Infectious diseases are common in children and can be caused by viruses, bacteria, fungi or parasites. Common childhood illnesses include the common cold, flu, ear infections, pneumonia, urinary tract infections, chickenpox and fifth disease. Symptoms vary depending on the infection but may include fever, cough, runny nose, ear pain, vomiting and rash. Infections spread through direct contact, droplets or contaminated surfaces. Proper hygiene and vaccinations can help prevent spread of disease.