You walk around, you go to work, you look after the kids… You feel ok – a bit tired, maybe, but you get by. There’s nothing wrong with you…

Except that, if you’re like three billion other people around the planet, you could be playing host to a colony of intestinal worms.

Intestinal worms are parasites. They live inside us and they feed off us. And no, they don’t just eat the food we eat, they feed off our bodies too.

The Enemy Within

Intestinal parasites fall into two categories. There are the protozoa – the single cell organisms like giardia and cryptosporidium. And then there are the others – the larger, wriggling, worm-like creatures, our unwanted passengers, our dark intestinal companions – the helminth.

Helminth (from the Greek for worm) are not micro-organisms you can pretend don’t exist. They’re real. You can see them without a microscope – some of them grow up to 13 cm long! And there’s a chance they could be inside you right now – living.

There are four common types of helminth.


Rounded, pinkish white, 10cm to 13cm long – these are the monsters of the helminth world. Want to know about their lifecycle? Really? Ok, get this…

The female roundworm, living in our intestines, produces around 2 million eggs per day. These eggs enter the environment in faeces. Outside the body, in warm, moist conditions, they mature into an infective state and are then ingested by other humans through contaminated water or food.

When these infective eggs reach the intestines they hatch into larvae which burrow through the intestinal wall, enter blood and lymph vessels, and make their way into the lungs. Here, they grow and develop before making their way to the throat where they are swallowed. Back in the intestine again, they start laying eggs…


Think you’re safe if you wash your food and drink only clean water? Forget it. You can get these babies just walking around in bare feet.

When hookworm eggs are excreted in faeces they lie in warm, moist ground and hatch into larvae which live in the surface of the soil. These larvae infect humans by boring through the skin, entering the bloodstream, migrating to the lungs, then to the throat and on to the intestines where they attach themselves to the intestinal wall with sharp teeth and grow to between 6mm and 12mm long. And lay eggs.


When whipworm eggs are swallowed they mature into larvae in the small intestine and then migrate to another part of the intestines called the cecum. Here, they attach themselves to the cecum wall and start producing eggs.


In many developed countries these are the most prevalent form of helminth, they are also the most geographically widespread intestinal worm. It is estimated that over 200 million people and 30 percent of children worldwide are infected with them.

Threadworm are relatively small – 5mm to 10mm long. They live primarily in the cecum and it is from here, each night, that the female migrates to lay her eggs. Where? On the outside of the anus and on the perineum (yes, they actually crawl out of your bottom at night!) These eggs can be picked up by others, thereby spreading the infection. The saliva of infected persons is also a conduit for the transmission of threadworm.

Risk Factors

Given the lifecycles outlined above it is reasonably easy to see that the risk of infection by intestinal worms will be higher in areas with poor sanitation and in populations with sub-standard hygiene education. Other contributing risk factors are:

  • International travel (to risky areas).
  • Age – children and the elderly are more likely to be colonised by the worm.
  • Exposure to large numbers of children.
  • AIDS, HIV and other immunodeficiency diseases make the body both less able to rid itself of parasites, and more susceptible to their damaging effects.

Worm Damage

As the worm colonises a host, the body tries to defend itself with a Th2 immune response. The gut becomes inflamed and cyst-like structures form around worm egg deposits. But it isn’t enough. The worm survives. Even the high levels of acid in the digestive tract are no defence – the worm protects itself by producing a protective keratin layer.

Intestinal worms cause malnutrition by reducing appetite and by stopping the food which is eaten being absorbed properly. Heavy infestations of roundworm can cause bowel obstructions. Hookworm infestations, especially, can lead to anaemia as they cause bleeding in the intestines (each hookworm consumes 0.25ml of blood a day).

All intestinal worms release toxins into the lymph system and bloodstream, promoting sickness and compromising health. Chronic infestations can lead to the retardation of physical and mental development in children.

Symptoms of Infection

Low level worm infections may produce no symptoms. Larger infections, though produce a range of symptoms which include:

  • Painful abdomen
  • Coughing
  • Bloating
  • Diarrhoea
  • Flatulence
  • Diminished sex-drive
  • Bloody stools
  • Fever
  • Nausea
  • Tiredness
  • General lack of wellbeing

The most common signs of infestation, though, particularly in children, are anal and vaginal itching, restlessness and irritability, decreased appetite, and worms in the stool.


Although the idea of having something living inside you is gruesome, you can take heart from the fact that conventional medicine offers a range of highly effective treatments. These include:

  • Albendazole (Albenza, Zentel)
  • Mebendazole (Vermox)
  • Thiabendazole (Mintezol)

There are also numerous alternative treatments that purport to rid the body of worms. Among them: garlic (raw), grated carrot (taken by itself in the morning), papaya seeds, coconut (freshly grated – take one tablespoon at breakfast, followed by a dose of castor oil three hours later). Various herbal treatments like black walnut and wormwood are also recommended by natural medicine practitioners (be careful, they can be toxic).

An Anti-worm Diet

By making certain dietary modifications you can create an environment which allows healthy intestinal flora to flourish and discourages parasite colonisation.

  • Avoid simple carbohydrates – found in refined foods, fruit juices, dairy products and sugars.
  • Drink plenty of water to aid faecal elimination.
  • Eat plenty of fibre (good for flora, bad for worms)
  • Consider a probiotic supplement – better intestinal health discourages parasites.
  • Vitamins which support your immune system may help you weather the detrimental effects of infestation a little better.


Most intestinal worms, with the exception of hookworm, find their way into the body through ingestion. Good hygiene habits, then, will help reduce the chances of infection. Wash all fruit and vegetables well, wash your hands after going to the toilet and before eating or preparing food, avoid contaminated drinking water, avoid high risk environments (faeces contaminated soil and sandpits etc.).

The Good News

In New Zealand, threadworm is the only prevalent species of helminth. Occurrences of roundworm, whipworm and especially hookworm are very rare. Disease caused by threadworm is relatively innocuous – anal and vaginal itching. While this itching can lead to sleep disturbance, it rarely progresses to anything more serious. In a small number of cases, though, conditions including weight loss, urinary tract infection and appendicitis have been observed.

Threadworms are easily treatable (usually one tablet of Vermox will do the trick), and the transmission of infection is controllable by the simple application of good hygiene habits.

So, if watching Alien has got you thinking that you may not be alone, even though there’s no one else in the room, don’t panic. A quick trip to the chemist is probably all you need to get rid of those sinister friends you’ve been carrying around.

If you’d like to take a look at worms in action check out this video (no sound).

Intestinal Worms – The Threat Inside You, 2.3 out of 5 based on 4 ratings

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