Climate Changes and Zoonotic Epidemiology in Wildlife Systems (ZEWS)

Bacillus anthracis can, under suitable environmental conditions, infect new hosts from a soil reservoir for more than five years. New hosts are infected on pastures where other hosts have died previously and this is central for epidemiology. This has been demonstrated through field studies conducted in Namibia at the Etosha Ecological Institute (EEI) in Etosha National Park (ENP), sequenced by the Defense Research Institute (FFI) at Kjeller. Our previous studies show that neither zebra, springbok nor wildebeest avoids places where other animals have died of anthrax. On the contrary, such contagious pastures become grazing more than control sites. This is most likely because the grass receives nutrients from the dead animal. A long term study of the bacterial concentration in soil, grass and sediments at the watering holes in the ENP indicates that waterholes are not an important source of infection for the main hosts. Elephants, may however be at risk of infection due to larger intake. This can explain the observed difference in climate effects on anthrax outbreaks on different animal species. Studies of soil microbial dynamics in spots infected with dead hosts compared to control spots have been conducted in the ENP, and combined with realistic laboratory studies of the movement, survival and propagation of anthrax bacteria under various conditions in water, grass and soil. These studies show an alternative methodological approach to epidemiologically important "invisible" variables, especially pathogen dose-response relationships. What constitutes a lethal dose for wild animals can often not be determined experimentally because of ethics and conservation, but it is possible to measure mortality by monitoring and to estimate exposure to infection and dose ratios in various protected species so that effective lethal dose can be calculated statistically. Experiments to investigate the possibilities for internal transport of spores in grass capillaries, soil replication, soil transportation and natural microflora sources are made in the ENP. These data are used in mathematical modeling of the effect of anthrax eruptions due to annual variation in climate and disease, and the potential for density-dependent regulation of the population under certain climatic conditions using population-time series and climate data. The doctoral student of the project is working on a study of the impact of climate and anthrax eruptions in the elephant population in Etosha, where historical data has recently been made available. The master student writes her thesis based on the studies of physical transport of anthrax in the environment. The studies of bacterial growth and physical transport under controlled conditions demonstrate the challenges of ecological work in the third world as they have been frustrated by the local infrastructure where power outages and supply problems have repeatedly destroyed half-completed tests that have therefore had to be restarted. An emergence of poacher activity in the ENP has also hampered sampling and delayed progress of large parts of the project. However, those involved will continue the research under other umbrellas to utilize the unique data and experience gained. The unexpected outbreaks of anthrax in the Yamal area in Siberia in 2016 have been subject to investigations as they probably coincide with abnormally high temperatures in which anthrax spores of unknown age tear out from the permafrost and are made available to host animals. As anthrax has historically been common in Siberia, the potential for anthrax eruptions due to global warming is high. This relationship with climate was not expected to be visible during the project period, but has been incorporated in a newly established collaboration with Russian and international researchers. It is believed that borreliosis mainly responds to climate change through population dynamics at the host animal and vector. We have collected population data on deer, rodents and ticks, as well as genotype data and data on the spread of borrelia through field studies on the west coast outside Førde and in Son at Oslofjorden. A lot of laboratory and field work has been done, and an article is published in Nature Communication that incorporates this work. The theoretical work on models of adaptive dynamics in the evolution of virulence has continued and awaits publication, suggesting that external factors such as climate can affect the evolutionary stability of host pathogen interactions. A synthesis of anthrax epidemiology is pre-published on bioRxiv, incorporating new findings in a summary of current knowledge and pointing out interdisciplinary factors for further work. Cooperation with Russian scientists about Siberian outbreaks has resulted in two new applications, and an upcoming bilingual report on climate impacts on anthrax in Siberia.

Among the most serious effects of climate change is its capacity to drastically alter the ecology of diseases that are vectors-borne, have wildlife and/or environmental reservoirs (WVE diseases). Theory and observation suggest that disease outbreaks can result from gradual changes in transmission, susceptibility, host or vector density, resulting in tipping points where epidemiological characteristics suddenly change [1]. The understanding required to plan and implement mitigation strategies for WVE dise ases requires broad interdisciplinary collaborations to provide: - Integration and overview of research on WVE diseases likely to respond to climate change. - New data where critical information is found to be missing. - Improved risk models taking differ ent scenarios into account. To make the most of limited resources, we use three systems that are important in their own right while being complementary as model systems: Lyme disease, anthrax and tularemia. They are chosen for being; (a) currently or pot entially important in Scandinavia, (b) likely to respond strongly to climate change, and (c) giving complementary perspectives on how WVE diseases responds climate change. The project is led by the SFF UiO Center for Ecological and Evolutionary Synthesi s (CEES) and performed in collaboration with prominent members of the international medical, biosecurity, veterinary medicine, climatological and public health communities. The project will also be linked to the IGBP through the Global Environmental Chang e and Human Health (GECHH). The project will be led by highly experienced scientists, but will recruit and train young scientists in research and project leadership. To strengthen collaboration with critical third-word partners a NORGLOBAL proposal is in cluded in this project.