MOLECULAR IDENTIFICATION OF THE AGENTS OF TRAUMATIC MYIASIS OF SMALL MAMMALS IN UK

Catherine Hale1, Martin Hall2, April Wardhana2, Zoe Adams2 and Paul Ready2  

Royal Veterinary College1, London and Natural History Museum2, London

Traumatic myiasis can be a problem in a great range of mammal species. Adult flies are attracted to wounds, excrement or other sites of soiling on the host and lay eggs or first instar larvae. The larvae that hatch (or those laid already hatched, e.g., Sarcophagidae) begin feeding on the dead or living tissues of the host. Myiasis is a condition likely to be under-reported in wild species of small mammals, such as hedgehogs, due to their habits and limited contact with humans. However in domestic species, particularly rabbits, myiasis is commonly reported and can be an indicator of poor welfare, neglect or even cruelty. Forensic entomology techniques can be used to determine the period of neglect and, if necessary, the elapsed time since death. In order to apply correct larval growth data to each case and, therefore, estimate the length of time the maggots have been present on the host, accurate identification of the fly species is crucial. Different species have slightly different growth profiles and, if the identification is uncertain, this could potentially be a problem for successful prosecution in an animal welfare or neglect case.

This study looks at the identification of agents of small mammal myiasis using molecular rather than morphological methods. Accurate identification of the immature stages of these agents by morphological methods is very difficult and past records of species responsible for small mammal myiasis based on such identifications could be unreliable. Results from an analysis of the cytochrome-b gene of mitochondrial DNA of larvae from a wide range of small mammal hosts have shown a greater diversity of fly species involved in traumatic myiasis than is reported in the published literature, where L. sericata is generally acknowledged to be the most common species. The ability to identify a specific species using molecular methods will enable correct growth data to be used in determining time periods for neglect in welfare cases and this knowledge will prove vital in the conviction of neglectful owners.