Clothing lice ferry typhus when hygiene collapses
The body louse lives in the seams of clothing rather than on the scalp and spreads only by close contact. It looks exactly like a head louse yet keeps to a different habitat, and it can spread the germs behind typhus, relapsing fever, and trench fever wherever crowding and a lack of clean clothes let it thrive.
Pediculus humanus humanus—also called the clothing louse or cootie—is a blood-feeding ectoparasite of humans, one of three human lice alongside head and pubic lice. Females glue most eggs into clothing rather than hair. Unable to jump or fly, lice move by person-to-person contact or, less often, via infested garments and bedding. Adults are wingless and six-legged, tan to greyish-white, and roughly 2.5 to 3.5 millimetres long.
As disease vectors they can transmit agents of epidemic typhus, trench fever, and relapsing fever. In wealthy countries infestations cluster where poverty, crowding, and limited washing or laundry access coincide. Under lab conditions body and head lice interbreed and look alike, yet in nature they occupy different niches and seldom meet; both can take several blood meals a day. Its split from the head louse, once dated to about 107,000 years ago, was used to fix the latest date for humans adopting clothes, but newer transcriptome studies question whether lice can answer that at all.
Life cycles run egg, nymph, adult. Cemented nits may linger months on fabric after hatching. Newly emerged nymphs feed immediately, retreat into clothing, and molt three times over roughly nine to twelve days before adulthood. Because the insect lives in fabric, the basic remedy is to change clothes and bedding regularly and launder them in water of at least 50 °C. Linnaeus first described the species, and when its genome was sequenced in 2010 it was the smallest insect genome then known. The diseases it carries are serious: untreated epidemic typhus kills about 30 percent of patients and relapsing fever between 10 and 40 percent, although one dose of doxycycline can cure typhus.
Source: Body louse
