No Evidence of Prolonged Hendra Virus Shedding by 2 Patients, Australia

Carmel Taylor, Elliott G. Playford, William J.H. McBride, Jamie McMahon, and David Warrilow

Author affiliations: Queensland Health Forensic and Scientific Services, Archerfield, Queensland, Australia (C. Taylor, J. McMahon, D. Warrilow); Princess Alexandra Hospital, Brisbane, Queensland, Australia (E.G. Playford); University of Queensland School of Medicine, Brisbane (E.G. Playford); and James Cook University School of Medicine and Dentistry, Cairns, Queensland, Australia (W.J.H. McBride)

Abstract

To better understand the natural history of Hendra virus infection and its tendency to relapse, 2 humans infected with this virus were monitored after acute infection. Virus was not detected in blood samples when patients were followed-up at 2 and 6 years. Thus, no evidence was found for prolonged virus shedding.

Most virus infections resolve after an acute phase. A small subset can cause persistent infection and result in continual shedding of virus, and others use a latency mechanism to evade the host immune response. Hendra and Nipah viruses (family Paramyxoviridae, genus Henipavirus) can cause respiratory disease and encephalitis in humans. Hendra virus infection is acquired by close contact with horses infected by spillover infection from fruit bats, which are the natural reservoir for these viruses (1).
In a small proportion of cases, relapse with encephalitis after a mild acute phase is a feature of henipavirus infection and is often fatal. For example, several cases of relapsing encephalitis caused by Nipah infection in humans have been reported (2–4), as well as 1 case caused by Hendra virus in a human (5,6). Whether virus shedding occurs after an acute infection of any severity is currently unclear. Because standard veterinary practice in Australia is to destroy animals that survive natural or experimental Hendra virus infection (7), long-term monitoring for virus shedding has not been possible.
To address the nature of viral persistence in cases of Hendra virus infection, virus shedding and serologic changes were monitored in 2 of 3 infected persons. In addition, multiple samples from 1 of these persons and from 2 persons who died were compared to determine the most appropriate specimen type for detection by quantitative reverse transcription PCR (qRT-PCR).