Seasonal (or common) flu is a respiratory illness that can be transmitted person to person. Most people have some immunity, and a vaccine is available.
Avian (or bird) flu is caused by influenza viruses that occur naturally among wild birds. The H5N1 variant is deadly to domestic fowl and, in rare cases, can be transmitted from birds to humans. There is currently no human immunity and no vaccine available.
A pandemic flu is a virulent human flu that causes a global outbreak, or pandemic, of serious illness. Because there is little natural immunity, the disease can spread easily from person to person. Guidelines and resources from the CDC are available here.
The Los Angeles County Department of Public Health has produced a Public Heath Emergency Toolkit to assist schools in dealing with issues surrounding pandemic influenza and infectious diseases.
American Red Cross Home Care for Pandemic Flu (.pdf)
Avian Influenza Infection in Humans
Keep Our School Healthy Flyer (.pdf)
Pandemic Flu Planning Checklist for Individuals and Families (.pdf)
Pandemic Influenza: Characteristics & Challenges (.pdf)
Respiratory Hygiene/Cough Etiquette in Healthcare Settings (.pdf)
Stop Disease Flyer (.pdf)
Stopping Germs at Home, Work, and School (.pdf)
U.S. Department of Health & Human Services
California Department of Health Services, Division of Communicable Disease Control
Centers for Disease Control and Prevention
World Health Organization