The human body is an ecosystem. In short, this means it’s made up of a host of other organisms.
From microscopic parasites to creeping insects, these creatures may live symbiotically, cause illness or – most likely – go entirely unnoticed. Here are a few that can live on or in your body.
10 animals that live on or in humans
Demodex mite
Tiny mites known as Demodex live on human skin, specifically in hair follicles and sebaceous glands. They are invisible to the naked eye, and most people are unaware of their presence. These mites are typically harmless, though in some cases, they can cause skin conditions such as rosacea.
Tapeworm
Tapeworms are parasitic flatworms that can reside in the intestines of humans after ingesting undercooked meat or contaminated water. These worms latch onto the intestinal wall, absorbing nutrients directly from their host. A tapeworm infection can lead to malnutrition, abdominal discomfort, and weight loss if left untreated.
Hookworm
Hookworms are parasitic worms that enter the body through the skin, usually via contaminated soil. Once inside, they migrate to the intestines where they attach and feed on blood. Symptoms of infection can include anemia, fatigue, and gastrointestinal distress, though some infections may go unnoticed for long periods.
Ascaris (Roundworm)
Ascaris lumbricoides is a large roundworm that infects the human intestines. The larvae can migrate through the bloodstream to the lungs before being swallowed back into the digestive tract. These worms can cause malnutrition and intestinal blockage, especially in severe infections, and are common in areas with poor sanitation.
Pinworm
Pinworms are tiny white worms that live in the intestines and lay their eggs around the anus at night, causing intense itching. Commonly affecting children, the infection spreads easily through contact with contaminated surfaces. While not usually dangerous, pinworm infections are highly irritating and can disrupt sleep.
Scabies Mite
Scabies is caused by the Sarcoptes scabiei mite, which burrows into the skin to lay eggs, causing intense itching and a rash. The infestation spreads through direct contact with an infected person. Without treatment, the mites continue to reproduce, leading to widespread skin irritation and secondary infections.
Loa Loa (Eye Worm)
Loa loa is a parasitic worm found in tropical regions that can live in the human eye. Transmitted through the bite of infected flies, the worm can migrate across the eye’s surface, causing irritation and swelling (and frankly, it's too gross to include a picture of). While the infection can be alarming, it’s treatable through medication or surgical removal.
Lice
Lice are small, wingless insects that infest human hair and feed on blood from the scalp. They spread through close contact and can cause intense itching due to their bites. Head lice are particularly common in children, but they are not harmful and can be treated with medicated shampoos or combing.
Toxoplasma gondii
This single-celled parasite can live in human tissues, particularly the brain and muscles, after being ingested via contaminated food or contact with cat faeces. While most infections cause no symptoms, toxoplasmosis can be dangerous for pregnant women and immunocompromised individuals, potentially leading to birth defects or serious illness.
Leech
Though typically found in freshwater, leeches can attach to human skin and suck blood. In rare cases, leeches can enter the body through the nose or mouth, such as when swimming in contaminated water. While leech bites are usually not dangerous, the blood loss and discomfort can be significant if left untreated.
