Mites are small eight-legged creatures, grouped together in the subclass Acari. Some of them may transmit or cause disease. Here are the well-known mite-associated diseases.
Scabies
It is the most well-known mite-borne disease. Scabies is a contagious skin condition caused by tiny Sarcoptes scabiei mites that burrow under the skin, causing intense itching (especially at night) and small red bumps or burrows, often in skin folds (between fingers/toes, wrists, elbows, armpits, groin, waist, breasts, genitals, and in infants even head, face, palms or soles). It spreads through prolonged skin-to-skin contact, or shared bedding/clothing. It spreads easily in childcare centres, nursing homes, and dorms, camps, and other crowded places of close contact.
It is treated with prescription creams or oral medications (like permethrin or ivermectin) to kill the mites. Proper hygiene and treatment of close contacts are crucial for stopping transmission.
- Permethrin cream (5%) is a common, safe choice for most, including pregnant individuals and children over 2 months, applied from neck down.
- Other topical creams or ointments like sulfur, crotamiton, malathion, or benzyl benzoate may also be used. The creams are to be applied to the entire skin, including hands, feet, skin folds, under nails, and scalp (especially in infants/elderly), and left on for the prescribed time (often overnight) before washing off.
- Ivermectin pills are prescribed for severe or crusted scabies, often in multiple doses, or when creams fail. Itching may last 1-2 weeks after the mites are gone due to an allergic reaction, so antihistamines may be prescribed.
- Everyone in close contact should be treated simultaneously to stop the cycle.
- Inadequate application of medicines can lead to persistent symptoms or re-infestation.
- Wash bedding, clothes, and towels used in the last few days in hot water (60°C/140°F) and dry on a hot setting. Items that can’t be washed should be sealed in a plastic bag for at least 3 days, ideally a week, to kill mites.
Scrub Typhus (Bush Typhus)
It is a bacterial infection (bacteria – Orientia tsutsugamushi) that spreads via bites from infected trombiculid larval mites, commonly referred to as chiggers or harvest mites, and also known as berry bugs, bush-mites, red bugs or scrub-itch mites, found in rural Asia-Pacific. The chiggers bite rodents (rats, mice) and become infected, and they then transmit the bacteria to humans. Scrub Typhus is endemic in rural parts of Asia (India, Japan, China), Southeast Asia, Indonesia, and northern Australia.
Symptoms typically appear 1-3 weeks post-bite and include sudden high fever, chills, headache, body aches, fatigue, swollen lymph nodes (lymphadenopathy), rash, and red eyes. A black, scabbed sore at the chigger bite site called eschar is the most common sign. It is diagnosed by ELISA IgM blood tests based on the region and symptoms.
Treatment is with early antibiotics, but without treatment, symptoms can last weeks, and it can be severe. First-line antibiotics are doxycycline, the drug of choice for adults and children, taken orally (e.g., 100mg twice daily) for at least 7 days or until 48 hours fever-free. Azithromycin is a good alternative, especially for pregnant women or those allergic to doxycycline, often given as a single or short course. Other antibiotics include chloramphenicol (reserved for severe cases due to potential side effects), and ciprofloxacin (used, especially if first-line treatments fail). Maintaining hydration is important, and analgesic-antipyretic drugs like paracetamol may be used for fever and pain. Severe Cases may require intravenous (IV) antibiotics, oxygen, or mechanical ventilation, and dialysis for kidney failure. While death is rare, it can occur due to severe disease causing multiorgan failure, seen mostly when treatment is not started timely. Scrub typhus mortality varies significantly by region and treatment, ranging from around 1.5% overall to over 8% in hospital settings, potentially reaching 30% if untreated.
Precautions include avoiding rural, bushy areas in endemic regions, using insect repellent on skin and clothing, and wearing protective clothing (long sleeves, pants) when in vulnerable areas.
Rickettsialpox
It is a mite-borne infectious disease caused by the bacterium Rickettsia akari that spreads by the bite of an infected house mouse mite. Symptoms start about a week post-bite with a small sore that appears at the bite site, which develops into a fluid-filled blister that forms a black scab sore (eschar). Other symptoms include fever with chills and sweating, headache, muscle pain, in some cases sensitivity to light (photophobia), and a generalized rash appearing on the face, trunk, and extremities consisting of firm, red, raised bumps (papules) that can become blister-like (vesicular).
Diagnosis is based on symptoms confirmed by blood ELISA tests and skin biopsy. The condition is typically mild with almost zero mortality rate. It is treated with antibiotics, and usually resolves on its own in two to three weeks. Doxycycline is the drug of choice and can significantly shorten the duration of symptoms. Preventing contact with house mouse mites is key, by keeping homes and workplaces clean and free of rodents, and wearing protective gear when in high-risk areas.
Other mites
Other known skin mites are Demodex mites, common inhabitants on human skin and its pores, and house dust mite (HDM) in indoor environments. Demodex mites are common inhabitants on human skin and its pores and hair follicles, and usually don’t cause any harm. But these mites can multiply in conditions of poor hygiene or low immunity and cause skin irritation and rash (demodicosis). House dust mites can trigger allergies (like allergic rhinitis, asthma, and atopic dermatitis) in those susceptible.
Also read:
Skin Conditions causing Itching (Pruritis), Dermatitis (Eczema), or Rash
Skin Infections – Types, Predisposing Factors and Health Measures
Overview of 10 Zoonotic Diseases: Infections that spread from Animals to Humans