The World Health Organization (WHO) defines key terms used in the discussion of pandemic diseases: "A disease epidemic occurs when there are more cases of that disease than normal. A pandemic is a worldwide epidemic of a disease." Scientific research has assisted in eradicating diseases that created pandemics in earlier generations, but the threat of new pandemics increases in an age where large numbers of people travel the continents quickly by air.
The Centers for Disease Control defines the plague as "...an infectious disease of animals and humans caused by a bacterium named 'Yersinia pestis.'" The plague, transferred by fleas hiding on goods and people traveling from region to region, killed millions of people during the Middle Ages. The CDC notes that the plague continues to infect people living in rural and remote areas. The last major urban epidemic occurred in Los Angeles during the mid-1920s. Campgrounds are routinely closed today due to plague infestations of squirrels and rodents. As of 2009, the disease is controlled by early dosages of antibiotics.
- The Centers for Disease Control defines the plague as "...an infectious disease of animals and humans caused by a bacterium named 'Yersinia pestis.'"
- The CDC notes that the plague continues to infect people living in rural and remote areas.
What Is the Chain of Infection for Tuberculosis?
Tuberculosis (TB) was the leading cause of world death after World War I, with returning troops serving as carriers of the pandemic disease. TB is caused by "...a bacterium called 'Mycobacterium tuberculosis,'" according to the CDC. It can attack any part of the body, but the lungs are infected in most patients. TB is spread by breathing in bacteria from an infected person. Current outbreaks of the disease involve a virulent, mutated strain typed "XDR-TB" that is resistant to modern drugs (the "DR" designation stands for "drug resistant").
- Tuberculosis (TB) was the leading cause of world death after World War I, with returning troops serving as carriers of the pandemic disease.
- Current outbreaks of the disease involve a virulent, mutated strain typed "XDR-TB" that is resistant to modern drugs (the "DR" designation stands for "drug resistant").
Polio was a pandemic disease in the 1950s. Due to a subsequent world effort, it was considered eradicated until the 1980s when countries ceased immunizing children against the disease. WHO's efforts to bring polio under control have reduced the number of cases from 350,000 in 1988 to less than 1,200 in 2005. The clear lesson is that constant medical vigilance is necessary to prevent pandemic outbreaks from reoccurring.
- Polio was a pandemic disease in the 1950s.
- Due to a subsequent world effort, it was considered eradicated until the 1980s when countries ceased immunizing children against the disease.
Lota Skin Disease
The influenza (flu) pandemics of 1918 and the 1950s killed millions of people. WHO estimates more than 40 million died in the 1918 to 1919 outbreak alone and speculates that more than seven million may die in a contemporary flu pandemic. WHO, the U.S. Centers for Disease Control (CDC), heads of world government, and corporate and non-profit agencies work together each year to develop flu vaccines to slow the spread of the disease.
Any disease has the potential to become a pandemic if treatment is delayed and it is transferred from the host geographic region to other areas. The Voice of America (VOA) lists Ebola Hemorrhagic Fever and AIDS as potential 21st century pandemics. Influenza, TB and severe acute respiratory syndrome (SARS), diseases that impacted the world as pandemics from the past, also top the VOA list for future pandemics.
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- Center for Strategic & International Studies. The world's largest HIV epidemic in crisis: HIV in South Africa. Updated April 2, 2019.
- Merriam-Webster. When does an outbreak become an epidemic?
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- Association for Professionals in Infection Control and Epidemiology. Outbreaks, epidemics, and pandemics - what you need to know.
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- Centers for Disease Control and Prevention. Influenza (flu) national pandemic strategy. Updated June 15, 2017.
- Pandemic influenza preparedness and response: a WHO guidance document. Geneva: World Health Organization; 2009. 4, The WHO Pandemic Phases.
- Ancient History Encyclopedia. Justinian's plague (541-542 CE). Updated December 26, 2014.
- New World Encyclopedia. Black death. Updated September 3, 2019.
- Centers for Disease Control and Prevention. 1918 pandemic (H1N1 virus). Updated March 20, 2019.
- Voigt EA, Kennedy RB, Poland GA. Defending against smallpox: a focus on vaccines. Expert Rev Vaccines. 2016;15(9):1197-211. doi:10.1080/14760584.2016.1175305
- TB Alliance. The pandemic.
David B. Ryan has been a professional writer since 1989. His work includes various books, articles for "The Plain Dealer" in Cleveland and essays for Oxford University Press. Ryan holds degrees from the University of Cincinnati and Indiana University and certifications in emergency management and health disaster response.