European diseases, like measles and whooping cough, spread through the groups of Indians being moved on the Trail of Tears.  Problems like heat, cold and rain caused many Indians to become sick.  Without medicine or a place to get better, they died on the trip.  Problems like overcrowding, poor sanitation, and shortages of food and fresh drinking water, made life along the Trail miserable, and caused much disease and death, especially among the very young, elderly or sick.