Bats are a natural host and vector of many zoonotic diseases, including the enzootic Australian Bat Lyssavirus (ABLV) and Hendra virus, and the exotic Nipah, Ebola, Melaka, and Marburg viruses. Presented here is a case of ABLV infection in a little red flying fox (Pteropus scapulatus). Not only did the case have immediate public health implications, but it serves as an example of how we are taking novel approaches to disease diagnosis and management, collaborative diagnostics, biosecurity preparedness, development of capabilities, and maintenance of diagnostic standards.
The bat was necropsied by a private practitioner after showing neurological signs (change in vocalisation, and paresis progressing to grand mal seizures), and the fixed brain submitted to the Elizabeth Macarthur Agricultural Institute (EMAI) for exclusion of ABLV. On routine H&E staining, there were multifocal lymphoplasmacytic perivascular cuffs, a lymphoplasmacytic ganglioneuritis, and eosinophilic intracytoplasmic inclusions within neurons in the thalamus, brainstem, and cerebellum, suggestive of Negri bodies. In collaboration with the Australian Animal Health Laboratory (AAHL), immunohistochemistry (IHC) against rabies nucleoprotein showed strong positive reactions, with multiple intracytoplasmic viral inclusions in neurons throughout the cerebral cortex, brainstem, and cerebellum.
Routine ABLV exclusion does not involve histopathology as a diagnostic test, but due to a submission error, only fixed tissues were available. The collaborative efforts between EMAI and AAHL meant that a good diagnostic outcome was able to be achieved. Both the private practitioner and the carer who had initially handled the bat were fully vaccinated against rabies, and appropriate notifications were made, but the case highlights the need to achieve a rapid and accurate diagnostic outcome in cases of this nature. To that end, EMAI is in the process of expanding our collaborative network and diagnostic capabilities, initially via a digital histology platform. The system already allows cases to be shared in real time between different institutions, and efforts have begun to further develop the system as part of our current residency training program and professional standards program.