MALATTIE TRASMESSE DA ZECCHE E RISCHIO PROFESSIONALE: INDAGINE SIEROLOGICA IN LAVORATORI DEL COMPARTO AGRICOLO E ZOOTECNICO.

Climate changes imply an increased zoonotic risk, especially for tick borne diseases, such as Lyme Borreliosis, so far considered of major concern mainly for forestry workers. This study aims to assess the occupational risk of Lyme Disease for: 1) shepherds devoted to mountain pasture and transhumance and 2) workers employed in intensive swine and cattle breeding facilities. All subjects were asked to fulfil an informed consensus. Workers were reached at the workplace. Exclusion criteria were considered those clinical conditions determining immunodeficiency. In the first part of the study, sera for the detection of antibodies to Borrelia burgdorferi were collected from 28 shepherds (exposed) and 22 locals (not exposed). The subjects provided information about health status, age, exposure to tick bites, house location, pets and outdoor activities (hunting, fishing, trekking). Moreover, shepherds were asked about previous ticks’ bites. Significant difference has been found among groups (exposed/not exposed) respect to the number of tick bites; just one subject – from the not exposed group – was found to have IgG against Borrelia burgdorferi s.l., confirmed with Western Blotting. Leisure activities were pointed out as major risk factors. In the second part of the study, sera from 100 workers employed in Po Valley were collected in the frame of the health surveillance programme held by the Occupational health Department of the San Paolo Hospital. A two step detection of IgG against Borrelia burgdorferi was conducted. Nine workers were found positive to the first step of the serological survey. The second step by immunoblotting confirmed just 6 of them. For the confirmation test, workers were addressed to the general practitioner for medical prescription. Results show a statistically significant difference between mountain shepherds and Po Valley breeders with regard to ticks’ bites (60% versus 24%, p< 0,05). This difference was not found between breeders and agricultural workers not devoted to animal care. Interestingly, migrant workers were found to be more often interested by tick bites and by positive results to serological test when compare to Italian workers (32% versus 18%, p< 0,05). Main limitation of the study was the sample size which has not allowed inferential statistics on data. Some suggestions can be taken by these partial results: tick bite is still a threat to working population and general population. Borrelia burgdorferi s.l. diffusion seems to be quite low, in comparison to literature data which, in turn, come mainly by other geographical regions. Data from the second group (Po Valley) are not fully in line with the registry of Local health Unit of Lodi: from 2000 to 2009 no case of Lyme disease was notified to the health authority. Underestimation of cases, due to subclinical patterns and not specific clinical features has to be taken into account. In conclusion, this study, despite the small sample, has the specificity to deal with tick borne diseases risk for breeders: so far, in literature, mainly data from forestry workers were published. This study is part of a more extensive serological survey on agricultural workers focused on biological risk. A more extensive longitudinal prospective study has already started, with the aim of identify possible changing in antibody title during years.