Sarcoptes Scabiei Life Cycle

Sarcoptes scabiei, parasitic mites better known as scabies, infest both animals and humans everywhere in the world. According to the Centers for Disease Control, the mites spread by skin-to-skin contact and are especially troublesome in crowded living conditions.

Symptoms of scabies are a skin rash accompanied by extreme itching. These symptoms, however, do not surface for between 2 and 6 weeks. Their hosts may spread the infestations during this time. The Sarcoptes scabiei life cycle has 4 stages.

Eggs

The Sarcoptes scabiei life cycle begins when a fertilized adult female mite burrows into the skin of a new host. It takes approximately 1 hour, according to Kansas State University, for the mite to make a burrow paralleling the skin's surface. Feeding on lymphatic tissue, she will extend the burrow between 0.5 and 5mm each day while laying her eggs behind her.

Larvae

Hatching in from 3 to 4 days, the 6-legged scabies larvae leave their burrows for the skin's surface, where they tunnel into shallow molting pouches around the hair follicles. After another 3 to 4 days in the pouches, they molt and become nymphs.

Nymphs

The 8-legged scabies nymphs remain sheltered in the hair follicles while molting. They first molt from protomymphs to tritonymphs and then to the adult stage. The process of developing from larvae to adult mites takes between 4 and 6 days.

Adults

While the adult males may make shallow burrows of up to 1mm, they normally remain on the skin's surface looking for females. The new adult females also create shallow burrows but, according to Kansas State University, the adults probably mate on the surface of the skin. The mortality rate of mites is highest while they search for mates. The entire Sarcoptes scabiei life cycle from egg to fertilized female lasts from 10 days to 2 weeks.

Treating Scabies

All scabies treatments require prescriptions. They include topical creams or lotions used over the entire body below the neck on adults and over the entire body including the head and neck in babies and children.

Sealing bedding, clothes, linens, and other personal items handled by infested people in plastic for 72 hours or more as part of the treatment will decontaminate them. Scabies mites, says the CDC, seldom survive longer than longer than that away from skin.

References

• CentersforDiseaseControl: Scabies
• Kansas State University: Pests that Affect Human Health

Resources

• McKinley Health Center: More about Scabies