Investigation of the parasitic nematode Ascaridia galli (Shrank 1788) as apotential vector for Salmonella enterica dissemination in poultry

During recent years, the level of organically farmed poultry in Denmark has increased. Subsequent investigations have demonstrated an incidence of 64% of Ascaridia galli infections in layers established organic Farming system s. Studies interaction of Salmonella enterica with the parasitic nematode A . galli associated with poultry were undertaken to establish the significan ce of A. galli in the dissemination of S. enterica. A. gali was isolated fr om 40-week-old Lohmann Brown Salmonella-free layers. Worms were subsequentl y maintained in vitro and exposed to S. e. serovar Typhimurium at concentra tions of 10(5)-10(6) colony forming units/ml for varying times (24-144 h). Eggs were harvested aseptically from the worms and the associations of S. c . Typhimurium in relation both to the eggs and to structures on the surface of the worm were studied, using immunofluorescence, viable counts and in s itu hybridisation. Results show attachment of S. e. Typhimurium to the oute r coating of the eggs and possible internalisation. Evidence of association of the bacteria with the nematode eggs was further substantiated by establ ishing Salmonella infection in day-old chicks after dosing them with eggs h arvested from parasitic worms infected in vitro with Salmonella.