In Reply.—
The comments of Groves et al are pertinent and support our impression of the limited recognition of human orf infections. We feel that the diagnostic approach to this infection is best determined by the site and stage of the lesion, as well as the facilities and expertise available locally.A history of exposure to an infected animal and a characteristic appearance may be adequate for a clinical diagnosis. If electron microscopy is available, aspiration of vesicular fluid before the scab forms appears painless and sensitive in our hands. Scab examination by electron microscopy can be appropriate in the later stages of infection. If there is no electron microscopy, but a skilled dermatopathologist is available, an invasive technique such as skin biopsy may be useful. It would exclude other diagnoses and, provided no superinfection is present, would be sensitive in confirming the diagnosis of orf.1