No increase in human cases of Mycobacterium bovis disease despite resurgence of infections in cattle in the United Kingdom

Abstract

A resurgence of Mycobacterium bovis infections in cattle in the United Kingdom since the 1980s has raised concern about risks to human health. Enhanced surveillance data for England, Wales and Northern Ireland between 1993 and 2003 of culture-positive human M. bovis cases identified 315 M. bovis infections; the mean annual number of cases was 28 (range 12-41). The most frequently reported exposures were consumption of unpasteurized dairy products 41/83 (49%) and exposure to cattle 45/123 (37%). Of all cases, 249 (83%) were born before 1960. Of 50 cases born after 1960, only 14 were born in the United Kingdom. Over the same time period the annual number of new herd infections increased from 332 to 1749 as derived from the UK State Veterinary Service database. In conclusion, despite a more than fivefold increase in cattle herd infections during the 1990s, there was no increase in reported human cases.

Fig. 1

Human M. bovis infections in England, Wales and Northern Ireland between 1993 and 2003. ■, Born in the United Kingdom after 1960; □, Others.

Fig. 2

Incidence of confirmed bovine tuberculosis by skin test reactors and slaughterhouse findings in England and Wales in (a) 1993 and (b) 2003. , Present, but in <1% of animals; , in 1–10% of animals; ■, >10% of animals.