The necessity of a One Health perspective for managing urban primates

We live an epoch, the Anthropocene, of a major human-driven environmental change associated with a multiplication of contact zones where humans and wildlife interact and compete for resources. While most of the primate species experience population decline due to human activity, some more adaptive species can benefit and proliferate in anthropogenic environments. Primate overpopulation in cities correlates with multiplied conflicts with humans. The issue of urban primates has multilevel implications including harmful conflicts, threats for public health due to zoonotic risks, nuisance problems for people, and threats for primate survival, health and welfare. Given the interconnected implications between humans and primates in these shared ecosystems, a holistic and integrated approach for conservation, management and health care has become urgently needed during the recent decades. This pluridisciplinary approach roots in the One Health Initiative that seeks integration of biology, human and veterinary medicine, as well as social sciences to tackle such complex situations. Here, we aim at advocating the necessity to adopt a One Health perspective for research on urban primates, by illustrating it with our long-term research on Balinese macaques in Indonesia.

Bali provides a remarkable example of extensive human-macaque interface, with Monkey Forest tourist sites providing substantial economic value to local people. However, high macaque fecundity and low mortality driven by food provisioning and lack of natural predators have resulted in exponentially growing populations. Six years ago, questionnaire surveys with local people revealed that the cultural and economic values of macaques for Balinese Hindu communities promoted a substantial level of tolerance towards macaques. However, a more recent survey in 2019 revealed that negative attitudes and complaints are multiplying due to growing nuisances that overabundant macaques caused to human properties, crops, forest and people safety. We also noted an increase in bite and aggression frequencies towards humans, raising concern for public health, but also serious injuries amongst the macaques as a consequence of the sharp overpopulation-related social tension. This risk of zoonotic transmission is real as macaques are potential hosts of several zoonotic pathogens including the Simian foamy virus and Herpesvirus B. However, the risk for pathogen transmission is also bidirectional: over 15 years, we recorded two outbreaks due to Streptococcus equi zooepidemicus with a suspected livestock-related source, causing a significant mortality in macaques. Macaques are also subjected to frequent harassment and attacks from humans, raising concern for their welfare. This human-wildlife conflict has to be managed via a One Health perspective, by considering simultaneously the threats for primate population sustainability, public health implications, consequences of environment anthropization, and the cultural and economic dimensions for local communities. In several places in Asia, measures have been carried out to limit monkey overpopulation. In Bali, at the request of the local stakeholders and as an ethical alternative to culling and translocation, we are conducting since 2017 a sterilization program using female tubectomy. Outcomes of this program on population dynamics are monitored, as well as the potential side-effects on macaque behaviours and the outcomes in terms of conflict mitigation. Viral screening analysis are also planned to better assess and manage the zoonotic risks. This study case in Bali is a typical example of necessary collaborations among primatologists, veterinarians, social scientists and local stakeholders working together towards an integrative and holistic understanding of the best ways to manage urban primates in a sustainable basis for both primates and humans.