They live among us: The hidden germs that make us & our pets ill

We like to think of our homes as islands cut off from the rest of the world. But the home-as-an-island worldview is not an accurate one. Actually, our homes are the ideal habitat for a whole range of creatures — as they tend to be abundant in food, warm, and cosy. Some creepy-crawlies live naturally in our homes, and there is not much we can do about them except reduce their numbers. While others are true invaders, and live and breed where they absolutely should not.

None of these creatures are without consequences. They can make us and our pets very ill. Most often than not they are opportunists, taking advantage of bad cleaning habits on our part, and our ignorances. Here are some of the most common types of house-dwellers that can make you and the other animals you love sick, and what you can do to prevent or eliminate them:

Dust mites

Most people will be familiar with dust mites. They live in every home, and are a fact of life. In fact, up to 10 million of them may live on a single mattress. These invisible (to the naked eye) creatures aren’t harmless, however. In fact, it is estimated that as many as 12 million people in the UK suffer allergies to dust mite poo. In dirty conditions, dust mites breed rapidly, and the more they breed, the more they defecate. 

Hypersensitivity to house dust mites is a common pain for cats and dogs, not just people. Dust mite allergies typically involve sneezing, itchy eyes, and wheezing. Up to 20% of the population may be sensitive to their droppings at any one time. 

Cleaning to avoid dust mites: A spring clean is a good way to cull some of the excess dust mites that might be causing your allergies. Regular damp dusting will get rid of a lot of them. Wash yours (and your pet’s) bedding, and clothes on high temperatures, as dust mites will die at temperatures of 60 degrees Celsius and more. Finally, it is recommended that you change your mattress every seven years, to start afresh from the dust mite droppings and their ill effects. 

Toxoplasma gondii, the ‘mind-control’ parasite

Toxoplasma gondii is one of the most common parasites on Earth, and yet it sounds like something out of a sci-fi movie. It lives naturally in garden soil, and can easily make its way inside the stomachs of cats and some dogs. Its eggs then pass out through their droppings. This puts us directly at risk whenever we touch something that might have come into contact with the droppings, such as a litter-tray. 

Once inside the human body, the parasite then works its way up to the brain where it can subtly influence our emotions, and make us more likely to take risks. Although the numbers are difficult to quantify, the parasite may kill thousands of people indirectly, every year. 

When the parasite can make us ill, in what is called toxoplasmosis. Symptoms in humans, cats and dogs can include seizures, tremors, paralysis, weight loss, lethargy and more.

How to avoid toxoplasmosis: Toxoplasmosis is also one of the most difficult to keep away and requires vigilance: that means, cleaning thoroughly the feet of your pets and quickly discarding their droppings. Do not let your pets roam freely in areas where food is prepared. Clean quickly and often, and do not let your hands touch your face, eyes, or nose, especially after recently touching an animal that might be infected. 


We tend to think of cockroaches as a “foreign” problem, but there are three species that live in the UK (although ironically they are all immigrant species, the German cockroach, the Oriental cockroach and the American cockroach). In recent years, there have been reports of massive increases in the amount of cockroach infestations — mostly in London

They make their way into the house, drawn in by animal food and food that we leave about ourselves, and then hide in cracks and crevices. If when they return they can’t find food, they leave “smear marks” that spread diseases — such as gastroenteritis — like wildfire. They can also trigger allergies. Gastroenteritis manifests as abnormal vomiting and diarrhoea in dogs and can even lead be fatal if untreated. 

How to avoid cockroaches: Use your spring clean as an example to finally apply some sealant to any cracks and crevices in your home. Then give everywhere a good clean, making sure to pick up any dropped food, and especially pet food. Give the house a good hoover afterwards, to clear away any eggs. 


Ticks generally cannot survive for long inside the house, which makes them more of a garden menace — where they bite and attack pets along with humans. Even several UK species of tick can spread the dreaded Lyme disease, and it is possible that a tick could make its way from your pet’s fur on to you, passing along the illness. Lyme disease is less common in cats than dogs, but it is still capable of infecting both.

There is, however, one species of tick that can survive in the house: the Brown Dog Tick can even breed in human habitation. As the name suggests, this creature usually rides in on the back of a dog. This tick is not a native to the UK, but it has been known to hitchhike over from abroad.

How to avoid ticks: To fight off ticks, keep the grass and the bush in the garden well pruned, to limit their travel. Consider putting furniture on a patio only, and keep the grass short. Don’t let your dog run through long grass on walks. Finally, check your dog for ticks before letting it enter the home, and hoover well to be on the safe side. 

This article was written by Thomas Owens of Pure Freedom, a company that manufactures window cleaning systems for professional cleaners

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