The following article was taken from Travel Immunization - Infection - Body & Health
© 1996 - 2008 MediResource Inc. Republished here under the rules of fair-use for review of the members.
The Facts on Travel Immunization
Immunizations are among the most important and effective ways to prevent travel-related infections. Immunizations for travel include the "routine" childhood or adult immunizations that you would receive in Canada, those (like yellow fever) that are "required" to cross international borders, and "recommended" immunizations according to risk of infection. The Canadian government maintains a website with current information for travellers at Public Health Agency of Canada (PHAC) | Agence de la santé publique du Canada (ASPC) and the US government has an excellent travel health site at Redirect: www.cdc.gov.
For Canadians who travel abroad, there is a small but very real risk of requiring emergency medical treatment in a foreign country. Very few travellers die of serious illness; infectious diseases account for 1% of travel-related deaths whereas almost 50% die from motor vehicle accidents or drowning.
The most common illness to strike Canadian tourists in developing countries is travellers' diarrhea (TD). This is also known as Montezuma's revenge, turista (in Mexico), or Delhi belly (in India). It is an acute diarrheal illness that usually lasts two or three days. It can be caused by any of a number of bacteria (and less often, parasites), which are usually different from home-based varieties and therefore pose a temporary challenge to the immune system. There is no vaccination against travellers' diarrhea except for a recent new vaccine against cholera and a specific strain of E.coli bacteria. However, TD can often be prevented or self-treated with medications. It is very important to check with a health care professional or travel clinic before travelling in order to obtain a prescription for self-treatment.
Tourists may be at risk for the following serious infectious diseases - all of which are preventable by vaccine:
* hepatitis A & B
* Japanese encephalitis
* yellow fever
Diseases like measles, mumps, German measles (rubella), tetanus, polio, and diphtheria are all far more common in developing countries than in Canada. However, while abroad, Canadians rarely acquire these diseases because we are immunized against them from routine childhood vaccinations.
The chance of being exposed to infections abroad depends entirely on the style, location, and duration of travel. A two-week stay in a downtown five-star hotel is much less likely to result in disease than a six-month backpacking trip through the countryside. The one activity that will enormously increase the risk of acquiring a serious disease is unprotected sexual contact with a new partner, which brings a high risk of hepatitis B and HIV (AIDS), as well as other sexually transmitted diseases.
Globally, the infectious diseases that kill the most people, particularly those living in developing countries, are respiratory diseases (including influenza and pneumonia), AIDS, infections causing diarrhea, tuberculosis, malaria, and measles. Hepatitis infrequently kills during its acute phase, but chronic liver problems caused by this disease are another major cause of death worldwide.
Travel vaccines to consider
A vaccination that provides lifetime protection against hepatitis A & B may now be given with one combined vaccine in three doses over 21 days.
Canadians should have already been vaccinated against measles-mumps-rubella (one shot covers all three), diphtheria-tetanus (called Dt, one shot covers both), and polio (one shot covers all three). Diphtheria is making a comeback in Eastern Europe, and the bacteria that cause tetanus are everywhere. The DT shot provides protection for 10 years. One dose of polio vaccine in adulthood provides lifetime protection
Flu viruses and flu vaccines vary in different parts of the world, and change every year, but the Canadian vaccine is usually a fairly typical one, and will offer a lot of protection against catching flu on most airline routes. Airplanes are extremely infectious places for respiratory diseases because to a variable extent, the same air is continually recirculated. The flu vaccine needs to be injected every year, in the late autumn, to get full protection. Influenza is transmitted during the winter in the Northern hemisphere, during the summer in the Southern hemisphere, and year-long at the equator.
Typhoid vaccine is likely to be needed by travellers to any country with under-developed water treatment systems and sanitation, particularly when travel is off tourist routes or involves budget accommodations. Those at highest risk are new Canadians returning to their homeland to visit friends and relatives. Typhoid vaccine, which lasts three to four years, provides only 70% protection.
Yellow fever vaccine, which lasts 10 years, is recommended when travelling to large areas of Africa and South America. In addition, according to the World Health Organization, it is one of the only vaccines required by health officials to cross international borders. Currently, 21 countries in Central Africa and South America require yellow fever vaccination certificates for any entry, and 102 other countries demand them from people who have been in yellow fever zones. Yellow fever has a high mortality rate among those who acquire the infection.
Other vaccines to consider
Meningococcal (bacterial) meningitis is found throughout sub-Saharan Africa. This very dangerous disease is contagious (it is passed between people by cough or sneeze). Normally, one doesn't need to be vaccinated if staying in a good hotel, but one might consider it if planning on living more closely among the local population in sub-Saharan Africa (especially during the dry season [winter]). Those going to the Hajj in Saudia Arabia now require the vaccine for entry. Travellers should talk with a travel health professional to determine their individual risk.
Japanese encephalitis, like malaria and yellow fever, is transmitted by a mosquito bite - in this case, by an evening-biting mosquito found only in rural areas of South and Southeast Asia. This virus causes symptoms similar to meningitis and is sometimes fatal or leaves victims with severe neurological effects. It is widespread in East Asia, especially around late summer, and vaccination against it is recommended for anyone planning to spend more than a month in affected areas. Contact a travel health clinic to determine your specific needs. The vaccine is protective for two to three years and does have allergic reactions associated with its administration.
European tick-borne encephalitis is caused by a virus carried by ticks and has symptoms that are similar to the Japanese version, but often more severe. Russia and the rest of the former Soviet Union is the homeland of this disease, but it can be found in other parts of Europe in the summer months. One should be vaccinated if planning a long stay in or around the former Soviet Union during summer months. Measures to prevent tick bites will also help to reduce the risk of this serious viral disease. Your doctor or clinic will need to order this vaccine, so plan ahead.
Rabies is a uniformly fatal disease of the brain and central nervous system transmitted mostly by animal bites (particularly dog bites) throughout the world, including North America. There is a safe and very effective, but very expensive, rabies vaccine that can be used to prevent rabies. However, even with the vaccine, two additional doses are required in the event of an animal bite, whether provoked or not. However, without the preventative vaccine, in the event of a potential exposure, five doses of vaccine and one of rabies immune globulin will be required. Unfortunately, rabies immune globulin is often not available in the developing world, putting the exposed person at serious risk. The vaccine is recommended for long-stay travellers, especially children who often relate to small animals with affection and engage them in activity.
E.coli vaccine, a new immunization that is also effective against cholera, provides 60% protection for three months against the ETEC strain of E.coli, the most frequent cause of travellers' diarrhea. However, since E.coli is responsible for less than half of the cases of travellers' diarrhea, carrying an antibiotic regimen for self-treatment of travellers' diarrhea is a more cost-effective approach than being immunized with this new vaccine.
Not all vaccines are created equal. While the yellow fever vaccine provides almost 100% protection, the cholera vaccine is not completely effective and provides good protection for only a brief period of time. Since the infection is rarely acquired by travellers (less than one in 500,000), the World Health Organization and most national governments do not recommend cholera vaccination except for aid and health care workers in endemic areas.
Malaria prevention requires a combination of antimalarial pills and personal protection measures against insect bites. Unfortunately, we do not yet have a malaria vaccine, but there are now three first-line antimalarial drugs recommended for the prevention of malaria. Depending on the medication, malaria prophylactic medications should be taken for several weeks or even the day before exposure, during the travel period, and for one to four weeks after returning home. Since no antimalarial pill is 100% effective, measures must be taken to prevent infection from the night-biting mosquito that transmits malaria. Using DEET-containing insect repellents, permethrin-impregnated bed nets, air-conditioned or screened accommodation, and wearing trousers and long-sleeved shirts after dark will reduce the risk of this potentially fatal infection.
Before you go
Travellers should visit their doctor or a travel clinic at least two months before departure. This will give time for the slower-acting vaccines to take effect. All travel clinics have up-to-date information on which shots are required and recommended for various destinations as well as information on the most up-to-date medications used to prevent malaria. Make sure to tell your health care professional about any pre-existing medical conditions or the possibility of pregnancy at the time of the visit or during travel.
After you return
If you fall ill in the year after returning home from travels, particularly within the first two months, it is important that you tell your doctor that you have been abroad. Canadian family doctors are accustomed to looking for diseases common in Canada. They are very unlikely to test you for malaria, for example, unless they know that you have been in a malarial zone.
If you have been in very underdeveloped areas for a long time, you should also consider getting screened for tuberculosis even if you have no symptoms. If this disease is caught early during the latent phase, treatment is likely to be easier.
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