A Microscopic Battle: Emerging and Re-emerging Infectious Diseases

Infectious diseases are not only a problem in third world countries; they affect every nation around the world. Sadly, an alarming number of people fall victim to infectious diseases, every year millions of people die of these confounding conditions worldwide. The battle between disease and man is raging, and scientific and medical researchers are racing to find cures and vaccines for many of the world's most threatening conditions. What's more unsettling is that many of these diseases were once kept in check by medications that no longer faze them. Among these now drug resistant infectious diseases are malaria, multiple drug resistant tuberculosis, and bacterial pneumonias (Cumbey, Gimarc, N.d). This, in addition to the emerging and re-emerging infectious diseases that never were given a cure or vaccine, creates an extremely volatile situation for humans that take part in the lives of these diseases as hosts.

Before I go on, it is important to make the distinction between the terms used in this paper. What is an infectious disease? What does it mean to be an emerging or re-emerging infectious disease? Infectious diseases are contagious diseases that are spread from person to person, and sometimes animal to human. A disease results when a pathogen enters the body during the infection phase, and grows within the body destroying or impairing tissue function (NIAID, N.d). Infectious diseases are caused by six different agents: bacteria, viruses, fungi, protozoa, helminthes, and prions[1] (NIAID, N.d). Some examples of diseases are HIV/AIDS, the flu, mononucleosis, tuberculosis, and polio, just to name a few.

The term "emerging infectious diseases" refers to infectious diseases that have recently arisen or been discovered, or known diseases which have shown a significant increase in incidence in the previous decade or two (Cumbey, Gimarc, N.d). Today, such infectious diseases as West Nile, HIV/AIDS, and SARS are some examples of those diseases currently considered as emerging infectious diseases. Re-emerging infectious diseases are those infectious diseases which have, as the name states, re-emerged after period of decline in incidence (Cumbey, Gimarc, N.d). It is both the emergence of new infectious diseases, and the re-emergence of past infectious diseases that remind us that our microscopic battle is nowhere near over, as it was once thought to be.

This microscopic battle isn't new; humans have been at war with infectious diseases for ages. I'm sure you remember the plagues that are reported in the history books and their devastating effects. While we do have a better grasp on how to nurse a flu or pneumonia, our knowledge on infectious diseases is far from perfect.

Going not so far back in our history to the 1920s when penicillin was first discovered, and its uses for medical purposes coming shortly after, the war against bacterial infections seemed a thing of the past. In short, penicillin became the wonder drug. Antibiotics became the cure of the future and were prescribed to solve every bacterial infection that "walked" into the doctor's office. Tuberculosis and typhoid fever were both treated with antibiotics and saw astonishing results. Polio, whooping cough, and diphtheria were all, as they are now, treated with a vaccine. We now know the devastating effects of over-prescribing antibiotics. By the 1950s penicillin had begun losing its effectiveness against infections of Staphyloccus Aureus origin. The remainder of the fifties saw new influenza strains emerge, the seventies a resurgence of sexually transmitted diseases as well as new diseases such as Legionnaire's Disease, Toxic Shock Syndrome, and Lyme disease. In the eighties HIV came into the picture along with a resurgence of Tuberculosis, but this time armed with an antibiotic resistance. The remainder of the eighties, and on into the early nineties, the death rate from infectious diseases rose drastically (Cumbey, Gimarc, N.d). Today, the World Health Organization notes that since 2001 there have been more than 1100 epidemics that impacted the human population on an international level. (World Health Organization, 2006). Additionally, diseases such as certain forms of cancer and heart disease are now being regarded as infectious disease related, increasing the number of infectious diseases currently affecting society. These join the ranks of the global HIV/AIDS pandemic and the bacterial plagues sweeping the African and Asian continents causing increased concern over spread to Europe and the Americas. It is alarming to note that modern practices, behaviors, and the growth of global connections are causing infectious diseases to rise and become stronger than the human immune system.

So how do infectious diseases emerge? The World Health Organization reported in 1997 in a broadcast on World Health Day that "over the last 20 years, over 30 new and highly infectious diseases have been identified" (World Health Organization, 2006). How is this possible?

One reason for the emergence of new infectious diseases is the fact that viruses and bacteria have the ability to replicate and evolve or mutate. In fact, it is noted in the NIAID's booklet Understanding Emerging and Re-emerging Infectious Diseasesthat bacteria and viruses can perform mutations billions of times in one human generation. (N.d). The book additionally states that there are currently 5,000 types of viruses and over 300,000 species of bacteria (N.d). Undoubtedly many of these are evolved forms of former viruses and bacteria; and at the current rate of evolution or mutation, the viral and bacterial count is sure to double in less time than it took to become such a prominent threat to today's society. Furthermore, existing animal viruses (zoonotic viruses) can mutate with a human virus to create a "highly pathogenic virus" (Tabor, 2007). Drug resistance only further exacerbates the problem as once antibiotic susceptible diseases mutate beyond the reaches of modern medicine. One example of such a disease is Tuberculosis, a disease that was formerly thought to be under control, but is now wide spread in a drug resistant form.

This mutation renders the human immune system inadequate to fight the viruses and bacteria at hand. Some mutated microbes are even able to slip past the preverbal radar and can go undetected in the body for some time, save for the symptoms exhibited by the host. Such infectious diseases as these serve to further confound the medical community since blood tests are one of the best ways to check for and monitor infection in the body.

Another aggravator of microbial mutations is the growing non-compliance with vaccination requirements. With part of the population getting vaccinations and the other part not, it's as if we were handing over important information to the enemy. The microbes have the time and the resources to utilize in order to effectively mutate into an antibiotic/vaccine resistant form. We're so easily giving up our best line of defense! Vaccinations are extremely important in protecting the population from infectious diseases and their rapidly mutating counterparts. By refusing to participate in vaccinations, we are contributing to the increasing number of drug resistant and highly pathogenic microbes.

Think vaccinations are the only way we're giving away our defenses? In February of 2006 the Mayo Clinic reported in their article Antibiotics: Too Much of a Good Thing, "Each year in the United States, doctors write an estimated 50 million antibiotic prescriptions for viral illnesses for which antibiotics offer no benefit." What does this mean? 50 million prescriptions a year are contributing not to the healing of an illness, but to adaptation of pathogenic microbes. What is needed at this point is education; bacterial infections need antibiotics, viral infections don't. If you have a cold or flu, you have a virus and don't need a prescription for antibiotics. Medications such as Sudafed and Therflu along with rest is best course of action. It is only with bacterial infections that antibiotics are necessary, and then the first line (lowest) should be used. Doctors need to be able to work up, using the weakest drug and moving up in strength only if absolutely necessary, instead of prescribing the last line of defense first. Thanks to the over-prescription of powerful or last defense antibiotics there are now strains of Pneumonia and Staphlycoccus that are drug resistant. It seems the question many biologists, and medical professionals are asking is...are we headed to another antibiotic-less era? Are we watching ourselves go backward, as far as infectious disease treatment, instead of forward?

Mutations and re-combinations of infectious microbes aren't the only things to look out for. Unfortunately, not everyone has an immune system able to handle even the most common of illnesses. Even common influenza can be a life-threatening disease for some. Most notably young children, pregnant women, the elderly, and the malnourished are those with weaker immune systems in which even the commonest of infections can cause severe problems. Changes in the host population can also cause changes to viruses and bacteria allowing easier adaptation (Tabor, 2007). Tabor states that these host changes can include "acquisition of new customs, new diets, or new living conditions" (2007). For example, high rates of sexual promiscuity have caused an increase in sexually transmitted diseases, gonorrhea is now at large in a drug resistant strain, and HIV/AIDS has killed around 25 million people since its first reported case 26 years ago (Sweat, 2006).

What does all this mean for biology and medicine? Well, if we're to avoid another era of minimal to no defense against infectious agents, we have to hit the problem hard and take strong preemptive measures. Biologists and medical researchers are working to develop cures for such devastating diseases as AIDS, and to create new vaccines for drug resistant diseases as well as those without current vaccines in place. These researchers need to follow the changes taking place within the microbial world in order to be able to treat the infections and diseases they cause. Thomas Monath, a chief scientific officer from Acambis Inc, states that "We're a long way from eliminating the health threat posed by the avian flu, HIV, malaria, or a long list of other infectious diseases. It's pretty scary, really. I don't think there's a lot of good news to report right now when it comes to infectious diseases" (Sweat, 2006). We need to make a difference in the world of infectious diseases, and we need to make it now. Our susceptibility to, and mortality rate from, infectious diseases is rising and this is something that affects everyone in every nation around the world.

Biology studies the microscopic world, and our understanding of it seems quite advanced. Still, we're fighting a tough fight now, and biologists will have to stretch in order to prevent the next pandemic, and biology and medicine may be the only ones that can truly prevent it.

References:

Chalk, P., & Brower, J. (2003). The Global Threat of New and Reemerging Infectious Diseases: Reconciling U.S National Security and Public Health Policy.Santa Monica, CA: RAND.

Cumbey, D. Ph.D., RN., Gimarc, J.D. MA. (N.d). Emerging Infectious Diseases. Retrieved May 27, 2007, from South Carolina Department of Health and Environmental Control: http://iier.isciii.es/supercourse/lecture/lec4281/001.htm

Goldsmith, C. (2006). Invisible Invaders: Dangerous Infectious Diseases. Minneapolis, MN: Twenty-First Century Books.

NIAID. (N.d). Understanding Emerging and Re-emerging Infectious Diseases. Retrieved May 29, 2007, from NIAID Website: http://www.niaid.nih.gov/publications/pdf/curriculum.pdf

Sweat, R (2006).A Modern Menace: Emerging Infectious Diseases. Retrieved May 30, 2007 from Vision. : http://www.vision.org/visionmedia/article.aspx?id=1895

Tabor, E. (2007). Emerging Viruses in Human Populations. Amsterdam, The Netherlands: Elsevier.

World Health Organization. (2006). Threat of Pandemic Influenza and Emerging Diseases. Retrieved May 27, 2007, from World Health Organization Web site: http://www.who.int/mediacentre/events/2006/g8summit/influenza/en/

World Health Organization. (2006). Communicable and Non-Communicable Diseases. Retrieved May 27, 2007, from World Health Organization Web site: http://www.searo.who.int/en/Section980/Section1162/Section1167/Section1171_4750.htm

A List of Some Emerging and Re-emerging Diseases:

Avian Flu

West Nile

Dengue

Malaria (Drug resistant)

Tuberculosis (Drug resistant)

Hantavirus

Ebola

SARS

Lassa Fever

Lyme Disease

Staphylococcal infection (Drug resistant)

Salmonellosis

HIV/AIDS

Marbung

Influenza

Gonorrhea

Legionnaire's disease

Bacterial pneumonia

Creutzfeldt-Jakob disease

E. Coli

[1] Prions, according to (NIAID, N.d) are a newly recognized infectious particle consisting of protein. It is prions which are responsible for Creutzfeldt-Jakob disease, otherwise known by the general public as "Mad Cow Disease" (N.d).