Scabies is a skin infestation caused by a tiny, eight-legged mite known as Sarcoptes scabiei var. hominis. This microscopic parasite burrows into the outermost layer of human skin, where it lives and lays its eggs. The presence of these mites, their eggs, and their waste products triggers an allergic reaction in the host. This reaction typically manifests as intense itching, often worse at night, and a characteristic pimple-like rash on the skin.
Scabies Mites and Water Survival
Scabies mites cannot be effectively drowned or washed away with water. Female mites burrow into the stratum corneum, the tough, outermost layer of the skin. These burrows are tiny tunnels, typically a few millimeters to a centimeter in length, where the female mite resides and lays two to three eggs daily. Water from bathing, showering, or swimming cannot penetrate these protective burrows to reach and eliminate the mites.
The mites are microscopic. While scabies mites generally do not survive more than 72 hours away from human skin, they can persist longer in conditions like crusted scabies. Simple water exposure is not a viable method for eradicating an infestation. Even in swimming pools, transmission or effective treatment is extremely low because the mites are protected within the skin and are not easily dislodged.
Proven Scabies Treatments
Since water is ineffective against scabies, medical intervention is necessary to eliminate the infestation. Treatment primarily involves prescription medications designed to kill the mites and their eggs. A healthcare professional can provide an accurate diagnosis and prescribe the most appropriate treatment plan.
Topical medications are a common first-line approach, with permethrin 5% cream widely recommended for its effectiveness against both mites and their eggs. Patients typically apply the cream to all body areas from the neck down, leaving it on for 8 to 14 hours before washing it off; infants and young children require application to their entire head and neck as well. Often, a second application is needed about one week later to ensure all newly hatched mites are eliminated. Sulfur cream is another topical option, sometimes used for infants younger than two months or pregnant individuals.
In some situations, oral medications like ivermectin may be prescribed, especially for more severe cases such as crusted scabies or when topical treatments are not feasible. Ivermectin is taken as a pill and is effective, though it is generally not recommended for pregnant or nursing individuals, or children below a certain weight. While these medications kill the mites, itching can persist for several weeks after treatment as the body continues to react to the dead mites and their byproducts.
Environmental cleaning is an important complementary step to prevent re-infestation. All bedding, clothing, and towels used by the infested person within the last three days should be washed in hot water and dried on a high heat setting. Items that cannot be machine-washed, such as stuffed animals or delicate fabrics, should be sealed in plastic bags for at least 72 hours to a week to starve any remaining mites. Vacuuming upholstered furniture, carpets, and mattresses can help remove any mites that may have fallen off the host.