Permafrost dynamics and the risk of anthrax transmission: a modelling study

Abstract

A recent outbreak of anthrax disease, severely affecting reindeer herds in Siberia, has been reportedly associated to the presence of infected carcasses or spores released from the active layer over permafrost, which is thawing and thickening at increasing rates, thus underlying the re-emerging nature of this pathogen in the Arctic region because of warming temperatures. Anthrax is a global zoonotic and epizootic disease, with a high case-fatality ratio in infected animals. Its transmission is mediated by environmental contamination through highly resistant spores which can persist in the soil for several decades. Here we develop and analyze a new epidemiological model for anthrax transmission that is specifically tailored to the Arctic environmental conditions. The model describes transmission dynamics including also herding practices (e.g. seasonal grazing) and the role of the active layer over permafrost acting as a long-term storage of spores that could be viable for disease transmission during thawing periods. Model dynamics are investigated through linear stability analysis, Floquet theory for periodically forced systems, and a series of simulations with realistic forcings. Results show how the temporal variability of grazing and active layer thawing may influence the dynamics of anthrax disease and, specifically, favor sustained pathogen transmission. Particularly warm years, favoring deep active layers, are shown to be associated with an increase risk of anthrax outbreaks, and may also foster infections in the following years. Our results enable preliminary insights into measures (e.g. changes in herding practice) that may be adopted to decrease the risk of infection and lay the basis to possibly establish optimal procedures for preventing transmission; furthermore, they elicit the need of further investigations and observation campaigns focused on anthrax dynamics in the Arctic environment.

Enlightenment on oscillatory properties of 23 class B notifiable infectious diseases in the mainland of China from 2004 to 2020

“…This finding will increase the understanding of the regularity of the diseases and guide in epidemic prevention. Importantly, some infectious diseases, like HBV [47], HCV [48], HEV [49,50], Anthrax [51], Gonorrhea [52,53], Treponema pallidum [54], and Leptospirosis [55,56] are thought to be more sporadic rather than seasonal or cyclical. In our work, we found that they have distinct oscillatory properties despite relatively lower selectivity compared with other seasonal diseases.…”

Climatic Factors Influencing the Anthrax Outbreak of 2016 in Siberia, Russia

“…Regional models with higher resolution can therefore be recommended for the monitoring and forecasts of weather conditions causing unfavorable epidemiological situations in cold climates. In addition, mathematical models can be applied on a local scale (Friedman and Yakubu 2013;Saad-Roy et al 2017;Gomez et al 2018;Stella et al 2020).…”

Post-Translational Protein Deimination Signatures in Plasma and Plasma EVs of Reindeer (Rangifer tarandus)

“…Brucella spp., is a zoonotic bacteria that is one of the most widespread and economically impactful zoonosis affecting reindeer and can be transmitted to human via raw animal products, including from reindeer and caribou [ 138 , 139 ]. Anthrax, a global zoonotic and epizoonotic disease, is another bacterial pathogen identified in reindeer, particularly in relation to infected carcasses, as recently found in Siberian permafrost and therefore also indicative of a possible rise in the Arctic due to climate change [ 140 ]. Reindeer have in addition been found to carry Clostridium perfringens [ 141 ] and can suffer from severe bacterial intestinal infections and endotoxemia by Clostridium sp [ 142 , 143 ], while other bacteria inside the order Clostridiales aid in processing of lichen secondary metabolites [ 144 ].…”