Unfortunately, controlling the spread of colds, coughs, and sore throats within a family unit is usually impractical, although there are some measures that may help. How Infectious Diseases Spread Nose, mouth, and eye secretions are the most common sources of respiratory infections. These secretions are usually spread by contaminated hands or occasionally by kissing. Toddlers are especially prone to spreading these infections because of their habits of touching and mouthing everything. Droplets that spread through the air by coughing or sneezing are a less common means of transmitting respiratory infections.
Droplets can travel up to six feet.
The discharge from sores such as chickenpox and fever blisters can be contagious. Most red rashes without a discharge do not spread by skin contact, however. Contaminated food or water accounted for many epidemics in earlier times. Even today some foods commonly contain bacteria that cause diarrhea. Contaminated utensils such as bottles and dishes can occasionally spread respiratory or intestinal infections.