A 9-month-old infant presentedwithvesicles on the arm in theeighthcervicaldermatomesinceseveraldays. PCR analysis of thefluid of thevesiclesrevealedthepresence of the varicella zoster virus (VZV). It turned out thatthe infant had been in contact withthis virus at theage of 5 months; bythenthechild was protectedbymaternal VZV-antibodies, whichprevented adequate development of immunityagainstthe virus. Therefore, herpes zoster coulddevelop a few months later.