Roosting behaviour and habitat selection of Pteropus giganteus reveal potential links to Nipah virus epidemiology

Abstract

Summary 1. Flying foxes Pteropus spp. play a key role in forest regeneration as seed dispersers and are also the reservoir of many viruses, including Nipah virus in Bangladesh. Little is known about their habitat requirements, particularly in South Asia. Identifying Pteropus habitat preferences could assist in understanding the risk of zoonotic disease transmission broadly, and in Bangladesh, could help explain the spatial distribution of human Nipah virus cases. 2. We analysed characteristics of Pteropus giganteus roosts and constructed an ecological niche model to identify suitable habitat in Bangladesh. We also assessed the distribution of suitable habitat in relation to the location of human Nipah virus cases. 3. Compared to non-roost trees, P. giganteus roost trees are taller with larger diameters, and are more frequently canopy trees. Colony size was larger in densely forested regions and smaller in flood-affected areas. Roosts were located in areas with lower annual precipitation and higher human population density than non-roost sites. 4. We predicted that 2–17% of Bangladesh's land area is suitable roosting habitat. Nipah virus outbreak villages were 2.6 times more likely to be located in areas predicted as highly suitable habitat for P. giganteus compared to non-outbreak villages. 5. Synthesis and applications. Habitat suitability modelling may help identify previously undocumented Nipah outbreak locations and improve our understanding of Nipah virus ecology by highlighting regions where there is suitable bat habitat but no reported human Nipah virus. Conservation and public health education is a key component of P. giganteus management in Bangladesh due to the general misunderstanding and fear of bats that are a reservoir of Nipah virus. Affiliation between Old World fruit bats (Pteropodidae) and people is common throughout their range, and in order to conserve these keystone bat species and prevent emergence of zoonotic viruses, it is imperative that we continue to improve our understanding of Pteropus resource requirements and routes of virus transmission from bats to people. Results presented here can be utilized to develop land management strategies and conservation policies that simultaneously protect fruit bats and public health.

Zoonotic Potential of Emerging Paramyxoviruses

“…However, consumption of date palm sap, as well as hunting bats for bushmeat, are relatively common practices throughout Bangladesh (Openshaw et al 2016), and yet the majority of outbreaks have occurred in central and northwest Bangladesh, to the extent that these regions are colloquially referred to as the ‘Nipah belt’. This has provoked attempts to correlate ecological factors in these regions with the high outbreak prevalence (Hahn et al 2014a; Hahn et al 2014b). One analysis found that Nipah belt villages have significantly higher population densities, and occur in regions where forest land is more fragmented, suggesting these factors could promote NiV outbreaks (Hahn et al 2014b).…”

“…One analysis found that Nipah belt villages have significantly higher population densities, and occur in regions where forest land is more fragmented, suggesting these factors could promote NiV outbreaks (Hahn et al 2014b). A similar analysis sought to identify risk factors by better understanding the features of preferred habitats of P. giganteus , a key NiV reservoir bat species – an approach validated by their finding that outbreak villages were 2.6 times more likely to map to a location their model predicts as a likely preferred habitat (Hahn et al 2014a). The major contributing factors determining habitat preference included tree species, forest fragmentation, rainfall, temperature gradients and human disturbance levels.…”

“…The major contributing factors determining habitat preference included tree species, forest fragmentation, rainfall, temperature gradients and human disturbance levels. Interestingly, this model also identifies a number of villages outside the Nipah belt where outbreaks seem likely, which raises the possibility that outbreaks may go undetected in some regions, due to a lack of local awareness or surveillance bias (Hahn et al 2014a). …”

“…In particular, if birthing pulses or population level stresses increase the likelihood of spillover events, then attempting to curb risk by reducing urban and peri-urban bat colony population size, as has been proposed in Australia, could have the opposite effect to that intended, as recently discussed elsewhere (Plowright et al 2015; Plowright et al 2016). In this instance, as suggested by Hahn et al , land management strategies such as forest conservation of known ideal roosting sites for bat reservoir species in areas away from villages could be a useful means of risk management (Hahn et al 2014a). Similarly, by identifying at-risk communities based on more detailed understanding of ecological drivers of spillover risk, education of the most at-risk human populations could be used to minimize the social and cultural practices that are known to determine infection risk at the individual level (Kamins et al 2015; Nahar et al 2010), combined with targeted surveillance to allow early identification of outbreaks.…”

Who acquires infection from whom and how? Disentangling multi-host and multi-mode transmission dynamics in the ‘elimination’ era

“…which hosts are potentially involved in transmission (key hosts)?/which species in the ecosystem are infected?epidemiological studies, such as seroprevalence, parasitological and/or molecular typing studies from humans and animals can be used to identify potential hosts.[70,81,91–93]comparison of human and veterinary surveillance data can provide early indication that an outbreak of disease in humans may have a zoonotic origin.[94–96]2. is there potential for effective contact between host species and, if so, how do contact rates compare between versus within species?GPS tracking can be used to asses contact between wildlife species and between wildlife and domestic livestock.[94]ecological studies of wildlife hosts can identify potential interspecies transmission pathways to humans.[25]3. is there evidence of cross-species transmission and host shifts?population genomic and genetic studies can type infecting pathogen species and demonstrate gene flow across known host species.…”