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Why climate change could bring more infectious diseases

Human impact on climate and environment is a topic of many discussions and research. While the social, economic, and environmental effects of climate change are important, climate change could also increase the spread of infectious diseases dramatically. Many infectious agents affect humans and animals. Shifts of their habitats or health as a result of climate change and pollution can lead to the spread of infectious diseases.

One of the first signs of climate change is non-typical behaviour of animal populations. Raising temperatures and humidity are favourable for the development of infectious agents. Ticks are transmitters of various infectious diseases which have a seasonal occurrence in temperate regions – from early spring to late fall. Mild winters and humid, warm summers lead to longer times for tick-borne diseases like Lyme disease to develop. Migratory birds are a major vehicle for the spread of infectious diseases. Some of the pathogens can be transmitted directly to humans. Disturbing their migration route thanks to climate change can spread diseases to new territories. Migratory birds can carry ticks, which if have time to develop into adult form, can spread other deadly diseases.

Mosquitoes, which live in the tropical and subtropical areas of the world, carry and transmit a variety of infectious agents like malaria, Zika virus, dengue virus, and West Nile virus. Long-term changes in temperature and rainfall patterns could lead mosquitoes to spread into habitats where they weren’t detected before.  The increasing levels of carbon dioxide and temperatures trigger mosquito expansion and higher rate of transmitting diseases as a result. Migratory birds can also promote the spread of mosquitoes and infectious agents.

The stress of dealing with unusual environmental conditions makes animals that transmit human diseases more susceptible to infections. The stress weakens their immunity, allowing parasites to multiply much easier.

Influenza is a respiratory infection found in all parts of the world. Seasonal disease outbreaks are quite common, but vaccination helps to reduce their occurrence. The nature of the virus makes it difficult to find a universal vaccine so researchers manage infection by adjusting vaccines according predicted global influenza circulation; a change in the environment and virus occurrence would make vaccine prevention much more difficult.

Climate change is already taking lives because of the extreme rainfalls, which lead to flooding and contamination from wastewater treatment facilities. The increasing rain frequency will cause outbreaks that could be impossible to handle, especially if the area is already depleted. Extreme weather can as well affect negatively human immunity and increase human-to-human disease transmissions.

Melting ice caps and glaciers as a result of climate change not only will increase sea level but reveal unknown microorganisms. It’s likely melting ice caps will expose unknown infectious agents.

The information above sounds disturbing, but it’s important not to panic. Climate change is inevitable yet humankind has the tools to reduce its impact. The public and governments should be aware about climate change complexity and prepare. Poor regions need more help with supplies and expertise. We also shouldn’t forget about the importance of taking measures to reduce our environmental impact and reduce climate change. It’s much easier to avoid a catastrophe altogether than to be forced to marshal resources to combat it later on.

Featured image: “Mosquito” by mikadago. Pixabay License via Pixabay.

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