House flies represent one of the most common pest insects. Dense human populations offering ready access to food sources and ideal living conditions make the eastern states along the U.S. seaboard substantial breeding grounds for the insect. Due to close contact with human beings as well as the typical habits and habitats of the flying pest, house flies, or Musca domestica, are known to spread many disease causing organisms. The insects spread disease through contact with contaminated matter, like garbage, decaying carrion, and feces. In homes, house flies land on food and other items and areas that humans contact regularly. Humans then contract the diseases flies carry through the physical osmosis or ingestion of the contaminated materials.
Some scientists claim house flies possess the ability to transmit more than 60 diseases to human beings. In order to feed, flies regurgitate amounts of acid to breakdown food sources. The act of feeding often serves as one of the primary ways house flies communicate diseases to humans, in addition to defecating on foods and landing on other surfaces regularly handled by humans. Common diseases suspected to be spread by house flies include typhoid, cholera, dysentery, anthrax, salmonella, chlamydia, tuberculosis, and several forms of parasitic worms.