Generalized parapoxvirus infection associated with increased antibody titres for varicella zoster virus and measles.

Human parapoxvirus infections are rare, self-limiting, zoonotic diseases. A 35-year-old veterinarian presented with a generalized rash of large umbilicated vesicles that appeared after antibiotic treatment for erysipelas on the forearm. The erysipelas arose from an erupted pustular thumb lesion that appeared after examining a sheep. An outbreak of chickenpox in the village suggested parapoxvirus or varicella zoster virus (VZV) was the most likely agent. No poxvirus was detected by electron microscopy or in cell cultures from lesion material. PCR revealed parapoxvirus DNA with a sequence similar to orf-viruses from Finland. Orf-virus immunofluorescence showed a titre increase, supporting the parapoxvirus diagnosis. VZV was not detected by PCR, but varicella antibodies increased three-fold in serum samples drawn two weeks apart. In addition, the patient had high antibody titres for measles and reported recent contact with individuals exposed to an outbreak of measles in nearby Austria. To explain the unusually generalized symptoms in this young and healthy patient, these findings could be variously interpreted as: i) a booster by community VZV infections; ii) a subclinical VZV (re)infection that was superinfected by the parapoxvirus; iii) an orf-virus mediated immune stimulation; iv) a post-infectious syndrome; or v) a temporary immunosuppression by subclinical measles.