A 49-year-old countryman got an itching papule on the dorsum of his right hand. In the centre there is a vesicle with serosanginous exudate. Within the next 2 days the patient developed a painless edema of hand and forearm. On the 4th day the temperature rose to 38,5°C, in the right axillary region a large painful lymph node was found. One day before the onset of the disease the patient had examined a dead calf. What is the most likely diagnosis?