This article is from the December 1995 - January 1996 The Mexico File newsletter.
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Tropical Diseases to Avoid Like the Plague

The of the many hazards of travel to Central American countries like Mexico is the possibility of exposure to one or more of the many tropical diseases endemic to this region. Most U.S. citizens have had little contact with these diseases so that they are more vulnerable to an unfortunate exposure than natives might be.

Fortunately, by taking some sensible precautions the Mexico traveler should be able to enjoy this country without having to bed down for days on end, seeking out medical care or having to suffer with the consequences for many months after the trip has ended.

Traveler's Diarrhea

The most frequently reported illness by travelers to Mexico is more formally called traveler's diarrhea. Some may remember the international gravity of Jimmy Carter's faux pas, and it truly it was a slight to the sensibilities of the Mexican people, when he called it by the colloquialism, "Montezuma's revenge." Traveler's diarrhea can be caused by viruses, bacteria, or parasites which are found at large throughout the region. Transmission occurs most often through contaminated food or water. Infections can cause anything from minor discomfort to severe cases of diarrhea and vomiting. Be warned, however: it can also result in liver damage or muscle paralysis!

To avoid traveler's diarrhea, eat only thoroughly cooked foods and peel your own fruit. Drink only boiled water, bottled carbonated water or bottled carbonated soft drinks... although one may also indulge in margaritas, of course (but watch the ice for creepy crawlies...and you don't usually see them!).

Dengue Fever

Dengue Fever is transmitted by mosquito bites and is usually a danger in areas of human habitation, like cities. The mosquitoes are usually most active at dusk and at dawn, but may bite at any time during the day. The illness results in flu-like symptoms with a sudden onset, rash, severe headache, high fever, and joint and muscle pain. The rash will appear three or four days after the onset of the fever, which is the first symptom. (One might assume that this is not quite what you had in mind when you embarked on your journey.) Fortunately, the risk of exposure for the traveler is quite small, except during periods of epidemic.

Of course, there are other mosquito-linked diseases in Mexico as well. Malaria is caused by the bite of the mosquito...although these particular bugs usually fly and bite at night, from dusk until dawn. They are found in rural areas primarily, especially in the states of Oaxaca, Chiapas, Tabasco, Colima, Nayarit, Guerrero, Campeche, Sinaloa, Michoacan and Quintana Roo. (It is recommended that you take chloroquine for one week prior to entering a malarial area, once a week while there and four weeks after leaving.) Yellow fever is also caused by the mosquito, but cases are rare in Mexico. And try to avoid flea bites: they carry the plague! (But this is rare as well.)

To decrease the probability of exposure to insect bites, the traveler should wear clothing which covers most of the body, use a mosquito net and stay in well screened areas. Use an insect repellent on any exposed areas of your skin. The most effective repellent is DEET, which is found in most insect repellents, but it is important to avoid using the higher concentration (above 35%) products directly on the skin. Also avoid putting it on your hands if they can come into contact with the mouth and eyes. It is also helpful to buy a spray for flying insects to use in sleeping areas in the evening. While one might object highly to using all these toxins, just remember that it is not something that you will be doing for a prolonged period of time...and it is much less damaging than the alternative.


An epidemic of cholera has recently swept through Central America, including Mexico, although the risk to travelers is usually quite low. This disease is caused by a bacterium and results in an acute intestinal infection. The symptoms include massive watery diarrhea, vomiting, dehydration and muscle cramps. There is a vaccine available, although it is only 50% effective in reducing the symptoms of the illness. One would want to follow the recommendations previously described for traveler's diarrhea with reference to food and water.

Despite the dangers, and they are a reality, taking a sensible approach during your journey should greatly reduce, if not eliminate, any dangers these tropical diseases may pose. Travel wisely and enjoy! R.S.


The Centers for Disease Control recommends the following precautions for traveling to Mexico and other areas of Central America:

1.) If malaria may be a problem, take chloroquine or mefloquine.

2.) Take the precautions described on this page for preventing insect bites.

3.) Pay attention to the dangers associated with drinking water and food and take appropriate measures to avoid contamination.

4.) Take a dose of immune serum globulin (formerly called gamma globulin) to protect against hepatitis A.

5.) Consider having a booster dose of tetanus.

6.) Depending on where you may be traveling and what activities you may engage in, consider a vaccine for hepatitis B, yellow fever, typhoid, pre-exposure rabies, and cholera.

7.) Make sure your normal "childhood" vaccines are up to date: measles, mumps, rubella, diptheria, and pertussis (DTP vaccine).