In this video lesson, you will identify different disease-causing agents. You will also explore examples of types of disease-causing agents and their effects on human health.
Being sick is no fun, but it can actually be good for your body. When you're sick, your body has a chance to build up an immunity to whatever is causing you to feel badly.
This is because your immune system is like a small but powerful army - it attacks foreign objects and organisms that may harm you and then stores that information so it can remember how to attack again in the future.
But, how do we get sick in the first place? Diseases, which are any illness-causing conditions that affect an organism's body, are transmitted by disease-causing agents, which are biological pathogens that cause or spread disease. Disease-causing agents are delivered to your body through various carriers, and they can get inside in all sorts of ways. The disease is worrisome, but the disease-causing agent is just as problematic because it is what actually transports the disease that makes you sick.
Viruses are the disease-causing agent that most people are familiar with. They cause colds, the flu, HIV, meningitis, polio, chicken pox, rabies, West Nile, and a number of other diseases. Viruses themselves aren't living things, but they do get transmitted between living organisms.
Take West Nile, for example: this is a virus that is carried by mosquitoes. A mosquito bites you and spreads the West Nile virus into your blood. This unwelcome guest makes a home in your body, attacking your living cells and then reproducing.
Viruses can often be controlled by vaccines, which are exposures to an inert version of the virus or a safe agent that resembles the virus. This allows your body to build up that immune response before you ever get the virus, so that instead of getting sick first, you already have your army ready to fight ahead of time.
Bacteria get a bad rap. Many people confuse bacteria for viruses, and in fact, most of the bacteria that you come in contact with are either not harmful or actually provide some health benefits to you. You are literally covered with good bacteria, both inside and outside your body. Your digestive system wouldn't be able to function properly without the numerous types of bacteria that help break down and absorb the nutrients in all the foods you eat.
There are, of course, some bad bacteria and these can be quite dangerous. In contrast to viruses, bacteria are living organisms, but they are usually made up of just one cell. Bacteria are especially hard to control because they are extremely prolific - they can multiply into colonies of millions and billions of organisms in a very short amount of time.
Bacteria cause infections and disease. As mentioned before, meningitis is caused by a virus, but there is also a bacterium that will cause a different type of meningitis. Pneumonia, strep throat, Lyme disease, and many intestinal conditions are caused by bacteria. Antibiotics are used to treat diseases caused by bacteria because they are medications that kill bacterial infections.
Protozoa are also small, unicellular organisms. They can live in all different types of environments and are able to move around really well. They are parasitic, which means that they live and feed off of a host organism.
Amoebas and sleeping sickness are examples of diseases caused by protozoa, as well as some common gastrointestinal ailments. Amoebas are actually a type of protozoa, but we use the term to describe disease caused by them as well. Protozoa are sneaky little guys because they can slip into your body through food, water, or skin contact.
They are microscopic, so you can't see them, and sometimes they even fool your immune system and hide in your body for long periods of time undetected.
Parasitic worms are definitely not the wonderful worms you have in your garden! Parasitic worms are dangerous parasites like hookworm, tapeworm, roundworm, and heartworm. Interestingly, ringworm isn't actually a worm - it's a fungal infection on your skin, and it gets its name from the round-shaped ring that appears on the skin (which looks like a worm).
Parasitic worms live off of host organisms and can cause a variety of problems. They are well-known for their effects on other organisms, such as the tape worm. Some tapeworms can grow to over 50 feet long and live for over 20 years inside your body! They sap all of your nutrition as it comes into your digestive system and can cause severe starvation and gastrointestinal issues.
Believe it or not, tapeworm 'pills' were once marketed as a way to lose weight! Though it is not clear if the pills actually contained tapeworms, the thought of ingesting one of these creepy parasites sure doesn't sound very appetizing!
We can get diseases in a number of ways. Any biological pathogen that transmits a disease is a disease-causing agent. The most common disease-causing agents are viruses, bacteria, protozoa, and parasitic worms.
Viruses are not living, but do get transferred between living organisms. The West Nile Virus is transferred from mosquitoes to humans. Vaccines are a good way to prevent the spread of viruses.
In contrast to viruses, bacteria are living, unicellular organisms. Most are either beneficial or not harmful, but some can be hazardous, such as Lyme disease. Bacteria can often be controlled by antibiotic medications.
Protozoa are also living, unicellular organisms. They are parasitic, so they feed off of their host. Protozoa are rather sneaky, and can get into your body undetected, living that way for long periods of time.
Parasitic worms are things like roundworm, heartworm, and tapeworms. These parasites can grow very long, live for long periods of time, and cause gastrointestinal discomforts, starvation, and death.
After finishing with this lesson, you will be able to:
- Define disease-causing agent
- Explain the mechanisms by which viruses, bacteria, protozoa, and parasitic worms cause disease
- Identify examples of these disease-causing agents
- Describe the difference between a vaccine and an antibiotic