You will be given a definition of a task first, then some input of the task.
Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Context: The similarities of the larval and nymph stages of the tick and louse (Pthirus pubis) may lead to misdiagnosis in rare cases of infestation of the eyelashes. The most frequent manifestations of tick in the eye are conjunctivitis, uveitis, keratitis, and vasculitis. Tick inoculation of the skin can locally lead to formation of granuloma and abscess. More concerning is the potential systemic sequelae that can result from transmission of zoonoses such as Lyme disease. P. pubis can cause pruritic eyelid margins or unusual blepharoconjunctivitis. We present a case of phthiriasis palpebrarum in a 4-year-old boy.
Question: What is the cause of Phthiriasis Palpebrarum?
Output:
pthirus pubis