Head-to-head contact is by far the most common route of lice transmission.The United Kingdoms National Health Service, and many American health agencies, report that lice "prefer" clean hair, because its easier to attach eggs and to cling to the strands.Head lice (Pediculus humanus capitis) are not known to be vectors of diseases, unlike body lice (Pediculus humanus humanus), which are known vectors of epidemic or louse-borne typhus (Rickettsia prowazekii), trench fever (Rochalimaea quintana) and louse-borne relapsing fever (Borrelia recurrentis). Body lice
This condition is caused by body louse (Pediculus humanus humanus, sometimes called Pediculus humanus corporis), a louse which infests humans and is adapted to lay eggs in clothing, rather than at the base of hairs, and is thus of recent evolutionary origin. Pediculosis is a more serious threat due to possible contagion of diseases such as typhus. Epidemiology and treatment of human body lice is described in the article on body lice. Pubic lice
The pubic or crab louse (Pthirus pubis) is a parasitic insect which spends its entire life on human hair and feeds exclusively on blood. Humans are the only known host of this parasite, although it is more closely related to the louse parasites in other primate species, than are human head or body lice which probably evolved from it as the "original" louse infestation of humans. Epidemiology and treatment of pubic lice is discussed in the article on pubic lice. Other animals
Pediculosis is more common in cattle than any other type of domesticated animal.
Chemotherapy-induced acral erythema, also known as palmar-plantar erythrodysesthesia or hand-foot syndrome is reddening, swelling, numbness and desquamation (skin sloughing or peeling) on palms of the hands and soles of the feet (and, occasionally, on the knees, elbows, and elsewhere) that can occur after chemotherapy in patients with cancer. Hand-foot syndrome is also rarely seen in sickle-cell disease. These skin changes usually are well demarcated. Acral erythema typically disappears within a few weeks after discontinuation of the offending drug. Signs and symptoms
The symptoms can occur anywhere between days to months after administration of the offending medication, depending on the dose and speed of administration. The patient first experiences tingling and/or numbness of the palms and soles. This is followed 2-4 days later by bright redness, which is symmetrical and sharply defined.In severe cases this may be followed by burning pain and swelling, blistering and ulceration, peeling of the skin. Healing occurs without scarring unless there has been skin ulceration or necrosis (skin loss/death). With each subsequent cycle of chemotherapy, the reaction will appear more quickly, be more severe and will take longer to heal. Causes
Acral erythema is a common adverse reaction to cytotoxic chemotherapy drugs, particularly cabozantinib, cytarabine, doxorubicin, and fluorouracil and its prodrug capecitabine.Targeted cancer therapies, especially the tyrosine kinase inhibitors sorafenib and sunitinib, have also been associated with a high incidence of acral erythema. However, acral erythema due to tyrosine kinase inhibitors seems to differ somewhat from acral erythema due to classic chemotherapy drugs. Pathogenesis
The cause of Palmar-plantar erythrodysesthesia (PPE) is unknown.