Epidemics
An epidemic is
a disease outbreak in which some or many people in a
community or region become infected with the same disease, either because the disease has been
brought into the community by an outside source
(such as a traveler infected with the disease, or an insect that carries the disease and infects
people with its bite), or because a pathogen
(a virus or bacteria) has changed in a way that either
enables it to evade the immune system
or has made it more virulent--that is, stronger and more aggressive. Some epidemics occur when an
entirely new disease, such as AIDS, or a new version of an old disease, such as influenza,
emerges.
Pandemics
A pandemic is
an epidemic that spreads throughout the world, as influenza did in 1918. Pandemics may involve an
old disease, such as smallpox or the bubonic plague, or they may occur when a new disease or a new
form of an old disease develops and spreads. If the source of the pandemic is a new virulent
pathogen or a new form of an old virulent pathogen, very few people, if any, may be resistant to
the disease, and the rates of illness and death may be high around the world, unless effective
prevention strategies can be rapidly developed and implemented. Vaccine development is an example
of a very effective prevention strategy; however, it takes a good deal of time to develop a
vaccine and make sure that it is safe and effective.
The pandemic of 1918: A
common disease killed millions
Influenza should never be mistaken as a harmless disease. In addition
to its miserable symptoms, serious life-threatening complications can occur, especially in
infants, the elderly, and in people whose immunity
is weak. And some strains of flu are deadly.
Like smallpox, influenza is a very old disease. In 412 BC,
Hippocrates, the Greek physician who is known as the "Father of Medicine," recorded an
epidemic of an infection resembling flu that wiped out an entire Athenian army.(55)
Explorers brought an epidemic of the disease to North America from
Valencia, Spain in 1647.(56) Two pandemics of influenza occurred
in 1847-1848 and 1889, but these were relatively mild in United States.(57)
In 1918 and 1919, however, a terrible pandemic of influenza struck. This was an especially
dangerous form of "Spanish" influenza. The virus entered through the nasal passages and
caused very sudden, severe illness in 20% to 40% of the population of most countries, especially
in young adults. The speed with which this flu killed was frightful. Many people who woke up
feeling well, became ill by mid-day and were dead by nightfall.
According to the historian Adolph A. Hoehling, among the first cases
in the 1918 epidemic were two cavalrymen who suddenly took ill at Fort Riley, Kansas, on March 11,
1918. By noon that day, 107 men were in the hospital; by the end of the week, 522 cases had
occurred.(58) The disease quickly spread across the country, from
Nome and Seattle to Los Angeles, where more than a quarter-million cases occurred; to
Wilkes-Barre, Pennsylvania, and Atlanta, Georgia, and to the states along the Gulf of Mexico.
Philadelphia, Pennsylvania was among the hardest hit, with many hundreds dying per day. Baltimore,
Maryland developed 20,000 cases over one night, and the city of New Orleans was so stricken that
it had to shut down.(59)
As Hoehling describes in his book, The Great Epidemic, both
individuals and governments were gripped with fear and took extreme measures to try to stop the
disease from spreading. Some cities closed down theaters and schools. Some communities shut down
completely until the worst had passed. Families with small children were in serious trouble if the
parents were stricken, because friends and family members were often too frightened to enter the
household to assist and care for the little ones. Over twenty million people died, representing
the highest mortality for any influenza pandemic in recorded history.(60)
Many senior citizens living today have recollections of this pandemic and lost family members and
neighbors during that terrible time.
Even today, the 1918 pandemic sparks many questions about infectious
diseases and human survival. Some tenacious scientists are still trying to understand what
happened in that pandemic. In September, 1997, the New Yorker magazine reported that a
group of researchers are examining tissue samples from seven Norwegian men who died during the
epidemic, in an attempt to crack the genetic code of the Spanish flu. They believe that the virus
may have originated with a wild duck, then mutated in the duck to a form that could infect and
thrive in humans. Avian species (ducks, birds) are known to carry most of the known strains of the
flu.(61) Pigs also play a large role in incubating and shaping
viruses for the human species.
Monitoring and controlling
epidemics and pandemics
Several centers at the CDC play various roles in monitoring and
controlling epidemics and pandemics. Among their efforts, the National Center for Infectious
Diseases reports the number and locations of cases of influenza and the type of influenza in
circulation during the annual flu season. Links to home pages are provided below.
*Epidemiology
Program Office
*International Health Program Office
National Center for Infectious Diseases
*General information
*Seasonal influenza
updates
*National Center for HIV, Sexually Transmitted Diseases, and Tuberculosis
Prevention
The Pandemic Plan
Fortunately, not all pandemics are as serious as the one that
occurred in 1918. A pandemic can be relatively mild. However, many scientists believe that another
pandemic of a serious form of influenza will occur sometime in the near future. When it strikes,
few people, if any, may be immune to it. This would be a serious challenge, and we have to be
prepared to deal with it. Because so many people become ill in a pandemic, such an outbreak could
bring the normal and necessary activities of entire cities or nations to a halt. How would we make
sure that essential services continue to operate? Would schools shut down? What if our police
force or military were suddenly weakened when a large percentage of people became ill? How would
hospitals, clinics, and pharmacies cope, especially if thousands of doctors and nurses become ill?
Would it be possible to develop a vaccine in time to save lives, or perhaps even stall the
pandemic?
Although there is no way at this time to predict with 100% certainty
that such a pandemic will develop, NVPO and its interagency group take the threat seriously, and
is working to develop a Pandemic Preparedness Plan to prepare for such an event.
*The Pandemic Preparedness Plan will be posted on this
site when it is completed.
You can also search the CDC home page for specific topics such as Legionnaire's Disease, Hanta virus,
and polio.
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