Viruses and Climate Change

Posted by Lisa Bauer, Melissa Navarro and Roberto Manganaro on January 16, 2017

Increasing levels of CO2, temperature and globalization are key factors in making optimal conditions for virus spreading. Latest outbreaks of Zika, Dengue and West Nile Virus have been correlated to climate change and the distribution of their arthropod vectors. The constant changing weather conditions in the environment affect arthropod vectors like mosquitos or midges, which carry viruses around. The Earth’s surface is getting warmer and rainfall has severely increased leading to a more suitable environment for mosquitoes and midges to spread in a shorter time period. Further, the vectors occupy new habitats where they have not been reported before. Viruses can adapt to the new environmental factors to accelerate their development, increase infectivity, and expand their broadness to different hosts. West Nile Virus is a clear example, where the outbreaks in Northern America infected over 100 different species ranging from birds, mosquitoes, primates to last but not least humans.

Marine ecosystems are vulnerable environments; oceans play a key role in regulating climate by storing solar energy, exchanging heat with the atmosphere as well as distributing salt and minerals. Importantly, the ocean is able to absorb large quantities of the greenhouse gas CO2 and furthermore to produce almost half of earth’s oxygen. As part of the marine ecosystems of the ocean, viruses are the most abundant “life forms” in the aquatic system. Viruses can infect a broad spectrum of hosts like bacteria, microalga, and phytoplankton as well as vertebrates and mammals. Changes in ocean chemistry or temperature affect the infection cycle and the infectivity of viruses. Marine viruses influence biogeochemical cycles including carbon and gas exchanges. As an example of the unbalanced gas exchange, we know that cyanobacteria infection can change the CO2 fixation rate and this can be shut down by viruses resulting in acidification of the oceans.

There is a big interest in the interaction between viruses and their host regardless of the ecosystem (aquatic or terrestrial). At the moment, it is unclear whether viruses under the present climate conditions will stabilize or destabilize the dynamics of different ecosystems. Certain is, that due to climate change (especially raising of the temperature and increase in rainfall) the distribution of viral vectors to regions where these vectors were not endemic is a fact which is causing outbreaks of different viral diseases. In conclusion, the study of emerging viruses and their vectors is important to improve our resilience towards climate change related viral infections. A more complete understanding of viral processes is necessary for the improvement of predictive models that are used for development of counteractive strategies against new or old spreading infections.