An Aspiration Worthy of Pursuit or an Impossible Dream?
By Nathan Kurtz
Thesis Statement:
Disease eradication should not be an automatic “yes.” Careful consideration needs to be taken in order to determine if it is a worthwhile pursuit.
Outline:
1) Introduction
a) History
i) Yellow fever
ii) Yaws
iii) Malaria
iv) Smallpox
b) Current Progress
i) Polio
ii) Dracunculiasis
2) Current Methods, Concerns, and Implications
a) Determining if Eradication Is Possible
b) Determining if Eradication Is Worthwhile
c) Implications
i) Bioterrorism
ii) Deliberately Causing Extinction
3) Conclusion
a) The Future of Eradication
b) The Final Word
4) References
Introduction:
Eradication is defined as “the complete destruction of every trace of something” by the web dictionary Dictionary.com (Eradication, n.d). Disease eradication by this definition would be the “complete destruction” of every aspect of an infectious disease. This idea at first glance seems very straight forward. It is also difficult to argue that the prospect of eliminating a harmful pathogen is anything less than ideal. In practice, however, eradication is extremely complex, costly, and at times impossible. How then can we determine if disease eradication is a possibility, and if it is, do the benefits outweigh the costs? It is important to bear in mind that the answers to these questions should not be an automatic “yes.” Careful consideration needs to be taken in order to determine if disease eradication is a worthwhile pursuit.
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History:
There have been a total of six worldwide eradication efforts in modern history so far: yellow fever, malaria, yaws, smallpox, polio, and dracunculiasis. Yellow fever is a disease endemic to many African and South American countries and has been estimated to be responsible for 200,000 illnesses and 30,000 deaths each year by the World Health Organization (Yellow fever fact sheet, 2001). The effort to eliminate yellow fever began in 1915, but was found to be futile shortly thereafter with the discovery that a non-human (monkey) host also harbored the virus (Aylward & Birmingham, 2005). The second and third worldwide eradication efforts, yaws and malaria, were started at about the same time in 1955. Yaws is a bacterial infection that affects the skin and bones. The movement to eliminate this disease was initiated with the development of a single-dose, injectable penicillin treatment. However, the program was abandoned 12 years later in 1967 largely due to poor planning and insufficient surveillance strategies, but also because of the emergence of resistant strains of the bacterium (Henderson, 1999).
Malaria is perhaps the most famous of these first three eradication efforts, a result of the large amount of publicity and funding that the elimination effort received. During its 15 year run, the program was manned by about 500 WHO employees and received roughly one-third of all WHO’s expenditures. Funding was at an all time high, with the U.S. alone contributing over 1 billion dollars to the effort. In contrast, the yaws program was under-funded and undermanned and received little attention in the United States. Unfortunately, another reason that the malaria campaign is so famous is because it ended in huge failure. One of the primary strategies had been to get rid of the mosquito vector through the widespread use of the chemical DDT (Henderson, 1999). Initially, success appeared imminent, with some countries reporting as much as a 100,000 fold decrease in incidence of the disease. However, with the rapid development of DDT resistance in the mosquitoes, it became apparent that efforts would have to increase further for progress to continue. Countries such as the United States decided to withdraw funding, and soon, the program collapsed. As a result, prevalence of the disease in certain regions rebounded and even greatly exceeded previous highs (Joiner, 1997).
After the substantial failure of the first three eradication efforts, public opinion of such programs was understandably low. Billions of dollars had been wasted and the diseases were now more prevalent than ever before. Despite this, in 1967 at about the same time that it was concluded that the yaws and malaria campaigns had failed, a new program to eliminate smallpox was put into action by WHO. With a newly acquired understanding of what is necessary for eradication efforts to succeed, scientists had decided that smallpox was a more ideal pathogen to eliminate. There were no non-human hosts in which the disease could hide and there was a readily available, relatively inexpensive vaccine with a proven record of success (Aylward et al., 2000). Also, success was determined to be well worth the cost. For example, in as recent as 1967, 2-3 million people were killed each year by the smallpox virus (Aylward & Birmingham, 2005). Because of all the previously mentioned aspects and because of high levels of cooperation between governments, the fourth global eradication effort to be implemented finally succeeded. On May 8, 1980, the global eradication of smallpox was declared a success. Several years later, distribution of the smallpox vaccine was gradually decreased until, today, immunizations no longer occur and a large percentage of the world’s population has no immunity to the disease (Henderson, 1999).
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Current Progress:
The fifth and sixth eradication programs to be implemented are currently underway. Complete elimination of either polio or dracunculiasis has not yet been achieved, but progress is being made. At the time that the initiative to eliminate polio was first set into motion in 1988, polio was endemic in 125 countries and paralyzed 350,000 children every year. In 2004, these numbers had decreased to six countries and 1263 cases (Guatam, n.d.). As of March 2006, progress is still being made. Polio is now only endemic in four countries (Afghanistan, India, Nigeria, and Pakistan). This is good progress considering a brief yet serious outbreak occurred in 2003 which reinfected 22 previously polio-free countries in Africa and Asia. In addition to this, India and Pakistan (two of the remaining polio-endemic countries) are getting closer to achieving eradication, reporting a fifty percent decrease in incidence in 2005 as compared to 2004 (Progress...Poliovirus, 2006).
Dracunculiasis, better known as Guinea worm disease, is caused by an infection from the parasitic worm Dracunculus medinensis and is associated with skin lesions and severe pain (Dracunculiasis fact sheet, 2004). The eradication effort for dracunculiasis was started in 1986, and as of July 2005, prevalence of the disease has decreased substantially. In this period of time, incidence of new cases has dropped from 3.5 million yearly in 20 countries to 8,191 in nine countries. Despite the huge progress that has been achieved in the eradication of both dracunculiasis and polio, the campaigns are at a critical stage in achieving the ultimate goal of global eradication. Ever increasing commitment and surveillance as well as continued cooperation from governments will be necessary to keep making progress (Progress...Dracunculiasis, 2005).
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Current Methods, Concerns, and Implications:
Determining if Eradication Is Possible:
Historically, the eradication of disease does not have a very good success rate. Half of the attempts failed outright and one-third are currently underway but it is unknown if they will succeed. Only one of six ended successfully, and even then, it could have just as easily been another failure. With this kind of statistic, it does not seem like global eradication of diseases has a very promising future. Theoretically, however, every disease can potentially be eliminated. The problem is that the technology, cooperation, and funding does not exist that would make this feasible. Instead, potential candidates for eradication must be carefully examined in order to determine which have a possibility of being eradicated and which would be the most beneficial to eradicate (in regards to both financing and health benefits). Walter Dowdle (1999) of the CDC states that in order for a disease to be considered eradicable, it must possess the following characteristics:
An effective intervention is available to interrupt transmission of the agent; practical diagnostic tools with sufficient sensitivity and specificity are available to detect levels of infection that can lead to transmission; and humans are essential for the life-cycle of the agent, which has no other vertebrate reservoir and does not amplify in the environment (p. 24).
Unfortunately, the vast majority of diseases do not fit these criteria, and even when one does fulfill these requirements, achieving eradication is far from simple. For example, polio has an oral vaccine that has been proven to be very effective; surveillance of the disease has been very successful; and it has no other non-human hosts. Even so, the polio eradication program is struggling to achieve total global eradication. When this initiative was set into motion in 1988, the goal was to have globally eliminated polio by the year 2000. Since then, this date has been pushed back first to 2005 and then to 2008 (Guatam, n.d.). Why the delay? Already, over 20 times what was spent on eliminating smallpox has been spent in an effort to rid the world of polio (Henderson, 2002).
The problem that the polio campaign is now facing is that reaching everyone in the world is a very difficult thing to achieve. Imagine the challenge of immunizing 550 million children in 85 different countries. The amount of manpower and coordination that is required is substantial and often times proves to be too much, as can be seen in the failure of some of the earlier eradication programs. The existing health care infrastructure was not (and even now is not) sufficient for a mass distribution of a vaccine or treatment of another kind, especially in isolated and impoverished parts of the world (Aylward, 2001).
Specific problems faced by different programs are varied. In some instances, indigenous populations have refused treatment out of fear and naivety. In response, the vaccinations or treatments have been forcibly administered to these groups. In other instances, difficulties have been encountered in reaching populations in war-ridden areas. Often times, however, temporary cease-fires have been arranged to allow health workers access to the people in need of vaccination. Besides these, there are many other situations that increase the complexity of reaching certain populations, and largely because of this, current day eradication programs are having trouble eliminating the last strongholds of their respective diseases. The difficulties the polio eradication program is facing just goes to show that, even with theoretically “perfect” candidates for eradication, unforeseen complications are a nearly unavoidable likelihood, if not a given (Aylward, 2001).
In order to overcome this and to be successful in eradicating a disease, efforts must not diminish as progress is made. The opposite is true; efforts should increase because the last strongholds of a disease are usually the most difficult to eliminate. Often times what will happen is that a country will be declared disease-free and will then decrease preventative efforts (such as administering vaccinations) with the intention of saving funds. This line of thought is understandable; however, it is also incorrect. Yes, eradicating a disease is very expensive and can certainly take a toll on the budget of a country, especially if it is an impoverished area. Even so, by letting down their guard, this country becomes susceptible to an outbreak. In today’s world of easy travel, disease can spread across the globe incredibly fast. This was the cause of the previously mentioned polio outbreaks that occurred in Africa and Asia. Once a plan for eradication has been set into motion, it is essential that commitment and cooperation are maintained until the plan has been finished. Even then, with perfect planning and implementation, a little bit of luck is always helpful in achieving success (Aylward, 2001).
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Determining if Eradication Is Worthwhile:
Another issue that is important to consider when discussing eradication is costs versus benefits. Perhaps the most obvious benefit is the direct effect on human morbidity and mortality. With the eradication of diseases, unnecessary suffering would be diminished and quality of life would be increased. In addition to direct health benefits, large financial and organizational gains would be made. In regards to finances, since there would no longer be any need to control the disease, vaccination programs could be eliminated. For example, by removing the need to vaccinate people for polio, the United States alone stands to save $1.5 billion per year. Organizational gains include “stronger immunization and surveillance systems, a global laboratory network, thousands of trained health care workers, and a strong advocacy movement” (Aylward et al., 2000).
Though these benefits are significant, they must be weighed against the costs of eradication. Ironically, some of the benefits are very much related to some of the costs. Financially, even though large savings are anticipated once the disease has been successfully eradicated, the likelihood that the program will succeed is low. Considering the vast amounts of resources that are put into the eradication effort and the slim chance that the program will be a complete success, is it possible that these funds would do more good elsewhere? This is a question worth considering (Henderson, 2002).
Besides finances, health benefits are considered a major positive aspect of eradication. However, one of the major concerns is that, once immunization programs have ceased, humans will have no immunity to these diseases. In theory, this would never be a problem because, if the disease no longer exists, there is no way to get infected. The problem is that the disease probably does still exist. In the case of smallpox, laboratories still harbor samples of the live virus. If these samples were to somehow be reintroduced into the general populace, say through an act of bioterrorism for example, the consequences would be astronomical. Further implications of bioterrorism will be discussed at a later point (Henderson, 1998).
Other costs include the huge amount and time and commitment necessary for planning and implementation of any eradication effort. Failure would equal a lot of wasted resources.
It is important to note that the benefits listed above are almost entirely dependent on the successful elimination of the disease. It could be argued that the increasing amount of healthy, immune people is an example of a benefit that does not rely on successful elimination. However, this is a benefit that could just as easily be attributed to an effort to control the disease rather than an effort to eliminate it. The primary difference between the two is funding and organization. Where eradication costs billions and billions of dollars and requires intensive planning, control of a disease requires less (though still significant) of these two things. Because of this, if an increase in healthy, immune people is the ultimate goal, then control would probably be the better course of action. But if the previously mentioned benefits are of the utmost importance, then a successful eradication is the best bet. Since this is such a difficult task to achieve, it is imperative that intense scrutiny should be used when deciding what diseases are potential candidates for eradication. Even if the disease is deemed eradicable, careful consideration is necessary to decide if the benefits are worth the effort or if this effort would be better placed elsewhere. Such decisions are not easy to make and have no simple answer.
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Implications:
In 1994, a group of Russian scientists concluded that smallpox is the most likely agent to be used in the development of bio-weapons. This conclusion was based on several reasons. Smallpox virus is easy to produce and store, it can be transmitted as an aerosol, less than 10 percent of the world’s population has any residual immunity, and it has a high death rate. About 30 percent of people who become infected with the virus die within a couple of weeks. Theoretically, “exploding a light bulb containing virus in a…subway” (Henderson, 1998) is enough to infect an entire city and possibly an entire country. The implications of such an attack are appalling. As was stated previously, the reason that this disease would make such a successful weapon is because very few people have immunity to it. Prior to its eradication when smallpox was still endemic in certain regions, the effects of a terrorist attack using this organism would have been much less severe because natural immunities to the disease would have been prevalent. This means that eradicating smallpox has made it even more deadly (Henderson, 1998). Currently, the CDC is undertaking measures to become more prepared for a possible attack. They have stockpiled about 286 million doses of the smallpox vaccine (enough for everyone in the United States) and are writing a plan of action to be followed in the event of an attack (What CDC, 2006). Hopefully, smallpox will never be used as a weapon, but the possibility exists. This is certainly something to think about before initiating new programs to eradicate deadly diseases.
Another consideration that should be made is: what are the implications of knowingly causing the extinction of a living organism? Granted, diseases such as smallpox and polio are caused by viruses, and it can be debated whether or not these are living organisms. However, dracunculiasis is caused by a worm and yaws is caused by a bacterium, both of which are unanimously considered to be forms of life. Do we as humans have the right to decide that another living thing should not be allowed to live? Do these organisms even have rights? For example, some people refuse to swat flies because they are opposed to taking the life of any other living thing, while others go hunting on a regular basis. There are no right or wrong answers to these questions because they are dependent upon personal choice. Nevertheless, these issues might help a person decide whether they want to be for or against eradication.
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Conclusion:
The Future of Eradication:
In 1998, participants at the Atlanta conference on eradication concluded that only measles, rubella, hepatitis A, and hepatitis B fit the requirements for future eradication efforts. Measles and rubella topped the list because it was decided that a joint eradication would improve the cost-benefit equation. The challenge of putting such a plan into action is in raising enough societal and political support to fund and sustain such an effort through to its completion (Aylward et al., 2000). Perhaps it might be wise to first see the current eradication efforts through to completion. Then additional eradication programs can be considered.
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The Final Word:
Feasibility, technology, financing, cooperation, costs, benefits, and moral/ethical concerns are all issues that need to be thought about before making a decision to pursue eradication. As was stated before and is now evident, disease eradication should not be an automatic “yes.” Rather, it should usually be an automatic “no.” It most cases it is simply too costly and too likely to fail to be considered practical. However, for those instances that have potential to be successful, careful consideration still needs to be taken in order to determine if it is a worthwhile pursuit.
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References:
Aylward, B., and Birmingham, M. (2005, November 26). Eradicating Pathogens: The Human Story. BMJ, 331, 1261-1262.
Aylward, B. (2001). The Zero-Sum Goal: The Challenge of Disease Eradication. Harvard International Review, 71-75.
Aylward, B., Hennessey, K. A., Zagaria, N., Olivé, J., Cochi, S. (2000, October). When Is a Disease Eradicable? 100 Years of Lessons Learned. American Journal of Public Health, 10(90), 1515-1520.
Dowdle, W. R. (1999, December 31). The Principles of Disease Eradication and Elimination. MMWR, 48(SU01), 23-27.
Dracunculiasis fact sheet. (2004, September). WHO: Dracunculiasis. Retrieved November 2, 2006, from http://www.cdc.gov/ncidod/dpd/parasites/dracunculiasis/factsht_ dracunculiasis.htm.
Eradication. (n.d.). WordNet® 2.0. Retrieved November 4, 2006, from Dictionary.com website: http://dictionary.reference.com/browse/eradication.
Guatam, K. (n.d.). A History of Global Polio Eradication. Retrieved November 2, 2006, from http://www.unicef.org/immunization/files/the_history_of_polio.pdf.
Henderson, D. A. (1998). Bioterrorism as a Public Health Threat. Emerging Infectious Diseases, 4(3).
Henderson, D. A. (1999, December 31). Eradication: Lessons From the Past. MMWR, 48(SU01), 16-22.
Henderson, D. A. (2002, December 15). Why Eradicate Disease? OB/GYN News. Retrieved November 1, 2006, from http://findarticles.com/p/articles/mi_m0CYD /is_24_37/ai_95792125.
Joiner, K. (1997, July 23). The World-Wide Malaria Eradication Effort. Retrieved November 1, 2006, from http://www.bact.wisc.edu/Microtextbook/index.php? name=Sections&req=viewarticle&artid=181&page=1.
Progress Toward Global Eradication of Dracunculiasis, January 2004-July 2005. (2005, October 28). MMWR, 54(42), 1075-1077.
Progress Toward Interruption of Wild Poliovirus Transmission: Worldwide, January 2005-March 2006. (2006, April 8). MMWR, 55(16), 485-462.
What CDC Is Doing to Protect the Public from Smallpox. (2006, February 21). CDC: Emergency Preparedness & Response. Retrieved November 3, 2006, from http://www.bt.cdc.gov/agent/smallpox/prep/cdc-prep.asp.
Yellow fever fact sheet. (2001, December). WHO: Yellow fever. Retrieved November 1, 2006, from http://www.who.int/mediacentre/factsheets/fs100/en/.
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