Recrudescent Infection Supports Hendra Virus Persistence in Australian Flying-Fox Populations

Abstract

Zoonoses from wildlife threaten global public health. Hendra virus is one of several zoonotic viral diseases that have recently emerged from Pteropus species fruit-bats (flying-foxes). Most hypotheses regarding persistence of Hendra virus within flying-fox populations emphasize horizontal transmission within local populations (colonies) via urine and other secretions, and transmission among colonies via migration. As an alternative hypothesis, we explore the role of recrudescence in persistence of Hendra virus in flying-fox populations via computer simulation using a model that integrates published information on the ecology of flying-foxes, and the ecology and epidemiology of Hendra virus. Simulated infection patterns agree with infection patterns observed in the field and suggest that Hendra virus could be maintained in an isolated flying-fox population indefinitely via periodic recrudescence in a manner indistinguishable from maintenance via periodic immigration of infected individuals. Further, post-recrudescence pulses of infectious flying-foxes provide a plausible basis for the observed seasonal clustering of equine cases. Correct understanding of the infection dynamics of Hendra virus in flying-foxes is fundamental to effectively managing risk of infection in horses and humans. Given the lack of clear empirical evidence on how the virus is maintained within populations, the role of recrudescence merits increased attention.

Chronic disease in the Mojave desert tortoise: Host physiology and recrudescence obscure patterns of pathogen transmission

“…In wildlife populations, the explicit study of recrudescent diseases and the population dynamics of such diseases are rare. The study by Wang et al () is a notable exception, and they found that the role of recrudescence in the maintenance of viral infection in flying foxes ( Pteros species) is biologically significant and warrants more attention. Recrudescence may be particularly influential in disease persistence in long‐lived host species, especially when transmission rates are low (Slater et al., ; Wang et al., ).…”

“…The study by Wang et al () is a notable exception, and they found that the role of recrudescence in the maintenance of viral infection in flying foxes ( Pteros species) is biologically significant and warrants more attention. Recrudescence may be particularly influential in disease persistence in long‐lived host species, especially when transmission rates are low (Slater et al., ; Wang et al., ). Furthermore, if transmission rates are high, such as in dense populations, then recrudescence can lead to intensified disease outbreaks in the absence of other perturbations (e.g., Slater et al., ).…”

Changing resource landscapes and spillover of henipaviruses

“…This suggests that cell‐mediated immunity in bats may be biased toward regulatory and anti‐inflammatory processes. Combined with reduced viral burden from innate immune activity, the low titers and slow antibody responses of bats and patterns of cellular immunity could prevent viral clearance, leading to the hypothesized patterns of persistent HNV infection and reactivation in bats …”

“…This can scale to effects on HNV transmission between bats, between bat populations, and to other species. For example, poor nutritional condition is perhaps more likely to drive reactivation of latent infections, either by reduction in immunocompetence or immunity trade‐offs during pregnancy, both of which are suspected drivers of viral recrudescence in bats . By contrast, transmission between hosts will likely be more affected by the distribution of resources and its effects on bat population density and connectivity …”

Bats: carriers of zoonotic viral and emerging infectious diseases

“…Later on it was named as Hendra and Nipah virus (Murray et al, 1995). Several bat species such as fruit bats (flying foxes) of the genus Pteropus, including gray headed flying fox (Pteropus poliocephalus), black flying fox (P. alecto), spectacled flying fox (P. conspicillatus) and little red flying fox (P. scapulatus) were reported as probable reservoir hosts of Hendra virus (Field et al, 2011;Wang et al, 2013). The qRT-PCR assay showed that P. alecto is potent reservoir host than P. poliocephalus and P. scapulatus for Hendra virus in Australia (Edson et al, 2015).…”