Visitors to Mexico should be aware that problems may arise when bites, stings or scratches occur. We have reviewed the main causes below, along with suggestions for how to treat them. As always, when possible consult with a physician if first aid is not enough.
Unlike other cuts or wounds, a human or animal bite that breaks the skin may transfer large quantities of bacteria that can cause a spreading infection of the skin called "cellulitis." Teeth can also puncture deep into the skin, depositing bacteria that cannot drain to the surface or be reached with topical remedies. These bacteria may be so aggressive and hard to reach that oral antibiotics are necessary to prevent more serious infection.
We treat these wounds with ampicillin/sulbactam (Augmentin, 875 mg/125 mg). If you are allergic to penicillin, use cefuroxime (Ceftin) or cefprozil (Cefzil). (See www.medtogo.com for medication guidelines.) If you have not received a tetanus shot in the previous five years, ask a local doctor for a tetanus booster.
Keep the wound clean and dry. If the bite is on an arm or leg, elevate the limb above the level of the heart. Use light sterile bandages rather than constricting wraps. As most bites are on a limb, soak the affected area in warm, soapy water two or three times a day to assist in recovery. If superficial or deep tissue infection develops despite oral antibiotic therapy, consult a local MedToGo physician immediately. Deep puncture wounds are more susceptible to aggressive, spreading infection that may require intravenous antibiotics or surgery.
If your immune system is weakened, or if you have chronic medical problems such as diabetes, poor circulation, or severe heart disease, always consult with a physician about skin infections, as they can develop into more serious problems.
Animal control and rabies vaccinations are less rigorously enforced in Mexico than in the U.S. Therefore, always assume a risk of rabies in an undomesticated, stray, or unhealthy animal, as well as in bat, raccoon, fox, or skunk bites. Consult with a physician to receive the appropriate rabies treatment.
Most spider bites, although painful, are harmless. Brown recluse, black widow, and selected rare species may, however, cause skin damage from venom and are therefore worth mentioning.
The brown recluse spider injects venom that can cause local skin and tissue death. Symptoms start about three to four hours after the bite with exaggerated pain, itching, swelling, and redness. If left untreated, the process may stop there on its own or, in more severe cases, may result in extended tissue and nerve damage. If you suspect you have been bitten by a brown recluse spider, consult with a physician. Early treatment with Dapsone may halt the process. Cold compresses, wound cleansing, antihistamines (for itching), anti-inflammatory medications (e.g. Ibuprofen, Naproxen), and limb elevation are components of basic treatment. Always attempt to capture the spider for identification.
Black widow spider bites are identified as side-by-side pinpricks surrounded by small areas of redness and swelling. Many bites do not cause problems, but the ones that do start with painful muscle cramping of the affected limb within one hour of the bite. It is rare for severe problems to follow. If you suspect a black widow spider from the classic bite pattern and painful muscle cramping, seek medical attention. Anti-venom is available in the U.S. but we have not documented availability at specific hospitals in Mexico. Again, always attempt to capture the spider for identification.
Stings from these insects are typically limited to annoying pain, itching, and redness. Applying ice and taking acetaminophen (Tylenol) may relieve pain and discomfort, while over-the-counter antihistamines such as diphenhydramine (Benadryl) or clemastine (Tavist) can help reduce itching. If local, yet mild symptoms persist, you may apply 1% hydrocortisone cream or make a paste of baking soda and water and apply it to the skin. Do this at least twice daily to relieve your symptoms, which should ease after two days. If the redness spreads to more than two inches from the site of the bite, seek medical attention.
Rarely, individuals may develop potentially life-threatening allergic reactions to stings. If you develop difficulty breathing, a rapid heart rate, swelling about the face or mouth, nausea and/or vomiting, hives, dizziness, or mental confusion after an insect bite, seek medical attention immediately.
Anyone with a history of such reactions should always carry epinephrine for injection. If you do not start treatment shortly after the sting, you may experience severe breathing difficulties, blood pressure collapse, and in some cases, death. Most epinephrine kits contain injection instructions.
Robert H. Page, MD and Curtis P. Page, MD are authors of the MEXICO: Health and Safety Travel Guide and the Healthy Traveler Regional Series.