Varicella Chickenpox. Varicella Chickenpox is caused by a virus of the herpes group. The disease is highly contagious and is spread by droplet or direct contact. The incubation period for chickenpox ranges from 11 to 21 days. Prodromal symptoms consist of low-grade fever, headache, anorexia, and malaise. On the following day, the characteristic rash begins to appear. The lesions evolve from erythematous macules to form small papules. Quickly, a clear vesicle arises on this erythematous base. The classic lesion of chickenpox has been poetically described as a “dewdrop on a rose petal.” Over the next several days, the vesicles rupture and then crust. The rash begins on the chest and back and spreads centrifugally to involve the face, scalp, and the extremities. New lesions of chickenpox arise in crops over a period of several days.
The sting of the Portuguese man-of-war. One of the most painful effects on skin is the consequence of attack by oceanic hydrozoans known as Portuguese men-of-war, which are amazing for their size, brilliant color, and power to induce whealing. They have a small float that buoys them up and from which hang long tentacles. The wrap of these tentacles results in linear stripes, which look like whiplashes, caused not by the force of their swing but from deposition of urticariogenic and irritant substances.