Humans Can Host a Variety of Parasitic Worms. Here's How to Spot The Signs.

The comedian Shappi Khorsandi once commented that she used the mythical concept of 'sugar worms' to get her children to brush their teeth after sweets. It's a trick I poached to convince my daughter to do the same.

She's since grown wise to this, but now luckily manages to navigate her way around a toothbrush twice a day without resistance.

Real worms have now replaced fictitious worms as a point of discussion in many other households with young children. Every few weeks, nurseries and schools inform parents of yet another occurrence of threadworm.

It's not surprising that these wriggly beasties keep rearing their heads, considering how easily transmissible they are.

Threadworm

Threadworm infestation is a common minor ailment, particularly in kids. The worm species that causes it – Enterobius vermicularis – goes by many other names, including pinworm.

This is because it really is as thin and pointy as a pin, and silvery-white in appearance. It's also sometimes known as seatworm, possibly because the body parts it most commonly affects are those which you sit on.

The circle of life for a threadworm is simple. Their larvae come from ingested eggs that then hatch in the small intestine. They typically form a colony within the first part of the large intestine (the caecum).

But their most noticeable effect appears to be on the back passage, since the female worms migrate there, usually at nighttime, to lay their eggs. This results in the common symptoms of a very itchy bottom, especially at night.

The itching naturally makes the sufferer scratch, installing the newly laid eggs under their fingernails and allowing them to spread to other hosts through contact. It can affect anyone – both adults and children.

It's possible to spot threadworms in the stool after a bowel movement. They can make themselves known in several other ways, including nighttime irritability and bed wetting.

Because the worms prefer living in the intestine, in rare conditions they may cause abdominal pain and mimic appendicitis. In fact, in some cases the appendix is removed and found to be chock-full of wriggling worms.

The condition is usually mild and can be treated at home. Mebendazole, an oral anti-worm medication, can be bought over the counter at most pharmacies and is normally effective.

It's recommended to treat everyone in the household over the age of two, in case they have already spread – remembering that sometimes there are no symptoms to be noted at all.

But it's important to speak to a doctor for children younger than two years old, and pregnant or breastfeeding women with threadworm, as medication may not be suitable.

Hygiene measures are important to help clear the infection and prevent the spread, especially in those who can't take medication. This involves scrupulous washing of hands, laundry and avoiding scratching the affected areas. It's a good idea to trim fingernails too, to prevent the eggs from getting caught under them.

Hookworm

Threadworms aren't the only worms (helminths) that invade humans. Hookworms, for example, affect about 470 million people worldwide. Infections in the UK are rarer, since hookworms favour a warmer climate.

Like threadworm, they also tend to take up residence in the small intestine – though they can also get there in a much more complicated way. The larvae of hookworms are able to pass through the skin and travel to the lungs in the bloodstream. Once there, they journey upwards into the throat where they can then be swallowed down.

Since the respiratory tract and gut are the favourite places for these worms to bunk down, the symptoms of a hookworm infection tend to be associated with them – such as coughing and wheezing. Inflammation in the small intestine, triggered by the infestation can generate abdominal pain and diarrhoea.

It can also hamper the absorption of proteins and iron from the gut, causing anaemia.

A characteristic rash might be noted in the stage where the larvae start to burrow through the skin – looking a bit like a snake writhing through it. In the medical profession, we call this cutaneous larva migrans.

Like threadworm, hookworm can also be treated with oral medications.

Filariae

Worms don't just invade the gut or lungs. Some of them work their way into other regions of the body. Take lymphatic filariasis, a condition that arises when certain worms of the Filariidae order, infiltrate the lymphatic system.

The lymph vessels act as drainage pipes, removing excess fluid from the tissues and returning it to the bloodstream. When the worms invade and inflame the lymphatic system, the result is lymphoedema – an accumulation of fluid in the extremities (like the legs), which causes swelling and discomfort.

In extreme cases, the swelling can be profound, resulting in a condition known as elephantiasis. This is because the worm infestation causes not just swelling, but also skin changes – making it thicker and tougher, and taking on the appearance of elephant skin.

These are just a few of the helminth conditions that can affect humans. Other examples include tapeworms and whipworms – which are also intestinal. Ringworm is a misnomer though, and not a worm at all – it's actually caused by a fungal infection.

Dan Baumgardt, Senior Lecturer, School of Physiology, Pharmacology and Neuroscience, University of Bristol

This article is republished from The Conversation under a Creative Commons license. Read the original article.