We are a bit paranoid in our house about bugs getting in – my husband will stalk a fly or a mosquito with a can of spray or a swat and a lot of muttering until there is a triumphant cry of ‘Got ya, you little ****!’, or something along those lines. He has a chronic allergy problem, so the home remains a bug free zone as much as possible.

But there are bugs that are way too small to see with the naked eye, that will bite and even burrow in your skin. These are called microscopic bugs or white bugs, and I am itching just thinking about them. One of the most common you would think of is bed bugs, but you can actually see these, so they don’t count as invisible.

Scabies

One of the ones that can’t be seen is the scabies mite, Sarcoptes scabiei, which are whitish-brown and only half a millimetre long. They burrow in the outer layer of your skin and lay eggs underneath, but before burrowing, these microscopic bugs bite your skin and are so tiny that you can’t see them even if you look at the bitten area at the very moment when they bite. Symptoms take four to six weeks to show up, and you might misinterpret these as mosquito bites or acne, but the most compelling evidence of scabies is relentless itching, and you’ll see track-like burrows underneath your skin, which lead to rashes. If left untreated, newborn scabies will spread underneath your skin and multiply.

Body lice

This one will infest and lay eggs on the seams of dirty clothes. Like bed bugs, body lice need to feed on human blood to survive. The good thing is you’ll only find these microscopic biting bugs in utterly dirty places with crowded living conditions. Symptoms of body lice are intense itching and rash, and repeated biting by them causes the skin to thicken and discolour. This condition is known as vagabond disease.

Body lice infestation is unlikely to be on a hygienic person who bathes daily, has access to clean clothes, and has a clean living place. Body lice will look like tiny black specks on your skin.

Rat Mites And Bird Mites

Rat mites and bird mites are parasites on their hosts and will feed on their blood, latching onto their bodies or hiding in their nests. But if you discover rat or bird nests in your home and get rid of them, you will need to clean up thoroughly, as any mites left will look for alternative hosts - and it could be you.

Both unfed rat mites and bird mites are microscopic and are impossible to see with the naked eye, and can be cream or black, but after their blood meals, their size increases and they turn red, which can make them visible, and it might take a professional to eliminate them.

Even smaller bugs

Once you get past the gnats and flitty things that are small enough to get through your fly screen, you come up against bacterial bugs, which - amongst other things - include tuberculosis, anthrax, tetanus, leptospirosis, pneumonia, cholera and botulism, with E-coli and salmonella probably being the most common. All bugs we can certainly do without!

But not all bacteria are bad guys, and in fact, our bodies are home to an estimated 100 trillion ‘good’ bacteria, many of which reside in our gut. Not only do we live in harmony with these good guys, but they are also essential to our survival. Some help our bodies digest food and absorb nutrients in the intestinal tract. According to research, beneficial bacteria may also protect us against their dangerous relatives by producing acids that inhibit their growth and stimulating the immune system to fight them off, so beware – when we take antibiotics for an infection, we also kill all those good guys at the same time.