Anthrax is caused by contact with Bacillus anthracis bacteria, and it commonly infects hoofed animals, including cows, sheep, and goats. 

Botulism is caused by Clostridium botulinum bacteria and can be spread through open sores, via contact with soil and untreated water, and by eating canned food that has been improperly preserved. 

Campylobacteriosis is a diarrheal illness caused by bacteria of the genus Campylobacter, which live harmlessly in most warm-blooded animals and grow best in the intestines of birds. 

Chickenpox is a highly contagious disease characterized by itchy, blister-like sores all over the body. It is caused by the varicella-zoster virus, part of the herpesvirus family. 

Cholera is an infection of the small intestine that is caused by Vibrio cholerae bacteria and often results in diarrhea. About 3 to 5 million cases of cholera occur each year around the world, resulting in more than 100,000 deaths annually. 

Creutzfeldt-Jakob disease, or CJD, is a brain disorder caused by prions, proteins that induce abnormal folding of normal brain proteins. About 85 percent of CJD cases occur sporadically and have unknown origins. 

Dengue fever is caused by four closely related dengue viruses typically found in tropical areas. Humans contract the illness by being bitten by an infected mosquito. 

Caused by viruses, bacteria, or parasites, diarrheal diseases are spread through contaminated food or water, or because of insufficient hygiene practices. Diarrhea is defined as having three or more loose stools per day. 

Dysentery is the inflammation of the colon characterized by frequent, watery stools, often tinged with blood and mucus. Dysentery is usually caused by one of two different organisms—Shigella bacteria or an amoeba, Entamoeba histolytica. 

Ebola virus disease, formerly known as Ebola hemorrhagic fever, is a serious disease that is spread by an RNA virus in the family Filoviridae. The disease is named after a river in the Democratic Republic of the Congo. 

Escherichia coli, or E.coli, are bacteria found in the human gut. Most strains of E. coli are harmless; however, several can cause severe illness. 

Hantavirus pulmonary syndrome, or HPS, is a rare but deadly disease that was first recognized in 1993 and has since been identified throughout the United States. 

Helicobacter pylori, or H. pylori, are bacteria that live in human gastric mucosa. About half of the human population has an H. pylori infection, making it one of the world’s most common bacterial infections. 

Hepatitis B is a contagious, usually acute infection of the liver caused by the Hepatitis B virus. The virus can be spread through contact with the blood or other body fluids of an infected person. 

Hepatitis C is a serious, contagious infection of the liver caused by the Hepatitis C virus and usually leads to chronic liver disease. The virus can be spread through contact with the blood of an infected person. 

Histoplasmosis is caused by Histoplasma capsulatum, a fungus that lives in the environment, especially in soil contaminated with bat or bird droppings. When contaminated soil is disturbed, spores become airborne and can be inhaled. 

HIV, or human immunodeficiency virus, is the virus that can lead to AIDS, or acquired immune deficiency syndrome. 

HPV, or human papillomavirus, is the most common sexually transmitted infection. More than 50 percent of sexually active people carry HPV at some point in their lives. 

Influenza, or flu, is a viral respiratory disease that can affect anyone, from babies to senior citizens. It is a seasonal disease, most prevalent in the fall and winter months. 

Leptospirosis is a disease caused by bacteria carried in the urine of infected animals. Many different kinds of wild and domestic animals may carry the bacteria, such as cattle, pigs, horses, dogs, and rodents. 

Lyme disease is an inflammatory disease caused by Borrelia burgdorferi bacteria, which normally live in mice, squirrels, and other small animals. The bacteria are transmitted among these animals—and to humans—through the bites of certain species of ticks. 

Humans become infected with malaria, a serious and sometimes fatal disease, when they are bitten by a mosquito carrying a malaria parasite. About 1,500 cases are diagnosed in the United States each year. 

Measles is a highly contagious respiratory disease caused by a virus. The virus lives in mucus in the nose and throat of an infected person. An infected person can spread the disease through the air by breathing, coughing, or sneezing. 

Meningitis is the inflammation of the meninges, the coverings of the brain and spinal cord. Meningitis is usually caused by either a virus or bacteria, and treatment differs depending on the cause. 

MRSA, or methicillin-resistant Staphylococcus aureus, is a type of staph bacteria that is resistant to many of the antibiotics commonly used to treat ordinary staph infections, including penicillin, amoxicillin, and oxacillin. 

Mumps is a contagious viral infection that affects the salivary glands. Before a vaccine was introduced, mumps was a common illness of childhood. 

Nipah virus is an emerging zoonotic virus, a virus transmitted to humans via animals. First recognized in 1999 during an outbreak among pig farmers in Malaysia, there have been 12 outbreaks since then, all in South Asia. 

Noroviruses are a group of related viruses, sometimes called “Norwalk-like viruses,” that cause acute gastroenteritis, the inflammation of the stomach and intestines. 

Pneumonia is an infection of the lungs most often caused by bacteria or viruses present in the environment. In most instances, these organisms cause only a mild form of the disease. 

Polio is a highly infectious disease caused by a virus that affects the nervous system. The virus can be spread by direct person-to-person contact, contact with infected mucus or phlegm from the nose or mouth, or contact with infected feces. 

Salmonella bacteria can cause the infection salmonellosis. Every year, approximately 40,000 cases of salmonellosis are reported in the United States. 

SARS, or severe acute respiratory syndrome, is a viral respiratory illness. Because it spreads fairly easily, possibly even through the air, SARS was difficult to stop during the 2003 global outbreak. 

Schistosomiasis is a disease caused by parasitic worms that live in certain types of freshwater snails. 

Smallpox is caused by the variola virus, which emerged in human populations thousands of years ago. The disease comes in two forms—variola major and variola minor. 

Tetanus is a disease that affects the nervous system, characterized by painful tightening and spasms of the muscles. It is caused by Clostridium tetani bacteria, which produce a toxin that can impair the nerves that control muscles. 

Toxoplasmosis is a disease caused by a parasite called Toxoplasma gondii. Eating undercooked, contaminated meat; drinking water that contains the parasite; and contact with cat feces—by cleaning a litter box, for example—are the most common ways to become infected with the parasite. 

Trichinosis is caused by the larvae of roundworms, which live in contaminated meat. If people eat contaminated meat that has not been cooked long enough, the larvae can enter the intestine. 

Tuberculosis, or TB, is caused by Mycobacterium tuberculosis bacteria. Although TB usually settles in the lungs, it can affect other parts of the body, including the kidney, spine, and brain. 

West Nile virus is a flavivirus commonly found in Africa, West Asia, and the Middle East. 

Yellow fever is caused by a virus transmitted by mosquitoes. The disease cannot be spread from person to person. 

Zika is usually caused by a virus transmitted by mosquitoes. Although Zika has been documented since 1947, the latest outbreak was reported in Brazil in 2015, with the accompanying news that it causes a serious birth defect called microcephaly.