Mites on Our Skin Explained: Demodex, Scabies, and Why They Itch

Overview

In this Strange Health episode from The Conversation, host Katie Edwards and GP Dan Bamga explore mites that live on our skin, focusing on Demodex in the face and the public health relevance of scabies outbreaks. They explain what these tiny organisms do, how common they are, and why itching is not always caused by an infestation, while debunking myths about fumigation and hygiene.

Key topics

• Demodex biology and nighttime activity
• Scabies symptoms, transmission, and treatment
• Impact of mites on skin conditions and public health messaging

Introduction

In this Strange Health episode from The Conversation, host Katie Edwards and GP Dan Bamga introduce listeners to the world of skin mites. They explain that our bodies host trillions of microorganisms, including two species of follicular mites Demodex, which are generally harmless and active at night, feeding on oils in the pores. The episode moves from cute descriptions to a science-based framework for distinguishing normal skin flora from pathogenic infestations such as scabies, which has seen a surge in the UK and parts of Europe.

Demodex Mites on the Face

The conversation shifts to Demodex, focusing on how these mites live in hair follicles, particularly around the eyelashes. Alejandra Perrotti, an invertebrate biology professor at the University of Reading, explains that both Demodex folliculorum and Demodex brevis are common in adults, increase with age, and are usually harmless. She describes their nocturnal activity, their reliance on host melatonin, and their mating behavior inside pores. The host experiences itchiness less often caused by mites, with other skin conditions more likely behind face itching.

Public Health Context: Scabies

The hosts discuss scabies as a contagious skin infestation with intense itching. They explain that scabies transmission requires prolonged skin contact and that the condition is treatable with topical creams such as permethrin, typically applied from the neck down and repeated a week later to cover eggs. They mention crusted crusty Norwegian scabies as a severe form, now more accurately called crusted scabies, with historical anecdotes. They emphasize that scabies risk is linked to immune compromise or neglect, not dirtiness, and highlight the importance of treating close contacts and washing clothes at high temperatures to prevent re-infestation.

Myths, Misconceptions and Psychology

They address online misinformation about killing Demodex, delusional parasitosis, and the contagious nature of itching. They describe how humans fear infestation while the mites are a normal part of the human microbiome, and how itch can be contagious via neural mimicry. They emphasize that the skin is an ecosystem with defensive barriers but also a habitat for many organisms. The expert notes that if there is any skin disease, the mites may congregate due to the host's immune status, not due to the mites causing the problem.

Expert Perspective and Practical Takeaways

Alejandra Perrotti discusses life history traits of Demodex and their role in skin ecology. The show also covers lice and other parasites, and offers practical guidance on management. For head lice, wet combing with a fine-toothed comb on conditioned hair is recommended, with caution about resistance to chemical lotions and the value of combining methods. For scabies, close contacts should be treated, and all clothing and bedding washed at 60C or hotter, with tumble drying to kill mites and eggs. The conversation ends with a reminder that mites are part of our bodies and that fear should be replaced with understanding and evidence-based care.

Guest Spotlight

Alejandra Perrotti, an invertebrate biologist from the University of Reading, explains the Demodex species, their size around 200 micrometers, and how they can cluster inside pores, especially in older adults. She clarifies that Demodex do not produce melatonin themselves but are responsive to the host's melatonin, which triggers nocturnal activity and reproduction. Her insights ground the discussion in biology rather than sensationalism, and she stresses that most people carry these mites without problems unless immunity is compromised.

Conclusion

The episode concludes with a constructive message that mites are a natural part of the human ecosystem and that evidence-based medicine, rather than fear, should guide diagnosis and treatment. Listeners are invited to share questions and health claims for future episodes.