Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Hepatitis A, Hepatitis B, and Japanese Encephalitis
Hepatitis A: Hepatitis is an inflammation of the liver. Hepatitis A is found throughout the world and is transmitted primarily when tiny amounts of human waste are inadvertently swallowed. The disease is caused by a virus that attacks the liver.
Infection is common throughout the developing world. In developed countries, including the United States, community outbreaks still occur.
Food that is handled by infected workers can transmit the disease to unwary tourists, as can vegetables or fruit grown in human night soil. Risk for infection increases with a longer duration of travel. The risk is higher for those traveling to rural areas and for those who eat and drink in settings with poor sanitation. To decrease this risk, it is important to wash hands frequently and observe food and water precautions.
Symptoms don't appear immediately. It takes about a month before the sudden onset of fever, fatigue, nausea, and a yellowing of the skin called jaundice. Full recovery may take weeks. Death is rare but does occur. Unlike some other types of viral hepatitis, hepatitis A goes away completely and does not cause chronic disease.
Protection against hepatitis A is recommended for all those traveling to developing countries. The vaccine is especially important for those who will visit rural areas or eat in local restaurants. Three options exist to protect the traveler from hepatitis A:
A single dose of the inactivated vaccine in adults is 94-100% effective in preventing disease and provides protection for at least one year. Frequent travelers or those with prolonged stays should get a booster dose at least six months after the first shot. Estimates suggest that the booster shot may protect against hepatitis A for 20 years. The vaccine is not approved for children younger than 2 years.
Immune globulin, also known as gamma globulin, is about 85% effective in preventing hepatitis A. Unfortunately, the protection lasts only two to five months (depending on the dose). Those traveling with children under 2 years of age and those who are allergic to a vaccine component should consider immune globulin.
A combined vaccination protecting against both hepatitis A and hepatitis B is available for adults. This vaccination is given in three doses, the same as the regular hepatitis B vaccine schedule.
Hepatitis B: Like hepatitis A, hepatitis B is caused by a virus that attacks the liver. The two diseases have significant differences, however.
Hepatitis B is transmitted through sexual intercourse, dirty needles used to inject drugs, and contaminated blood transfusions. In addition, the virus can be transmitted when having medical, dental, or cosmetic procedures (including tattooing or body piercing) with needles or contaminated equipment. Hepatitis B is not transmitted through more casual contact such as shaking hands, eating, or drinking.
Hepatitis B infection occurs throughout the world. The areas with the highest number of people with chronic infection include Africa, Southeast Asia, the Middle East, Pacific Islands, Amazon regions, and certain parts of the Caribbean.
Once the virus enters the body, the virus begins to attack the liver. It takes an average of four months for symptoms to develop. Symptoms include nausea, vomiting, and abdominal pain. The hallmark of the disease is the yellowing of the skin called jaundice. Death is rare, but does occur.
Most people can clear their body of the virus after a few weeks, but about 6-10% of adults and 30-90% of infants and children fail to clear the virus and become chronic carriers of the disease. Chronic carriers may develop cirrhosis (irreversible scarring of the liver) or primary cancer of the liver.
Effective vaccines are available to prevent hepatitis B. The vaccine is recommended for those traveling to areas with increased levels of transmission, especially travelers contemplating sexual intercourse abroad, those likely to seek medical and dental care in local facilities, and those providing health care. All unvaccinated children and adolescents in the United States should receive the vaccine. The vaccine is safe and is actually recommended as one of the routine childhood vaccines for U.S. children. Complete protection requires three shots over six months, but even one or two shots offer significant protection. In addition, a combined vaccination is available that offers protection against both the hepatitis A and hepatitis B virus.
Japanese encephalitis: Japanese encephalitis is caused by a virus that is transmitted by mosquitoes. This rare disease exists in much of Asia, but it is very unusual for travelers to contract it. Transmission is more marked in rural areas, in flooded rice paddies, and during wet seasons. Even where the disease is common, only 1-3% of mosquitoes are infected. The risk to the average traveler is less than one case per million per year. The risk is increased by prolonged stays in infected areas.
Symptoms include fever, lethargy, and coma. Up to one in five infected people die, and the remainder often have nerve or brain damage.
An effective vaccine is given as a three-shot series over two to four weeks. The vaccine can cause side effects including arm pain, fever, and even serious allergic reactions. Vaccination should be reserved for long-term (usually more than one month in duration) travelers to Asia with significant exposure to infected areas during appropriate seasons (often May through October). The CDC has listed the important areas and seasons for transmission on their Web site.