Mycobacterium caprae in cattle and humans in Croatia

This paper describes an outbreak of human and related bovine tuberculosis (TB) caused by Mycobacterium caprae in Croatia. A 13-year-old boy clinically presented enlargement of cervical lymph node with consecutive isolation of M. caprae. His 7-year-old sister, who had no clinical signs of disease, hyper-reacted to the purified protein derivative (PPD) test (>25 mm) and peribronchial infiltration was found by radiology. The children came from a family that ran a small-sized cattle dairy farm.

All cattle on the farm were subjected to cutaneous TB testing: six of the 14 reacted positive, while three were suspicious. The entire herd was slaughtered, their carcasses examined and collected material subjected to pertinent diagnostic procedures.

Gross examination findings consistent with TB were observed in the PPD-positive cows. Mycobacteria isolated from the boy and cattle were identified by classical and molecular methods, confirming M. caprae as the causative agent.

Although not bacteriologically proven, consumption of raw milk or non-pasteurised milk products from infected dairy cattle was suspected as the source of infection in humans. Our findings confirm the domination of M. caprae among cattle in Croatia and represent the first evidence of M. caprae infection in humans in Croatia.