Bacterial Survival and Feeding Pattern in Hydrotaea Irritans: Two Essential Variables for a Transmission Model of Summer Mastitis

Abstract

Numerous attempts to replicate Tarry’s successful transmission of summer mastitis pathogens using the sheep head fly as a vector have proved negative in England, Denmark and The Netherlands. The hypothesis is proposed that one of the reasons underlying this failure is lack of knowledge not only regarding survival of pathogens in the fly but also the feeding behaviour and hunger state of the vector. Experiments were carried out to investigate these variables. Feeding behaviour takes approximately 4 days to recover after a full meal but can be manipulated using interrupted feeding and intermeal intervals. Bacterial survival in the fly was investigated using both mixed and monocultures of summer mastitis pathogens. Successful artificial techniques were developed in which it was possible to transmit C. pyogenes and P. indolicus using artificial substrates.