They’re living rent free... and may be the most successful lifeform on Earth

The saying goes that there is no such thing as a free lunch, and that is pretty much true even for parasites. They are considered one of the most successful lifeforms on Earth, and there is a plethora of them, making up between 40% and 50% of all life on our planet.

The word parasite is derived from the Greek word parásitos, which essentially means “a person who eats at another’s table.” These freeloaders come in all shapes and sizes and they feast on a host organism, and humans are no exception.

Some are more or less innocuous but others are downright nasty. There are three types that can cause disease in humans; protozoa (microscopic, one-celled organisms), helminths (worms), and ectoparasites (blood-sucking insects).

Thanks to public health campaigns over the years, parasitic infections in the United States are less common than in developing countries but still millions occur each year. Here are some of the more common evolutionary survivalists that still plague humans in America.

Parasites you may be hauling around

Giardia: You may be tempted to take a drink from the crystal-clear water of a mountain stream or glacier thinking it pure and clean, but don’t. It most likely contains Giardia, or ‘beaver fever’ which is found worldwide. These protozoa cause an intestinal infection marked by stomach cramps, bloating, nausea and bouts of watery diarrhea explains the Mayo Clinic.

Hookworms: People get infected by this “intestinal Dracula” when they walk barefoot on or consume contaminated soil. It then sets up shop in the intestines where it feeds on your blood and produces offspring. Fortunately, the eggs typically leave through your feces and don’t multiply into new adults inside you. However, sever infections, 500 or more hookworms, can cause “anaemia and/or death (especially in children) can occur, if treatment is not carried out consistently,” explains a study in Springer Nature.

Pinworms: While generally harmless, these little creatures have a serious ‘yuck’ factor. They come out of your anus at night while you are asleep to lay their eggs which cause irritation. That in turn makes the host scratch the spot and then they contaminate whatever they touch if they don’t wash their hands. If one person in the family has them, most likely everyone has them.

Tapeworms: These worms come in both large and small able to live for years in your body without you noticing. They absorb the nutrients being digested in your intestines where they typically make their home. Generally, people get infected with tapeworms when they eat infected beef or pork that isn’t properly cooked.

Toxoplasma: This common single-celled parasite is found worldwide making birds, mammals, and numerous other animals, commonly cats, their host. Most people don’t experience any symptoms but they can be dangerous for people with weakened immune systems and pregnant women, causing complications for the fetus.

Get your game on! Whether you’re into NFL touchdowns, NBA buzzer-beaters, world-class soccer goals, or MLB home runs, our app has it all.

Dive into live coverage, expert insights, breaking news, exclusive videos, and more – plus, stay updated on the latest in current affairs and entertainment. Download now for all-access coverage, right at your fingertips – anytime, anywhere.