Scabies is a skin condition caused by the parasite Sarcoptes scabiei.

The intense itching associated with scabies is thought to be caused by the immune system reacting to the mites and their saliva, eggs and faeces.

The scabies mite life cycle

A scabies infestation starts when a female mite burrows into your skin.

Male mites move between different burrow sites looking to mate. After mating, the male mite dies and the female begins to lay eggs, which hatch around three to four days later.

After hatching, the young mites move to the surface of the skin, where they mature into adults after 10 to 15 days. Male mites stay on the surface of the skin, while female mites burrow back into the skin to create a new burrow. The life cycle is then repeated.

Without effective treatment, the life cycle of the scabies mite can continue indefinitely. Scabies mites are resistant to soap and hot water and can't be scrubbed out of the skin.

How scabies is spread

Scabies mites can't fly or jump, which means they can only move from one human body to another if two people have direct and prolonged physical contact.

For example, scabies mites can be transmitted by:

• holding hands with an infected person for a prolonged period of time
• having sex with an infected person 
• sharing clothing, towels and bedding with an infected person (although this is rare)

It's unlikely that scabies will be transmitted through brief physical contact, such as shaking hands or hugging.

Scabies mites can survive outside the human body for 24 to 36 hours, making infection by coming into contact with contaminated clothes, towels or bed linen a possibility. However, it's rare for someone to be infected in this way.

Scabies infestations can spread quickly because people are usually unaware they have the condition until two to three weeks after the initial infection.

There's an increased risk of catching scabies in confined environments, such as schools and nursing homes, where people are in close proximity to one another.