Moose (Alces alces) are a cold-adapted species with circumpolar distribution. Populations along their southern range limits in North American have fluctuated repeatedly and contend with varied and likely interacting stressors, including climate change, habitat alteration, conflict with humans, and disease. Moose are hosts for numerous parasite species, some of which cause severe pathology and impact survival and population trajectories. Two parasites, meningeal worm (Parelaphostrongylus tenuis) and giant liver fluke (Fascioloides magna), incidentally infect and sometimes kill moose, resulting from spatial overlap with the parasites’ definitive host, white-tailed deer (Odocoileus virginianus). To determine whether parasites function as a limiting factor for the low-density moose population in New York, I first evaluated the status of and primary threats to moose health in the area. I found that while body condition was generally good, moose were infected with combinations of eight parasite species and frequently demonstrated elevated immune responses to infection. Opportunistically sampled moose primarily succumbed to vehicle collisions (60%) and parasite infections (12%, P. tenuis and F. magna). Additionally, I monitored juvenile moose and estimated high winter calf survival, but lower survival of yearlings than measured elsewhere. Collared moose primarily died from disease associated with giant liver fluke infection, with mortality driven by the combination of fluke infection risk, coinfecting internal parasites, and nutritional energy available. In exploring interactions between moose and deer, I found that moose occupancy declined dramatically in locations with high parasite abundance, providing strong evidence for parasite-mediated competition. At the population level, simulations indicated that the population is stable but could decline with elevated parasite-induced mortality. These findings contribute to local and regional moose management and highlight the manipulation of deer overlap as a tangible tool for increasing the resilience of affected moose populations. Although moose currently persist and may increase in abundance in New York over the short term, the combination of nutritional limitations, coinfecting parasites, and disease may be exacerbated with climate change and threaten moose persistence in the future. Broadly, this work emphasizes the importance of considering disease and interactive effects of concomitant stressors on range-edge populations at multiple levels of biological organization.