Infectious Diseases

Infectious diseases are illnesses you can develop when bacteria, viruses, fungi, or other organisms enter your body. You may acquire an infectious disease from people, insects, animals, or contaminated food. There are many infectious diseases, and they can range in severity. Find out how to protect yourself from infectious diseases and what to do if you get one.

Types of Infectious Diseases

person washing hands to prevent getting a bacterial infection
What Is a Bacterial Infection?

Flu Basics

Person with the flu wraps themselves in a yellow blanket on the couch.
What To Know About Influenza (Flu)
little boy blowing his nose in a classroom because of influenza symptoms
Signs and Symptoms of Influenza (Flu)
sick woman taking her temperature
What Is the Flu Incubation Period?

How to Protect Yourself

older woman taking an antibiotic with water
What Are Antibiotics?
Doctor prepares to give patient a vaccine.
Does Vaccine Shedding Really Happen?
Nurse or nursing assistant giving female patient injection for flu vaccination campaign in a medical center to fight winter illnesses or infections
How Long Is the Flu Vaccine Effective?

Explore Infectious Diseases

man coughing
Real Talk: Is It Better to Spit Out Mucus When You’re Sick?
A woman applies mosquito spray during a hike
Rates of Babesiosis, a Tickborne Disease, are Soaring. What to Know About 'American Malaria'
Battery hens in a chicken shed.
Everything to Know About the Current US Bird Flu Situation—Including What's Going on In Missouri
A Culex mosquito on green background.
What to Know About ‘Sloth Fever,’ the Virus That Has Made Its Way to the U.S.
A mosquito on a person's body
Two Rare Mosquito-Borne Illnesses Are Making Headlines—Here's What to Know
man drinking milk
Should You Avoid Milk, Beef, and Eggs During the Bird Flu Outbreak? Here's What to Know
Doctor showing antibiotics to patient for C.diff
How Is Clostridiodes Difficile (C. Diff) Treated?
Doctor preparing vaccine
Measles Outbreak: Confirmed Cases in DC, Atlanta—Here's What to Know About the Virus
Sad and depressed woman sitting on the sofa at home
What Is Malaise?
Man getting a vaccine
Still Haven't Gotten Your Flu and COVID Shots? Now's the Time, CDC Director Says
Man getting a nasal swab test at the airport
CDC to Expand Airport Surveillance Program For Flu and RSV at These Major Airports
Person getting a vaccine
2023 Fall Vaccines: When to Get Vaccinated for COVID, Flu, RSV
Cruise ship
Norovirus Outbreaks on Cruise Ships: How to Avoid Getting Sick on Vacation
Woman sneezing into her arm
What Is Human Metapneumovirus? CDC Reports Unusual Spike of Respiratory Virus
Man waking up
CDC Reports New Mpox Outbreak, Experts Note Key Prevention Methods
young child with impetigo taking medication
What Is Impetigo?
older woman receiving vaccine
FDA Approves First-Ever RSV Vaccine for Adults 60 and Older
black-legged tick on human skin
What Is Babesiosis? Tickborne Disease on the Rise in the Northeast, CDC Says
Lone star tick (Amblyomma americanum)
What Is Heartland Virus? Tickborne Disease May Be Expanding Its Reach Across the U.S.
man looking out window holding abdomen in pain
CDC Warns About Drug-Resistant Stomach Bug on the Rise in the US: What to Know
A man lying down on a sofa, sleeping
Norovirus Outbreaks Have Increased to Pre-Pandemic Levels, CDC Data Show
Monkeypox virus particle
Monkeypox Has the Potential to Mutate and Resist Antiviral Treatment, FDA Warns
Monkeypox virus
First U.S. Monkeypox Death Confirmed in Los Angeles—Here's How the Disease Can Be Fatal
Doctor cleans a smiling woman's arm before giving her a shot
You May Be Better Protected if You Space Out Your COVID and Flu Shots—Here's Why
Mature doctor talking to senior man before applying vaccine - wearing face mask
New York Declares State of Emergency Over Growing Polio Concerns
African-American man getting covid vaccine close-up
Annual COVID Vaccine: U.S. Tries 'New Approach' With Omicron Boosters
A father holding his little girl in his lap while a mother is checking her temperature
'Tomato Flu' Is Likely Just an Unusual Presentation of Hand, Foot, and Mouth Disease
Kyle Planck, 26, who has recovered from monkeypox, shows Tecovirimat capsules, which is used for monkeypox treatment, during an interview in New York on July 19, 2022. - I don't want anyone to have to go through what I went through just cured of monkeypox, which gave him "the worst pain of his life" despite rapid treatment, Planck, 26, regrets the lack of response from health authorities when the epidemic appeared in the US. (Photo by Yuki IWAMURA / AFP) (Photo by YUKI IWAMURA/AFP via Getty Images)
TPOXX Is the Only Treatment Available for Monkeypox—Here's What To Know
Digitally-colorized electron microscopic (EM) image depicting a monkeypox virion (virus particle), obtained from a clinical sample associated with a 2003 prairie dog outbreak, published June 6, 2022. The image depicts a thin section image from a human skin sample. On the left are mature, oval-shaped virus particles, and on the right are the crescents and spherical particles of immature virions. Courtesy CDC/Goldsmith at al. (Photo via Smith Collection/Gado/Getty Images)
How Monkeypox Spreads: What to Know About Transmission and How to Protect Yourself
LOS ANGELES, CALIFORNIA - AUGUST 10: Licensed Vocational Nurse (LVN) Gabriela Solis prepares a dose of the Jynneos monkeypox vaccine at an L.A. County vaccination site in East Los Angeles on August 10, 2022 in Los Angeles, California. Los Angeles County reported 683 monkeypox cases as of August 9th, double the amount of cases from ten days earlier. California Governor Gavin Newsom declared a state of emergency on August 1st over the monkeypox outbreak which continues to grow globally. (Photo by Mario Tama/Getty Images)
What to Know About Monkeypox Vaccine Side Effects—Even With a Lower Dose
Smoke Emitting From Chimney Against Sky
How Climate Change Is Worsening Infectious Diseases Across the Globe
A mom puts her hand on her daughter's forehead while looking at a thermometer
The Stages of Hand, Foot, and Mouth Disease (HFMD)
Man applying insect repellent to his arm to help prevent mosquitos from biting him.
What To Know About Yellow Fever
Young man in bed sick blowing his nose and checking his temperature.
What Is the Difference Between a Cold and the Flu?
Little girl receiving chickenpox vaccination in clinic, closeup. Varicella virus prevention
What To Know about Varicella-Zoster Virus, the Cause of Chickenpox and Shingles
close up image of person with extremely swollen cheeks
Everything To Know About Mumps
Redness on child's cheeks caused by fifth disease, which is sometimes called slapped cheek disease
What To Know about Fifth Disease ("Slapped Cheek" Disease)
Adult applying ointment to arm of child with chickenpox
What To Know about Chickenpox (Varicella-Zoster Virus)
young child with thermometer in her mouth experiencing fever while laying down on a couch and holding a box of tissues
Signs and Symptoms of Rotavirus
person in green shirt sitting on cough holding stomach in pain and experiencing nausea
A Complete Guide to Norovirus
boy with red cheeks due to fifth disease, a result of parvovirus b19
Signs and Symptoms of Fifth Disease (Parvovirus B19)
Person applying mosquito repellant on their arm while on a park hike
Signs and Symptoms of West Nile Virus (WNV)
Pregnant person coughing a lot over telemed appointment
Is Whooping Cough (Pertussis) Hard To Diagnose?
Signs of an Anal Fissure
Signs and Symptoms of an Anal Fissure
Man Preparing Vaccine
Do You Need a Polio Booster? What Vaccinated People Should Know
Health Photo Composite - Whooping Cough
Signs and Symptoms of Whooping Cough
A doctor listens to a child's lungs as the child coughs
How Is Whooping Cough (Pertussis) Treated?
Health Photo Composite - Bird Flu
Signs and Symptoms of Bird Flu
A healthcare worker prepares to administer a monkeypox vaccine
Monkeypox (Mpox) Rash: What Does Monkeypox Look Like?
Health Photo Composite - Listeria
What Is Listeria?
free-range chickens and turkeys
CDC Confirms Human Case of Bird Flu in Texas—What Does This Mean for Public Health?
Person choosing packaged meat at grocery store
What Is Salmonella?
Health Photo Composite - Listeriosis
Signs and Symptoms of Listeria Infection
Health Photo Composite - Salmonella
Signs and Symptoms of Salmonella
person taking antibiotics to treat staph infection
How Is a Staph Infection Treated?
Finding parasites in feces in laboratory.
What Is a Tapeworm Infection?
a dad helping his son with RSV blow his nose
Signs and Symptoms of Respiratory Syncytial Virus (RSV)
person getting vaccinated
Flu, COVID, and RSV Cases Are on the Rise, But Few Americans Are Vaccinated, CDC Warns
person with stomach flu sick on cough with stomach pain
Signs and Symptoms of Stomach Flu
health.com illustration showing the common and less common symptoms of norovirus
Signs and Symptoms of Norovirus
Young adult man suffering from sore throat
What Are the First Signs of Monkeypox? Here's When Symptoms Typically Show Up
Photo Composite - TSS
Signs and Symptoms of Toxic Shock Syndrome
Doctor examining patient's arm
Signs and Symptoms of Staph Infection