Upon transmission of the pathogen into moose, the worm causes cerebrospinal nematodiasis, a disease of the nervous system that often results in death. P. tenuis may be one factor that has contributed to moose declines in southern portions of their range. This disruption of host-pathogen dynamics due to habitat alterations has promoted the spread of this parasite to a naïve host and has potentially contributed to declines in moose abundance and productivity in regions with high deer densities. Continued increase in deer abundance and density in the southern fringes of moose range are predicted to facilitate sustained transmission of P. tenuis to moose. Continued transmission of deer-related parasites, coupled with low productivity, habitat degradation, and a northward shift in the moose thermoneutral zone, leads to a troubling prognosis for southern moose populations. Murray et al. (2006) predict, if current trends continue, moose populations in these regions will not be viable and population declines will persist. Treatment Currently, there is no definitive treatment for P. tenuis in mammals, though research is still being conducted. The use of anthelmintics (ivermectin and fenbendazole) have been attempted in white-tailed deer. The results indicate, however, that ivermectin was ineffective against larvae that had already reached the spinal cord. Fenbendazole and ivermectin, combined with anti-inflammatory therapy have been used to manage infections in goats. Current and past research The majority of moose brainworm research in North America has been conducted in northern Minnesota, where a historical moose population of 4,000 to 5,000 moose had declined to an estimated 1,200 individuals by 1997. In this region, wildlife managers are challenged to predict and attempt to mitigate moose declines resulting from deer-related pathogens. Because no effective methods to prevent the transmission or infection of brainworm in moose have been found, managers have focused their efforts on decreasing deer densities in these regions. The Minnesota DNR identified that population densities greater than 12 deer/square mile result in increased moose mortality as a result of brainworm. Managers in these areas are responsible for evaluating suitable habitat for moose and deer, as well as setting management priorities and population goals to decrease the transmission of Parelaphostrongylus tenuis in moose. Though the main focus of research has been on white-tailed deer and moose, research has found that the guinea pig can be used as an experimental model of P. tenuis infection. References Ruminant diseases Parasitic nematodes of mammals Nematodes described in 1945