Environmental risk and Alpha-gal Syndrome (AGS) in the Mid-Atlantic United States

Alpha-gal syndrome (AGS), commonly referred to as the tick bite red meat allergy, has been reported worldwide with the number of suspected cases in the United States increasing from 24 in 2009 to over 34,000 in 2019. Within the US, AGS is associated with the bite of two tick species, Amblyomma americanum and Ixodes scapularis, and has particularly high incidence rates in the mid-Atlantic region. Because AGS is associated with tick bites, the risk of developing AGS is affected by the environment individuals visit. Despite this, as well as the numerous studies associating the environment with Am. americanum, no work to-date has evaluated AGS risk factors associated with the surrounding landscape. We test the hypothesis that AGS risk is associated with habitat fragmentation typically seen in areas classified as open space and low intensity development that are suitable for human-tick interactions, using a combination of generalized linear modeling (GLM), boosted regression trees (BRT), and Maximum Entropy (MaxEnt). We qualitatively compare results from the models, as well as their predictions within the mid-Atlantic region. We found that models mostly agree when determining important environmental variables, with open space development and population density being highly predictive across all models. BRT and GLM predicted a strong east to west gradient of risk across the mid-Atlantic, which largely mirrors the environmental transition from mountains to coastal plains. MaxEnt predicted a much patchier distribution across the region with no discernable patterns. These results provide evidence that AGS is associated with land uses that are associated with habitat fragmentation, the preferred habitat of Am. americanum. This information can be used to inform future education programs aimed at reducing AGS incidence in the region.