Scabies - mite it be a problem on the foot?

I came across an article in the paper with the headline “Medieval skin disease leaving patients’ flesh ‘crawling’ surges through the UK”. It was referring to an age-old infestation that is having somewhat of a renaissance in the UK, particularly amongst university students throughout the UK. So, I thought it might be good to have a look in this blog at scabies and how it may present in the podiatry clinic.

Scabies on the foot of a young man. Intensely icthy, particularly in bed at night. Similar lesions were observed on the hands.

What is Scabies?

 

Scabies is a contagious infestation caused by Sarcoptes Scabiei var. Hominis. Perhaps it's surprising to learn that it is part of the spider family (Arachnida) but the 8 legs are probably a strong clue. The female mite is just visible with the naked eye at 0.4mm long and 0.3mm wide with the male being about a third smaller.

The female scabies mite : Source

The infestation is most commonly acquired from skin-to-skin contact with an infected individual. Rarely, it can be acquired from contaminated clothes and bed clothes and so outbreaks are frequently seen in places where people live in close proximity such as family and communal premises. The female burrows into the epidermis and lays 40-50 eggs in her burrow in her short 6-week lifespan (2-3 eggs daily). The mite prefers areas where there are fewer pilosebaceous units hence it is seldom found on the head and neck [1].

The eggs hatch within 4 days as larvae that migrate to the surface mature to adulthood in around 10 days and make their own burrows on the skin, spread to a new host or they are scratched from the skin's surface by the suffering individual. In a classic infection, the numbers of mites may be small (5-10) but the itching caused is significant to the sufferer. Mites can survive up to 36 hours off of the host, particularly at lower temperatures. 

How common is Scabies?

Globally around 200 million people are affected at any one time, with around 400 million being infected every year [2].

Clinical Presentation

Often termed the easiest and yet the most difficult diagnosis in dermatology, scabies can have a varied clinical presentation and morphology. Itching is the cardinal symptom associated with the condition, particularly worse at night when the female mites become active. The onset of symptoms occurs up to four weeks after infection although reinfection can trigger the symptoms much more rapidly. Common areas include the fingers (particularly the web spaces), armpits, buttocks, areola (women) and genitalia (in men) although lesions on the foot are not uncommon, particularly in the elderly and young children. Bullous scabies is also a rare but recognised presentation of the disease [3].

Visually the patient may present with a papular rash with short excoriations. The burrows are typically brownish and tortuous. Redness, papules and itching may arise due to hypersensitivity to the presence of the mites and their faeces and so can vary from person to person.

Diagnosis

The diagnosis of scabies does not have strict criteria as it's often based on clinical appearance. Until recently, diagnosis of scabies infestation was made via skin scraping, a method similar to the procedure in the 16th century [4]. Confirmation of the diagnosis was made by extracting and identifying a female mite from a burrow, various techniques exist but a drop of ink onto affected skin highlights the burrow from which a needle is carefully inserted to impale and remove the kicking female mite. Barely visible with the naked eye a microscope can provide conclusive proof to the practitioner (and a patient who may deny they have the infestation).

The 2020 Consensus Meeting on the topic suggest at least one of the following to secure a solid diagnosis [5]:

1. Mites, eggs or faeces on light microscopy of skin samples.

2. Mites, eggs or faeces visualized on an individual using a high-powered imaging device.

3. Mites, visualized on an individual using dermoscopy.

When this is lacking, diagnosis is normally based on the clinical features of nocturnal itch and lesion distribution when other diagnoses have been ruled out.

More recently the use of dermoscopy has reduced the need for mite mining and its associated discomfort. Under polarised light the head part of the mite in a burrow appears as a triangular or “delta” shape [6]. More recently, dermatoscopes equipped with UV light can more easily highlight the presence of a tunnel, a mite or its faeces as it produces a bright fluorescence [7].

Dermatoscopic view of a burrow, eggs and mite .Source.

Complications

For a few patients scratching can lead to secondary issues such as bacterial infection with staphylococcus (impetiginisation) or eczematisation. Excoriation can break the skin's natural barrier and secondary infection of the skin or deeper (including septicaemia, glomerular nephritis and rheumatic fever). The condition has also led to amputation in a diabetic patient through secondary infection [8].

In cases of infestation where the patient is immunocompromised, crusted scabies may develop. Extensive mite infestation occurs with thick crusting and fissuring in immunocompromised individuals. Often there is no pruritus associated with the condition. Common areas affected include the hands, fingers and feet.  Typical underlying conditions include AIDS, T-cell leukaemia, organ transplantation or diabetes mellitus or patients using systemic steroids [9].

Crusted scabies on the plantar surface. Source

Treatment  

In the UK, 5% permethrin cream is the first line treatment - a natural chemical derived from a flowering plant of the aster family [4]. The cream is applied uniformly over all the body from the neck downwards. Every part of skin must be covered with special attention paid to skin creases, the genitalia and underneath the nails. The face and scalp should only be treated if they are affected. The cream is washed off after 12-24 hours. The procedure is repeated in 7 days. Pts should be advised that the itching can continue for a weeks after successful eradication of the mite. Any family members are generally treated in the same way, but with only one application.

Oral Ivermectin (licensed this year for scabies in the UK) is used when the permethrin treatment fails, or is unavailable, or difficult to apply (such as in care homes with large numbers of people, for example). Two doses of the drug (15mgs) 14 days apart to treat any recently hatched mites (details here). 

The History of Scabies

Scabies has plagued humans for centuries. The name of the mite is a blend of two languages. Sarcoptes from sarx koptein - meaning flesh cutting (Greek) and scabiei from “scabere” to scratch (Latin), with Celsus first coining the term “scabies”. Despite this, the causative mite wasn't discovered until the 17th century. Hauptmann first sketched it in 1657 [10] but it was first extracted and identified under a microscope in 1687 by Giovanni Cosim Bonomo. Joseph Adams demonstrated its infectivity when he self-infected himself in 1801 .

Questions about how it was spread remained until the 1940’s, during the war, when Mellanby experimented on willing conscious objectors [11]. By various experiments he demonstrated that skin to skin contact was the main transmission route and infection from infected bed linen and clothes, whilst possible, was rare. Such work inspired the following poem [12]:

Recondite research on Sarcoptes

Has revealed that infections begin

At home with your wives and your children

Or when you are living in sin

Except in the case of the clergy

We accomplish remarkable feats

And catch scabies and crabs

From door handles and cabs

And from blankets and lavatory seats.

Current Infection rates

In the last two years we have seen reports in the media and from dermatological colleagues that cases are surging in the UK, at a five-year peak. The reasons for this are not clear with some suggestion the infestation naturally goes through peaks and troughs in prevalence, others suggesting some form of resistance to treatment. Whilst there is no evidence of drug-resistant mites, other factors may be at play.

Firstly, public awareness of the condition maybe low. An itchy skin rash may not be considered serious enough to warrant seeking medical attention, or access to GP services may be delayed with many patients unaware they may have an infestation. In addition, shortages of medicines mean cases may be prolonged and so prevalence rates are increased. Finally, eradication of scabies using a topical agent require meticulous application and re-application, following the correct procedure. Failure to achieve this may lead to relapse and reinfection. Close family members and house mates should also be treated in the same way as incubation can be up to 4-6 weeks.

Calls have been made to healthcare practitioners to be mindful of the condition and not neglect the diagnosis as a minor skin complaint and to initiate treatment to prevent further spread of the disease and reduce the risks of serious secondary effects. As podiatrists, its important to be aware that scabies is particularly prevalent in the community at the moment in the UK. Any patient with a particularly itchy skin rash on their feet or legs (worse in bed at night) should certainly have scabies ruled out as a diagnosis.

References

1.            Griffiths, C.E., et al., eds. Rooks's Textbook of Dermatology. 9th ed. 2016, Wiley: London.

2.            Thomas, C., et al., Ectoparasites: Scabies. Journal of the American Academy of Dermatology, 2020. 82(3): p. 533–548.

3.            Luo, D.-Q., et al., Bullous Scabies. The American journal of tropical medicine and hygiene, 2016. 95(3): p. 689–693.

4.            Lam, J.M. and W. Rehmus, Scabies: a historical perspective. International Journal of Dermatology, 2024. n/a(n/a).

5.            Engelman, D., et al., The 2020 International Alliance for the Control of Scabies Consensus Criteria for the Diagnosis of Scabies. British Journal of Dermatology, 2020. 183(5): p. 808–820.

6.            Argenziano, G., G. Fabbrocini, and M. Delfino, Epiluminescence microscopy. A new approach to in vivo detection of Sarcoptes scabiei. Arch Dermatol, 1997. 133(6): p. 751–3.

7.            Yürekli, A., et al., Using ultraviolet dermoscopy in diagnosing scabies. Experimental Dermatology, 2023. 32(11): p. 1996–1999.

8.            Kruse, M., et al., Crusted Scabies leading to osteomyelitis and bilateral below-the-knee amputations - a case report. The American Journal of Emergency Medicine, 2025.

9.            Cuellar-Barboza, A., et al., A case of hyperkeratotic crusted scabies. PLoS Negl Trop Dis, 2020. 14(3): p. e0007918.

10.         Burton, J.L., Essentials of Dermatology. 1985, Edinburgh: Churchill LIvingstone.

11.         Ryan, S.-L. and B. Kirby, Scabies: a historical perspective. Clinical and Experimental Dermatology, 2025. 50(11): p. 2308–2309.

12.         Burns, D.A., A potpourri of parasites in poetry and proverb. BMJ, 1991. 303(6817): p. 1611–4.