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infectious disease
Table of Contents
References & Edit History Quick Facts & Related Topics
Images, Videos & Interactives
West Nile virus Basic reproduction number of select viral diseases Vaccines by the numbers Vaccine timeline
The difference between bacteria and viruses
MRSA and neutrophil Chlamydia Epidemic typhus and Rickettsia prowazekii Herpes zoster SARS-CoV-2
For Students
Gram-negative bacteria such as Neisseria meningitidis are a common cause of septicemia.
infection summary
Quizzes
Encyclopaedia Britannica thistle graphic to be used with a Mendel/Consumer quiz in place of a photograph.
44 Questions from Britannica’s Most Popular Health and Medicine Quizzes
Read Next
Marina Spelzini, a registered nurse, measures out an H1N1 vaccine shot at the Miami Dade County Health Department downtown clinic on November 3, 2009 in Miami, Florida. (influenza, swine flu)
When Was the Last Pandemic?
Infographic on the Influenza Pandemic of 1918-19
Influenza Pandemic of 1918–19 Chart
Shoppers crowd London's Oxford Street (main retail district) on 'Black Friday' discount day in the lead up to Christmas
What Is a Superspreader Event?
Scanning electron micrograph showing the spiral-shaped bacteria of the genus Leptospira. These organisms cause leptospirosis.
8 Zoonotic Diseases
People wearing surgical masks (also called face mask or medical masks or safety masks) walk through the city center of Milan, Italy on Feb. 23, 2020. Coronavirus disease COVID-19 pandemic
How Do Face Masks Control the Spread of Disease?
Discover
Cuban Bee Hummingbird (Mellisuga helenae) single adult male, Zapata peninsula, Cuba, Caribbean.Bee hummingbirds are the smallest birds in the world.
Queen Mab’s Stable: 7 of the Smallest Animals
Germans from East and West stand on the Berlin Wall in front of the Brandenburg Gate in the November 10, 1989, photo, one day after the wall opened.
Timeline of the 1980s
The Colosseum, Rome, Italy. Giant amphitheatre built in Rome under the Flavian emperors. (ancient architecture; architectural ruins)
New Seven Wonders of the World
American bison (Bison bison) also known as buffalo or plains buffalo on the prairie, western U.S.
What’s the Difference Between Bison and Buffalo?
The impeachment trial of Pres. Andrew Johnson, illustration from Frank Leslie's Illustrated Newspaper, March 28, 1868.
What If the President Is Impeached?
Amendments 1-10 to the Constitution of the United States constitute what is known as the Bill of Rights on an American flag.
What Is the Emoluments Clause?
Figure 13: A Maxim machine gun, belt-fed and water-cooled, operated by German infantrymen, World War I.
7 Deadliest Weapons in History

infectious disease: Media

Videos

The difference between bacteria and viruses
Knowing the difference isn't just a technical distinction—it can save lives.
Video: Encyclopædia Britannica, Inc.
Why is it so hard to fight tuberculosis?
Learn why tuberculosis is still a threat to the human population.
Video: © American Chemical Society (A Britannica Publishing Partner)
How did the polio vaccine change the world?
The original formulation of the polio vaccine was announced in 1953.
Video: Encyclopædia Britannica, Inc.
Why don't flu shots always work?
Learn about the search for a universal flu vaccine.
Video: © American Chemical Society (A Britannica Publishing Partner)

Images

West Nile virus
Birds are the primary reservoirs of West Nile virus. The virus is transmitted to...
Encyclopædia Britannica, Inc.
Basic reproduction number of select viral diseases
The contagiousness of infectious pathogens is measured by R0 (R naught),...
Encyclopædia Britannica, Inc.
MRSA and neutrophil
Four methicillin-resistant Staphylococcus aureus (MRSA) bacteria (purple)...
National Institute of Allergy and Infectious Diseases/Centers for Disease Control and Prevention (CDC)
Chlamydia
A Pap smear specimen showing the bacterium Chlamydia trachomatis, the cause...
Laboratory of Dr. Lance Liotta/National Cancer Institute
Epidemic typhus and Rickettsia prowazekii
Colorized scanning electron micrograph of the bacterium Rickettsia prowazekii,...
© CNRI/Science Source
Herpes zoster
Blisters characteristic of herpes zoster (shingles) shown on the neck and shoulder.
John Pozniak
SARS-CoV-2
An image taken with a scanning electron microscope shows SARS-CoV-2 (in orange),...
Courtesy, NIAID/RML
Viral disease researchers Hilary Koprowski and Herald R. Cox
Hilary Koprowski (left) and Herald R. Cox, researchers in the field of viral diseases,...
Bettmann/Getty Images
Ethnic Uzbek refugees from Kyrgyzstan
Refugees from Kyrgyzstan waiting in a refugee camp near the village of Erkishlok,...
Anvar Ilyasov—AP/Shutterstock.com
Tetanus
Clostridium tetani bacteria, the cause of tetanus.
© KATERYNA KON—Science Photo Library/Getty Images
White blood cell
A neutrophil, a type of white blood cell (in blue), interacts with pneumonia bacteria...
David Dorward, Ph.D.—National Institute of Allergy and Infectious Diseases/Centers for Disease Control and Prevention (CDC)
Polio vaccine
A health care worker giving a polio vaccine to a child in Katsina state, Nigeria,...
Alford Williams/Centers for Disease Control and Prevention (CDC)
Vaccination
Army personnel working with a Gabonese woman and her child at a medical clinic that...
National Archives, Washington, D.C.
COVID-19 vaccine
Should employers be able to mandate vaccinations?
© Scaliger/Dreamstime.com
Gram-negative bacteria such as Neisseria meningitidis are a common cause...
© Ilexx/Dreamstime.com

Interactives

Vaccines by the numbers
Interactive chart displaying lives saved or birth rate increase from vaccines.
Encyclopædia Britannica, Inc.
Vaccine timeline
An interactive timeline on the development of vaccines.
Encyclopædia Britannica, Inc. / Lucia Barnum
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