Sick

http://www.flickr.com/photos/kalexanderson/5421517469

http://www.flickr.com/photos/selva/7637352

Medicine

Cells

http://www.flickr.com/photos/jonmcgovern/3069817485

Vaccination

http://www.flickr.com/photos/andresrueda/2983149263/

Disease

http://www.flickr.com/photos/yofotografista/4304540164

Virus

http://www.flickr.com/photos/mugley/4007138829

Antigen

http://www.flickr.com/photos/ringai/3974639591/

Pathogen

http://www.flickr.com/photos/28634332@N05/5984807021/

Fungi

http://www.flickr.com/photos/rachel_s/1518150683/

Bacteria

http://www.flickr.com/photos/kaibara/2234750993/