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Top 10 Interesting Facts About Parasites

Amanda is a retired educator with many years of experience teaching children of all ages and abilities in various contexts.

Parasites are creatures that live and feed in and on other creatures. The real alien invaders!

Parasites are creatures that live and feed in and on other creatures. The real alien invaders!

Parasites Are Everywhere!

Whether you can see them or not, parasites are pretty much everywhere. They are in the air, in the soil, in food, even inside you - hiding out on your skin, in your hair, and in your gut.

It's not true that you have to be dirty and forget to wash to get parasites (although some of the nastier ones will prefer you if you're a bit of a stinker). Many common parasites, such as head lice, prefer a clean environment.

There's no escaping the little critters.

And in many cases, you shouldn't want to. Many parasites are actually good for you. It's true. They'll eat up flakes of dead skin, absorb excess oils and keep your intestines clean. They're the helpful parasites.

Others just hitch a ride with you for a time, and you'd never even notice. They're the harmless parasites.

Some of them are mean. They'll eat you out from the inside, infect you with deadly diseases and otherwise give you more trouble than your kid brother when he's bored and got nothing better to do. They're the DEADLY PARASITES.

But wait a second. Aren't we jumping ahead here? I mean, what are parasites?

Easy. I just looked it up, and this is what my online dictionary says:

Parasite - definition.

an organism which lives in or on another organism (its host) and benefits by deriving nutrients at the other's expense.

— Online Dictionary

Common Parasites

So, now we know what parasites are, where they are and what they do.

Let's take a closer look at some of the most common parasites that we - and our pets, but more of that later - are most likely to encounter in our daily lives at home, work and school.

There are so many, it's hard to know where to begin. I guess we should start at the top.

Are you ready to find out all about head lice? Let's do it!

The Secret Life of Head Lice

Head Lice

Head lice are pretty small - which is true of many parasites. Being small is a good way of getting by unnoticed and sneaking into places on your host organism where they would probably rather you didn't.

As their name implies, these little critters live on your head: more precisely, in your hair. Sometimes they can even turn up in your eyelashes or eyebrows.

Head Louse - it can make you feel lousy!

The human head louse, Pediculus humanus capitis, nestles in amongst the hair follicles.

The human head louse, Pediculus humanus capitis, nestles in amongst the hair follicles.

Head lice breed very freely and so can spread rapidly not only through your own hair, but also onto other people that you come into contact with.

Outbreaks of head louse infestation tend to happen in places where lots of people mingle closely together - such as schools, for example.

What are nits? Isn't that just another name for lice?

Not exactly. Sometimes you'll hear people using these words interchangeably, but in fact nits is the term for a louse's eggs.

These eggs are very small but can be identified near the follicles of your hair (if you have lice) by an expert eye.

Nits - Head Louse Eggs

Commonly known as 'nits' these are actually the eggs of human head lice.

Commonly known as 'nits' these are actually the eggs of human head lice.

If you have head lice, then you will almost certainly have nits.

If you have nits and you don't do anything about it, then you will be sure to play host to a heck of a lot of lice.

If you do have lice or nits, it is important to get the situation treated.

Not only can head lice leave your skin feeling very sore and itchy, but if left alone, they can make you feel generally very unwell.

Fortunately, they can be gotten rid of pretty easily these days by using a special, medicated shampoo and a close-pronged 'nit comb.'

Fleas and Mosquitoes

Why have we put fleas and mosquitoes together?

Well, for the simple reason that they are both skin parasites. Some parasites just live on you - but these guys actually eat you.

Fleas live on your skin - not always for a long time as sometimes they'll just 'hitch a ride' and then jump off onto someone else. But whether they're with you just a few minutes or for days and weeks, they will be busy eating your skin, biting you and licking up excreted oils.

If they bite, they can leave you itching and sore.

A Human Flea

Fleas can infect humans and other animals with diseases.

Fleas can infect humans and other animals with diseases.

Mosquitoes can carry some pretty serious diseases in some parts of the world, including malaria, which is potentially fatal if it goes untreated.

Mosquitoes puncture your skin, insert a long, hollow proboscis down into a vein, and slurp up your blood.

Forget vampires, mosquitoes mean business - and unlike the characters from Twilight, mosquitoes are real!

A Mosquito Feeding on Human Blood

Mosquitoes insert a long proboscis through the skin and suck up the blood from a vein. They can infect their hosts with fatal diseases.

Mosquitoes insert a long proboscis through the skin and suck up the blood from a vein. They can infect their hosts with fatal diseases.


Mites are skin parasites, too, but they are almost completely harmless.

Mites live in the pores of your skin (yes, they are really small) and sometimes in your hair. You almost certainly have mites. So does everyone else in your family, probably. Maybe the dog has them, too.

But don't worry. Mites won't eat you. They're completely harmless and practically invisible.

I bet you didn't even know you had them, did you?


Mites are tiny and live in the pores of your skin. They are mostly harmless.

Mites are tiny and live in the pores of your skin. They are mostly harmless.


Roundworms aren't so nice.

Roundworms are a kind of nematode.

Roundworms, given the chance, will happily infest your guts where they can survive for a long time. They'll take up residence in your intestines, living, feeding and reproducing there. If they go undetected, they can spread in large numbers throughout other parts of your body, too.

A Roundworm

This is a roundworm. They are typically ingested as eggs and can grow several feet long.

This is a roundworm. They are typically ingested as eggs and can grow several feet long.

But how do they get to you in the first place? The most common way of becoming infested by roundworms is by ingesting their eggs. Their eggs are tiny and can be found on food and in dirty water.

Once you've swallowed the eggs, your gut is the perfect, warm, moist environment for them to hatch in.

Fully grown roundworms can be up to a foot long. The first most people know about having them is when they go to the bathroom and find that their poop is wriggling with living things.

An infection of roundworms (properly termed ascariasis) is, fortunately, pretty easy to treat.

It's a good idea to wash and clean all your fruit and vegetables before eating them, too.


Just when you thought you'd had enough of worms...

... then you find out about these particularly nasty parasites, tapeworms (properly called cestodes).

Tapeworms, like roundworms, also live in your intestines. Again, they usually enter your body as eggs and then hatch out inside you.

Parasite Poll

An Adult Tapeworm

An adult tapeworm. Tapeworm infection is rare in developed countries.

An adult tapeworm. Tapeworm infection is rare in developed countries.

Tapeworms can grow up to 30 feet long. Yes, you read that right - 30 feet long!

Fortunately, tapeworm infections are very rare in the USA, Great Britain and other developed countries.

Their eggs or small juvenile worms can be contracted by

  • contact with excrement, animal or human
  • ingesting dirty water
  • consuming raw animal products such as meat, fish and eggs

If your dog or cat has them and you let him lick your face, you can catch them that way, too.

Medical Footage of Tapeworms Living in the Intestines - NOT for the Squeamish!

Bed Bugs

Bed bugs? Yes, they're real.

While we call them 'bed bugs' they can actually thrive almost anywhere.

They are small, oval shaped, flightless insects. They can also survive for several months without needing to eat.

The best way to avoid these little beasties is through good hygiene and cleanliness. They love dirt. They prosper in airless, dirty, cramped places with lots of nooks and crannies to hide away in.

They got their name from a time when beds were mostly straw mattresses and modern hygiene practices had yet to be invented. Back in the day, dirty, unwashed beds - often crammed close together in squalid conditions, were a straightforward paradise for these parasites.

Bed bugs can easily be gotten rid of these days by treatment with a simple dose of an appropriate insecticide. In the old days, you had to burn your mattress.

Close Up of a Bed Bug

Bed bugs are real and prefer dirty environments with lots of places to hide in.

Bed bugs are real and prefer dirty environments with lots of places to hide in.


Ticks like blood.

And to get at yours, if they land on you, they'll bury their heads into your skin and start to feast.

They'll do the same to your dog or your cat, too, if they get the chance.

They live in long, rank grass - especially in areas grazed by sheep or cattle.

Ticks also harbor some nasty infections which they can transfer to you. If you ever find that you have a tick, don't try to pull it out yourself. If you do, most likely you'll pull the swollen, blood-filled body away and leave the head under your skin. Not nice.

If you pick up a tick - and it can happen - seek medical advice as soon as possible.

Close Up of a Tick

Ticks bury their heads into your skin and suck out your blood. As they suck the blood, their bodies become swelled and bloated. If you contract a tick, always seek medical advice.

Ticks bury their heads into your skin and suck out your blood. As they suck the blood, their bodies become swelled and bloated. If you contract a tick, always seek medical advice.

Pets and Parasites

Parasites, as we've seen, can be problematic for humans. Fortunately, the most unpleasant ones can mostly be avoided by keeping yourself and your environment clean.

However, they can also be a problem for our pets.

Most of the parasites that we've looked at here are even more common in the animals we live with. Dogs and cats, for example, can all succumb to fleas, lice, worms and ticks.

In some cases, these parasites can make our pets very unwell.

If your pet is scratching excessively, develops patchy fur or has faeces (poop) that are runny or wriggling, you'd be well advised to get him to the vet as soon as you can for a diagnosis.

Prevention is better than cure, they say. That's certainly true here. Most pets should be regularly treated for worms and fleas at least. This is usually a simple matter of adding something to their food or putting a few drops of medication under their fur.

Get some advice from your vet about the best products and practices for your pet.

One Question Quiz

For each question, choose the best answer. The answer key is below.

  1. What is the proper term for a roundworm infection?
    • Ascariasis
    • Apoptosis

Answer Key

  1. Ascariasis

© 2014 Amanda Littlejohn

What do you think about parasites? Do you have any experience of them? I'd love to read your comments and I always reply...

Amanda Littlejohn (author) on March 06, 2018:

Thank you for your comment, Jhanvi. I know what you mean! Parasites are fascinating to study, but they definitely have a "yuck factor", don't they?

JHANVI.SHAH on March 05, 2018:



Savvy on February 22, 2018:

Parasites are cool to learn about! I pove learning more about them and the more i learn the better i can prevent them!

Amanda Littlejohn (author) on April 21, 2017:

Thank you, Sam! So glad it was helpful. :)

sam likmen on April 20, 2017:

this is very helpful and interesting

Amanda Littlejohn (author) on October 06, 2016:

Thanks, gage, so glad you enjoyed it!


gage on October 06, 2016:

so cool

Amanda Littlejohn (author) on September 07, 2015:

Thanks KoffeeKlatch Gals ! Glad you enjoyed learning about parasites.

Bless you :)

Susan Hazelton from Northern New York on August 07, 2015:

Tis is a great article. I now know everything I didn't know I needed to know about parasites. Interesting.

Amanda Littlejohn (author) on February 09, 2015:

Hi eilval!

Thanks for your lovely comment. I'm glad that this article has helped to increase your understanding of parasites - even if you still don't like them!

Bless :)

Amanda Littlejohn (author) on February 09, 2015:

Hi Alun!

Thank you so much for a wonderful, thoughtful and amusing contribution to this article about parasites. I think you are absolutely right to point out that many of these creatures - once you overcome the evolved, instinctive revulsion - display some of the most successful adaptations for survival of any living things. Indeed, it's arguable that many of the families of parasites are doing a lot better than we humans are in terms of sustainable successes!

Thanks for voting in the poll - and so intelligently, too.

Thanks again and - keep clean!

Bless you :)

Eileen from Western Cape , South Africa on February 09, 2015:

I now do have a better understanding of parasite . I sure don't like them around but the facts were indeed informative .

Greensleeves Hubs from Essex, UK on February 07, 2015:

Gruesome, unpleasant, stomach churning - so this is a subject which is bound to be popular with kids! And indeed learning about creatures like this is useful for encouraging children to develop a real interest both in hygiene and also in the wider natural world of animals too. Very well presented, beautifully illustrated introduction to parasites Mindi, and important for removing some of the misconceptions and stigmas attached to these little charmers. Voted up and shared.

These creatures may anthropomorphically be regarded as the lowest of the low in the animal world, but in many cases perform a very necessary function in ecology, and exhibit some really clever and very specialised adaptations to their chosen lifestyles.

Having said that, and despite being a passionate believer in conservation and protecting all species from extinction, I just wish in future, mosquitoes and biting flies could be kept securely confined in cages in zoos so we could just look at them and not interact so painfully with them! :)

With 3 'no' votes currently in your poll, I thought in the interests of balance, I would vote 'yes'. Not - I hasten to add - because I've ever knowingly experienced ticks, lice, tapeworms, bed bugs etc, but because as you say, microscopic parasites of one kind or other are almost an inevitability. And of course I have had too many encounters with those aforementioned mosquitoes! Grrr! Alun :)

Amanda Littlejohn (author) on December 24, 2014:

Hi mylindaelliot!

Thanks for your contribution to this article about parasites. You know, some of the world's leading entomologists are women, so I don't think that an interest in bugs is just a 'boy thing' at all!

I don't think you are alone, however, in deciding not to dwell on all the little critters that actually live on and in you - I think most of us are with you on that one!

Thanks again and bless you! :)

mylindaelliott from Louisiana on December 23, 2014:

Oh my how special! Kids, particularly boys, must love this. I did like bugs and things when I was a child though. I prefer not to think about the parasites running around on me. I love the pictures though.

Amanda Littlejohn (author) on October 20, 2014:

Thanks ajwrites57!

Seems I've grossed quite a few folks out with this one - but, hey, they're parasites, what do you expect? Lol.

Thanks for your comment. Bless you :)

AJ Long from Pennsylvania on October 20, 2014:

Oh my gosh! stuff4kids wayyyy too much pest info. Gah. Informative and scary to think of these parasites in so much detail. Thanks a lot!!

Amanda Littlejohn (author) on October 20, 2014:

Hi pstraubie48,

You were warned!!! Yes, Nature isn't just all things bright and beautiful is it? There's all kinds of nasty stuff that would challenge even the twisted imagination of Stephen King to create...

Thanks for your comment. Bless. :)

Patricia Scott from North Central Florida on October 20, 2014:

Okay so the video of the tapeworm making a home in the intestines...not so much. I would hope that never happens.

We are surrounded by all kinds of critters that would use and abuse us, aren't we?

Angels are on the way to you this morning ps

Amanda Littlejohn (author) on October 20, 2014:

Why, thank you AliciaC - I'm so glad you enjoyed it.

Bless you :)

Amanda Littlejohn (author) on October 20, 2014:

Hi Shelley!

Thanks for that wonderful contribution to this article about parasites. I'm sorry that you are quite so paranoid about them, though - although with your usual humor, you had me laughing out loud about it!

Thanks again. Bless you :)

Linda Crampton from British Columbia, Canada on October 18, 2014:

This is an interesting and informative hub. It's enjoyable, too!

FlourishAnyway from USA on October 18, 2014:

The hypochondriac in me wants to go shower right now. I actually do tend to avoid movie theaters, public transportation and other places with fabric seating because I have a fear that bed bugs, lice, or some other type of heebie jeebie will get on me. I wasn't that conscious of it until the bed bug outbreak throughout the US several years back. Scabies was going around my child's daycare and it also made me aware and appalled. Going barefoot outside is a similar no-no. Such a great hub on a terrific topic. It's bound to educate and make others squirm, as it did me.

Emily Tack from USA on October 18, 2014:

My pleasure, my dear!

Amanda Littlejohn (author) on October 18, 2014:

Hi Shades-of-truth!

Thanks for your comment. Great that you enjoyed this!

I've come across the solution you offer for head lice - the cider vinegar and olive oil solution - as a cure for dandruff before. Great that it worked on the lice, too! I suspect it was the acidity in the vinegar that did it as most biological organisms prefer a relatively neutral environment (although there are plenty of exceptions to that rule).

'pretended their heads were salad' ! LOL!

Thanks so much for your contribution!

Bless you :)

Emily Tack from USA on October 18, 2014:

I love articles like this, too! I remember one time my children got head lice when we were had some animals back in the 1970s. I mixed apple cider vinegar and olive oil, and pretended that their heads were salads. The mixture was massaged thoroughly into their hair and scalps, and --- no more lice!

Amanda Littlejohn (author) on October 18, 2014:

Hi Bill!

Thanks for you encouraging comment. Glad you liked it.

Bless :)

Bill Holland from Olympia, WA on October 18, 2014:

I must be a science nerd because I love articles like this one. Great facts.