Manifestations of lice
Sensitivity to the effect of louse bites varies with the individual. When previously exposed persons are bitten, there may either be no signs or symptoms or a slight sting with little or no itching or redness. At least 5 days must pass before allergic sensitization can occur. At that point, the main symptom is itching, which leads to scratching, red skin, irritation, and inflammation. An individual who has been bitten by a large number of lice over a short period may have mild fever, malaise, and increased irritability.
Ectoparasites produce a variety of immunologic responses in the host. Apparently, many persons eventually develop some degree of immunity to the bite of the louse. Persons infested for a long time may even becomes oblivious to the lice on their bodies. The opposite may also occur. Excessive scratching may lead to superinfection. Characteristic small “blue spots” may appear in the skin as a result of the crab louse bites; these persist for several days. A tubo-ovarian inflammatory mass attributed to P. pubis has been reported.