The Impact of Climate Change on Disease Spread

CDC scientists are exploring how climate changes impact disease spread. In particular, how Lyme disease, West Nile virus and valley fever expand their geographic distribution with milder winters and less days of frost.

But existing modeling studies don’t always agree on how warming will influence infectious disease risk. To identify patterns, it is necessary to examine multiple factors.

Increased Temperatures

Climate is a key contributor to infectious disease spread. Warmer summers and milder winters increase mosquito, fly and tick populations while creating ideal conditions for them to flourish in new environments and spread illness among more people.

Scientists have yet to accurately predict how warming may impact disease risk due to climate change’s long-term shifts, rather than one-off events like extreme storms. Research is complicated and requires an in-depth knowledge of different climate variables’ relationships with human infectious disease pathogens, hosts/vectors and transmission.

Recent study conducted by wildlife veterinarian Lydia Franklinos and colleagues examined 46 modeling studies that attempted to predict climate’s effect on mosquito-borne disease risk at various geographic and temporal scales, but most failed to take into account factors like habitat fragmentation, population density or socioeconomic considerations like poverty and healthcare accessibility – possibly explaining why many models do not show positive correlations between temperature changes and disease incidence rates.

Climate change is having an immense effect on where, when, and how often we’re exposed to disease-causing pathogens–with potentially far-reaching ramifications on global populations’ health. Not only is its expansion expanding animals that carry ticks and mosquitoes but warmer temperatures make it easier for ticks and mosquitoes to survive and expand into new territories, increasing Lyme disease transmission rates as well as West Nile virus outbreaks.

The CDC has been monitoring the spread of disease-causing organisms as the seasons shift. Their researchers have observed that as the climate warms, ticks and other vectors – including rodents, deer, and racoons – are moving into new geographic locations more easily and becoming active earlier during spring and summer seasons; moreover they appear to be developing and maturing faster than ever before.

As temperatures warm further, diseases associated with climate change are set to grow even worse, placing especially vulnerable communities such as poor ones at greater risk from rising temperatures and related climate-induced health concerns.

Increased Rainfall

Many infectious diseases rely on certain climatic conditions for their survival, reproduction and transmission. Each pathogenic organism such as viruses, bacteria, fungi and parasites has their own individual set of ideal environmental conditions that vary based on temperature, rainfall, humidity levels and other variables; changes to these “normal” climate conditions can have direct implications on disease organism survival, spread and impact both humans and animal hosts.

As one example, hotter climates may enable malaria to flourish despite antimalarial drugs and other public health measures in place. A warmer climate also makes it more likely that mosquitoes and other insect vectors will find suitable breeding sites and food sources in new locations; when combined with higher temperatures this can increase incidences of infectious diseases transmitted via blood or airways.

Increased rainfall can contribute to disease outbreaks by providing more water available for infection. This is particularly relevant when considering diseases like diarrhea that thrive in warm freshwater environments like lakes and rivers; such infections often strike at those without access to sanitation services, or who already suffer from other issues like malnutrition or preexisting chronic illnesses, rendering them especially susceptible.

Researchers anticipate an increase in precipitation as global temperatures warm, with most rainfall concentrated at or near the equator and parts of southern Africa; Arctic region and western Australia expected to receive less rain in a world warmed by 2C under RCP8.5 scenario.

As climate change heats up, human immune systems will find it increasingly challenging to effectively defend against disease-causing organisms, and we can anticipate an escalation of some endemic diseases and an upsurge in new infectious pathogens that never threatened humanity before. Furthermore, heat waves and extreme weather events exacerbate existing health problems, such as poverty and hunger; contributing to displacement from homes that makes more susceptible to infectious disease infections; making communities even more susceptible.

Increased Fertilization

As more humans move into wildlife habitats, pathogens have greater opportunities to jump from animal to human hosts and spread through new routes of exposure. When combined with human mortality rates being far higher than animal deaths from diseases, this creates conditions that enable “spillover events”, where diseases once limited to wildlife may suddenly emerge as human epidemics.

As temperatures heat up, tick and mosquito vectors have the ability to expand their geographical reach and spread diseases like Lyme disease, dengue fever, malaria, Zika, and chikungunya. This shift is caused by climate change but also by urbanization, changing human mobility patterns, and changes in disease control measures.

Warmer temperatures also increase the ability of viruses and bacteria to multiply, increasing their potential for outbreaks and making them more dangerous if they spread from animals to humans. Influenza and norovirus infections could expand their range in response to warming temperatures as well.

Existing modeling studies don’t agree on when and by how much disease risk will increase as a result of climate change. A 2019 review examined 46 modeling studies which attempted to predict climate effects on mosquito-borne disease risks at various geographic and temporal scales and only 54% predicted any correlation between rising temperatures and increased disease incidence rates.

Climate change also differs in its effects for various diseases. For instance, in cool climates with high latitudes or elevations-warming may result in an increase of mosquito-borne infections; but in hotter regions with extreme hotter temperatures it might actually decrease those risks due to mosquitos not thriving as much in these extreme temperatures.

At its core, society’s ability to cope with climate-induced diseases hinges on its financial and medical resources, its public health system, and culture. Poorer societies may be particularly susceptible to higher health risks despite taking measures such as cutting heat-trapping carbon pollution sharply or protecting their environments.

Increased Human Mobility

Climate change isn’t only having detrimental health consequences for us through rising temperatures and more extreme weather events; it is also contributing to disease spread. By altering where ticks and mosquitoes reside, expanding their pathogen range, and speeding up disease transmission rates – Lyme disease, dengue fever, chikungunya fever, malaria and Zika can quickly spread between people. These changes pose particular threats for vulnerable groups like low-income communities, marginalized populations, ethnic minorities, migrants or displaced persons and those with existing medical conditions or health conditions.

Complex as it may be, this graphic illustrates the need for more research in this area. A variety of factors influence infectious disease risk and its spread – ecological changes, population dynamics and public health systems all play a part. Researchers who focus on climate and disease tend to divide into two broad camps: some study how changes to weather patterns directly impact disease pathogens/hosts/vectors transmission; while others take a broader view by trying to predict which combinations of climate impacts might result from extreme events like heat waves or hurricanes.

These groups each have distinct needs, yet share one goal: to improve understanding of the relationship between climate change and infectious diseases and early warning systems so as to prepare or avoid exposure. It will require both immediate vigilance such as vaccination or antibiotic use along with longer-term efforts such as cutting carbon emissions.

At its core, risk reduction lies with living healthy lifestyles and taking steps to build resilience against climate change risks. That means striking a balance between immediate vigilance and long-term measures like investing in clean energy or planting trees to limit human-caused global warming – which may require immediate action on our part but is absolutely worthwhile in the end.

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