There are four critical factors in looking after yourself on a trek. Avoiding altitude sickness, diarrhoea, malaria and dehydration. Detailed information about altitude sickness can be found here.
The most common health complaint for visitors to this part of the world is is travellers' diarrhoea. Significant diarrhoea is defined as three or more loose bowel movements within any given eight hour period or five or more loose bowel movements within any 24 hour period, especially if you also experience cramps, fever, vomiting or nausea, or blood in your stool. Anyone travelling to South America should bring a full course of antibiotics and an anti-diarrhoeal drug, and start them both promptly if they experience significant diarrhoea.
Most doctors prescribe one of the quinolone family of antibiotics, often ciprofloxacin (brand name Cipro) at 500 milligrams twice a day, or levofloxacin (Levaquin) at 500 milligrams once daily, each for a total of three days. Quinolone antibiotics are well-tolerated overall, but should not be taken by pregnant women, children, or anyone who is known to be allergic to quinolones. They can also cause sensitivity to sunlight in a few patients.
Other doctors prefer an antibiotic called rifaximin (brand name Xifaxan) at 200 milligrams three times a day, or azithromycin (Zithromax) at 500 milligrams once a day. Rifaximin should not be taken by anyone experiencing bloody stools or fever, and should not be used by children under 12 or pregnant women. Azithromycin should be avoided by anyone known to be allergic to the erythromycin family of antibiotics.
As to anti-diarrhoeal drugs, diphenoxylate (name brand Lomotil) or loperamide (Imodium) are good choices for travellers over two years of age (not that Andes mountain treks are really appropriate to children under two). They will make your bowel movements less frequent, but keep in mind that they won’t ‘just make you better’ instantly.
The good news is that the majority of Traveller’s Diarrhoea cases are quite mild, and don’t require either medication or antibiotics. Keeping yourself hydrated is often all it takes to get over it quickly. Medical attention is probably not needed unless diarrhoea is severe or bloody, you experience marked abdominal pain, or of it lasts more than three days running.
Better still, it is fairly easy to prevent if you follow certain precautions with your food and water fully and faithfully. Taking antibiotics prophylactically, though effective, is not advisable because of the risk of side effects. Of course, your own doctor will be able to provide advice specific to your medical circumstances. Prophylactic use may be appropriate for immunocompromised people, for example.
There are two primary ways to avoid contracting malaria. The first is to take a prophylactic course of anti-malarial medicine. The second is to avoid being bitten by any malaria-carrying mosquitoes. Peru has seen a sharp rise in malaria cases recently, partially due to changes in the settlement patterns in the country, and also due to increased irrigation leading to higher than normal mosquito populations.
Prophylactic treatment to prevent malaria is generally advisable for anyone visiting places below 2000 metres (6,500 feet) in Peru, which includes the cities of Puerto Maldonado and Iquitos. The most malaria-prone part of Peru is Loreto, where it is classed as an epidemic.
The exceptions to this rule are Lima (and the coast south of Lima), Ica, and Nazca. These regions are not prone to mosquitoes in great numbers due to the local climate.
The highland areas popular with tourists and trekkers (Machu Picchu itself, Cuzco, Lake Titicaca and the Inca Trail) are too high for mosquitoes to live. The southern cities of Tacna, Puno, Moquegua and Arequipa are not at significant risk of malaria either. The Pan American Health Organization has provided a map of which areas are at risk of malaria.
To prevent malaria, many doctors prescribe mefloquine (brand name Lariam), doxycycline or atovaquone/proguanil (Malarone).
Melfloquine/Lariam is generally given once a week for two weeks (at 250 milligrams per week) before travelling to a malaria-prone region, and should be taken for the entire duration of the trip and for four weeks thereafter. It sometimes causes certain mild neuropsychiatric side effects such as nightmares or insomnia, as well as nausea, vomiting or dizziness. On rare occasions it can cause more severe side effects, including seizures, hallucinations or psychosis, anxiety and/or depression. It should never be taken by anyone whose medical history includes psychiatric illness or seizures, certain cardiac problems or an allergy to quinidine or quinine.
Atovaquone/proguanil (sometimes called Malarone) is a combination of two separate malaria medications. It should be taken once a day with food, beginning at least two days before arriving in Peru (or any other malaria-prone area) and be continued during the trip and for two weeks after returning home. It has been known to cause a few mild side effects, such as vomiting or nausea, abdominal pain, diarrhoea, dizziness and headache. It is quite rare for Malarone to cause serious side effects.
Doxycycline is not generally used in the tropics, as it causes sunlight/UV sensitivity. Anything that makes you more prone to sunburn isn’t really suitable for someone trekking in Peru, where sunburn can already be a serious problem.
Protecting yourself from mosquitoes is vital whenever in a malaria-prone area, even if you are taking anti-malaria medications.
Bring plenty of insect repellent, and make sure it is a maximum-strength brand containing DEET. While there are a few people who feel DEET is not completely safe, we have certainly never had any trouble with it, and malaria is nothing to take chances with.
Dealing with malaria If you do get it is more complicated. If you are expecting to remain in country for some time or will otherwise be far from full medical care, you should bring medications to treat malaria with you. The symptoms of malaria include headache and muscle aches, fever and chills. If you experience these symptoms at any time after visiting a malaria-prone area and do not expect to be able to get proper medical care within 24 hours, begin treating yourself for malaria immediately.
Keep in mind that one can be exposed to malaria and have no symptoms for months or even years. The World Health Organization is an excellent source of information on malaria, both in Peru and elsewhere in the world.
Few people experience more than mild side effects, such as aches, pains and slight fevers. A very few have more serious reactions, including asthma or hives. There are generally associated only with those patients who are allergic to eggs, which are used in the manufacture of the vaccine.
Throughout the year the temperatures around Machu Picchu remain fairly high and in these conditions it is critical that you monitor and maintain your hydration levels. Drink plenty at all meal times and drink at least 2 litres of water while you are hiking. The symptoms of dehydration can easily be mistaken for altitude sickness and in order that we can monitor you for this you need to be sure that the problem you have is not just due to drinking insufficient water.