Diseases & Conditions

Research to understand and treat some of the world's most problematic diseases.

29 Results


Cholera is an acute, diarrheal illness caused by infection of the intestine with the bacterium Vibrio cholerae. An estimated 3-5 million cases and over 100,000 deaths occur each year around the world. The infection is often mild or without symptoms, but can sometimes be severe. Without treatment, death can occur within hours.

Image of cholera


Coronaviruses are a large family of viruses that usually cause mild to moderate upper-respiratory tract illnesses, like the common cold. However, three coronaviruses have caused more serious and fatal disease in people: SARS coronavirus (SARS-CoV), MERS coronavirus (MERS-CoV), and SARS-CoV-2 (which causes COVID-19).

MERS virus cells

Dengue Fever

Dengue fever is an infectious disease carried by mosquitoes and caused by any of four related dengue viruses. This disease used to be called "break-bone" fever because it sometimes causes severe joint and muscle pain that feels like bones are breaking. Health experts have known about dengue fever for more than 200 years. 

Aedes aegypti mosquito larvae

E. coli

Escherichia coli (E. coli) bacteria live in the intestines of people and animals, and are key to a healthy intestinal tract. Most E. coli strains are harmless, but some can cause diarrhea through contact with contaminated food or water while other strains can cause urinary tract infections, respiratory illness and pneumonia.

Image of E. coli bacteria

Ebola & Marburg

Ebola is a serious and often fatal illness caused by a virus. Several viruses can cause Ebola disease in humans, including Ebola virus and Sudan virus. Symptoms of Ebola include fever, headache, muscle pain, weakness, fatigue, diarrhea, vomiting, stomach pain, and severe bleeding and bruising.

Ebola virus particles both budding and attached to the surface of infected VERO E6 cells

Fungal Diseases

Fungi include a wide range of organisms, such as mushrooms, molds, and yeast, that are common outdoors in water, soil and air; indoors on surfaces; and on our skin and inside our bodies. Mold can worsen breathing problems in people with allergies or asthma, while various types of fungus can infect nails and cause skin rashes. 

Scanning electron micrograph of phagocytosis of a dead yeast particle (zymosan)


Gonorrhea is a sexually transmitted infection that can infect both men and women. Caused by Neisseria gonorrhoeae bacteria, gonorrhea can cause infections in the genitals, rectum and throat. Although treatable, drug-resistant forms of gonorrhea are increasing.

Neisseria gonorrhoeae bacteria

Group A Streptococcal Infections

Group A streptococcal (GAS) infections can range from a mild skin infection or a sore throat to severe, life-threatening conditions. Most people are familiar with strep throat, which along with minor skin infections, is the most common form of the disease.

NeutrophilScanning electron micrograph of Group A Streptococcus


Hepatitis is an inflammation of the liver. Viruses are the most common cause of hepatitis, but the condition can also be caused by other infections, heavy alcohol use, toxins, certain medications, and autoimmune disease. There are five main virus types that cause hepatitis---type A, B, C, D, and E.

Photo of liver tissue specimen extracted from a viral hepatitis patient.


HIV, or human immunodeficiency virus, is the virus that causes AIDS (acquired immunodeficiency syndrome) and can be transmitted during sexual intercourse; by sharing syringes; or perinatally during pregnancy, childbirth or breastfeeding. Since the first AIDS cases were reported in 1981, HIV/AIDS has been one of humanity’s deadliest and most persistent epidemics. Although extraordinary progress has been made in the fight against new HIV cases and AIDS deaths, the HIV pandemic continues.

Image of an HIV-infected T cell


Seasonal influenza, or flu, is a highly contagious respiratory disease caused by any of several human influenza viruses that circulate globally and cause annual outbreaks of varying severity. Influenza viruses infect the nose, throat, and lungs and produce symptoms that include sudden fever, extreme fatigue, coughing, chills, and muscle aches. Serious complications include pneumonia. Each year, flu causes millions of illnesses worldwide and kills many thousands. It is especially dangerous for people who are very young or old or who have other conditions such as heart disease or asthma. 

H1N1 Influenza Virus Particles


Leishmaniasis is a parasitic disease transmitted by the bites of infected sand flies. It is found in nearly 88 countries, from rain forests in Central and South America to deserts in the Middle East and west Asia. Some cases of the disease have also appeared in Mexico and Texas. The disease takes several different forms, including the most common cutaneous leishmaniasis, which causes skin lesions, and the more severe visceral leishmaniasis (also known as kala azar), which affects internal organs such as the spleen, liver, and bone marrow.

Leishmaniasis hero image

Leprosy (Hansen's Disease)

Leprosy (Hansen's Disease) is a chronic infectious disease that primarily affects the peripheral nerves, skin, upper respiratory tract, eyes, and nasal mucosa (lining of the nose). The disease is caused by a bacillus (rod-shaped) bacterium known as Mycobacterium leprae.

Leprosy micrograph

Lyme Disease

Lyme disease, or borreliosis, is caused by the bacterium Borrelia burgdorferi and is transmitted to humans through the bite of an infected blacklegged deer tick. It is the most common tickborne infectious disease in the United States.  

Lyme Disease Bacteria, Borrelia burgdorferi


Malaria is a mosquito-borne infectious disease caused by the bite of female Anopheles mosquitoes, which spread infectious Plasmodium parasites into a host. The WHO estimates that in 2020 about 240 million people had malaria and about 627,000 of them died. A vaccine to prevent malaria is available; however, its variable efficacy underscores the need for new interventions.

Malaria Infected Blood Cell

Mpox (formerly Monkeypox)

The monkeypox virus is part of the Orthopoxvirus genus, which also includes variola virus (the cause of smallpox), vaccinia virus, and cowpox virus. Although monkeypox is similar to smallpox, it is much less deadly. Initial symptoms of monkeypox infection include: fever, headache and body aches, fatigue, and swollen lymph nodes, followed by a rash of lesions on the skin. Human-to-human transmission of monkeypox occurs through direct contact with body fluids, lesions, prolonged face-to-face contact, and indirect contact with contaminated clothing or bedding. Animal-to-human transmission can occur through a bite or scratch, preparation of wild game, or direct or indirect contact with body fluids or lesions.

mpox particles in an infected cell.

Pertussis (Whooping Cough)

Pertussis, also known as whooping cough, is a highly contagious respiratory disease. It is caused by the bacterium Bordetella pertussis. Pertussis is known for uncontrollable, violent coughing that often makes it hard to breathe. After fits of many coughs, someone with pertussis often needs to take deep breaths, which result in a “whooping” sound.

Pertussis (bordetella pertussis) bacteria

Prion Diseases

Prion diseases are transmissible, untreatable, and fatal brain diseases of mammals. Their cause is highly unusual, and prion disease symptoms reflect the brain being destroyed. NIAID is exploring similarities between prion diseases and other protein misfolding diseases, such as Alzheimer’s and Parkinson’s diseases.

Prion protein fibrils

Respiratory Syncytial Virus (RSV)

Respiratory syncytial virus (RSV) infects the lungs and breathing passages, and, in the United States, nearly all children have been infected with RSV by age two. In healthy people, symptoms of RSV infection are usually mild and resolve within a week. However, RSV can cause serious illness or death in vulnerable individuals.

Colorized scanning electron micrograph of human respiratory syncytial virus (RSV) virions (blue) and labeled with anti-RSV F protein/gold antibodies (yellow) shedding from the surface of human lung epithelial cells.

Rocky Mountain Spotted Fever

Rocky Mountain spotted fever is a tickborne disease first recognized in 1896 in the Snake River Valley of Idaho. It was originally called “black measles” because of the look of its rash in the late stages of the illness, when the skin turns black. It was a dreaded, often fatal disease, affecting hundreds of people in Idaho. By the early 1900s, the disease could be found in Washington, Montana, California, Arizona, and New Mexico.

Rocky Mountain Spotted Fever Hero Image

Schistosomiasis (Bilharzia)

Schistosomiasis, also known as bilharzia or snail fever, is an acute and chronic disease caused by parasitic flatworms called schistosomes or blood flukes. Most human infections are caused by Schistosoma mansoni, S. haematobium, or S. japonicum. The parasites spend part of their lifecycle in freshwater snails. The infectious, larval form emerges from the snail and contaminates water.

Magnified image of Schistosoma mansoni trematodes

Sexually Transmitted Infections

Sexually transmitted infections (STIs) are infections transmitted from person to person through sexual contact. STIs can be caused by bacteria, viruses, or parasites. Examples include gonorrhea, genital herpes, human papillomavirus infection, HIV/AIDS, chlamydia, and syphilis.

Sexually Transmitted Diseases image


Shigellosis is an infectious, diarrheal disease caused by a group of bacteria called Shigella. It is transmitted via contact with contaminated food, water, surfaces or an infected person. The disease typically resolves in 5 to 7 days. Shigella causes roughly 500,000 cases of diarrhea in the United States each year.

Micrograph of Shigella sonnei bacteria


Smallpox, caused by the variola virus, was a highly contagious infectious disease that caused infected individuals to develop a fever and a progressive, disfiguring skin rash. Three of out 10 individuals infected with smallpox died. Many survivors have permanent scars, often on their faces, or were left blind. Through vaccination, the disease was eradicated in 1980.  However, research for effective vaccines, drugs and diagnostics for smallpox continues in the event it is used as a bioterror weapon.

Smallpox image


Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. It is transmitted from person to person via direct contact with a syphilitic sore, known as a chancre. These sores can be found on the genitals, vagina, anus, rectum, lips and mouth. Pregnant women can transmit the disease to their unborn child.  Syphilis can cause long-term health complications if left untreated.

Image of syphilis bacteria