Peru's official languages are Spanish and Quechua which is spoken by the majority of natives residing in Cusco, Sacred Valley of the incas and Machupicchu. In some areas, the Aymara which is the third language officially recognized by the Peruvian State, is spoken in some areas of the country. English is spoken by people who work in tourist services, such as travel agencies, tourist information center and hotel reception. "Spanglish" is a mixture of both languages and will help you quite a lot in your communication with local people in general.
The majority of U.S. and Occidental European citizens do not need a visa to enter Peru. citizens from Bolivia, Ecuador, Brazil, Argentina, Venezuela and Chile do not need a passaport or visa to go to certain parts of Peru. In these cases, the maximum stay is of 90 days (Which can be prorogated by the immigration service). To Peruvian consulate or embassy in your country.
Drink only bottled or boiled water. Be careful with raw vegetables and fruit and always wash them in abundant running tap water before you peal and consume them. Avoid eating food at street stands and in popular restaurants, without having checked out the kitchen's hygiene conditions. If you need medical assistance, get in touch with your hotel's staff or travel agent. If you wish to purchase a traveler's insurance, please get in touch with the travel agent of your choice.
It can be prevented if you rest on the first day of your stay in Cusco. Do not eat heavy food and drink coca leaf infusions. If you travel to Peru's cordillera or jungle, make sure you take insect repellent along, as well as a rain-proof jacket for the rain. Remenber that, in altitude, digestion is slower therefore do not ingest food that is hard to digest.