There is a very low potential for malaria in these sections of the Marañón canyon. We rarely see mosquitoes while on the rafting trip. Our guides do not take medication for malaria in this zone because they believe the risk to be very low, and the complications caused by Malaria medication are not worth it.
Some travelers do choose to use anti-malarials, while the majority prefer to use prevention techniques such as covering up exposed skin with clothing and utilizing repellents.
If completing the Heart of the Marañón section, when we arrive to the finishing city of Jaén there is a higher chance of seeing mosquitos. If you see mosquitos we encourage you to cover up exposed skin and use repellents.
If you take any prescription drugs or other medications, be certain to bring a large enough supply to last through the entire trip. When flying, pack these medications in your carry on luggage. You may not find the same drugs available in Peru that you can purchase internationally.
Please conduct you own research if unsure and consult your travel doctor for expert advice.
http://wwwnc.cdc.gov/travel/destinations/traveler/none/peru:*