This title examines viruses, bacteria, fungi and protozoa with a focus on flu viruses from how they infect the body and are spread from person-to-person, to symptoms and treatment, and when to see a doctor. Secondary complications and flu vaccines are also covered. A list of healthy habits is included to help readers combat disease. Aligned to Common Core Standards and correlated to state standards. Big Buddy Books is an imprint of Abdo Publishing, a division of ABDO.