the eyeballs). Many infections, particularly in early life, are without specific symptoms, or without jaundice. In others, jaundice may be severe and prolonged; complete liver failure may occur, and the patient may lapse into a coma.
Hepatitis A is common in all parts of the world, but the exact incidence is difficult to estimate because of the high proportion of asymptomatic cases, infections without jaundice, and differing patterns of disease. Surveys of antibody to hepatitis A have shown that while the prevalence of hepatitis A in industrialized countries (particularly northern Europe, North America, and Australia) is decreasing, the infection is virtually universal in most other regions, particularly in warm climate countries.
Only one form of hepatitis A has been identified, and the antibody that develops against it persists for many years, frequently for life, providing immunity.
An epidemic illness similar to that caused by hepatitis A, and commonly transmitted by contaminated water, has recently been noted in India, Burma, the eastern USSR, parts of the Middle East, and North Africa, but this illness is not caused by the recognized form of hepatitis A virus—since in the areas mentioned most people have already been infected with hepatitis A in early life, and are immune. The illness is due to a virus which is quite distinct from hepatitis A and is referred to as enteric non-A, non-B hepatitis. No specific tests are available for detecting this virus.
How it is spread
Hepatitis A virus is spread by the fecal-oral route, usually by person to person contact, and infection is particularly common in conditions of poor sanitation and overcrowding. Outbreaks result most frequently from fecal contamination of drinking water and food (although water-borne transmission is not a major factor in industrialized countries, or where the piped water supply has been adequately treated and chlorinated).
Food-borne outbreaks, which have become more important and frequent in developed countries, may be due to the shedding of the virus in the feces of infected food handlers during the incubation period of the illness: the source of the outbreak can often be traced to cooking. Raw or inadequately cooked shellfish cultivated in sewage-contaminated tidal or coastal water, and raw vegetables grown in soil fertilized with untreated human feces and excreta, are associated with a high risk of infection with hepatitis A virus. Hepatitis A infection is frequently contracted by travelers from areas of low to areas of high prevalence.
Hepatitis A virus is very rarely transmitted by blood transfusion or by inoculation.
The incubation period of the virus is between three and five weeks with an average of twenty-eight days.
Age incidence and Seasonal Patterns
All age groups are susceptible to infection. The highest incidence is observed in children of school age, but in North America and in many countries in northern Europe most cases occur in adults, frequently after travel abroad. In temperate zones the characteristic seasonal trend is for an increase in incidence in the autumn and early winter months, falling progressively to a minimum in midsummer; but recently this seasonal trend has been lost in some countries. In many tropical countries, the peak of reported infection tends to occur during the rainy season with low incidence in the dry months.
Consequences of infection
The illness caused by hepatitis A has described above. Although the disease has a low mortality, patients may be incapacitated for many weeks. There is no evidence of persistence of infection with hepatitis A virus nor of progression to chronic liver disease.
Enterically transmitted non-A, non-B hepatitis is very severe during pregnancy and is associated with high maternal mortality.
Like hepatitis A, there is no evidence that it progresses to chronic liver disease.
Prevention and control
Control of the infection is difficult. Since fecal shedding of the virus and therefore infectivity is at its highest during the incubation period, strict isolation of cases is not a useful measure. The spread of infection is reduced by simple hygienic measures and the sanitary disposal of excreta.
Normal human immunoglobulin, commonly referred to as gammaglobulin, contains the hepatitis A antibody and will prevent or lessen the severity of the illness, while not always preventing excretion of the virus or the development of asymptomatic hepatitis. Immunoglobulin injections may be required every four to six months for people at risk such as close personal contacts of patients with hepatitis A, and those exposed to contaminated food.
In such cases a 16 percent solution of immunoglobulin in a dose of 2 i.u. hepatitis A antibody/kg body weight may be given intramuscularly before exposure to the virus or early during the incubation period.
Current preparations of immunoglobulin do not afford protection against enterically transmitted non-A, non-B hepatitis.
Hepatitis A and the traveler
Prophylaxis with immunoglobulin is recommended for persons without hepatitis A antibody who are visiting highly endemic areas. Anyone can be given immunoglobulin—there are no general contradictions for its use.
Immunoglobulin prepared for intramuscular administration by cold ethanol fractionation according to the Cohn method is safe and without any risk of transmitting blood-borne infections including HIV (the virus causing AIDS). This is the method of preparation used by all reputable manufacturers in industrialized countries.
Vaccines against hepatitis A are being developed and clinical trials are in progress.
Other preventive measures include strict personal hygiene, avoiding eating raw or inadequately cooked shellfish, avoiding raw vegetables, and avoiding drinking untreated water and raw milk.
Like hepatitis A, hepatitis B occurs throughout the world. Its continued survival is ensured by the large number of individuals who are carriers of the virus, estimated to be at least 300 million worldwide. Hepatitis B can be spread either from carriers or from people with inapparent infection, or during the incubation period, illness, or early convalescence.
A person is defined as a carrier of hepatitis B surface antigen— a marker of the virus—persists in their circulation for more than six months following infection. A person may be a lifelong career and remain apparently healthy, although variable degrees of liver damage can occur.
The prevalence of hepatitis B carriers varies from one region of the world to another. In northern Europe, North America, and Australia, 0T percent of the population are carriers (at least among blood donors); in central and eastern Europe up to 5 percent; in southern Europe, countries bordering the Mediterranean and parts of Central and South America a higher frequency; and in parts of Africa, Asia, and the Pacific area, 20 percent or more of the apparently healthy population may be carriers.
The incidence of hepatitis B tends to be higher among adults living in urban communities and among those living in poor conditions. The infection may become established in closed institutions such as institutions for the mentally-handicapped.
Certain groups of people—recipients of unscreened blood transfusions and infusions of certain blood products, healthcare and laboratory personnel, staff in institutions for the mentally handicapped, male homosexuals, prostitutes, and abusers of injectable drugs and narcotics—are at considerably increased risk of contracting hepatitis B because of the means of transmission. Travellers or expatriates belonging to any of these groups are at higher risk in countries where the carrier rate is high.
How it is spread
Before the development of laboratory tests for hepatitis B, this infection was diagnosed whenever a hepatitis-like illness occurred about 60-180 days after the injection of human blood or plasma fractions or the use of inadequately sterilized syringes and needles. The development of specific laboratory tests for hepatitis B confirmed the importance of transmission by skin penetration, and infectivity appears to be especially related to blood.
Transmission of the infection may result from accidental inoculation with minute amounts of blood which may occur during medical, surgical, or dental procedures; during immunization with inadequately sterilized syringes and needles; sharing of needles during intravenous drug abuse; during tattooing, ear piercing, and nose piercing; during acupuncture, during laboratory accidents and accidental inoculation with razors and similar objects that have been contaminated with blood.
However, hepatitis B is not spread exclusively by blood or blood products. Hepatitis B surface antigen has been found in other body fluids such as saliva, menstrual and vaginal discharges, and seminal fluid, and these have been implicated as vehicles of transmission of the infection. In certain circumstances, the virus may be infective by mouth, and there is much evidence for the transmission of hepatitis B by sexual contact. The sexually promiscuous, particularly male homosexuals, are at high risk.
In the tropics and in warm climates, additional factors may be important for the transmission of hepatitis B. These include traditional tattooing and scarification, blood-letting, ritual circumcision, and repeated biting by blood-sucking insects. Results of investigations into the role that biting insects play in the spread of hepatitis B are conflicting. Hepatitis B surface antigen has been detected in several species of mosquito and in bed-bugs that have either been trapped in the wild or fed experimentally on infected blood, but no convincing evidence of multiplication of the virus in insects has been obtained. However, mechanical transmission of the infection via an insect’s biting parts is a possibility.
Hepatitis B also tends to occur within family groups, although the precise mechanism of intrafamilial spread is not known.
Transmission of hepatitis B virus from carrier mothers to their babies can occur around the time of birth and appears to be an important factor in determining the prevalence of the infection in some regions, particularly in China and South East Asia.
The carrier state
Progression to the carrier state is commoner in males, more likely to follow infections acquired in childhood than in adult life, and more likely to occur in people with natural or acquired immune deficiencies. The carrier state becomes established in approximately 5 to 10 percent of infected adults. In countries where hepatitis B infection is common the highest prevalence of surface antigen is found in children aged four to eight, with steadily declining rates among older age groups.
There is an urgent need to define the mechanisms which lead to the carrier state and to introduce methods of interruption of transmission. This is a complex and vexed issue, with considerable personal, social, and economic implications.
Consequences of infection
The symptoms and manifestations of hepatitis B are similar to those of the other types of viral hepatitis. However, the picture is complicated by the carrier state and by chronic liver disease, which may follow the infection. Chronic liver disease may be severe and may progress to primary liver cancer. In many parts of the world, primary liver cancer is one of the commonest human cancers, particularly in men.
Prevention and control
Immunization against hepatitis B can be carried out in two ways. Passive immunization involves the inoculation of hepatitis B immunoglobulin (hepatitis B gamma-globulin) containing antibody against hepatitis B. However, for hepatitis B, there is now also the possibility of active immunization, because a vaccine containing hepatitis B antigen has been developed. Inactive immunization the inoculation of inactivated antigen ‘primes’ the body’s immune system for production of its own antibodies.
Passive immunization Prevention with hepatitis B immunoglobulin is not required for travelers.
Hepatitis B immunoglobulin is of the greatest value as a protective measure in situations involving a single acute exposure to hepatitis B, as when blood or other material containing hepatitis B surface antigen is accidentally inoculated, swallowed, or splashed in the eyes. Two doses administered thirty days apart are required for efficacy: the first dose should preferably be administered within forty-eight hours of exposure. It should not be administered later than seven days following exposure.
Active immunization Hepatitis B vaccines have been prepared from antigen purified from the plasma of carriers of the virus, inactivated to ensure freedom from all infectious organisms and harmful contaminating material. Newer hepatitis B vaccines have been developed using recombinant DNA technology (genetic engineering). They are safe and effective and have been licensed in many countries, including the UK and USA.
Among the groups who might benefit from the vaccine are patients who require multiple transfusions, patients with immune deficiencies, patients with malignant disease, health-care personnel, homosexual men, drug addicts, and prostitutes.
In regions where transmission of hepatitis B from mothers to infants is common, protective immunization of susceptible women of child-bearing age and infants would be desirable. Immunization should also be considered by non-immune persons living in certain tropical and non-tropical areas where the prevalence of hepatitis B infection is high and where the carrier rate may reach 10-20 percent of the population, and where primary liver cancer is common.
The currently available vaccines are expensive, costing $100-150 for a course of immunization. Vaccination of travellers is not necessary unless: (1) they belong to a high risk category; (2) they will remain in an endemic area for longer than about six months; (3) they will reside in rural areas or engage in sporting or other activities that carry an increased risk of accidents, injury, or occupational exposure to blood.
Travellers likely to need medical treatment abroad—such as kidney dialysis or blood transfusion—should also receive the hepatitis B vaccine.
Hepatitis B and the traveler
Travellers should take commonsense precautions to reduce the risk of hepatitis B. They should employ great caution in any intimate or sexual contact (particularly male homosexual contact) with possible hepatitis B carriers; they should where possible avoid any procedure involving penetration of the skin, for example;, tattooing, ear piercing, any sort of injections, blood transfusions, and many medical, surgical and dental procedures carried out under dubious sanitary conditions.
The delta virus is a defective infectious agent that can only infect actively in the presence of hepatitis B. The infection is common in parts of Southern Europe, the Middle East, parts of tropical Africa, and in parts of South America. The virus is spread in the same way as hepatitis B and precautions against it are identical. Immunization against hepatitis B will also protect against Delta hepatitis.
Non-A, non-B hepatitis
Improved laboratory diagnosis of hepatitis A and hepatitis B has enabled a previously unrecognized form of hepatitis, unrelated to either type A or B, to be identified. It is referred to as non-A, non-B hepatitis, and it is now known to be the most common form of hepatitis occurring after a blood transfusion and the administration of blood-clotting factors in some countries. It has been found in every country in which it has been sought, has some features in common with hepatitis B, and has been detected in patients on dialysis and among drug addicts. In several countries a significant number of cases are not associated with transfusion, and such sporadic cases have been found to account for up to 15-20 percent of all adult patients with viral hepatitis.
In general, the illness is mild, often without jaundice or other symptoms. However, there is evidence that the infection may be followed by the development of a persistent carrier state: chronic hepatitis may occur in as many 40-50 percents of patients after infection associated with blood transfusion or treatment with renal dialysis. About 10 percent of patients with the sporadic form of the infection may progress to chronic liver damage.
There are no known methods of preventing non-A, non-B hepatitis (beyond precautions applicable to hepatitis B).
Treatment of viral hepatitis
No specific treatment is available for any of the types of viral hepatitis. A number of antiviral substances are under study for the management of chronic liver disease associated with hepatitis B. Bed rest is required during the acute phase. A low-fat diet is usually preferred during the acute phase of the disease. Alcohol should not be consumed for six months after recovery.
Women using oral contraceptives (the Pill or progestogen-only Pill) can carry on with this contraceptive method during convalescence and recovery from hepatitis.
Evacuation of a patient with acute hepatitis is not usually necessary unless serious complications develop, when special facilities may be required.
Summary of advice for travellers
Hepatitis A and the enteric form of non-A, non-B hepatitis are a risk to travellers in areas of the world where hygienic and sanitary conditions are poor. Passive immunization with gammaglobulin should be considered for non-immune travellers anywhere outside northern Europe, the USA, Canada, Australia, and New Zealand. This should be given shortly before departure and provides reasonably complete protection. Long-term travellers may require further injections every four to six months. Strict personal hygiene, avoidance of untreated water and raw or inadequately cooked food, particularly raw vegetables,shellfish and milk, can help prevent infection.
Hepatitis B is a risk to certain groups of people in industrialized countries, notably health-care personnel and male homosexuals. The risk increases in developing countries, where there are generally more carriers. Caution should be observed with regard to intimate or sexual encounters with inhabitants of these countries. Passive immunization with hepatitis B immunoglobulin is not necessary fortravellers. Active immunization with hepatitis B vaccine is expensive but is advisable for health-care personnel, members of other risk categories working in the subtropics or tropics, and long stay travellers to endemic areas.
Penetration of the skin by any object that may have come in contact with someone else’s blood or other body fluids—as in tattooing, ear piercing, sharing of razors, acupuncture, sharing of needles by drug abusers, and any medical, dental, or surgical procedure, including blood transfusion and donation under dubious hygienic conditions—should be avoided.
Non-A, non-B hepatitis is principally a risk of blood transfusion. No preventative immunization is available, and avoidance is by measures similar to those advised for hepatitis B.
Travellers who develop a general malaise and symptoms such as right upper abdominal pain, jaundice, and dark-coloured urine either abroad or after their return should suspect viral hepatitis, and should seek medical advice immediately.