The Eradication of Diseases (by Michael Chong)

Since humans live in a world filled with advanced technology, it is easy to forget that we inhabit a planet filled with other life, yet only a fraction of life found on Earth is visible to the human eye. The most abundant life forms are bacterial and therefore, impossible to see. Crawling on our skin and inside our bodies, bacteria number in the trillions and play an essential part in our lives. Without them, we would not exist.

There are good microbes that aid digestion, but there are also microbes that cause havoc to the body. Don't go shower yourself with disinfectant just yet - the ratio of good to bad is very much in favour of the good. Occasionally, humans are exposed to a harmful pathogen, causing the body's defenses to kick into action. A popular analogy used to explain this process is a war, where countless battles are taking place inside the body. As much as we would like to be the final victor, there are certain bacteria that the human body cannot handle, and therefore we turn to aid from antibiotics, antivirals, and vaccines. If that fails, the pathogen has won the battle.

Since the onset of the 20th century and the invention of the microscope, it has become possible to peer into the world of bacteria in order to understand how they live and devise ways to control them. The first 'scientific' antibiotic was Alexander Fleming's penicillin, upon which he stumbled accidentally while studying bacteria. This was a lucky break to say the least; if his petri dish had been uncontaminated, it may have taken many more years before penicillin was discovered.

By testing large amount of possible drugs, scientists may accidentally find something that works. This could be described as a near miracle, though it is short-lived. Looking back at penicillin, it worked on almost all common bacteria, but a couple years later, a resistant strain of bacteria emerged against which penicillin was powerless. Soon, another effective antibiotic was discovered, and the cycle continues to repeat itself in this way.

So far, we have examined the battle at the individual level, but it is important to explore how a disease affects the entire world population. In the 1330s, the Bubonic Plague, or Black Death, killed a third of Europe's total population. Thankfully, it was relatively isolated and did not reach other continents. The Hong Kong Flu in 1968 did not kill as many people as the Bubonic Plague, but spread across the entire globe due to advancements in travel technology. Now, to eradicate a disease requires more planning and resources than ever before. Note, however, that "eradicate" is different from "eliminate". Eliminating a disease entails removing it from a specific geographical area, whereas eradication refers to removing the disease on a global level. So, what do scientists do to eradicate a disease?

Consider polio, a viral disease that is highly infectious and incurable. The only escape is through vaccination. Before the 1950s, the word "polio" caused people to panic. Two vaccines later (one oral, the other injected), people were able to put their worries aside. Unfortunately, these people were unique to developed nations, which had the resources to provide people with such vaccines. Third-world nations were less fortunate and still suffer from the paralyzing effects of the virus. Researchers have found that polio infects its host by entering through the mouth, multiplying in the intestines, and causing trouble in the nervous system. Thus, we have succeeded in the first step in the eradication of a disease: achieving an understanding of how it works and how it is transmitted. Now we can find strategies with which to combat it.

Generally, diseases have three requirements for survival: a suitable host, a mode of transmission, and a method of replication. Attacking one of these can stop the spread of the pathogen. Take Malaria, for example, which is one of the leading causes of death in the developing world. It is spread via the Anopheles mosquito and attacks red blood cells in humans. One of the things scientists have been trying to do is rid these places of mosquitoes. Knowing that they need a moist environment to lay eggs and breed their young, scientists have taken measures to remove these habitats. Like a war, we have destroyed the enemy's ability to bring in fresh troops and damaged their war effort. An added bonus is that malaria must complete part of its life cycle inside the mosquito, which means we have also eliminated its mode of replication. It may be recognized that the key to a successful battle is often found in exercising proper hygiene. Because polio it is spread from human to human through feces, proper sanitation of water and food will prevent transmission.

Perhaps the most effective way to eradicate a disease is to develop vaccinations against it. By doing so, we have removed 'a suitable host' from the list of survival needs. In developed nations, citizens are given vaccines at childhood that protect them from diseases such as tetanus, measles, hepatitis, and so on. To eradicate disease, these vaccines must be provided for everyone in the world. Again, this is easier said than done, as making medicine for six billion people is not a simple task.

Stepping aside for a moment, let's take a quick look at diseases that do not affect humans directly. We are concerned about diseases in the food we eat and the animals we tend to, such as livestock and domestic animals. Scientists take great care not to ignore these because through evolution, they may someday invade the human race. At the moment, the best example is HIV/AIDS. Theories suggest that this virus originated in apes yet they caused them little harm. Somewhere along the line of its evolution, HIV/AIDS migrated into humans and raced its way up the ranks to become a leading killer. Another more recent example is SARS as well as the possibility of avian influenza that may affect humans. For these, researchers utilize the same strategies to combat them. They also have an additional method of eradication, which is to massacre all infected animals; however, this is not an option for sick humans.

While scientists are slowly working on cures, the main problem we face is the shortage of funds and personnel. Billions of dollars must be invested, probably without a direct return, and more people are needed to travel overseas to implement these plans. With constant political and economic barriers, it seems unlikely that we will ever be able to eradicate these pests.

Sources

"The Black Death: Bubonic Plague." Wideopendoors.net. 2005. 24 May 2005. <http://www.themiddleages.net/plague.html>.

de Savigny, Dr Don. "Malaria - Africa's Silent Tsunami." The International Development Research Centre. 4 Apr. 2005. 25 May 2005. <http://web.idrc.ca/en/ev-80526-201-1-DO_TOPIC.html>.

"Global Polio Eradication." WHO - Polio Eradication. 2005. 24 May 2005. <http://www.polioeradication.org>.

"Infectious Disease." Wikipedia. 2005. 25 May 2005. <http://en.wikipedia.org/wiki/Infectious_diseases>.

"Polio Vaccine's 50th Anniversary: Building on a Half Century of Success." National Institutes of Health. 7 Apr. 2005. 25 May 2005. <http://www.niaid.nih.gov/dmid/polio/>.

Rock, Andrea. "The Lethal Dangers of the Billion-Dollar Vaccine Business." Money - Time Inc. Dec. 1996. 25 May 2005. <http://www.mindspring.com/~schlafly/vac/money.txt>.

"Vaccine research and development." World Health Organization. 2005. 24 May 2005. <http://www.who.int/vaccine_research/en/>.

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