Most travellers visit Mexico without catching anything more serious than a dose of "Montezuma’s Revenge". You will still want the security of health insurance, but the important thing is to keep your resistance high and to be aware of the health risks linked to poor hygiene, untreated water, mosquito bites and undressed open cuts.
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Lack of sanitation in Mexico is much exaggerated, but a degree of caution is wise. Avoid food that looks like it has been on display for a while or not freshly cooked, and always peel fruit before eating it. Avoid raw shellfish, and don’t eat anywhere that is obviously dirty (easily spotted, since most Mexican restaurants are scrupulously clean). Salads are healthy, but think twice before eating them if you have a sensitive stomach. In general, keep an eye out for cleanliness of street stalls – beware of food that has been left out to breed germs rather than food that has been freshly cooked.
There are no required vaccinations for Mexico, but it’s worth visiting your doctor at least four weeks before you leave to check that you are up to date with tetanus, typhoid and hepatitis A shots, as well as a rabies shot and anti-malarial pills if you’re going to be in areas where they are recommended.
Diarrhoea ("Montezuma’s Revenge", or simply turista as it’s also known in Mexico) is the medical problem you’re most likely to encounter, and no one, however cautious, seems to avoid it altogether. If you go down with a mild dose unaccompanied by other symptoms, it may simply be due to your body being unfamiliar with the local bacteria, but if your diarrhoea is accompanied by cramps and vomiting, it could be food poisoning of some sort. Either way, it will probably pass of its own accord in 24 to 48 hours without treatment. In the meantime, it’s essential to replace the fluid and salts you’re losing, so drink lots of water. If you have severe diarrhoea, and whenever young children have it, add oral rehydration salts – suero oral (brand names: Dioralyte, Electrosol, Rehidrat). If you can’t get these, dissolve half a teaspoon of salt and three of sugar in a litre of water.
Avoid greasy food, heavy spices, caffeine and most fruit and dairy products; some say bananas, papayas, guavas and prickly pears (tunas) help, while plain yogurt or a broth made from yeast extract (such as Marmite or Vegemite, if you happen to have some with you) can be easily absorbed by your body when you have diarrhoea. Drugs like Lomotil or Imodium plug you up – and thus undermine the body’s efforts to rid itself of infection – but they can be a temporary stop-gap if you have to travel. If symptoms persist for more than three days, or if you have a fever or blood in your stool, seek medical advice.
Malaria and dengue fever
Malaria, caused by a parasite that lives in the saliva of female Anopheles mosquitoes, is endemic in some parts of Mexico. Areas above 1000m (such as the capital) are malaria-free, as are Cancún, Cozumel, Isla Mujeres and all the beach resorts of the Baja and the Pacific coasts. Daytime visits to archeological sites are risk-free, too, but low-lying inland areas can be risky, especially at night. According to the US-based Centers for Disease Control and Prevention (CDC) the main risk areas are Chihuahua, Chiapas, Durango, Nayarit and Sinaloa, with rare cases in Campeche, Jalisco, Oaxaca, Sonora, Tabasco and the municipality of Othon P. Blanco in the southern part of Quintana Roo, bordering Belize. Chloroquine (brand names: Nivaquin, Resochin, Avloclor, Aralen) is the recommended malaria prophylactic for travellers to Mexico; you need to start taking the pills one week before you arrive and continue for one month after you depart. Chloroquine is unsuitable for sufferers from various complaints such as epilepsy and psoriasis but daily proguanil (brand name Paludrine) can be used in its place. Consult a physician before beginning any course of medication; see wwwnc.cdc.gov/travel for more information on malaria in Mexico.
If you go down with malaria, you’ll probably know. The fever, shivering and headaches are like severe flu and come in waves, usually beginning in the early evening. Malaria is not infectious, but can be dangerous and sometimes even fatal if not treated quickly, so you should seek medical help immediately.
The most important thing, obviously, is to avoid mosquito bites altogether. Though active from dusk till dawn, female Anopheles mosquitoes prefer to bite in the evening. Wear long sleeves, skirts or trousers, avoid dark colours, which attract mosquitoes, and put repellent on all exposed skin, especially feet and ankles, which are their favourite targets. Plenty of good brands are sold locally, though health departments recommend carrying high-DEET brands available from travel clinics at home. An alternative is to burn coils of pyrethrum incense such as Raidolitos (these are readily available and burn all night if whole, but break easily). Sleep under a net if you can – one that hangs from a single point is best if you’re going to buy one (you can usually find a way to tie a string across your room to hang it from). Special mosquito nets for hammocks are available in Mexico.
Another illness spread by mosquito bites is dengue fever, whose symptoms are similar to those of malaria, plus a headache and aching bones. Dengue-carrying mosquitoes are particularly prevalent in urban areas during the rainy season and fly during the day, so wear insect repellent in the daytime if mosquitoes are around. The only treatment is complete rest, with drugs to assuage the fever – and take note that a second infection can be fatal.
Other bites and stings
Other biting insects can also be a nuisance. These include bed bugs, sometimes found in cheap (and, occasionally, in not so cheap) hotels – look for squashed ones around the bed. Sandflies, often present on beaches, are quite small, but their bites, usually on feet and ankles, itch like hell and last for days. Head or body lice can be picked up from people or bedding, and are best treated with medicated soap or shampoo.
Scorpions are mostly nocturnal and hide during the day under rocks and in crevices, so poking around in such places when in the countryside is generally ill-advised. If sleeping in a place where they might enter (such as a beach cabaña), shake your shoes out before putting them on in the morning, and try not to wander round barefoot. Some scorpion stings are dangerous and medical treatment should always be sought – cold-pack the sting in the meantime. Snakes are unlikely to bite unless accidentally disturbed – walk heavily and they will usually slither away. A fifth or so of Mexico’s snake species are venomous, the most dangerous being rattlesnakes (cascabel, found in the north), coral snakes (coralillo, found particularly in Guerrero, Oaxaca, Veracruz and Chiapas), and the nauyacas (found mainly in the south and the Yucatán). If you do get bitten or stung, remember what the snake or scorpion looked like (kill it if you can do so without receiving more bites), try not to move the affected part (tourniquets are not recommended due to dangerous risk of gangrene – if you do use one, it is vital to relieve it for at least ninety seconds every fifteen minutes), and seek medical help: antivenins are available in most hospitals. Black widow spiders also exist in Mexico; tarantulas are more fearsome-looking, but a lot less dangerous.
Altitude and heat problems
Two other common causes of health problems in Mexico are altitude and the sun. The solution in both cases is to take it easy. Arriving in Mexico City (2240m), in particular, you may find any activity strenuous, and the thin air is made worse by the high concentration of pollutants. Allow yourself time to acclimatize. If going to higher altitudes (mountain climbing, for example), you may develop symptoms of Acute Mountain Sickness (AMS), such as breathlessness, headaches, dizziness, nausea and appetite loss. More extreme cases may include vomiting, disorientation, loss of balance and coughing up of pink frothy phlegm. A slow descent almost always brings immediate recovery.
Tolerance to the sun, too, takes a while to build up: use a strong sunscreen and, if you’re walking during the day, wear a hat or keep to the shade. Be sure to avoid dehydration by drinking enough (water or fruit juice rather than beer or coffee and aim to drink at least three litres a day), and don’t exert yourself for long periods in the hot sun. Be aware that overheating can cause heatstroke, which is potentially fatal. Signs are a very high body temperature without a feeling of fever, accompanied by headaches, disorientation and even irrational behaviour. Lowering body temperature (a tepid shower, for example) is the first step in treatment.
Less serious is prickly heat, an itchy rash that is in fact an infection of the sweat ducts caused by excessive perspiration that doesn’t dry off. A cool shower, zinc oxide powder and loose cotton clothes should help.
Hepatitis A is transmitted through contaminated food and water, or through saliva, and thrives in conditions of poor hygiene. It can lay a victim low for several months with exhaustion, fever and diarrhoea, and can even cause liver damage. The Havrix vaccine has been shown to be extremely effective; with a booster after six months, protection lasts for ten years.
Hepatitis symptoms include a yellowing of the whites of the eyes, general malaise, orange urine (though dehydration can also cause this) and light-coloured stools. If you think you have it and are unable immediately to see a doctor, it is important to get lots of rest, avoid alcohol and do your best not to spread the disease. If medical insurance coverage is an issue, you can go to a pathology lab (most towns have them) to get blood tests before paying a greater amount to see a doctor.
More serious is hepatitis B, which is passed through blood or sexual contact, in the same way as HIV, but more easily. A hepatitis B jab is recommended if you will be in contact with those with weaker immunity systems, for example, working around medical patients or with children. Ideally three doses are given over six months but if time is short, there are other options that take one to two months, with a booster given after a year.
Typhoid and cholera are spread in the same way as hepatitis A. Typhoid produces a persistent high fever with malaise, headaches and abdominal pains, followed by diarrhoea. Vaccination can be by injection or orally, though the oral alternative is less effective, more expensive and only lasts a year, as opposed to three for a shot in the arm. Cholera appears in epidemics rather than isolated cases – if it’s about, you will probably hear about it. Cholera is characterized by sudden attacks of watery diarrhoea with severe cramps and debilitation. The vaccination is no longer given, as it is ineffective.
Immunizations against mumps, measles, TB and rubella are a good idea for anyone who wasn’t vaccinated as a child and hasn’t had the diseases, and it’s worth making sure you are covered for tetanus. You don’t need a shot for yellow fever unless you’re coming from a country where it’s endemic (in which case you need to carry your vaccination certificate).
Rabies exists in Mexico and the rabies vaccine is advised for anyone who will be more than 24 hours away from medical help, for example if going trekking in remote areas. The best advice is simply to give dogs a wide berth, and not to play with animals at all, no matter how cuddly they may look. A bite, a scratch or even a lick from an infected animal could spread the disease – rabies can be fatal, so if you are bitten, assume the worst and get medical help as quickly as possible. While waiting, wash any such wound immediately but gently with soap or detergent and apply alcohol or iodine if possible. If you decide to get the vaccination, you’ll need three shots spread over a four-week period prior to travel.
Getting medical help
For minor medical problems, head for a farmacia – look for a green cross and the Farmacia sign. Pharmacists are knowledgeable and helpful, and many speak some English. One word of warning however: in many Mexican pharmacies you can still buy drugs such as Entero-Vioform and Mexaform (both used to treat diarrhoea), which can cause optic nerve damage and have been banned elsewhere; it is not a good idea, therefore, to use local brands unless you know what they are. Note that the purchase of prescription drugs without a Mexican prescription is illegal; a US prescription will not suffice.
For more serious complaints you can get a list of English-speaking doctors from your government’s nearest consulate. Big hotels and tourist offices may also be able to recommend medical services. Every Mexican border town has hundreds of doctors (dentists, too) experienced in treating gringos, since they charge less than their colleagues across the border. Every reasonably sized town should also have a state- or Red Cross-run health centre (centro de salud), where treatment is free. Treatment at health centres should be adequate for minor problems, but for anything involving an overnight stay, go to a private hospital (for which your travel insurance should cover you).