Scabies is a skin infestation caused by the microscopic mite Sarcoptes scabiei, which burrows into the outer layer of human skin to live and lay eggs. Because the condition is highly contagious, people often search for how long the mites can survive on inanimate objects like clothing and bedding. Environmental cleaning is an important measure to take in conjunction with medical treatment for an infested individual.
Survival Time Off the Human Host
The scabies mite cannot survive for long periods once it is separated from the human body, as it requires the warmth and sustenance of its host to live. For common scabies, mites typically survive for 24 to 72 hours away from the skin on fabric items like clothes and towels. This short lifespan is due to the mite’s inability to regulate its body temperature and its susceptibility to dehydration in typical indoor environments. Survival time is highly dependent on environmental conditions, with low humidity and high temperatures significantly decreasing viability.
Under cooler temperatures and higher humidity levels, the mites can potentially survive for a slightly longer duration, though they become less active and infectious. In the case of crusted scabies, a more severe form of the infestation where the host harbors thousands of mites, the number of mites shed into the environment is much higher, and they may survive for up to seven days. The risk of transmission from contaminated objects is higher with crusted scabies compared to the more common form. For common scabies, environmental contamination is a low-risk source of transmission after the three-day mark.
Environmental Decontamination Methods
Since mites can survive on fabrics for a limited time, treating clothing and other household linens is a necessary step in managing an infestation. The most effective method for decontamination is using high heat to kill the mites and their eggs. All clothing, bedding, and towels used by an infested person in the three days prior to treatment should be addressed on the same day the individual begins medical treatment.
Washing these items in a washing machine using a hot water cycle is recommended, specifically temperatures exceeding 50°C (122°F) for at least 10 minutes. Following the wash, drying the items in a hot dryer cycle is an equally effective measure, with 20 minutes on high heat being sufficient to kill any remaining mites. For items that cannot be washed or exposed to high heat, such as stuffed animals or dry-clean-only garments, isolation is an alternative method. These non-washable items should be sealed inside a plastic bag and stored for at least 72 hours, ensuring the mites die from lack of a host.
Addressing Reinfestation Risks
While environmental cleaning is a helpful measure, it is only one part of successful scabies eradication and is secondary to treating the infested person. The primary way scabies spreads is through direct, prolonged skin-to-skin contact with an infested individual. Transmission from inanimate objects, known as fomites, is unlikely for common scabies because the mite cannot reproduce or sustain itself off-host.
Simultaneous medical treatment of all close contacts and household members is the most important action to prevent reinfestation. Cleaning the environment helps eliminate the small risk of acquiring mites from clothes or bedding, but it does not address the source of the infestation. The risk of transmission from surfaces like furniture or carpet is low, and routine cleaning and vacuuming are sufficient for non-crusted scabies cases.