Nonhuman Primates in India: A Barometer of Zoonosis Risk in Asia

The Indian subcontinent is home to Asia’s largest populations of nonhuman primates, with a total of fifteen species, including seven species of macaques, five species of langurs, two species of lorises, and one species of gibbon. Among them, rhesus macaques (Macaca mulatta) are a key species in biomedical research. Following a period of massive exports for research in the 1950s and 1960s—which ceased in 1978—Indian primates remain essential animal models today in neuroscience, immunology, infectious diseases, and preclinical evaluation. Beyond the laboratories, these primates live at the interface with humans, domestic animals, and synanthropic species—where the risk of transmission of zoonotic agents is highest.  

From Biomedical History to Contemporary Challenges

The rhesus macaque’s historic role in the development of vaccines and drugs in the United States has shaped a lasting scientific legacy. Research colonies, zoos, and wild populations now contribute to a continuum of knowledge that serves both conservation and the prevention of zoonoses. This foundation is unfolding against a new backdrop of rapid urbanization, habitat loss, and ecological shifts linked to climate change—factors that are increasing contact between humans and primates, particularly at the interface between peri-urban and rural areas, as well as in cultural spaces such as temples and tourist sites.  

A High-Risk Human-Animal Interface

In many Indian cities and villages, macaques, langurs, and lorises forage for food waste, crops, water sources, and offerings at places of worship. This proximity creates corridors of interaction where humans, primates, livestock, and synanthropic species (notably stray dogs, rodents, and birds) come into contact. The spatiotemporal aggregation of these potential hosts acts as a risk amplifier, facilitating both spillover (animal to human) and spillback (human to animal), which requires coordinated responses based on a “One Health” approach.  

Pathogens to Monitor

Recent studies identify non-human primates as reservoirs or accidental hosts for a wide range of pathogens. Among bacteria, Mycobacterium tuberculosis remains a major threat, while resistant Enterobacteriaceae such as Escherichia coli and Klebsiella pneumoniae underscore the challenge of antimicrobial resistance. Among parasites, zoonotic malaria caused by Plasmodium knowlesi requires increased vigilance. Viral risks include herpesvirus B (Macacine alpha 1 simplexvirus), Kyasanur Forest Fever Virus (KFDV), mpox virus (a simian orthopoxvirus), and, more recently, documented transmissions of SARS-CoV-2 from humans to primates, against a backdrop of concerns regarding the circulation of orthopoxviruses in these animal populations. This multi-agent landscape warrants an integrated approach combining wildlife ecology, veterinary medicine, genomics, and public health.  

Habitat loss, urbanization, and climate

Three factors converge and automatically increase the frequency and intensity of contact. Fragmentation of habitat and loss are driving primates to the edges of urban and agricultural areas. The expansion of cities and road networks fragments their territory, while introducing new sources of attraction such as waste dumps, fruit orchards, and water sources. Climate change alters resource availability, seasonality, and ranges, reorganizing the spatiotemporal patterns of interactions and revealing new epidemiological hotspots.  

Toward Operational Surveillance

The priority is to reduce risks and protect both primates and humans. This involves targeted surveillance in multiple settings, with observation and reporting protocols at temples and tourist sites, supported by clear educational messaging for visitors to discourage feeding and handling; joint monitoring by veterinarians and public health officials in livestock farms and villages, incorporating mapping of primate-livestock contacts and water source hygiene; periodic screening and systematic genomics sequencing in zoos and monkey colonies for research purposes, to link health events and document transmission chains. In terms of diagnostics and data, the adoption of PCR and antigen tests tailored to the local spectrum must be accompanied by viral and bacterial genomics to trace the origin, circulation, and mechanisms of resistance. Data platforms linking wildlife, animal health, and human health—with early warning systems and secure data sharing—form the backbone of surveillance. Prevention relies on rigorous management of waste and water sources to reduce the attractiveness of urban peripheries, on hygiene and the use of personal protective equipment for field staff, caregivers, and communities in regular contact with primates, as well as on public outreach through posters in temples, schools, and clinics. These actions become more effective when they are part of response plans developed in collaboration with authorities, local communities, and cultural site managers. Finally, governance and ethics are inseparable from long-term success. A “One Health” framework bringing together ecologists, veterinarians, geneticists, health authorities, and religious leaders enables decisions to be made with complete transparency. Animal welfare protocols must govern all captures, examinations, and relocations, while clear communication fosters public support and strengthens conservation efforts.  

Impact Measures

The effectiveness of such a system is measured by the reduction in the time between the first clinical signs and diagnostic confirmation, the expansion of the surveillance zone for priority sites, the number of correlated alerts across different networks (wildlife, animal health, and human health), changes in co-exposures such as the association between antimicrobial resistance and enteropathogens, and the quality of genomics signals related to lineages, reassortments, and resistance genes. Local acceptability, as measured by surveys; the decline in incidents involving humans and primates; and compliance with guidelines round out this assessment.  

Preventing the Next Crisis at the Human-Animal Interface

India is home to a uniquely rich diversity of primate populations, but it also contributes significantly to the global zoonotic risk. Investing in systematic surveillance of nonhuman primates—whether in the natural environment, in zoos, in research colonies, or at cultural sites—is as much a matter of conservation as it is of health security. Strengthening truly integrated and ethical “One Health” frameworks remains the best way to protect primates, reduce the risk of epizootics, and safeguard public health.