In Switzerland, both for ecological and economical reasons, composting of organic yard and kitchen wastes, disposed separately by the citizen before being collected, has been increasingly promoted. The biggest part of the collected material is now treated in large municipal or regional of composting facilities using different types of systems and management. The majority of these are open air or send-closed facilities. These installations are sources of repeated or continuous (in automated composting facilities) air dispersal of organic particles, bacterial particles and mold particles, mostly Aspergillus fumigatus (Af) occuring essentially within the limits of the workplace and its immediate vicinity. While the quantity and quality of this aerosolized material greatly varies with the type of management used on the compost site (Beffa et al, Mycol. Helv., 7:125-130) the compost workers (CW) are however always exposed at one time or the other to the aerosolized waste and/or compost dust which may contain varying quantities of Af or other microbial contaminants. With an extensive type of management, which used to be one of the most frequent methods of composting, Af is largely dispersed into the atmosphere. Exposed CW in such sites are strongly immunized, both serologically and cellularly, towards Af antigens and compost antigenic extracts (Gumowski et al, Eur. Resp. J., (15):405-406),1992). As part of a 3 years multidisciplinary pilot follow up study began in 1992 in a large composting facility in the Geneva area we have studied the evoloution of the immune response towards a panel of Af antigens in a group of ten exposed CW recruited on a voluntary basis. Each facility was visited twice in the year and each CW was submitted to: 1) Lung function tests 2) laboratory investigations and 3) non-invasive microbiological samplings. Lung functions Spirographic measures (Vitalograph), consistently showed a transient weak to moderate decrease of the lung function only after work periods or over 3-4 hours on compost piles. However no significant deterioration has appeared during the 3 year of the survey. Immune response: Af immunity was assessed with a purified precipitate (F27) from the culture filtrate, and various mycelial and purified extracts both for Ig-specific ELISA tests and lymphocyte transformation tests (LTT). The cellular and specific IgG, lgM, IgA and lgE responses in 10 Af allergic patients towards Af antigens were compared to the responses observed in 10 Af allergic patients (AP) and in 10 normal non exposed subjects non allergic to Af (CP). LTT responses were significantly increased in CW and AP subjects in comparison to the response in CP. No statistical differences could be observed between CW and AP. Specific IgG and lgA responses were increased in CW compared to CP. However no statistical differences could be observed between CW and AP. With IgM specific Ab, no differentiation between the three groups could be made (no statistical difference). lgE were present in all AP and could be detected in low amounts in most of the CW, with a seasonal fluctuation, though all CW were asymptomatic. No lgE could be found in CP. In newly engaged CW, an hyperimmunity state towards Af equivalent to that of longt erm exposed CW appeared after 9-18 months. The appearance of this immunity was essentially related with the frequency of exposure. Af isolates: culture swabs (nose and/or ear external ducts) are positive for Af in >90% of CW after direct work on compost piles over 2-3 hours: positive isolates were found in 45% after 15 hours, in 15-20% after 24 hours and were all negative after 48 hours.
Full conference title:
13th Congress of the International Society for Human and Animal Mycology
- ISHAM 13th (1997)