Nonhuman Primates of the Indian Subcontinent: Diversity, Diseases, and One Health Implications

Abstract

The Indian subcontinent harbors one of the richest assemblages of non-human primates (NHPs) in Asia, with 15 recognized species: 7 macaques, 5 langurs, 2 lorises, and a single gibbon species. India alone supports some of the largest free-ranging populations of rhesus macaques (Macaca mulatta), a species that has historically played a pivotal role in biomedical research. During the 1950s–1960s, India was among the largest global exporters of rhesus macaques, primarily for vaccine and drug development in the United States, before exports were banned in 1978. Today, Indian NHPs remain indispensable models in neuroscience, immunology, infectious disease research, and preclinical evaluation of vaccines and therapeutics. Beyond their biomedical importance, NHPs are critical from a One Health perspective. Free-ranging populations frequently inhabit peri-urban and rural landscapes, increasing contact with humans, livestock, and synanthropic species. This interface amplifies the risk of bidirectional pathogen transmission. Recent investigations have highlighted NHPs as reservoirs or incidental hosts for diverse pathogens, including Mycobacterium tuberculosis, Plasmodium knowlesi, Herpes B virus, Kyasanur Forest Disease virus (KFDV), antimicrobial-resistant Escherichia coli and Klebsiella pneumoniae, and more recently, monkeypox virus (mpox). Reports of SARS-CoV-2 transmission from humans to NHPs and concerns about orthopoxvirus circulation further emphasize their role in emerging and re-emerging zoonoses. Accelerating habitat loss, urban expansion, and climate-driven ecological shifts are intensifying human–NHP interactions across South Asia. Systematic surveillance of NHPs in natural habitats, zoological facilities, research colonies, and cultural landscapes such as temples is urgently needed to evaluate and mitigate spillover risks. Strengthening One Health frameworks that integrate wildlife ecology, veterinary science, genomics, and public health will be essential for both primate conservation and the prevention of future epidemics at the human–animal interface.