climate change and infectious diseases climate change and infectious diseases global climate change has resulted in a wide range of impacts on the spread of infectious diseases. like other climate change impacts on human health, climate change exacerbates existing inequalities and challenges in managing infectious disease. infectious diseases whose transmission can be impacted by climate change include dengue fever, malaria, tick-borne diseases, leishmaniasis and ebola virus disease. for example, climate change is altering the geographic range and seasonality of the mosquito that can carry dengue. aedes aegypti, the mosquito that is the vector for dengue transmission. one health, a model that considers veterinary and human health parts of an integrated whole, is partly a response to the increase of epidemic risks that arise from climate change. there is no direct evidence that the spread of covid-19 is worsened or is caused by climate change, although investigations continue. background part of a series onclimate change andsociety effects mitigation adaptation economics business action climate finance economic impacts economics of mitigation emissions trading low-carbon economy social issues agriculture cities climate justice children ethics gender indigenous people fisheries human rights security poverty migration women health and psychology climate grief eco-anxiety infectious diseases mental health psychology of denial waterborne diseases communication carbon literacy climate crisis education media coverage popular culture fiction art games public opinion adaptation resilience vulnerability disaster risk reduction ecosystem-based adaptation flood control politics history political economy climate governance climate movement denial global warming controversy litigation individual actions unfccc un conferences kyoto protocol paris agreement portal glossary index the world health organization and united nations environment programme established the intergovernmental panel on climate change (ipcc) in 1988 because little was known about health issues caused by global climate change. intergovernmental panel on climate change has presented three assessment reports. ipcc first assessment report, ipcc second assessment report and ipcc third assessment report wrote about climate change, potential health risks caused by climate change and early evidence of actual health impacts. ippc and other policy-related assessments at the regional and national levels stimulated scientific studies to understand the climate-health relationships. a noticeable effect of global climate change is the increase of temperature. since the beginning of record-keeping of temperature in the u.s. in 1895, the average temperature has increased by 1.3 °f to 1.9 °f.: 26 this is because the concentrations of greenhouse gases increase. based on this information the annual average u.s. temperatures are expected to increase by 3 °f (−16 °c) to 10 °f (−12 °c), which will have direct effects on human health. extreme temperatures affect the body by compromising its ability to regulate its internal temperature and by worsening chronic conditions such as cardiovascular and respiratory diseases. air quality is also negatively affected by climate change, which produces higher concentrations of co2, higher temperatures and changes in precipitation. this is expected to worsen respiratory conditions. climate change affects the growing season and the pollen because the start or duration of the growing season becomes extended, and the quantity, the allergenicity and the spatial distribution of pollen increase. climate change affects vector-borne diseases by affecting the survival, distribution and behavior of vectors such as mosquitoes, ticks and rodents.: 29 the viruses, bacteria and protozoa are carried by these vectors transferring it from carrier to another. vector and pathogen can adapt to the climate fluctuations by shifting and expanding their geographic ranges, which can alter the rate of new cases of disease depending on vector-host interaction, host immunity and pathogen evolution. this means that climate change affects infectious diseases by impacting their length of the transmission season and their geographical range. vector-borne diseases are a concern because they have played a significant role in human history by determining the rise and fall of civilizations. this is why the world health organization considers climate change as one of the greatest threats to human health. diseases that are products of climate change fall under the scope of environmental health professionals, who study how to control environmental factors that affect human health. another study concluded in 2022 that "58% (that is, 218 out of 375) of infectious diseases confronted by humanity worldwide have been at some point aggravated by climatic hazards". malaria further information: malaria increased precipitation like rain could increase the number of mosquitos indirectly by expanding larval habitat and food supply. malaria, which kills approximately 300,000 children (under age 5) annually, poses an imminent threat through temperature increase. models suggest, conservatively, that risk of malaria will increase 5–15% by 2100 due to climate change. in africa alone, according to the mara project (mapping malaria risk in africa), there is a projected increase of 16–28% in person-month exposures to malaria by 2100. climate is an influential driving force of vector-borne diseases such as malaria. malaria is especially susceptible to the effects of climate change because mosquitoes lack the mechanisms to regulate their internal temperature. this implies that there is a limited range of climatic conditions within which the pathogen (malaria) and vector (a mosquito) can survive, reproduce, and infect hosts. vector-borne diseases, such as malaria, have distinctive characteristics that determine pathogenicity. these include the survival and reproduction rate of the vector, the level of vector activity (i.e., the biting or feeding rate), and the development and reproduction rate of the pathogen within the vector or host. changes in climate factors substantially affect reproduction, development, distribution, and seasonal transmissions of malaria. malaria is a mosquito-borne parasitic disease that infects humans and other animals caused by microorganisms in the plasmodium family. it begins with a bite from an infected female mosquito, which introduces the parasite through its saliva and into the infected host's circulatory system. it then travels through the bloodstream into the liver where it can mature and reproduce. the disease causes symptoms that typically include fever, headache, shaking chills, anemia, and in severe cases can progress to coma or death. "about 3.2 billion people – nearly half of the world's population – are at risk of malaria. in 2015, there were roughly 214 million malaria cases and an estimated 438,000 malaria deaths." mosquitoes have a small window for preferential conditions for breeding and maturation. the ultimate breeding and maturing temperature for mosquitoes ranges from 16 to 18 degrees celsius. if the temperature is decreased by 2 degrees, most of the insects will succumb to death. this is why malaria is unsustainable in places with cool winters. when a climate with an average of approximately 16 degrees celsius experiences an increase of about two degrees, the mature bugs, and the larvae flourish. anopheles mosquitoes will need more food (human/animal blood) to sustain life and to stimulate production of eggs. this increases the chance of spreading malaria due to more human contact and a higher number of the blood sucking insects surviving and living longer. mosquitoes are also highly sensitive to changes in precipitation and humidity. increased precipitation can increase mosquito population indirectly by expanding larval habitat and food supply. these prime temperatures are creating large breeding grounds for the insects and places for the larvae to mature. increased temperature is causing snow to melt and stagnant pools of water to become more common. bugs that are already carrying the disease are more likely to multiply and infect other mosquitoes causing a dangerous spread of the deadly disease. climate change has a direct impact on people's health in places where malaria was originally not prevalent. mosquitoes are sensitive to temperature changes and the warming of their environment will boost their rates of production. a fluctuation of two or three degrees is creating exceptional breeding grounds for mosquitoes, for larvae to grow and mature mosquitoes carrying the virus to infect people that have never been exposed before. in communities living in the higher altitudes in africa and south america, people are at a higher risk for developing malaria because of the increase in the average temperature of the surroundings. this is a severe problem because people in these communities have never been exposed to this disease, causing an increased risk for complications from malaria such as cerebral malaria (a type of malaria that causes mental disability, paralysis and has a high mortality rate) and death by the disease. residents of these communities are being hit hard by malaria because they are unfamiliar with it; they do not know the signs and symptoms and have little to no immunity. the population at risk of malaria in the absence of climate change is projected to double between 1990 and 2080 to 8820 million, however; unmitigated climate change would, by the 2080s, further increase the population at risk of malaria by another 257 to 323 million. therefore, reducing the effects of climate change in the present would reduce the total by about 3.5%, saving tens of thousands of lives worldwide. exposures "the epidemiologic triad" is a model that explains the relationship between exposure, transmission, and causation of infectious diseases and it illustrates the shifting malaria transmission rates. with regards to malaria transmission rates in the african highlands, factors and exposures resulting from drastic environmental changes like warmer climates, shifts in weather patterns, and increases in human impact such as deforestation, provide appropriate conditions for malaria transmission between carrier and host. because of this, vectors will adapt, thrive, and multiply at a fast pace. an increase in the number of vectors that carry parasites, microbes, and pathogens that cause disease will become a health hazard for the human population. specifically, malaria is caused by the plasmodium falciparum and plasmodium vivax parasites which are carried by the vector anopheles mosquito. even though the plasmodium vivax parasite can survive in lower temperatures, the plasmodium falciparum parasite will only survive and replicate in the mosquito when climate temperatures are above 20°c. increases in humidity and rain also contribute to the replication and survival of this infectious agent., increasing global temperatures combined with changes in land cover because of extreme deforestation will create ideal habitats for mosquitoes to survive in the african highlands. if deforestation continues at its current rate, more land will be available for mosquito breeding grounds, and the population of mosquitos will rapidly increase. the increase in mosquitoes will thus increase the opportunity for both plasmodium falciparum and plasmodium vivax parasites to proliferate. exposure to malaria will become a greater risk to humans as the number of female anopheles mosquitos infected with either the plasmodium falciparum or plasmodium vivax parasite increases. the mosquito will transmit the parasite to the human host through a bite, resulting in infection. then, when an uninfected mosquito bites the infected human host, the parasite will be transmitted to the mosquitoes which will then become exposure to other uninfected human hosts. individuals who are constantly exposed to the malaria parasite due to multiple bites by mosquitoes that carry the parasite are at greater risk of dying. infected humans can also transmit the disease to uninfected or healthy humans via contaminated blood. health effects the health effects caused by shifts in malaria transmission rates in the african highlands have the potential to be severe. the effects of climate change on health will impact most populations over the next few decades. however, africa, and specifically, the african highlands, are susceptible to being particularly negatively affected. in 2010, 91% of the global burden due to malaria deaths occurred in africa. several spatiotemporal models have been studied to assess the potential effect of projected climate scenarios on malaria transmission in africa. it is expected that the most significant climate change effects are confined to specific regions, including the african highlands. studies show an overall increase in climate suitability for malaria transmission resulting in an increase in the population at risk of contracting the disease. of significant importance is the increase of epidemic potential at higher altitudes (like the african highlands). rising temperatures in these areas have the potential to change normally non-malarial areas to areas with seasonal epidemics. consequently, new populations will be exposed to the disease resulting in healthy years lost. in addition, the disease burden may be more detrimental to areas that lack the ability and resources to effectively respond to such challenges and stresses. prevention main article: malaria § prevention the challenges of controlling and possibly eradicating malaria in the african highlands are many and varied. many of the strategies used to control malaria have not changed,