Occupational zoonoses in farming and abattoir personnel: some investigations in Italy.

Some epidemiological investigations will be here reported conducted on farming and abattoir personnel, which allowed us to determine the transmission risk for some zoonoses and, in some cases, to assess their prevalence and incidence in the workers examined. In a sero-epidemiological survey on leptospirosis carried out in 1996 on 75 workers on 12 swine farms in the province of Mantua, 32% proved positive to pathogenic leptospira strains with titres >1:50. The highest prevalences were recorded for serogroups pomona, australis and tarassovi, which are the most widespread in pigs in the Po Valley. Some months after the investigation, a worker found seronegative contracted a serious form of leptospirosis and was hospitalised. During the same period, a similar research was performed on the workers of an industrial slaughterhouse where the pigs were brought from the farms under test. Two blood samples were taken at 20 months’ interval, involving 65% and 87% of the workers of the plant, respectively. Considering 1:100 as threshold titre, 11.7% and 21.6% of workers proved positive to at least one leptospiral strain at the first and the second sampling, respectively. During such a period the incidence was reckoned to be 12.5%. In this case too, the strains with the highest prevalence were the same most frequently found in the pigs of the farms previously considered. With regard to Streptococcus suis 2 (reported as a cause of occupational zoonosis in farmers and slaughtering personnel, which manifests itself with septicaemia and meningitis), investigations performed in the ‘90s led to the isolation of the organism in swabs from the trachea and tonsils in 34% of pigs regularly slaughtered and in tonsilar swabs from swine slaughterers and farmers in the province of Mantua. An episode of brucellosis reported in 1993 in the personnel of an industrial abattoir in Lombardy involved 8 workers, 7 of whom showed evident clinical symptoms and 5 were hospitalised. The infection prevalences were 20% and 60% of the total number of slaughter workers and of the workers who had only contacts with uteruses and udders, respectively. Serological investigations to detect antibodies against verocytotoxin-producing Escherichia coli were carried out in 63 workers of three different cattle abattoirs and in control subjects (1996). The abattoir workers exhibited antibody titres significantly higher than those of the control group. The occupational risk by Erysipelothrix rhusiopathiae was confirmed by a serological survey conducted in 1991 in workers of a slaughterhouse plant where erysipelas-affected pigs had been brought during the previous two years. Fifteen out of the 52 individuals tested proved positive to complement fixation test (titre ≥ 1:8) whereas no individual was found positive of the 42 control people working in sectors completely alien to animal productions. The highest titres were observed in 6 workers with active clinical forms (2 cases of erysipeloid and 4 of influenza syndrome).