"The jungle is not a comfortable place" is something our guide kept repeating. The rainforest has all kinds of biting and scratching things that can cause discomfort and even death!
1. Before you leave home, make sure you have all of your shots and medications. Yellow Fever, Dengue Fever and Malaria are all things you don't want to get. See a travel medicine doctor for the appropriate treatment (immunizations for Yellow Fever), pills (prophylaxis) for malaria and avoidance for Dengue.
2. If venturing out into the rain forest - have appropirate clothing. Knee-high rubber boots, long sleeved shirt and long pants are a must. A comfortable hat and sunglasses are also high on my hit lits.
3. Insect replellent - bring lots. Better too much than too little. Use ones that have at least 30% DEET.