Occupational risks of zoonotic infections in Dutch forestry workers and muskrat catchers.
Lyme borreliosis (LB), haemorrhagic fever with renal syndrome (HFRS), lymphocytic choriomeningitis (LCM), tick-borne encephalitis (TBE), Q Fever, and Weil's disease (WD) are known to be occupational diseases for rural outdoor workers. Antibodies to these agents were assessed in 312 forestry workers and muskrat catchers and in 356 matched office workers in the Netherlands. Three levels of occupational exposure were distinguished: high for active forestry workers, low for supervisory forestry staff and muskrat catchers and zero for office workers. At high exposure the prevalence odds ratios (with 95% CI between brackets) were: LB 15 (5.5-42), HFRS 11 (1.3-501), LCM 5.4 (1.0-50). TBE 1.0 (0.3-3.0), Q Fever 1.0 (0.4-2.1), and WD 0 (0.0-33). No significant risk of infection was found at low exposure. Part of the present group had also been studied in 1989 and 1990. Within this cohort the conversion rates to Borrelia burgdorferi have been estimated for the periods 1989-90 and 1990-93 as 0.23 and 0.066/year, respectively, and the reversion rate as 0.44/year. The corresponding values for HFRS were 0.031, 0.018 and 1.42/year. It is concluded that active forestry workers in the Netherlands are at high risk of infection by LB, HFRS and LCM. Prevalence of antibodies to LB and HFRS appeared to reflect the levels of these infection hazards in recent history.