The hallmark symptoms of scabies, itchy skin and rashes, are said to be triggered by your immune system, in response to the parasite that burrows into your body. But to know exactly what causes this infestation, you must know more about Sarcoptes scabiei – the mite that leads to scabies.
Facts About Scabies Mites
Sarcoptes scabiei is an eight-legged microscopic bug that thrives on human skin. Also called the “human itch mite,”1 this parasite is so tiny that it cannot be seen clearly with the naked eye, and may only appear as a speck.
Sarcoptes scabiei mites have a cream-colored body, with spines and bristles on their back. They feed using their mouths and use their front legs to burrow into the outer layer of skin (epidermis).2
Female scabies mites are bigger than males, measuring at least 0.4 x 0.3 millimeters. Males only grow up to 0.2 x 0.15 millimeters. The female mites are the ones that “burrow” into your skin and lay eggs. Here’s how their life cycle works:3
1. The female mites tunnels into the person’s skin, causing visible pencil-like lines to appear, where she then deposits her eggs. Each female mite lays around 40 to 50 eggs in her lifetime.
2. The larvae begin to hatch within three to 10 days. They then morph and become nymphs.
3. The nymphs mature and become adults within 10 to 15 days, with a lifespan of approximately four weeks. They then deposit additional eggs on the skin.
The burrowing and the movement of the mites inside the human skin cause extreme itching, as it triggers an allergic reaction to the mite proteins. The saliva and the feces of the mites may also trigger this allergic reaction.
How Are Scabies Mites Transmitted?
Sarcoptes scabiei mites cannot fly or jump; instead, they crawl slowly. For this reason, the most common transmission method is through direct and prolonged skin-to-skin contact that lasts at least 15 to 20 minutes. This means holding hands or sexual intercourse can transmit the mites, but a quick handshake or a hug cannot.4
Once scabies mites transfer to another host, they will usually move to warm areas of the body, where they thrive best. These include the skin folds, between the fingers and under the fingernails, around the buttocks and genital areas, and in the creases of the breast. They may also hide under rings, watch straps, and bracelets.5
Although these parasites cannot live without a human host, the bad news is that they can live for a short amount of time in the external environment, even without feeding on human skin. This means that they can be transferred on surfaces, clothes, bedding, and furniture, where they can live for a few days.
Unfortunately, scabies symptoms do not immediately show up after a person has been infested, especially if it’s for the first time. The symptoms typically show up in around four to six weeks. They also develop more quickly in individuals who already experienced a scabies infestation before. Usually, if it’s a recurrence, the symptoms can appear within one to four days after the exposure.
Beware because once a scabies mite infestation has been passed onto you, you become immediately contagious – you can pass scabies to other people even if you have not developed any symptoms yet. This is known as the incubation period.6