1. Pneumonia
Pneumonia is a bacteria or virus which spreads faster in low temperatures. Respiratory syncytial virus, flu, and Rhinovirus are not treatable by antibiotics, making pneumonia a dangerous issue for children under the age of 5. Worldwide the disease is the leading cause of death for those under 5 years of age and rated as the 8th leading cause in the United States.
The danger from pneumonia comes from the white blood cells fighting the infections which fill the air sacs in the lungs with mucus and fluid. Watch for fever and cough to develop from a bad cold and white, yellow or green mucus. Below the age of 2, children can be vaccinated against pneumonia, and as you can see from the dangers of the disease, this should be a no-brainer.