This Rash Is Often Mistaken for Eczema—But It’s Contagious! Seek Care If You Notice These Symptoms

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I came across a post online: A family has been itching for over a month, and tried all kinds of medicines without improvement. Finally, they were diagnosed with scabies.

Many people may not be familiar with ‘scabies,’ but it is a common problem for those who stay in budget hotels, share accommodations, or visit public bathhouses.

Its most typical characteristic is that it hardly itches during the day, but at night it becomes unbearably itchy, making it impossible to sleep. Many people initially treat it as eczema, but the condition worsens.

What exactly is this disease, and how is it contracted?

What is Scabies?

Scabies is a disease caused by Sarcoptes scabiei that takes up residence on the surface layer of the human skin. The skin is highly sensitive to this invasion, and as mites burrow into the skin and lay eggs, this disturbance leads to persistent rashes and itching.

Scabies mites are tiny, with adult bodies measuring about 0.3-0.5mm in length, ranging from milky white to brown, almost invisible to the naked eye, with four pairs of legs, male mites are slightly smaller, female mites are slightly larger, female mites are the primary causative agents (females tunnel and lay eggs in the skin, causing inflammatory reactions that lead to severe itching) .

The life cycle of scabies mites includes four stages: eggs, larvae, nymphs, and adults, all of which can be completed within the human skin, with a life cycle of about 2-3 weeks .

Female mites dig tunnels in the epidermis of the skin, lay eggs inside the tunnels, and after the eggs hatch, they develop into larvae, nymphs, and eventually adults. After mating, the male mites die, while female mites continue to dig tunnels and lay eggs, reproducing continuously.

Scabies mites mainly parasitize on the thin, wrinkled parts of the human skin, commonly affected areas include: sides and webs of fingers, flexor aspects of wrists, extensor aspects of elbows, anterior and posterior axillary folds, areolae and surrounding skin (especially in women) , periumbilical skin, waist, male genitalia (scrotum, penis, glans penis) , extensor aspects of knees, lower half of buttocks and adjacent thighs, lateral and posterior aspects of feet, infants and young children may be affected on the face, scalp.

How is Scabies Contracted?

In the TV series ‘Ruyi’s Royal Love in the Palace,’ the wise and noble Consort Gao Xiyue, who felt manipulated by Emperor Qianlong, used a cushion infested with scabies mites to infect the emperor with scabies.

Of course, for dramatic tension and plot requirements, films and TV dramas often contain fictional elements about the condition and treatment, but this plot also expresses a major characteristic of ‘scabies’ – its contagiousness.

Scabies mites are usually transmitted through long-term skin contact, and places like hotels, hostels, dormitories, nursing homes, welfare institutions, and public bathhouses are high-risk venues.

However, scabies mites do not jump or fly, and their crawling speed is also very slow, so, quick handshakes, hugs, and medical examinations are unlikely to spread scabies.

How to Determine if It’s Scabies?

Scabies in its early stages looks very similar to other rashes and may be confused with other skin diseases. The following image compares scabies with common acne and mosquito bites.

Left: Scabies; Upper Right: Acne; Lower Right: Mosquito Bites

The most distinctive feature of scabies is paroxysmal severe itching , which worsens at night or in warm environments (such as under the covers) , severely affecting sleep. Scratching can lead to skin scratches, scabs, and even secondary infections. Eczema can also be itchy, but it does not necessarily worsen at night, and family members are generally not itchy over a large area at the same time.

A typical skin manifestation of scabies is multiple red papules that are often scratched open. Sometimes, 2-15mm long gray, red, or brown serpentine fine lines, i.e., tunnels, can be seen. Tunnels are another characteristic manifestation of scabies , but they are usually not visible due to skin scratching or secondary infections.

In addition to tunnels, patients may also have various types of rashes, mostly caused by mite bites, secretion irritation, and scratching-induced inflammatory reactions , such as small papules the size of rice grains, and clear vesicles the size of pinheads to green peas.

In real life, there are also some diseases that are very similar to scabies, such as herpetiform dermatitis, bullous pemphigoid, and infantile acropustulosis. The differential diagnosis of these diseases is more complex and will not be discussed in detail here. It is recommended to consult a dermatologist, but there is one issue that everyone should pay attention to, namely delusional infestation .

It is also known as delusional parasitosis, a rare condition where patients have persistent false beliefs (delusions) that they are infected by ‘bugs,’ such as parasites, worms, mites, bacteria, fungi, living linear objects, or other organisms. Like all delusions, this belief cannot be corrected by reasoning, persuasion, or logical arguments.

Many patients function well, but a few people with delusional parasitosis may have their daily activities disrupted, and occasionally there are patients with other itching diseases who firmly believe they have scabies, but this is not the case.

It is hoped that patients suffering from delusions, after being ruled out of parasitic infections by professional doctors, can recognize that their condition may not be caused by bugs, and seek help from psychiatrists or psychologists when necessary.

How to Treat Scabies?

If you unfortunately find yourself experiencing severe itching that worsens at night and can’t be relieved by scratching, especially if you have recently traveled, stayed in hotels, or visited saunas where you may have had close contact with unclean bedding and towels, it is recommended to seek medical attention promptly.

The principles of treating scabies are: to eradicate the pathogen, isolate and disinfect, and provide symptomatic treatment.

1. Medication

Different countries use different anti-scabies drugs for the treatment of classical scabies. The most commonly used first-line treatments internationally are topical 5% permethrin and oral ivermectin.

However, oral ivermectin is not approved in our country, and 5% permethrin is not available with a national drug approval number. The permethrin available through domestic e-commerce channels is mixed in quality, so it is recommended to purchase or use it under the guidance of a dermatologist.

The most commonly used drugs in our country are sulfur ointment, benzyl benzoate cream, and 1% y-666 cream.

The most commonly used is sulfur ointment (adults use 10-20% concentration, children use 5-10%) ; adults apply it to the entire body from the neck down, once a day for three days, and then take a bath and change clothes on the fourth day, which is one course of treatment, during the treatment, do not bathe or change clothes, if there are still rashes or night itching after treatment, repeat the treatment until cured.

In addition, when itching is severe, oral antihistamines can be taken or sedating anti-itch medications can be taken before bedtime. If scabies nodules occur, topical corticosteroid creams or tar gels can be applied, or betamethasone suspension can be injected into the nodules, etc.

2. Disinfection

Under normal conditions (ambient temperature and average humidity) , scabies mites can survive for 24-36 hours after leaving the host, and can survive for a longer time at lower temperatures and higher relative humidity , sobedding or towels can also be transmission routes.

This makes scabies easily transmitted among family members or sexual partners. As part of the treatment, patients should be isolated in a timely manner, and patients in households or dormitories should be treated simultaneously, and contaminated items (clothing, towels, bedding) should be disinfected by boiling.

Scabies mites belong to the class Arachnida, order Sarcoptiformes, family Sarcoptidae, and are divided into human scabies mites and animal scabies mites, which are different types of mites.

Humans who come into contact with pets infected with scabies may be infected with animal scabies mites, but these mites cannot reproduce on human skin , they will die naturally and thus will not cause symptoms.

Disclaimer: The article is intended to provide general health information. For personal medical issues, please consult a doctor. To reprint the article, please contact: medicine@distinctclinic.com.