Aviators travel the world and explore every human environment. Air crew also may encounter diseases in various environments that they do not encounter in their home locale. As such, we can be come "food" for these diseases that are constantly searching for a new homestead. However, many of these diseases can be prevented by vaccinations and other prophylactic measures.

There is only one required, international travel vaccination. That is yellow fever. This is a virus transmitted by mosquitoes in tropical regions. It is limited to South America from Panama to Peru and Brazil, and tropical Africa from south of the Sahara Desert, all the way to southern Africa. Anyone entering or leaving these zones may be required to have proof of a yellow fever vaccination. These vaccinations, which must be attested to by an international certificate, are valid for ten years. The vaccine itself is safe and highly effective. Once vaccinated, you will probably acquire a lifelong immunity to this deadly disease. However, international regulations require revaccination every ten years. If you are unvaccinated, the disease has a very high risk of being fatal. Other than vaccination, only avoiding being bitten by a mosquito, such as insect repellents, netting, and other preventive measures, will prevent this disease.

The disease that concerns us the most in aviation is tuberculosis. While the risk of acquiring tuberculosis from a passenger onboard an aircraft is very remote, it has happened on rare occasions that an infection has been transferred. I discussed tuberculosis in a previous issue, and I would refer you to that (reference Plane Safe). All air crew should have a skin test for tuberculosis done annually, if their skin test is negative. A vaccine called BCG is available, but is not generally used in the United States due to its relatively low efficiency. It provides protection only about fifty percent of the time, and makes the skin test results difficult to interpret.

Other major diseases that can effect travellers in the airplane include mumps, measles, rubella (German measles), and chicken pox. For those of us who were born before 1957, we naturally acquired immunity to all these diseases. However, if you were born after 1957, you may have had one of the early vaccines that did not provide lifelong protection. You should consider being revaccinated by the new quadrivalent vaccine. A single dose protects against all four of these viral illnesses.

While most of us have good protection against tetanus, relatively few Americans are well protected against a bacterial disease called diphtheria. Diphtheria can cause a fatal infection, and outbreaks are becoming more and more common in the former countries of the Soviet Union as well as third world countries. A single dose, combined with a tetanus vaccine and known as "Td", will provide a ten year protection against both tetanus and diphtheria.

Polio, we hope, will soon join smallpox as an extinct disease in the wild. Polio is extinct in North and South America, as well as Europe, but retains pockets of activity in Africa and Southern Asia. If your itinerary should every carry you to any of these areas, a single dose of oral polio vaccine will protect you. We do recommend that if you have never had a polio vaccination in your entire life, that you should have the inactivated (Salk) vaccine as an injection first, and follow this several months later by the lifelong protection conferred by the oral polio vaccine. All adults should have at least one additional dose, even if you had the full treatment and boosters as a child.

New vaccines are available to protect against hepatitis A and B. Although both these diseases effect the human liver, they are quite different in their cause. Hepatitis A (infectious hepatitis) is a viral disease spread by faecal-contaminated food. It is quite common to have this problem when dealing with street vendors or fresh vegetables in much of the developing world. Two doses of the hepatitis A vaccine, given six months or more apart, will provide highly effective protection against this illness. Alternatively, you can avoid ever eating contaminated foods by making sure that your food has been thoroughly cooked or boiled and any fruits or vegetables are peeled before you eat them. In other words, salads are out. Handling contaminated glasses and plates can only be a source of infection if you proceed to put your fingers next in your mouth or eyes. Remember, one of the most effective ways to prevent infection is to wash your hands!

Hepatitis B is a virus spread by blood and body fluids. In other words, its spread is identical to the HIV virus. However, many more people are infected and die from hepatitis B each year than from HIV. The difference is that there is a hepatitis B vaccine given in three doses over six months. The vaccine is safe and very effective.

You should consider two other vaccines as well. Each fall, the annual influenza vaccine becomes available. This is actually a mix against three strains of the influenza A and B viruses, which the Centers for Disease Control and Prevention has selected as being the candidates most likely to cause illness that year. Influenza itself is usually not a deadly disease, but its side effects can linger for up to two months after the infection. Within the next two years, the injectable trivalent influenza vaccine should be replaced with a nasal spray vaccine. However, due to the fact that the influenza virus mutates slightly or "shifts and drifts" every few years, the vaccine changes almost annually and protection from last year’s vaccine may not protect you against next year’s viruses. So, you must repeat this vaccination annually.

The final recommended vaccine is the pneumonia vaccine. This single dose, lifetime vaccination, will protect you against twenty-three strains of the pneumococcus pneumonia bacteria. It is recommended for any smoker over age 50, and all individuals over age 65.

You may also wish to consider the typhoid vaccines. Typhoid is a salmonella bacteria infection acquired from eating faecal-contaminated food, so its distribution pattern is similar to hepatitis A; however, typhoid is much rarer. There have been no major outbreaks in the United States in several years. There are two vaccines currently available. One is a single injection which provides excellent protection. Even better is the four oral capsules, which must be taken over a period of seven days. Both are safe and effective.

There are two other vaccines which I do not currently recommend. One is plague and the other cholera. Plague, of course, is the extremely dangerous bacterial disease spread by fleas or occasionally by air. This disease is quite rare, and in fact is only endemic to Viet Nam, but more importantly the vaccine is very painful and not very effective. Its efficacy is considered to be less than thirty percent, and it lasts for less than six months. Likewise, the cholera vaccine is also an inefficient vaccine. Its limited ability to protect is lost within a few months.