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Travel Medicine (cont.)

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Cholera is an infection caused by bacteria (Vibrio cholerae) that look like curved rods when viewed under the microscope. The bacteria attach to the lining of the intestines and secrete a toxin. The cholera toxin can causes the cells in the intestines to pour out life-threatening amounts of fluid. The excess water loss can lead to watery diarrhea, so severe that it is difficult to keep the body hydrated. The term "rice water" is often used to describe this diarrhea because of the appearance of small white flecks of mucus in liquid.

Cholera spreads when human waste contaminates water and food. Because it takes high numbers of bacteria to cause infection, the contamination usually has to be quite significant. For example, in areas of poor sanitation, cholera can be spread when the drinking water supply is contaminated by feces from people who are sick.

Cholera is most common in areas that have poor sanitation, with faulty sewage systems or contaminated drinking water. Asia, Africa, and Latin America have been affected for several decades. Cholera can be prevented by using proper sanitation and sewage treatment. Boiling, filtering, or chlorinating water can help to prevent the spread of cholera. Treatment is mainly oral rehydration with simple electrolyte solutions. There is no vaccine for cholera that is approved in the United States. Following food and water precautions is the first line of defense (see "What is safe to eat and drink while traveling?").

Cholera is very rare in recreational travelers, but travelers providing humanitarian aid to underdeveloped areas, or areas were sanitation and water supply is disrupted by disaster, should be aware of the risk of cholera. Basic knowledge of hand hygiene, infection control measures, and correct sanitation procedures can avoid inadvertent spread of infections and keep aid workers healthy and able to help.

What about diseases for which there is no vaccine or preventive medication?

There are several diseases of concern for travelers for which there is no vaccine or medicine to prevent infection. Among these are some viral infections, sexually transmitted diseases, and parasitic infections.

Many viral infections can be spread by biting insects such as ticks or mosquitoes. These include serious infections like hemorrhagic fevers, viral infections that cause high fever, and bleeding. While epidemics have been rare, Ebola virus has spread in an unprecedented way in recent years, in certain areas of Africa and beyond. Ebola has been associated with eating wild-caught bats, monkeys, and other animals. Most travelers do not encounter these types of viral hemorrhagic fevers.

Dengue fever occurs throughout the world in tropical areas. Symptoms of dengue fever are high fever, severe headache and joint pain, and a drop in blood pressure; occasionally, bleeding (hemorrhage) can occur in people who are reinfected. Chikungunya fever is native to Africa and Asia but has rapidly spread into the Caribbean in the same areas as dengue. Spread by the same mosquitoes, it causes high fever, severe joint pain, and may be indistinguishable from dengue; fever resolves after a few days. Severe joint pain may last for several weeks, but it leaves no permanent joint damage. The key to preventing these infections is to follow insect precautions (see "What can I do to avoid insect bites?").

Sexually transmitted diseases remain common and can be acquired anywhere in the world. HIV is a risk everywhere and remains incurable. Gonorrhea, chlamydia, and syphilis remain common. The only sure way to prevent disease is to abstain from sexual intercourse. Correct use of condoms will reduce risk as well as unintended pregnancy. HPV vaccines now available will reduce the risk of acquiring infection with the human papillomavirus virus that causes genital warts and cervical cancer.

Parasites occur in most areas of the world but are especially common in tropical and subtropical regions. Some are spread by eating contaminated food (see "What is safe to eat and drink while traveling?"), while others are spread by direct contact with infected water or soil. Most travelers do not get parasitic infections, but those who are going into rural areas of developing countries should ask their doctors about parasites they might encounter.

Infectious-disease outbreaks occur periodically, and officials may recommend additional precautions. Examples have included outbreaks of bovine spongiform encephalitis (mad cow disease) or severe acute respiratory syndrome (SARS). Travelers should check the CDC web site to obtain health and risk information specific to their destination country. CDC also has specific advice for special groups and situations (

Medically Reviewed by a Doctor on 10/26/2016


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