Over the past decade, we have focused on the role of pet and performing monkeys in disease transmission throughout Asia. Commonly trapped in the wild, these monkeys might be sold at wet markets, the putative source of several zoonotic outbreaks (3), where they might be caged next to any number of animal species (Figure 1 , panel A) (4). Pet and performing monkeys are likely conduits for cross-species transmission of respiratory pathogens like infl uenza viruses because of their close and long-term contact with their owners, audiences, domestic animals, wild animals, and birds ( Figure 1, panel B) (5) . However, the breadth and diversity of this interface presents a challenge for monitoring the emergence of infectious diseases. We have approached this challenge by conducting longitudinal studies at several sites and collecting biological samples and behavioral data representing various contexts of human-NHP contact (4-7). We used these historical and newly acquired samples, representing various countries and contexts of human-macaque contact, to determine whether NHPs are infected with infl uenza viruses in nature.