Epidemic, Pandemic and Endemic: What is the difference?

Influenza 1918: Teacher's Guide

In the spring of 1918, as the nation mobilized for war, Private Albert Gitchell reported to an army hospital in Kansas. He was diagnosed with the flu, a disease doctors knew little about. Before the year was out, America would be ravaged by a flu epidemic that killed 675,000 — more than in all the wars of this century combined — before disappearing as mysteriously as it began.

Influenza: Teacher's Guide (172.7 KB)

Time Period: 1918

Themes: influenza epidemic of 1918, World War I, public health policy, history of medicine

Before WatchingDivide students into two groups, and tell them they are going to see a film about a public health crisis. Make a list of what factors they think might have contributed to the spread of disease in 1918. Ask one group to jot down all the specific activities that contributed to the rapid spread of the disease. Ask the other group to note efforts by local or national officials to slow the spread of the illness and when these occurred.

After Watching1. Put two columns on the board: "Factors contributing to flu spread" and "Actions of public health officials." Using their notes, have the students complete the lists.

Looking back at the flu epidemic, what do students think should have been done to try to control the disease's spread? Why do they think these actions were not taken?

Then have groups of students study an infectious disease that has reemerged as a serious public health threat, particularly one we thought we had eradicated or controlled (e.G., tuberculosis, cholera, malaria, yellow fever, antibiotic-resistant bacterial infections, etc.), and develop recommendations for public health policy to halt its spread.

After each group presents and explains its recommendations to the class, encourage questions. For example: How will strategies be implemented? What are potential drawbacks? How can recommendations balance individual rights and the public welfare?

2. Why do students think Americans largely have not retained this incident in their collective memory? What do you think the impact of it was on those who lived through it? How much do you think the euphoria surrounding the Armistice overshadowed the experience of the epidemic? What can we learn from studying it? Is it an important incident to study? Why or why not?

3. According to the film, many people used home remedies to combat the flu. Have students choose different types of nontraditional medicine to research, including folk remedies, acupuncture, homeopathic remedies, biofeedback, or herbal remedies. They should look at the history of the practice, its strengths and weaknesses, and evidence of effectiveness. They might want to visit or interview staff at alternative medical establishments, homeopathic drugstores, acupuncture clinics, etc. Students may also want to look for parallels to traditional medicine (for example, willow bark and aspirin).

Students can create posters presenting their research, bring in pictures or examples of the medical practice they investigated, or share it through oral reports. What do students think should be the role of alternative medicine in treating illness? Do any of them use alternative medicine? If not, would they consider it? Under what circumstances?

Inside The Swift, Deadly History Of The Spanish Flu Pandemic

Scientist Johan Hultin traveled to Brevig Mission, Alaska, a town of a few hundred souls in the summer of 1997. He was searching for buried bodies, and Alaska's frozen ground was the perfect place to find them. Digging through the permafrost—with permission from the town's authorities—he eventually uncovered a woman who died almost 80 years previously and was in a state of excellent preservation. Hultin then extracted samples of the woman's lung before reinterring her. He intended to use this to decode the genetic sequence of the virus that had killed this Inuit woman along with 90 percent of the town's population.

Brevig Mission was just one place that was part of a global tragedy, one of the worst ever to befall humanity: the influenza pandemic of 1918-19. The outbreak of this influenza virus, also known as Spanish flu, spread with astonishing speed around the world, overwhelming India, and reaching Australia and the remote Pacific islands. In just 18 months at least a third of the world's population was infected. Estimates on the exact number of fatalities vary wildly, from 20 million to 50 million to 100 million deaths. If the upper end of that estimate is accurate, the 1918 pandemic killed more people than both World Wars put together. (Get the facts on influenza.)

The first official cases of the 1918 Spanish flu pandemic were recorded at the U.S. Army's Camp Funston, Kansas, where this emergency influenza ward held treated patients.

SPL/AGE FOTOSTOCK

War and pestilence

Several closely related viruses cause influenza, but one strain (type A) is linked to deadly epidemics. The 1918-19 pandemic was caused by an influenza A virus known as H1N1. Despite becoming known as the Spanish flu, the first recorded cases were in the United States in the final year of World War I. (Explore the memorials of World War I.)

A magnified view of the H1N1 virus responsible for the 1918 pandemic.

SPL/AGE FOTOSTOCK

By March 1918 the United States had been at war with Germany and the Central Powers for 11 months. During that time America's small, prewar army had grown into a vast fighting force that would eventually send more than two million men to Europe. (How the United States entered World War I.)

American forts experienced a massive expansion as the entire nation mobilized for war. One of these was Fort Riley, Kansas, where a new training facility, Camp Funston, was built to house some of the 50,000 men who would be inducted into the Army. It was here in early March that a feverish soldier reported to the infirmary. Within a few hours more than a hundred other soldiers had come down with a similar condition, and more would fall ill over the following weeks. In April more American troops arrived in Europe and brought the virus with them. The first wave of the pandemic had arrived. (What is the difference between an epidemic and a pandemic?)

Deadly speed

The Spanish flu strain killed its victims with a swiftness never seen before. In the United States stories abounded of people waking up sick and dying on their way to work. The symptoms were gruesome: Sufferers would develop a fever and become short of breath. Lack of oxygen meant their faces appeared tinged with blue. Hemorrhages filled the lungs with blood and caused catastrophic vomiting and nosebleeds, with victims drowning in their own fluids. Unlike so many strains of influenza before it, Spanish flu attacked not only the very young and the very old, but also healthy adults between the ages of 20 and 40.

Biologists at St. Bartholomew's Hospital in London are analyzing brain and lung tissue from victims of the 1918 pandemic as part of global efforts to understand the virus. Here, wax-mounted tissue samples sit on a list of children's names who fell victims to influenza in 1918.

SPL/AGE FOOTSTOCK

The principal factor in the virus's spread was, of course, the international conflict then in its last phase. Epidemiologists still dispute the exact origins of the virus, but there is some consensus it was the result of a genetic mutation that perhaps took place in China. But what is clear is that the new strain went global thanks to the massive and rapid movement of troops around the world.

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The drama of the war also served to obscure the unusually high mortality rates of the new virus. At this early stage, the illness was not well understood and deaths were often attributed to pneumonia. Strict wartime censorship meant that the European and North American press were unable to report outbreaks. Only in neutral Spain could the press speak freely about what was happening, and it was from this media coverage that the disease took its nickname.

Deadly Contact

Native Americans treat patients infected by European diseases in this 1591 engraving by Theodor de Bry.

GRANGER/ALBUM

Epidemics are as old as civilization: Signs of smallpox appear on 12th-century B.C. Egyptian mummies. Increased contact led to the spread of disease. In the sixth century A.D. The Plague of Justinian moved along trade routes, killing 25 million people across Asia, Africa, Arabia, and Europe. Eight centuries later, the Black Death wiped out 60 percent of Europe's population. When Europeans settled in the Americas in the 16th and 17th centuries, they introduced smallpox, influenza, and measles to the native peoples, killing an estimated 90 percent of the population. Here, Native Americans treat patients infected by European diseases in a 1591 engraving by Theodor de Bry.

The second wave

The overcrowded trenches and encampments of the First World War became the perfect hosts for the disease. As troops moved, so the infection traveled with them. The wave that had first appeared in Kansas abated after a few weeks, but this was only a temporary reprieve. By September 1918 the epidemic was ready to enter its most lethal phase.

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It has been calculated that the 13 weeks between September and December 1918 constituted the most intense period, taking the greatest number of lives. At least 195,000 Americans died in October alone. In comparison, total American military casualties for the whole of World War I came in at just over 116,000. Once again, it was the crowded military encampments where the second wave initially gained a hold. In September an outbreak of 6,674 cases was reported at Camp Devens, a military base in Massachusetts.

As the crisis reached its zenith, the medical services began to be overwhelmed. Morticians and gravediggers struggled, and conducting individual funerals became impossible. Many of the dead ended up in mass graves. The end of 1918 brought a hiatus in the spread of the illness and January 1919 saw the beginning of the third and final phase. By then the disease was a much diminished force. The ferocity of the autumn and winter of the previous year was not repeated and mortality rates fell.

Although the final wave was much less lethal than its predecessors, it was still able to wreak considerable damage. Australia, which had quickly enacted quarantine restrictions, managed to escape the worst of the flu until the beginning of 1919, when the disease finally arrived and took the lives of several thousand Australians.

The Spanish flu did not strike in Australia until 1919. Quarantine camps like this one, in Wallangarra, Queensland, were set up to treat and contain the illness.

PAUL FEARN/ALAMY/ACI

The general trend of mortality, however, was downward. There were cases of deaths from influenza—possibly a different strain—as late as 1920, but by the summer of 1919 health care policies and the natural genetic mutation of the virus brought the epidemic to a close. Even so, its effects, for those left bereaved or suffering long-term health complications, were to last decades.

Lasting impact

The pandemic left almost no part of the world untouched. In Great Britain 228,000 people died. The United States lost as many as 675,000 people, Japan some 400,000. The south Pacific island of Western Samoa (modern-day Samoa) lost one-fifth of its population. Researchers estimate that in India alone, fatalities totaled between 12 and 17 million. Exact data in the number of deaths is elusive, but global mortality figures are estimated to have been between 10 and 20 percent of those who were infected.

In 1997 the samples taken by Johan Hultin from the woman found in the frozen mass grave in Brevig Mission added to scientists'  knowledge as to how flu viruses mutate and spread. Drugs and improved public hygiene—in conjunction with international institutions such as the World Health Organization and national bodies such as the Centers for Disease Control and Prevention in the United States—put the international community in a much better position to meet the challenges of a new outbreak. However, scientists know a lethal mutation could occur at any time, and a century on from the mother of all pandemics, its effects on a crowded, interconnected world would be devastating.

Scientific Investigation Of The 1918 Flu

An electron microscope image of the CDC's recreated 1918 Influenza virus, seen here, 18 hours after infection. Courtesy: CDC/Dr. Terrence Tumpey

Despite recent advances in microbiology, early 20th-century scientists struggled to understand the source of the deadly 1918 influenza epidemic and how best to prevent it. Some thought it might develop from a germ planted by Germans trying to get an edge in World War I. Others tried to protect themselves from the flu by drinking noxious homemade elixirs. It was not until the late 1990s that researchers armed with the latest technology and a greater understanding of molecular biology were able to uncover some of the hidden mysteries surrounding the strain of influenza virus that triggered such a devastating epidemic in 1918.

In 1997, the Molecular Pathology Division of the Armed Forces Institute of Pathology (AFIP) identified genetic material from the 1918 influenza in the frozen remains of a Native Alaskan victim of the disease, buried for nearly 80 years in Brevig Mission, Alaska. AFIP scientists identified two more positive cases in formalin-fixed, paraffin-embedded tissue samples from the AFIP archives. Both archival cases were autopsies of U.S. Servicemen who died during the pandemic — the first in Fort Jackson, SC, the second in Camp Upton, NY. While all of the virus' genetic material – the RNA – was fragmented into tiny pieces, the scientists were able to use the latest molecular techniques to identify complete gene structures of the virus.

In 1999, the AFIP reported that after completely analyzing a critical gene from the 1918 influenza virus their researchers had determined that the 1918 virus apparently evolved in mammals, either humans or pigs, over a period of years before it matured into a virus strong enough to kill millions. Ann Reid, a molecular biologist with the AFIP and the main author of the study, told the Associated Press that the gene probably "was adapting in humans or in swine for maybe several years before it broke out as a pandemic virus." Reid added, "We can't tell whether it went from pigs into humans or from humans into pigs." Through this investigation, Reid was able to map a gene called the hemagglutinin, which is key to allowing the influenza virus to take hold. Reid reported that the hemagglutinin closely resembles mammal genes.

In 2005, researchers from the CDC, Mount Sinai School of Medicine, the Armed Forces Institute of Pathology and the U.S. Department of Agriculture successfully collaborated in sequencing and reconstructing the 1918 influenza virus. According to their research findings, the virus not only proved deadly to mammalian specimens, but also proved virulent against chicken embryos. The team, including Ann Reid and Jeffery Taubenberger, concluded that polymerase genes found in the 1918 reconstructed flu are more similar to those found in avian flu viruses than those found in other mammalian flu viruses. These findings have swung the scientific community pendulum back to attributing the 1918 influenza virus to an avian source rather than that of a swine. Since the publications of these findings, other members of the scientific community have debated and disputed these conclusions. It seems that despite advances in science and technology, many of the puzzles of the 1918 influenza virus may forever be clouded in mystery.

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