A 10-year-old school girl has recurrent episodes of boils on the scalp. The boils subside with antibiotic therapy but recur after some time. The most likely cause of the recurrences is -

Signs & symptoms. A ticklish feeling on the scalp or neck. An itchy scalp (the result of an allergic reaction to the bug's saliva). Small red bumps on the scalp, neck and shoulders. The presence of lice on the scalp. The presence of nits (lice eggs) on shafts of hair. Difficulty sleeping, which can lead to irritability Ref Harrison20th edition pg 1109