Chinese Medical Information Portal Website (Taiwan Medical Network-TMN) - OldDoc Wu's Series
(Established in March 1996)
|Prevention of viral hepatitis for international travelers |
(Posted Sep. 16, 1996; Updated May 14, 2009)
|What is hepatitis ? What is viral hepatitis ?|
- Hepatitis is a disease of the liver caused by damage and inflammation of liver cells induced by various causes such as: virus infection, alcohol abuse, drugs and autoimmune mechanism.
- Viral hepatitis is inflammation of the liver due to infection by hepatitis viruses.
- A group of viruses which mainly causes damage to the liver of humans is called Hepatitis viruses.
- These are Hepatitis A, B, C, D, E and G viruses.
- At present time, hepatitis G virus infection does not appear to be an important cause of clinical liver disease.
- Hepatitis A is caused by a virus called hepatitis A virus (HAV).
- Hepatitis A can affect anyone throughout the world in situations ranging from isolated cases of disease to widespread epidemics.
- Good personal hygiene and proper environmental sanitation can help prevent hepatitis A.
- Hepatitis B is caused by a virus called hepatitis B virus (HBV).
- Hepatitis B is hyperendemic in all of Africa, Southeast Asia, China, Korea, Indonesia, the Philippines, the Middle East except Israel, South and Western Pacific Islands, interior Amazon Basin, and certain parts of the Caribbean. Therefore, in the US, high prevalence of hepatitis B is found among immigrants from these regions.
- HBV may cause lifelong infection, resulting in chrnic hepatitis, cirrhosis (scarring) of the liver, liver cancer, liver failure, and death.
- Hepatitis C is caused by hepatitis C virus (HCV).
- You may be at risk for hepatitis C and should contact your medical care provider for a blood test: if you
- were notified that you received blood from a donor who later tested positive for hepatitis C
- have ever injected illegal drugs, even if you experimented a few times many years ago
- received a blood transfusion or solid organ transplant before July, 1992
- received a blood product for clotting problems produced before 1987
- have ever been on long-term kidney dialysis
- have evidence of liver disease (e.g., persistently abnormal ALT levels)
- Like with hepatitis B, hepatitis C also may cause lifelong infection, resulting in chrnic hepatitis, cirrhosis (scarring) of the liver, liver cancer, liver failure, and death.
- Hepatitis E is caused by hepatitis E virus (HEV).
- HEV is transmitted primarily through the fecal-oral route
- Contaminated drinking water is the most commonly documented vehicle of transmission.
- Unlike hepatitis A virus, which is also transmitted by the fecal-oral route, person-to-person transmission of HEV appears to be uncommon.
- The reported cases in the U.S. usually have history of travel to HEV-endemic areas
|How do the hepatitis viruses infect humans ?|
- There are two ways of transmission mode (route).
- The first one is fecal-oral (enteral) route, transmitted by direct person-to-person contact, intake of contaminated food, water, or utensils (through mouth).
- The second is transmitted through body fluid, so called blood-born infection, mainly through blood tranfusion and injection with contaminated needle or syringe, occasionally by sexual contact.
- Hepatitis A and E belong to the first group (fecal-oral, enteral transmission).
- Hepatitis B, C and D belong to the second group (parenteral, blood-born transmission).
- Sexual contact occasionally causes infection in hepatitis C, and rarely in male homosexual contact in hepatitis A. Hepatitis B carrier will be infected with hepatitis D from prostitute.
- You may be at risk for hepatitis B and C if you :
- have an opportunity to expose you to infected human blood
- inject drugs
- have sex with a person infected with Hep-B or C (low rate)
- have sex with multiple partners
- received blood transfusions in the past before screening test for Hep-B and C is available
- traveling internationally to areas with a high prevalence of hepatitis B
- sharing items such as razors, toothbrushes, or washcloths with Hep-B or C carriers
- use unsterilized needles in ear or body piercing, tattooing, or acupuncture
|What is the symptom of hepatitis ?|
- You may experience fever, anorexia, nausea, malaise, and deepening of urine color, but it is not uncommon that you will be free of any symptom.
- All types of hepatitis have the similar symptoms and clinical presentation, therefore, you can not tell what type of viral hepatitis you contract from the symptom and/or liver test except you have special serological test for differentiation of the type.
|What is the chance for getting infected ?|
- You may get infected by all kinds of hepatitis anywhere in the world, but there is regional preference.
- Hepatitis A is highly endemic throughout the developing countries, and in developed countries its incidence is much low. Before 1980, Taiwan is one of the highest endemic area of Hepatitis A infection, but now because of the rapid improvement in its environmental sanitation, very few hepatitis A cases are reported.
- Hepatitis E is most common in under-developed region and countries, and in Taiwan no epidemics is reported.
- Hepatitis B is prevalent in all of Africa, Southeast Asia, China, Korea, Indonesia, the Philippines, the Middle East except Israel, South and Western Pacific Islands, interior Amazon Basin, and certain parts of the Caribbean. Before 1984, the beginning of mass-vaccination program, Taiwan was one of the countries with high endemicity of hepatitis B infection. At present time, 15 + yrs after the nation-wide vaccination programe, new cases of hepatitis B are seldom reported.
- Hepatitis C has nearly the same prevalence throughtout the world.
- Hepatitis D is associated with hepatitis B, without infection with hepatitis B there will be no chance for infected by hepatitis D. In Taiwan, about 50% of female prostitute were infected with hepatitis D in late 1980s, but now this condition has improved in recent years.
|How can you tell whether you have been infected by hepatitis viruses ?|
- By serological tests for serum anti-body of these viruses.
|How to prevent infections by hepatitis viruses ?|
- In general, for the prevention of infectious diseases, the preventive measures you need to take while traveling in East Asia depend on the areas you visit and the length of time you stay. However, in highly developed areas of Japan, Hong Kong, South Korea, and Taiwan, you should observe health precautions similar to those that would apply while traveling in the United States.
- HAV (Hepatitis A Virus) is inactivated by boiling or cooking to 85 C for at least 1 minute.
- Cooked foods cannot serve as vehicles for HAV unless contaminated after cooking.
- Adequate chlorination of water will inactivate HAV.
- The vaccination is the best way for prevention of viral hepatitis.
- At present, there are vaccines against hepatitis A and B.
- No vaccine against hepatitis C and D is available.
- For hepatitis D, there is no chance of infection without the presence of hepatitis B.
- The best way of prevention for hepatits A is:
- In developing countries, travelers should minimize their risk of hepatitis A and other enteric diseases by avoiding potentially contaminated water or food.
- Drinking water (and beverages with ice) of unknown purity, uncooked shellfish, and uncooked fruits or vegetables that are not peeled or prepared by the traveler should be avoided.
- To keep good personal hygiene and habit of washing hands before intake of food.
- Keeping utensils for food intake uncontaminated.
- For prevention of hepatitis C and D:
- Avoid of transfusion of untested or unscreened blood.
- Use disposable needle and syringe in case of necessity of injection.
- For prevention of hepatitis D:
- Keep away from prostitute.
- Table of Schedules for Hep-A and B
[Dr. Wu's Health Note- Home]
[Taiwan Medical Network]
- For hepatitis A:
Two hepatitis A vaccines are currently licensed in the United States:
- HAVRIX (manufactured by Smith Kline Beecham) and VAQTA (manufactured by Merck & Co., Inc.).
- Both vaccines are made of inactivated virus adsorbed to aluminum hydroxide as an adjuvant.
- HAVRIX is prepared with 2-phenoxyethanol as a preservative while VAQTA is formulated without a preservative.
- The vaccine should be administered by intramuscular injection in the deltoid muscle.
- Both HAVRIX and VAQTA are currently licensed in two formulations, and the formulation and number of doses vary according to the person's age.
- For HAVRIX, the schedule for children and adolescents (aged 2 ~ 18 years) of age is two 720-EL.U. doses, with the second dose given 6 ~ 12 months after the first. For adults > 18 years of age, the schedule is two 1,440 EL.U. doses with the second dose given 6 ~ 12 months after the first.
- For VAQTA the schedule for children and adolescents (aged 2 ~ 18 years) of age is two 25-U doses given 6 ~ 18 months after the first, and for adults > 18 years of age, the schedule is two 50-U doses given 6 ~ 12 months after the first.
- The above schedules are preferred for persons who plan to travel repeatedly or reside for long periods in high-risk areas.
- Estimates of antibody persistence derived from kinetic models of antibody decline suggest that protective levels of anti-HAV could persist for at least 20 years. Protection can be assumed by 4 weeks after receiving the first vaccine dose, although a second dose is necessary for long-term protection. Because protection may not be complete until 4 weeks after vaccine administration, persons traveling to high-risk areas < 4 weeks after the initial dose should also be given IG (0.02 mL/kg) when available, but at a different injection site.
- Travelers < 2 years of age should receive a single dose of IG (0.02 mL/kg) because neither vaccine is licensed for children in this age group.
- Travelers who are allergic to a vaccine component or otherwise elect not to receive vaccine should receive a single dose of IG (0.02 mL/kg), which provides effective protection against hepatitis A for up to 3 months. For adults and children traveling > 3 months, an IG dose of 0.06 mL/kg should be given and must be repeated if the duration of travel is > 5 months. See Table 1 for approximate IG dosages.
- Although vaccination of an immune person is not contraindicated and does not increase the risk of adverse effects, screening for total antibodies to HAV (anti-HAV) before travel may be useful to determine susceptibility and eliminate unnecessary vaccination or IG prophylaxis of immune persons.
- Postvaccination testing for serologic response is not indicated.
- For hepatitis B:
- Hepatitis B vaccination should also be considered for persons who plan to reside for > 6 months in areas with intermediate to high levels of endemic HBV transmission and who will have any of the previously discussed types of contact with the local population.
- In particular, persons who anticipate sexual contact with the local population, who will live in rural areas and/or have daily physical contact with local populations; and persons who are likely to seek medical, dental or other treatment in local facilities during their stay should receive the vaccine.
- Vaccination should be considered for short-term travelers (<6months) who will have direct contact with blood, or sexual contact with residents of areas with moderate to high levels of endemic HBV transmission.
- The currently available vaccines are produced through recombinant DNA technology by common baker's yeast into which the gene for hepatitis B surface antigen (HBsAg) has been inserted.
- Hepatitis B vaccines have been shown to be very safe when given to adults and children. In the United States, it is estimated that more than 20 million adults and adolescents and 16 million infants or children have been vaccinated.
- Primary vaccination consists of three intramuscular doses of vaccine. The recommended dose varies by product and the recipient's age (see the table below). When the vaccine is administered as a three-dose series, the second dose should be given 1 month after the first dose, and the third dose 6 months after the first dose. Alternatively, the vaccine produced by one manufacturer is licensed to be administered as a four-dose schedule at 0, 1, 2, and 12 months.
- Vaccination should ideally begin at least 6 months before travel to complete the full vaccine series prior to departure. Since some protection is provided by one or two doses, the vaccine series should be initiated, if indicated, even if it cannot be completed prior to departure. However, optimal protection is not conferred until after the final (third or fourth) vaccine dose.
- There is no evidence of interference between hepatitis B vaccine and other simultaneously administered vaccine(s) or with immunoglobulin.
- The optimum site of injection in adults is the deltoid muscle; vaccination in the buttocks results in poorer antibody response. Long-term studies of healthy adults and children indicate that immunologic memory remains intact for at least 12 years and confers protection against chronic HBV infection, even though hepatitis B surface antibody (anti-HBs) levels may become low or decline below detectable levels.
- For children and adults whose immune status is normal, booster doses of vaccine are not recommended, nor is serologic testing to assess antibody levels necessary.
Recommended doses of currently licensed hepatitis B vaccines
infants (regardless of motherís
HBsAg status) and children birth
to 19 years of age
patients and other
vaccines are routinely administered in a three-dose
series. Engerix-B also has been licensed for a four-dose
series administered at 0, 1, 2, and 12 months.
formulation (40 mg
in 1.0 mL).
1.0-mL doses given at one site, in a four-dose schedule at
0, 1, 2, 6 months.
(From CDC's Travellers' Health)
- Adverse Events:
- Pain at the injection site and temperature > 37.7 C are the most frequently reported side effects among adults and children.
- A low rate of anaphylaxis has been observed in vaccine recipients based on reports to the Vaccine Adverse Event Reporting System (VAERS), with an estimated incidence of 1 case in 600,000 vaccine doses distributed.
- None of the persons who developed anaphylaxis died; however, anaphylaxis can cause a life-threatening hypersensitivity reaction in certain individuals.
- Vaccination with hepatitis B vaccine is contraindicated in persons with a history of anaphylaxis after a previous dose of vaccine.
- On the basis of limited data, there is no apparent risk of adverse events to the developing fetus on vaccination to pregnant women.
- The vaccine contains non-infectious HBsAg particles and there is no risk to the fetus.
- HBV infection affecting a pregnant woman may result in serious disease for the mother and chronic infection for the newborn.
- Neither pregnancy nor lactation should be considered a contraindication for vaccination.
[Web sites for medical students][Curriculum Vitae ]
(By Jau-Shin Wu, M.D.; Posted Sep. 16, 1996; Revised May 12, 2009)
(TMN) Since June 09, 2002
(Dr. Wu's Liver D) Since Jan. 01, 2008
(Olddoc)Since Jan. 01, 2008
(TMN) Since Jan. 01, 2008