Understanding the potential risks of viral shedding posed by animals that may be infected with Hendra virus but are not showing clinical signs allows these animals to be appropriately managed.
Hendra virus has been recovered from the nasal cavities of experimentally infected animals prior to the onset of clinical signs (Marsh et al 2011). However virus has not been detected in urine or faecal material from these animals. Viral loads have also been found to lower in preclinical animals than clinical animals, (with viral shedding highest immediately prior to death).
Oronasal secretions are therefore the primary risk (apart from direct contact with blood or tissues e.g. during surgery) from preclinical animals. This risk would be increased by invasive procedures involving the oronasal cavity including stomach tubing and dental work. Sharing of bits and bridles would also pose a risk.
Direct spread from one animal to another through normal interaction for example sniffing, or touching muzzles is unlikely in the preclinical phase.