parasites

Have you ever seen fleas or ticks that live on dogs and cats? Fleas and ticks have an interesting relationship with animals. Why is that relationship interesting? It is because only fleas and ticks benefit from it, and not the animals! The relationship between two living things, in which one member benefits and the other member is usually harmed is called Parasitism. The member which benefits is called a parasite and the member that is usually harmed is called a host. There are more examples of parasites in nature, like most fungi! Or flatworms! 

As you guess, in this lesson we are going to learn about PARASITES. We will discuss:

• What are parasites?
• Types of parasitism.
• Types of parasites.
• Disease caused by parasites.

What are parasites?

A parasite is an organism that lives on or in a host organism and gets its food from or at the expense of its host. Without a host, a parasite cannot live, grow, and multiply. But in turn, hosts never benefit from parasites. A parasite rarely kills its host, but it can spread diseases, some of which may be fatal.

Parasites are almost always smaller than the host and account for roughly 50% of all species found on Earth.

A few examples of parasites are tapeworms, fleas, and barnacles. 

Parasitic organisms are found almost everywhere, even in tropical and subtropical regions, as well as in Antarctica.

Parasitism types

Among parasites, you can find several different types of parasitism, from the parasite being totally dependent on the host to free living. See a few of the important types.

• Obligate parasitism - The parasite is completely dependent on the host to survive. For example, head lice will die without a host.
• Facultative parasitism - The parasite can live independently but also live off other organisms. A roundworm can infect mammals or live free.
• Social parasitism - This happens with social insects like ants, where they use their friends to raise young or work. For example, Tetramorium inquiline is a type of ant that rides on the backs of other ants.
• Brood parasitism - This happens among birds, where they will lay their eggs in another bird's nest and make them raise their young. Cowbirds and cuckoos are famous for this.

Types of parasites

When parasites cause disease in their host they are referred to as pathogens. There are three main classes of parasites that can cause disease in humans: protozoa, helminths, and ectoparasites.

• Protozoa: Protozoa are single-celled organisms that can multiply in humans. These parasites can spread through contaminated food and water, person-to-person contact, and insect bites. Protozoa include Plasmodium malaria, which causes malaria infection. In this case, the parasite is spread to humans through the bites of infected mosquitoes. 

• Helminths: Helminths, often called worms, are large multicellular organisms usually visible to the naked eye in their adult stages. They are often rooted in a person’s digestive tract. These parasites cannot multiply or divide within a human body and eventually pass through a person’s stool. Another major group of helminths is nematodes, commonly known as roundworms.

• Ectoparasites: Ectoparasites are small organisms that live on the outside of the body. These generally refer to organisms such as ticks, fleas, lice, and mites that can attach or burrow into the skin and remain there for long periods of time. 

Parasite diseases

Anyone can contract a parasitic infection and some people are at higher risk because of certain reasons. One of the most common ways of contracting this type of condition is through contaminated food such as undercooked meat or drinking unclean water.

There are many types of parasites, and that is why the symptoms can vary. Sometimes, these may resemble the symptoms of other conditions, such as pneumonia or food poisoning, so symptoms are hard to predict.

Tests (blood test, fecal exam, endoscopy, colonoscopy, etc.) may be ordered to diagnose a parasite infection depending on factors such as the person’s symptoms, other medical conditions, and travel history. If a parasite is confirmed, then treatment is needed. The treatment for parasite infections depends on the particular type of parasite. Doctors may prescribe medication that kills the parasite and medication that treats any symptoms, such as diarrhea.

Some of the methods for prevention are:

• using insect repellant in places where mosquitoes are common
• eat only well-cooked fish and meat
• drinking water only from bottles with a sealed top while traveling
• being careful when bathing in freshwater lakes or rivers