Fall Semester 1997

Emerging Diseases

A young woodcutter was admitted to a hospital in the village of Yambuku, Zaire. He was bleeding profusely from every orifice on his body. Blood had even begun to collect under his skin and form blisters. The patient struggled through delusions and severe blood loss throughout the night. The wood cutter lost his life within 48 hours after entering the hospital. Soon the whole village started to get sick with the same symptoms. The disease was fatal for nearly everyone who lived in or near the village within the first 17 days of contraction. News of the outbreak in Zaire soon reached the whole international community including researchers in the United States. When word of the outbreak hit the Centers for Disease Control in Atlanta, Georgia, doctors and researchers prepared for the worst. The agency had worked with hemorrhagic diseases and knew what to expect. (Hemorrhagic fevers caused mass hemorrhaging throughout the body accompanied by delusions and high fevers.) The CDC sprang into action by assembling a field team to travel to Yambuku and help contain the outbreak. After the CDC reached Yambuku, the doctors isolated the disease. Many inhabitants of the village succumbed to the virus as it continued to spread its bloody massacre within the confines of the quarantined hamlet. Only a handful of survivors were left behind. The CDC launched an investigation to determine the cause of the disease, but its origin was never found. Thanks to the quick response of the CDC and other disease control organizations the world was spared from a catastrophe. However, the chance still remains that Ebola may suddenly reappear and devastate the human population (Close).

This is what happened in 1976 when Ebola first appeared in Africa. Like many other emerging diseases, the virus came from an unknown source and unexpectedly infected a whole village of people. Researchers had seen outbreaks of hemorrhagic fevers like this before, but the outbreak of Ebola alerted the public to the massive fatal risk of emerging diseases. The horrific implication of a 90 percent fatality rate commanded the attention of the medical community and the concern of the rest of the world (Jacobson).

It is important for Americans to be properly informed about emerging diseases, the potential implications on their lives, and how they may be prevented. Each of our lives could be drastically effected, and our nations viability could be threatened if preventive measures are not used to control emerging diseases. For example, an uncontainable outbreak of a disease like Ebola could decimate a nation's whole population and send its government into chaos. Less fatal diseases like Herpes could severely impede an individual's life, while others like the flu could just make life miserable.

When we think of emerging diseases we do not think of minor diseases like the flu, instead our attention often turns to diseases like the Lassa, Hantavirus, Dengue Fever, and Ebola. These are by far the worst diseases whose symptoms include hemorrhaging, delusions, or even death. However, the spectrum of emerging diseases goes well beyond these illnesses. "'Emerging' infectious diseases can be defined as infections that have newly appeared in a population or have existed but are rapidly increasing in incidence or geographic range" (Morse). Emerging diseases are nothing new, in fact every malady now on earth was once emerging. Human infectious diseases have been materializing ever since man first roamed the plains of Africa (Satcher). Everybody has at one time or another actually had an emerging infectious disease. Experts estimate that 20 percent of Americans face one each year in the form of a new strain of influenza (Jacobson).

Historically, diseases were isolated specific local communities, and usually the diseases did not exist after the illnesses had infected all susceptible people in the localized area. However, if a disease found its way out of the small population into larger populations, massive outbreaks resulted. The Bubonic Plague is a good example of how a disease can overcome isolation to largely affect the world's population. Through medieval silk-trade caravans, rats and people carrying the plague migrated from small populations in Asia to the densely populated cities of Europe. Once in Europe the plague spread from city to city by the several means of transportation then available. Thus, the plague took heavy death tolls in European cities all over the continent (Morse).

Today, with rapid international travel and world wide commerce, theoretically, a disease can spread to every major city on earth within a matter of days. During the 1976 Ebola epidemic of Zaire, many infectious disease experts were afraid that Ebola would escape the quarantined area and annihilate the world population. Because of this threat they took immediate action to isolate the village of Yambuku and absolutely prevent any traffic between the village and the nation's capital city, Kinshasa. The city of Kinshasa has a population of over five million people and an international airport. If the virus had been transported into the city, the world's population would have most likely been exposed to Ebola (Jacobson).

Examining the 1976 outbreak of Ebola we see that disease can be cultivated and spread by four factors. First of all, the wide spread use of technology in our world has created an ideal system for distribution of disease. Technological advances have globalized the food supply, and international trade is common place. Air transportation to points all over the world has provided a swift route for transmission of disease. The recent infection of Hudson Foods' hamburger meat with pathogenic Escherichia coli shows how we can rapidly distribute a disease throughout a population via its food supply. Our technology has also provided new habitats in which pathogens can grow and transfer from one host to another. For example, in 1977 Legionnaires' disease (legionela) was introduced into the human population from mechanical cooling and plumbing systems. Since legionela thrives on stagnant water, the virus could flourish in accumulations of stale moisture in unused plumbing and inside idle air-conditioning machinery (Morse). Besides commercial technology, medical technology has also contributed to the emergence of disease. Advances in medical technology have allowed many once controllable diseases to re-emerge as formidable threats to the public. In fact, the most threatening emerging diseases are ones that were once easily controlled but are now re-emerging. The new challenge comes from existing diseases that have developed ways around our control measures. A good example of this is how super bacteria through genetic mutation have evolved antibiotic resistance. Now conventional control methods can no longer repress these though new strains of bacteria. Once easily treated, infections such as tuberculous, gonorrhea, and pneumonia are becoming more difficult to cure as they gain immunity to antibiotics (CDC 690). These bacteria are hard to control and are one of the greatest health threats that our society will face in the future.

Secondly, as diseases are becoming increasingly harder to fight people are migrating to urban areas compounding the problem of disease control. In urban environments diseases are easily transmitted from person to person in the dense population. Lack of public health infrastructures (such as sewers, pest control, and health regulations) in these urban environments can further increase the likely hood of disease transmission. Urban population is increasing and by the year 2025 analysts estimate that 65 percent of the worlds inhabitants will live in cities (Morse). This increase in urbanization affords the perfect opportunity for disease to spread rapidly through a compact population.

The third and hardest factor to control in the fight against emerging diseases is human behavior. People are free to do as they choose and often do not conduct themselves in a manner that prevents the transmission of disease. Thirty years ago AIDS was an emerging disease. Health agencies outlined steps to prevent transmission of AIDS. However, the public was slow to respond and many individuals exposed themselves to unnecessary risk through unprotected sex and drug use. AIDS has become rampant in the American population the epidemic shows how uncontrollable human behavior is the weakest link in disease control (Morse).

So far I have covered three of the mechanisms for emergence of diseases: international travel and commerce, technology, and changes in human demographics and behavior. However, the greatest reason for the emergence of diseases is human disturbance of ecology. Many of today's diseases have resulted from human interaction with the environment during such practices as agriculture, forest harvesting, and changing of water ecosystems. For example, recent outbreaks of Hantavirus (a hemorrhagic fever) were due to changes of farming methods, causing an increase in rodent populations. These rodents became host for the Hantavirus and found their way into human houses where they deposited excrement infected with the deadly virus. The many people living in agricultural areas of the southwest became infected. Human development of forests have resulted in an increase in cases of tick born lyme disease. Dams and water stagnation in aquatic environments have caused increases in the mosquito born diseases such as malaria (Morse).

Despite popular belief, most newly emerging diseases do not appear in the human population by spontaneous generation. New human diseases usually come from other animals and mutate to infect humans (Jacobson). For example, many scientists believe that monkeys are the original source of HIV, Ebola, and Marburg diseases, while pigs and birds are the sources of many human influenzas. As humans translocate into new environments, they expose themselves to animals never before contacted. Under the right set of circumstances, such exposures allow diseases to exchange hosts infecting the human population (Morse).

A major source of re-emerging diseases is decay of public infrastructures such as the break down in public health standards, the lack of sanitation, reduction of pest control, and cutbacks in public health campaigns. Diseases once contained in small pockets within a community can escape into the general population due to the lack of preventative measures. This is the case with of a recent outbreak of cholera in South America when government officials had reduced water chlorination to save money. Reduced chlorine levels allowed cholera bacteria to survive and spread into human population (Morse).

An important step in maintaining a health infrastructure is a vaccination program. Through the vaccination process, we can prevent viruses from becoming stronger or the evolution of an existing virus into a new one. Most importantly vaccination is our only tool for keeping a virus under control and preventing it from reemerging into the general population. The recent appearance of diphtheria in the former Soviet Union resulted from the elimination of the Russian immunization program. Even in America the importance immunization is not clearly understood. Insurance companies refuse to pay for vaccinations which are considered preventive medicine. As a result, doctors often do not strongly encourage patents to have immunization vaccinations (Morse). Since immunization is one of our few defenses against viral diseases, doctors should prescribe vaccination just as much as they do antibiotics for bacterial diseases.

The goal of our sophisticated health systems is to stop a disease before it has chance to spread. The Centers for Disease Control (CDC) is the US agency with primary responsibility for controlling emerging diseases. The CDC and other public health organizations are usually successful at eliminating or controlling diseases before they are able to spread into the vast human population. For example when E. coli was discovered in Hudson Foods hamburger the CDC and other public health officials implemented a immediate recall preventing it's consumption.

For the CDC to be successful at controlling emerging diseases, constant surveillance of all parts of the world for newly emerging disease is necessary. As previously discussed, with today's international travel a disease can move from anywhere in the world and can find its way into the United States population within a matter of days. Because of the ability for diseases to move from continent to continent within hours, the scope of the CDC has broadened to focus on international disease control also. Despite surveillance and attempts at containment, some diseases like AID's are not immediately obvious to public health officials because they are slow-acting and show very few initial symptoms. These types of diseases are usually not discovered until they have become rampant throughout the human population (Satcher).

If a disease escapes into the population, it is then the responsibility of the CDC and public health officials to prevent spreading and to control this disease. To accomplish this, the public must be made aware of symptoms of the disease and instructed on how to prevent transmission. The CDC must also implement systems to control new disease outbreaks. In addition to prevention and control of diseases, the CDC is responsible for studying diseases. Once a disease is discovered, it is necessary that research to be conducted to discover how the disease is transmitted and how to control its transmission. During this research vaccines and cures can sometimes be discovered which can be used to control or manage the disease (Satcher).

Public health programs are the primary weapon used by health agencies to keep existing diseases under control and to prevent emerging diseases from appearing . Once public health infrastructure and sanitation have been established to control a disease, it is important to maintain this infrastructure. Again, diseases often re-emerge if infrastructure is not maintained. Our principle disease fighter and control agency, the CDC, has operated with a stagnated budget for the past few years. In 1995 the CDC's budget was $11.5 billion, the same as the previous years. Despite budget problems, the demands on the CDC have increased as new diseases emerge and new programs have been developed to protect us (Jacobson). If the CDC is going to continue to function as the fast responder to emerging diseases, the budget must keep up with demands that have been placed upon the agency.

In 1993 we saw just how vulnerable the national security of the United Stated may be to emerging diseases. A strain of Ebola was found in a Reston, Virginia, a suburb of Washington D.C. Monkeys in a quarantine unit suddenly became ill with Ebola like symptoms. The Ebola virus in this quarantine unit was found to be airborne for the first time. The fatality rate was established at 90 percent. This meant that Ebola could be transmitted just like a cold, and once the victims were infected; death was certain to follow. After the outbreak was discovered, the special pathogens branch of the US Army responded and exterminated all monkeys under quarantine and sterilized the unit (Preston 155-282). The presence of Ebola in the United States was a great threat to the US population in general. However, the location of this outbreak in relation our nations capital made it a threat to national security. Thankfully, the virus was not able to change hosts from monkey to human. If the virus had been able to change host, there is an almost certain chance that the virus would have infected the general population . Most government employees live in the outlying areas of Washington D.C. such as Reston. If this strain of Ebola had been virulent to humans Ebola would have spread like a cold through the many government offices. The government could have lost so many workers that our country would have gone into anarchy. Studies show that if only 40 percent of government workers were lost, indeed we would have anarchy (Lederberg) This is a perfect example of how our lives and our nation could have been severely changed by a disease in a matter of days.

We are improving our methods of containing and eliminating disease from the population. However, to be successful in the fight against emerging diseases political leaders must understand that maintenance of public infrastructure must be properly funded. It is important that no budget cuts be made in the funding of the CDC and other disease control agencies. The war against emerging disease may be lost if public health efforts are not maintained. If we do not continue to take steps forward in the control and prevention of emerging diseases, we are taking steps backwards in the health and welfare of our nation.

Works Cited

Centers for Disease Control and Prevention. Addressing Emerging Infectious Disease Threats: a Prevention Strategy for the United States. Atlanta: CDC, 1994.

Close, William T., M.D. Ebola. New York: Ivy Books, 1995.

Jacobson, Alison. Emerging and Re-Emerging Viruses: an Essay. Online. Internet. 21 Oct. 1997 Available: http://www.uct.ac.za/microbiology/ebolaess.html

Lederberg, J. et al. Emerging Infections: Microbial Threats to Health in the United States. Washington D.C.: National Academy Press, 1992.

Morse, Stephen S., Ph.D. Factors in the Emergence of Infectious Diseases. Online. Internet 21 Oct. 1997 Available: http://www.cdc.gov/ncidod/EID/vol1no1/morse.htm

Preston, Richard. The Hot Zone. New York: Anchor Books Doubleday, 1994

Satcher, David, M.D. Ph.D. Emerging Infections: Getting Ahead of the Curve. Online. Internet 21 Oct. 1997 Available: http://www.cdc.gov/ncidod/EID/vol1no1/satcher.htm