Trends in Age, Weight, and Health Status among Cynomolgus Macaques (Macaca fascicularis) Imported into the United States during 2014-2023.

The domestic supply of nonhuman primates (NHPs) in the United States is not adequate to meet needs for biomedical research, and many NHP research programs rely on imported animals. Since 2020, several disruptions in supply have led importers to purchase NHPs from different foreign sources. This analysis reviews Centers for Disease Control surveillance data to characterize trends in age, weight, and health status in imported NHPs over a 10-year period with the goal of better understanding how changes in supply might affect the health status of imported NHPs. We used linear and binomial regression to explore relationships between shipment characteristics and health status. The source countries of imported NHPs shifted dramatically during the study period, with the majority of animals initially coming from China, then Cambodia, and then Mauritius. Median age and weight declined steadily for most of the study period but have begun to rebound in recent years. Predictors of illness and death in quarantine included lower median shipment weight, larger shipment size, and either China or Vietnam as the source country. The results of this analysis suggest that recent changes in supply may have contributed to an increase in adverse health events in quarantined NHPs. Having a more substantial domestic supply of NHPs for research may help to address these concerns. Until more stable sources of NHPs can be identified, import quarantine remains essential to protect the health of NHP workers.