The Germ Handbook: Protect Your Family from Infectious Diseases
Germs: What They Are
Germs. They are everywhere. Most of these organisms are not harmful, but if your immune system is weak, it can leave you vulnerable to infectious diseases. The issue is that the public knows very little about what they are and how they operate. If you are going to defeat the enemy, you first need to know the enemy.
In order to help you understand how germs attack your body, let me take you back to your grade school science class. Try to remember what it was like growing “stuff” in a little dish and learning about viruses, bacteria, cells, and the like. In this chapter I will cover four basic types of infectious agents: viruses, bacteria, parasites, and fungi. They are characterized by their types of cells, the basic unit of life. All contain representatives that may be infectious and may cause a range of infections from very mild to death.
Viruses (The Users)
Imagine how you would feel if someone came into your home without permission and took control of everything you own. My guess is that you would feel awful. You would probably want to do whatever is necessary to get rid of the home invader and prevent them from ever entering your home again.
This is what viruses do to our bodies—invade, take control, and make us feel awful. Viruses lack the basic units of life—cells—so they invade our bodies because they are unable to survive on their own. While everything that is living is made up of cells, viruses are simply made up of genetic material (genome) and protein (Fig. 1). They use our cells to carry out their life functions. For example, viruses cannot reproduce on their own. They use the materials in our cells to make copies of themselves. Imagine that! Our cells serve as surrogates. Viruses are indeed users of our bodies.
Viruses are grouped based on their structure and are also referred to by the name of the disease they cause. For example, the virus that causes AIDS is a retrovirus (genus), and is referred to as the Human Immunodeficiency virus or the AIDS virus (disease). Viruses are much smaller than bacteria. So small, in fact, that they require a special, high-powered microscope to view them with our eyes. Just to give you a perspective of their size, according to the American Society for Microbiology, if you were to enlarge an average virus to the size of a baseball, the average bacterium would be about the size of a pitcher’s mound. Examples of common diseases in humans caused by viruses are colds, flu, and Chickenpox.
Of all the germs to study, I find viruses the most interesting. They are responsible for so many of the diseases for which there is no cure, and they are the most puzzling. Many of the infections that lead to lifelong disability are caused by viruses. These include AIDS, polio, and shingles. They are capable of infecting all forms of life including plants, animals, and even other germs. Viruses are the most diverse of all the germs on earth.
Bacteria (The Nuisances)
Many people understand more about bacteria and preventing bacterial infections than they probably think. For example, what is the first thing a person does when they get a cut or scrape? They quickly use something to clean the wound and cover it with a bandage. They know that if they don’t, it can become infected. What about the mother preparing a chicken dinner for her family? She carefully washes her hands, cleans surfaces in the kitchen, and rinses the chicken before cooking. She believes that this may prevent her family from getting sick. These actions indicate an understanding of the most important fact about bacteria; they are everywhere. Unlike viruses, bacteria are made up of cells and are therefore capable of survival on their own. And, boy, do they do a great job of it! They survive in the foods we eat, the water we drink, and even on us. The truth is, it is impossible to get away from them, which is why they can be somewhat of a nuisance.
Bacteria are very simple when compared to other living things. One characteristic is that they have simple cells surrounded by a cell wall. For this reason survival functions for bacteria are simple as compared to other life forms. Bacteria can be found literally everywhere on earth and may survive in extreme conditions including very hot, cold, acidic, and basic conditions.
One example of a simple life function carried out by bacteria is reproduction. The usual (but not the only) method of reproduction in bacteria only requires one bacterium. Most life forms require at least both a male and female to have children, right? In this method, the genetic material is copied and the bacterium simply pulls apart or divides. One cell gives rise to two daughter cells. In some bacteria having children, if you will, only takes about thirty minutes. Now that’s simple! This may explain why they’re everywhere.
Bacteria are usually referred to by their genus name or both the genus and species name. Two common bacteria that infect our intestinal tract are Salmonella (genus) and Escherichia coli (genus and species), or E. coli for short. Some bacterial infections can cause severe complications and spread throughout the body. This is a condition known as septicemia. If left untreated, septicemia can lead to death. But not all bacteria is harmful. For example, if you eat yogurt, most yogurt products contain Lactobacillus acidophilus, a harmless bacterium that is found in the intestinal tract. L. acidophilus aids in digestion and destroys some disease-causing organisms.
Parasites (The Thieves)
All living things need nutrition to survive. We get nutrition from the foods that we eat. Parasites get nutrition like we do; by breaking down materials that they take in. The difference is that they steal nutrition by either living in or on other living things. Often they feed off of tissues and other fluids resulting in destruction. Some parasites cause only swelling in the infected areas, while others may cause severe infections that can lead to death. As if stealing from us isn’t bad enough, they can make us sick, or even kill us while they do it.
Like bacteria, parasites are also made up of cells so they are able to survive on their own. Unlike bacteria, however, they do not contain a cell wall. One way that scientists group parasites is by the type of cells. Parasites range in types and sizes from protozoa, which are small and made up of one cell (Fig. 3), to helminthes, (worms) which are large and made up of many cells (Fig. 4). Another way to group parasites is based on their ability to move. Some parasites cannot move (nonmotile), while others can (motile).
Fungi (The Irritators)
Have you ever had an irritating rash? Chances are that at some point you have been infected by some type of fungus. Fungi can also be found almost everywhere and many of them are important for the environment. However, many can cause problems such as allergies and a variety of infections. Many fungal infections involve the outer layers of the skin, such as nails and skin. Examples of a skin irritation caused by fungi are ringworm, jock itch, and athlete’s foot. Some fungal infections involve deeper layers of the skin such as tissue and bone. Severe fungal infections occur when the fungi spread through the body. These infections often occur in individuals with compromised immune systems, such as elderly people or people with AIDS. If not treated promptly and properly, these infections may lead to severe complications and even death.
Like bacteria and parasites, fungi are also made up of cells and are able to survive on their own. Most fungi are made up of many cells, however, yeast are an example of one-celled fungi. Fungi also get nutrition by breaking down materials that are taken in from other living things. Reproduction in fungi differs from other life forms. It often involves specialized structures called spores, and they may use them to reproduce sexually or asexually (without sex). These structures vary and scientists use them to group fungi.
To summarize, there are four basic types of germs that cause infectious diseases. Viruses are not true life forms because they do not have cells. They survive by using us, often resulting in sickness. Examples of common viral infections are colds and flu. Bacteria are the simplest of life forms. Remember, they have simple cells and many can have children without a mate. Although they are the simplest they can be the biggest nuisances because they are everywhere. Examples of common bacterial infections are wound and intestinal tract infections. Parasites are the nutrition thieves; they live in and on other living things for food. They can be very small or as large as a worm. An example of a common infection caused by parasites is intestinal tapeworms. Finally, there are fungi, complex and irritating. Fungi are responsible for a variety of infections from the outer to inner layers of our bodies. Examples are jock itch and athlete’s foot.
The Germ Handbook by Leslie Ann Dauphin, Ph.D. © 2005 by Leslie Ann Dauphin, Ph.D.
Published by Siloam, A Strang Company 600 Rinehart Road Lake Mary , Florida 32746. Used with permission.
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