Many organisms rely on humans as hosts, either for shelter, food, or part of their life cycle. Some are so small they go unnoticed, while others are more visible and can cause discomfort when they appear on the skin or in the environment around us.
These species form part of the broader relationship humans share with the natural world, and understanding how they interact with the body can help you recognise what is normal and when professional guidance may be necessary. This overview highlights a few of the organisms that commonly live on or inside people, based on well documented scientific knowledge.
This article is for general knowledge only and is based on information from online sources. Always consult qualified medical professionals for health concerns. Images are for illustrative purposes only.
1. Head Lice
Picture a creature with six spindly legs, each ending in tiny hooks designed to grip hair strands with frightening efficiency. Head lice are wingless insects about the size of a sesame seed that make their home on human scalps, feeding on blood several times daily.
Children in schools often pass these parasites through head-to-head contact during play or while sharing hats and hairbrushes. The female louse cements her eggs, called nits, near the scalp where warmth helps them develop. While they don’t transmit diseases, the itching from their bites can be intense and distracting.
2. Dust Mites
Millions of these eight-legged microscopic relatives of spiders are probably living in your mattress right now. Dust mites gorge themselves on the dead skin cells you shed every night, thriving in the warm, humid environment of bedding and upholstered furniture.
You can’t see them without magnification, but their waste particles become airborne and can trigger sneezing, watery eyes, or breathing difficulties in sensitive individuals. Regular washing of bedding in hot water helps control their populations, though eliminating them completely is nearly impossible.
3. Demodex Mites
Right now, tiny eight-legged mites are living headfirst in your facial pores and eyelash follicles. Demodex mites have elongated, worm-like bodies that burrow deep into hair follicles and oil glands, emerging at night to mate on your skin’s surface.
Nearly every adult carries these creatures without realizing it. They feast on dead skin cells and the oils your glands produce. Most people experience no symptoms from these permanent residents, though an overpopulation can sometimes contribute to skin irritation or redness around the eyes and nose.
4. Tapeworms
Imagine a flat, ribbon-like creature that can grow several metres long inside your digestive tract. Tapeworms enter through undercooked beef, pork, or fish, then use their hook-covered heads to latch onto intestinal walls.
These parasites have no mouth or digestive system of their own. Instead, they absorb nutrients directly through their skin as digested food passes by. Their bodies consist of repeating segments that break off and exit the body, potentially spreading eggs to continue the cycle. Proper cooking temperatures destroy tapeworm larvae before they can infect you.
5. Hookworms
Walking barefoot on contaminated soil can give these parasites an entry point through your skin. Hookworms have curved bodies and mouths equipped with sharp cutting plates that slice into intestinal tissue so they can feed on blood.
After penetrating the skin, often between toes, they travel through blood vessels to the lungs, get coughed up, swallowed, and finally settle in the small intestine. Heavy infections can cause anaemia and fatigue as the worms consume blood. Wearing shoes in areas with poor sanitation provides effective protection against these bloodsuckers.
6. Scabies Mites
Few things sound worse than microscopic bugs tunnelling under your skin to lay eggs. Scabies mites are eight-legged parasites that burrow into the upper skin layers, creating visible tracks as they move and deposit eggs along the way.
The intense itching comes not from the mites themselves but from your immune system reacting to their presence and waste. Transmission requires prolonged skin contact, making family members and close contacts vulnerable.
Medical treatment with prescription creams kills both mites and eggs, though itching may persist for weeks afterward as your body clears the allergic reaction.
