Travel Immunization - Plan now

Oct0ber-November 1995

This is an article from WaveLength Magazine, available in print in North America and globally on the web.

by Howard Stiff

If you're heading south this winter to some sunny, exotic paddling destination, NOW is the time to plan your travel immunizations with your doctor or local Travel Clinic.

Why? Some immunizations require a series of serum injections over the course of several weeks, and the serum takes time to build up effective immunization levels in your circulatory system. Certain vaccines, being living, potentially infectious organisms, are only available at your clinic one day per month for safety reasons.

Travel Clinics often become very busy this time of year, and due to the complicated factors associated with determining which vaccines you might need, at least one prior in-person consultation with the health unit nurse is generally required, and perhaps an appointment with your family doctor as well. So, before you set your departure date, talk to your health unit. And be warned that immunizations are not covered by your medical insurance, and they're not all that cheap, so be sure to include them in your travel budget too.

 

How Cows Help

Vaccination is the inoculation of a person to provide a measure of immunity to infectious viruses or bacteria, and is based on the ability of your immune system to respond much more effectively and rapidly the second or third time that the elements of your immune system encounter the invading microorganism. The term vaccination (from the Latin vacca, "cow") originally meant "immunization against smallpox", because the procedure originated in 1796 when English physician Edward Jenner discovered that milkmaids who had contracted the mild disease cowpox (vaccinia) were immune to deadly smallpox. The milkmaids' immune systems were "primed" by the cowpox virus to respond effectively to the closely related smallpox virus.The development of a cowpox vaccine against smallpox has since led to the production of vaccines against a wide range of diseases.

A vaccine may consist of living micro-organisms that are attenuated, or weakened, in a laboratory so that they create immunity but do not cause disease. It may also consist of killed organisms, of related organisms that cause a similar but milder disease, or of extracts of the organisms that can induce the desired immune response and subsequent immunity but do not cause the disease. Periodic booster immunizations are recommended with most vaccines, because the immunity caused by the initial inoculation may decrease with time. The time interval before booster shots are required varies greatly with the type of vaccine.

 

Trip Risk Factors

Vacation trips to resorts or major cities for two weeks or less are generally considered 'Low Risk' in terms of infectious diseases, and require only a tetanus/diptheria booster within the last 10 years and polio immunization if polio is endemic (i.e. occurs naturally and repeatedly) in that area.

If, however, you hope to stay anywhere for longer than two weeks, or you are paddling in areas remote or of 'poor or uncertain sanitation', you are considered to be in the 'High Risk' travel category, and, depending on your destination, you may be required to start vaccination series up to 8 weeks before your departure date.

While proper vaccination and common sense will enable you to avoid most health problems, it won't hurt to know what could happen to an unvaccinated traveller. Below are some of the delightful 'souvenirs' one could acquire through globe-hopping, and their corresponding preventive pharmaceuticals. Because diseases vary from location to location within countries and from year to year, recommendations for specific destinations can only be obtained through consultation with your medical doctor and/or health unit nurse. Note that drug costs listed here are only approximate.

 

Low Risk Destinations

Just about anywhere you travel you may encounter tetanus, or lockjaw, an acute and often fatal infectious disease of the human nervous system, characterized by severe spasms of the voluntary muscles and convulsions. The symptoms are caused by a toxin produced by Clostridium tetani, an anaerobic bacterium that can infect deep wounds (like sea urchin punctures) where oxygen is unavailable; its spores can be found in soil and in animal feces.

Diphtheria is caused by another bacterium that infects the throat or, occasionally, the nose, skin, or wounds, producing a toxin that circulates in the bloodstream and causes fever, sore throat, and swollen lymph nodes in the neck, and may, if not treated with antitoxin and penicillin, progress to obstruct breathing and cause paralysis. Most infants are routinely immunized with diphtheria toxoid.

The Tetanus/Diphtheria (TD) vaccination is recommended for all adults every 10 years for all travel destinations.

If your Health Unit says poliomyelitis is endemic in your travel destination area, get the Tetanus/Diphtheria/Polio (TDP) shot instead. Polio is an acute viral infection spread through contact with a polio patient or with human feces. The virus enters the body through the mouth and invades the bloodstream. If it enters the central nervous system, it attacks motor neurons and can cause lesions that result in paralysis.

 

High Risk Destinations

The following immunizations or pills, together with the 'Low Risk' vaccines above, are recommended or required for 'High Risk' destinations.

Malaria is a protozoan infection characterized by chills, fever, sweating, and anemia, with chronic relapses. Malaria means "bad air" in Italian, reflecting the pre-1880 view that it is caused by gases from the swampy regions where many cases occur. In 1898 it was discovered that malarial parasites are transmitted to humans by the bite of the anopheles mosquito,widespread in tropical Africa, Central America, and Southeast Asia. Prevention involves prescription drugs and insect repellents.

Typhoid fever is caused by the bacterium Salmonella typhi, which enters the body in water or food contaminated with the feces or urine of a carrier of the disease. After an incubation period of 7 to 21 days, the illness begins with fever, lethargy, headache, and loss of appetite. Increasing weakness and abdominal discomfort develop during the second week, when a rose-colored skin rash may appear. Intestinal bleeding or perforation may occur in the second or third week and can be fatal.

Typhoid vaccine consists of 4 capsules taken orally on alternate days and must be completed 2 weeks before starting any anti-malaria pills. This gives protection for up to 4 years.

Hepatitis is a disorder involving inflammation of the liver. Symptoms include loss of appetite, dark urine, fatigue, and sometimes fever. The liver may become enlarged and jaundice may occur, giving the skin a yellow tinge. The acute form of hepatitus can subside after about two months or, rarely, can result in liver failure.

Hepatitis A, once called infectious hepatitis, is the most common cause of acute hepatitis. Usually transmitted by food and water contaminated by human waste, such infections can reach epidemic proportions in unsanitary regions. Hepatitis B is spread mainly by blood or blood products.

Hepatitis A protection is available through:

• Gamma globulin serum injection, 3 to 10 days before your departure date, and preferably as the last of your immunizations. A gamma globulin is good for 3 months; get a second injection at the same time to double your immunization to 6 months. Approx. $5/shot.

• Havrix vaccine, 2 injections 2 to 4 weeks apart (4 weeks preferred), gives protection for 1 year. Much more expensive, at $40/shot, than gamma globulin but preferred for frequent travelers.

Hepatitus B vaccine may be required for endemic areas such as Thailand and involves 2 injections 4 weeks apart followed by a third injection 6 months later. This gives protection for 10 years.

Cerebrospinal meningitis is the epidemic disease caused by meningococcus, spherical bacteria that normally inhabit the nasopharynx of healthy human carriers. Sometimes, however, they infect the blood and cerebrospinal fluid, causing a potentially fatal inflammation of the meninges, or membranes, covering the brain and spinal cord.

Meningococcal vaccine is recommended for travelers going to the 'meningitis belt' of Africa, Egypt, parts of India and parts of Brazil. A $30 vaccination offers protection for 3-6 months.

Yellow fever, caused by a virus transmitted by the bite of an infected mosquito, may occur in a mild form like a flu but in severe cases is characterized by sudden fever, headache, backache, nausea, and vomiting. Mucosal bleeding causes "black vomit" and dark stools; degeneration of the liver, kidney, and heart is common. Victims often become jaundiced; this symptom accounts for the name of the disease. There is no specific treatment. Most victims recover spontaneously and thereafter have life-long immunity. Five to ten percent of victims die within 8 days of the onset of symptoms. Vaccination confers protection for at least 10 years. A certificate of vaccination is required by some countries if you have traveled in endemic zones in Africa or tropical America.