According to medical experts, infectious diseases caused by microbes are responsible for the deaths of more people around the world than any other single cause. It is estimated that the yearly cost of medical care for the treatment of infectious diseases in America alone is approximately $120 billion. The science of microbiology explores how microbes work as well as how to control them.
Microorganism (Microbe) - Microorganisms are very diverse and include all the bacteria and archaea and almost all the protozoa. They also include some fungi, algae, and certain animals, such as rotifers. Many macroscopic animals and plants have microscopic juvenile stages. Some microbiologists also classify viruses (and viroids) as microorganisms, but others consider these as nonliving.
Microbial Population Biology - Defined as the application of population ecology and population genetics toward understanding the ecology and evolution of bacteria, archaebacteria, microscopic fungi (such as yeasts), additional microscopic eukaryotes (e.g., "protozoa" and algae), and viruses.
Microbial Diseases - Defined as sicknesses or ailments caused in animals and humans by the introduction of one of four different types of microbes; Bacteria, Viruses, Fungi and Protozoa (also known as protoctista).
Microbiologists pursue knowledge to prevent and treat the diseases microbes cause. The 20th century saw an incredible increase in human knowledge concerning microbes. Microbiologists and other researchers experienced a number of successes in learning how microbes cause some infectious diseases and how to fight those microbes.
Microbes are far better at adapting to new environments than people are. They have existed on Earth for billions of years. Microbes are constantly challenging humans with ingenious new survival tactics. A number of microbes are developing new properties to resist drug treatments that were once effective at destroying them. Drug resistance has become a serious issue around the world today.
Changes in the environment have placed certain human populations in contact with newly identified microbes that cause diseases never seen before, or which previously happened only in isolated populations. Newly emerging diseases are an increasing global health concern; since 1976, scientists have identified around 30 new pathogens, to include HIV.
Ways Microbes are Transmitted:
A person can transmit microbes to someone else through the air by sneezing or coughing. These are common ways to get viruses that cause colds or the flu, or the bacteria that causes tuberculosis. International airplane travel may expose a person to germs not common in their own nation. Other ways microbes are transmitted include:
Shaking Hands or Touching Surfaces: It is possible for a person to pick up cold viruses by shaking someone's hand, or from touching surfaces that are contaminated such as a computer keyboard or a doorknob.
Sexual Intercourse: Microbes such as herpes simplex virus type 2 which causes genital herpes, HIV, or Neisseria gonorrhea bacteria are examples of germs that a person may pass to someone else during sexual intercourse.
Close Contact: Close contact may pass germs to another person. For example; through kissing. Scientists have identified more than 500 types of bacteria that live in people's mouths. Some keep the oral environment healthy, although others cause issues such as gum disease.
Fecal Transmission: A common way for some microbes to enter a person's body, particularly when providing care for young children, is through passing feces from hand to mouth, or the mouths of young children. Infant diarrhea is often times spread in this manner. Daycare workers; for example, might pass diarrhea-causing rotavirus or Giardia lamblia from one child to another between diaper changes or other childcare practices.
A Classic Example of Microbe Transmission:
The story of, 'Typhoid Mary,' is a classic example from medical history about how a person can pass germs to other people, yet remain unaffected by those same germs. The germs in this instance were, 'Salmonella typhi,' bacteria which cause typhoid fever. The germs are usually spread through water or food.
The early 20th century found Mary Mallon, an Irish immigrant, working as a cook for a number of New York City families. Greater than half of the first family Mary worked for experienced typhoid fever. Through deduction, a researcher determined the disease was caused by Mary, the family cook. The researcher concluded that while Mary had no symptoms of the disease, she most likely had experienced a mild typhoid infection at some point in the past. While not ill, she still carried the Salmonella bacteria and spread them to other people through food she had prepared.
Microbe Transmission and Pets:
A person may catch a variety of germs from animals, particularly household pets. The rabies virus, which may infect dogs and cats, is one of the most serious and deadly of these microbes. Luckily, rabies vaccine prevents animals from getting rabies. Vaccines also protect people from getting the virus from an animal. Vaccines prevent people who have already been exposed to the virus from becoming ill through an animal bite, for example.
Cat and dog saliva may contain any of more than 100 different germs that can make a person ill. 'Pasteurella,' bacteria is the most common type of germ and might be transmitted through bites that break a person's skin, causing serious and at times fatal diseases such as meningitis. Meningitis involves inflammation of the lining of a person's spinal cord and brain.
It is important to note that warm-blooded animals are not the only ones that might cause a person harm. Pet reptiles such as snakes, turtles or iguanas may give Salmonella bacteria to their owners.
Tiny Creatures and Microbe Transmission:
Mosquitoes might be the most common carriers or, 'vectors,' of pathogens. Anopheles Plasmodium, which causes malaria, from the blood of one infected person might be transmitted to another person. Fleas that pick up Yersinia pestis bacteria from rodents may transmit plague to human beings. Ticks are another common vector. A deer tick might infect a person with Borrelia burgdorferi, the bacterium that causes Lyme disease. Ticks pick up this bacterium from mice.
Microbe Transmission Through Food or Water:
Each year, millions of people around the world become ill from eating foods that are contaminated. While a number of instances of food-borne illness are not reported, the Centers for Disease Control and Prevention (CDC) estimates there are 76 million instances of such illness in America every year. The CDC also estimates 325,000 people are hospitalized and 5,000 deaths are related to food-borne diseases each year. Microbes can cause these illnesses, some of which may be fatal if they are not treated appropriately.
Poor food preparation or manufacturing processes can permit microbes to grow in food and go on to infect a person. Escherichia coli bacteria at times persist in food products such as unpasteurized fruit juice or undercooked meat. The bacteria may have fatal consequences in people who are vulnerable, particularly children and seniors.
Cryptosporidia are bacteria found in human and animal feces. The bacteria may get into river, lake and ocean water through animal waste, sewage spills, or water runoff. Millions can be released from infectious fecal matter. People who swim in, drink from, or play in infected water may become ill. Adults and children with diarrhea caused by Cryptosprodia or other diarrhea-causing microbes such as Salmonella or Giardia may infect other people while using water-parks, swimming pools, spas, or hot tubs.
Transplanted Animal Organs and Microbe Transmission:
Transplanted animal organs might harbor germs. Researchers are investigating the potential for transplanting animal organs such as pig hearts into people. The researchers have to remain on-guard against the risk that the organs may also transmit microbes that were harmless to the animal into people where they may cause disease.
Protecting Yourself from Microbes:
People become immune to germs through natural and artificial means. As long ago as the 5th century B.C., Greek doctors noticed that people who had recovered from the plague would never experience it again. They appeared to have become resistant or immune to the germ. A person may become immune or develop immunity to a microbe in a number of ways. The first time T cells and B cells in a person's immune system meet up with an antigen, such as bacterium or a virus, they prepare the person's immune system to destroy the antigen.
Naturally Acquired Immunity:
Due to the fact that a person's immune system can often remember its enemies, those cells become active if they meet that specific antigen again; something referred to as, 'naturally acquired immunity.' Another example of naturally acquired immunity happens when a woman who is pregnant passes antibodies to her unborn child. Babies are born with weak immune responses, although they are protected from some diseases for their first few months of life by antibodies they receive from their mothers before they are born. Babies who are nursed also receive antibodies from breast milk that helps to protect their digestive tracts.
Artificial immunity can come from vaccines. Immunization with vaccines is a way to gain protection from germs. Some vaccines contain microorganisms or parts of them that have been weakened or killed. If a person receives this type of vaccine, the microorganisms or their parts will start the person's immune response, which will destroy the foreign invader.
Immunity may be weak or strong, short or long-lived, depending upon the type of antigen, the amount of antigen, as well as the route by which it enters the person's body. When faced with the same antigen, some people's immune system respond feebly, others forcefully and some not at all. The genes a person inherits can also influence their likelihood of getting a disease. The genes a person receives from their parents may influence how their body reacts to some microbes.