The Impact of Microorganisms on Human Affairs free essay sample

Microbiology is the study of microorganisms or microbes. The word micro means small in Greek, implying that microbes are very minute or small life forms that cannot be seen with just the naked eye. One would need a microscope to see these small life forms. Microbes are everywhere and have a large impact on the world. It all started when one of the most important discoveries in history was made in 1665. Englishman, Robert Hooke discovered â€Å"little boxes† or â€Å"cells† in a slice of cork through the microscope and explained that these were life’s smallest structural unit (Tortora et al, 2010). This event marked the beginning of the cell theory, that all living things are composed of cells. As expected in the scientific world, a new finding leads to a cascade of experiments to expand on the newly discovered facts. This was shown when Anton Van Leeuwenhoek made the first observation of live microbes though a microscope that he designed himself. Van Leeuwenhoek used rain water, his feces, and his teeth scrapings to make observations from the microbes. For a few years after Van Leeuwenhoek’s discoveries the majority of the world believed that microorganisms spontaneously generated, which means that life forms came from nonliving matter such as toads and mice (Tortora et al, 2010). It was not until the discoveries of Louis Pasteur in 1861 that the theory of spontaneous generation was challenged and the call theory was confirmed. Pasteur resolved this issue by creating experiments demonstrating that microbes are present in the air and can contaminate sterile solutions, but the air itself cannot create microbes. The experiments contained beef broth in several flasks. Some were sealed after being boiled and the rest were kept open after they were boiled. The flasks that were kept open in the air accumulated microbes whereas the flasks that were sealed did not. Pasteur then followed up his first experiment by doing another experiment. He used the same principle, except he used a flask with an S-shaped neck that allowed air to pass through but the design of the flask trapped any bacteria in the neck. After boiling and allowing the broth to cool, there were no signs of microbial growth (Tortora et al, 2010). The final step toward identifying as a source of disease came with the findings or Robert Koch in 1881. Koch, using a series of observations, later known as Koch’s Postulates, found that specific microbes cause specific diseases. He proved that bacteria causes disease by observing animals for the presence of Bacillus anthracis, the causative agent of anthrax. He found that this bacterium was in the blood of the cow that had died from anthrax. Koch then retrieved the bacteria from the cow, grew it on pure culture, injected it into a healthy animal, and waited to see if the healthy animal had the same results. Like he thought, the animal became infected and Koch was able to isolate the same organism from the newly diseased animal. This process is still used today in the detection of microorganisms being responsible for causing disease (Tortora et al, 2010). These scientists and their experiments laid the foundation for the discovery of an unknown world and quickly became life changing. Before one can understand the impact of Microbes on human affairs, one must be aware of the types of microorganisms there are in this world. Microbes consist of six groups: Bacteria, Archaea, Fungi, Protozoa, Algae, and Viruses. These groups are very different but are similar in that they are small in size. Furthermore these groups are divided into two different groups: Eukaryotic and prokaryotic, excluding viruses. Fungi, Algae, and Protozoa are classified as Eukaryotic which means they are multicellular and include a nucleus and membrane-bound organelles. Bacteria and Archaea are classified as prokaryotic in which they are unicellular and do not have a nucleus nor membrane-bound organelles. Viruses do not belong is either group because they are noncellular. In fact, they require a cell host in order to replicate. Some unique characteristics about microbes are that they are ubiquitous, dominant, diverse, and free living. Since the experiments of the great scientists such as Pasteur and Koch, the world of microbiology has taken great strides in understanding the impact that microbes have on the world, whether beneficial or destructive. A period from 1857 to 1914 was called â€Å"The Golden Age of Microbiology† which marked the beginning of rapid advances and discoveries such as vaccines for disease to fermentation and pasteurization. This period came to be one of the most influential and ever-changing sciences in the world today. If it wasn’t for the first experiments in the field, we would not know that microorganisms are the main cause of most diseases in the world. We all live in a world filled with microbes from birth to death and we have numerous microorganisms on our bodies as well as inside of our bodies. These microorganisms are known as normal microbiota or normal flora. These microorganisms benefit us in that it prevents us from being sick all the time. They also produce growth factors such as Vitamin K and folic acid. Though these microbiota live in harmony with their host under normal conditions, they can be harmful if they find their way into different parts of the body or a different habitat. These microbes would be considered pathogenic or disease-causing, and are not exclusive to the body’s normal flora. An example of a normal microbiota that becomes harmful when introduced into a foreign environment is the bacterium Escherichia coli. This bacterium is normally found in the colon. The bacterium may come in contact with the stomach by ingestion and certain strains can cause food poisoning which leads to diarrhea, dehydration, and discomfort. Some diseases thought to be noninfectious may involve microbial infections such as Helicobacter pylori. This common bacterium is pathogenic and affect about half the world’s population. This bacterium has been known to be the cause of gastric ulcers in the upper GI tract (The Normal Bacterial Flora of Humans). Immunocompromised people are at a greater risk for infections especially respiratory infections such as pneumonia. Since their immune systems are very weak, they are susceptible to many diseases. There are several ways that these bacterium can be transmitted into the host and cause infection. The causative agents of disease can be transmitted into the host by three routes: contact, vehicles, and vectors. The most popular method of transmitting disease is by contact. Contact can be divided into three types which are direct contact, indirect contact, and droplet transmission. Direct contact is also known as person-to-person transmission where there is physical contact involved such as touching or kissing. The common cold, staphylococcal infections, hepatitis A and other infections can be transmitted during direct contact. Indirect contact involves transmission of the pathogen through a fomite, or inanimate object that is a reservoir for pathogens. The use of drinking bottles and eating utensils are good examples of indirect contact transmission. Finally, droplet transmission involves the spread of microorganisms by way of mucus droplets. The primary way this transmission occurs is through coughing and sneezing. The Vehicle transmission is when the disease is transmitted by a medium such as water, food, or air. Waterborne infections normally travel through poorly filtered water systems or sewage systems. Diseases such as cholera, waterborne shigellosis, and leptospirosis are transmitted through waterborne transmission. In foodborne transmission disease is transmitted by undercooked meat or poorly refrigerated. Airborne diseases usually involve droplet transmission or dust particles that can be spread in the air. Air filters are becoming more effective in preventing airborne transmission, however, still some pathogens are small enough to escape the filter (Tortora et al, 2010). The last route of transmission is vector transmission. A vector is another source, typically an insect, in which the pathogen reproduces before being transmitted into the host. Ticks and mosquitos are most often responsible for causing diseases via vector transmission. Some diseases that they cause include the West Nile Virus, which causes West Nile encephalitis. This disease is carried by mosquitoes. Another popular disease caused by this type of transmission is Lyme disease and this is carried by ticks. The cause of transmission results in either emerging infectious diseases or re-emerging infectious diseases. An emerging infectious disease is a disease that is new or is increasing in incidence whereas a re-emerging infectious disease is a disease that has already been described and has existed for years but is all of a sudden presenting reappearance. An example of an emerging infectious disease is the West Nile Virus. This is typically due to evolutionary changes in the existing o rganism where they are introduced to a new geographic region or populations. The West Nile Virus, as mentioned earlier, is carried by birds and is transmitted between birds and to horses and humans by mosquitos. This virus causes inflammation to the brain. Other symptoms include flu-like symptoms such as headache, fever, and body aches (West Nile Virus). An example of a re-emerging disease would be tuberculosis or cholera. Tuberculosis (TB) is a bacterial infection that involves the lungs as well as other parts of the body like the brain, kidneys or spine. TB is caused by the bacterium Mycobacterium tuberculosis and is contagious. There are two types of TB: primary TB and secondary TB. People who have primary TB are exposed for the first time whereas people who have secondary TB have already been infected previously. TB can spread very easily by breathing in air droplets that contain the tubercle bacillus from a cough or a sneeze of the infected person. Most people with primary TB are asymptomatic which means they do not have any symptoms or show any signs that they have TB. This bacterium is shown in people who have HIV or AIDS or other immunodeficiency disorders because their immune system is no good and cannot fight of the bacteria. Usually people who develop progressive disease have symptoms that are insidious and non-specific such as weight loss, fatigue, fever, and night sweats so they cannot tell right away that they have this disease (Porth, 2011). Secondary TB is often found in people who have impaired body defense mechanisms such as elderly people and infants. This time around the disease is much more serious and the upper lung lobes are most affected http://www. cdc. gov/tb/topic/basics/default. htm http://www. cdc. gov/tb/topic/basics/default. htm One way to get tested for TB is by the TB test or PPD. If the test is positive it does not mean that it is positive. It just means that the person has been exposed to TB. Not everyone that has been infected with TB gets sick. TB bacteria can live in the body without showing any symptoms; this is called latent TB infection. In this case, people who are infected have a good immune system that is able to fight off the bacteria and keep it from growing. These people also cannot spread the disease to others, however, if the body fails to fight off the bacteria it will grow and multiply and will cause the person to be sick with TB disease. At this point the disease is contagious and can be spread to other people. In rare cases, people who have latent TB never end up with TB disease and some people may have latent TB and will not get the disease years later. A major risk factor that could contribute to getting this disease would be living in crowded or unsanitary conditions because there are more people and therefore more chance of breathing in someone else’s air droplets. One cannot get the disease by just shaking someone’s hand or by sharing a drink. According to the Centers for Disease Control and Prevention website, a total of 10,521 TB cases were reported in the United States in 2011. However, there has been a significant decline since 2010. In fact, this has been the lowest rate recorded since reporting began in 1953. Although numbers of TB cases are gradually decreasing in the United States, outbreaks of TB in homeless shelters are rising. In January 2010, public health officials found an outbreak of TB among three overnight guests at a homeless shelter in Illinois and were diagnosed with TB disease.