Red mite (Dermanyssus gallinae; De Geer, 1778) is currently the most economically deleterious ectoparasite of layer hens in several countries (Chauve, 1998). D. gallinae is an obligatory haematophagous ectoparasite of both domestic and wild birds (Bruneau et al., 2001), only found on the host during darkness when obtaining a blood meal. The remaining part of its lifecycle is spent concealed deep in the house substructure, in cracks and crevices, with control typically implemented via chemical spraying. Mite exposure in laying hens generally results in irritation, restlessness, anaemia, and occasionally death and may subsequently lead to decreased egg production, poor shell integrity, blood staining and egg size reductions (Chauve, 1998; Cosoroaba, 2001). Natural exposure to mite-antigens during feeding activates humoral immunity of the fowl, in the form of immunoglobulin production. However, the magnitude of this serological response over a prolonged infestation period and at different mite population levels is unclear. Therefore the aim of this study was to determine the levels of anti-mite immunoglobulin present in egg yolks of laying hens in flocks infested with differing population levels of red mite over a period of 16 weeks.
Current knowledge on the structural proteins of porcine reproductive and respiratory syndrome (PRRS) virus: comparison of the North American and European isolates