Climate change and infectious diseases
[16] Infectious diseases have played a significant role in human history, impacting the rise and fall of civilizations and facilitating the conquest of new territories.
Other key factors, include the mobility of people, animals, and goods; control measures in place; availability of effective drugs; quality of public health services; human behavior; and political stability and conflicts.
Several spatiotemporal models have been studied to assess the potential effect of projected climate scenarios on malaria transmission in Africa.
Changes in climate and global warming have significant influences on the biology and distribution of vector-borne diseases, parasites, fungi, and their associated illnesses.
Some kinds of blue-green algae (cyanobacteria) create neurotoxins, hepatoxins, cytotoxins or endotoxins that can cause serious and sometimes fatal neurological, liver and digestive diseases in humans.
[38] Climate change is forecast to have substantial effects on the water cycle, with an increase in both frequency and intensity of droughts and heavy precipitation events.
The drivers for the recent spread of this disease are globalization, trade, urbanization, population growth, increased international travel, and climate change.
[62] Climate models project further expansion of tick habit north into Canada as progressing Northwest from the Northeastern United States.
[64][62] In the face of these expanding threats, strong collaboration between government officials and environmental scientists is necessary for advancing preventive and reactive response measures.
[67] For example, modelling studies have predicted that climate change will increase suitable conditions for Phlebotomus vector species in Central Europe.
[68][69] Another model that looked at the distribution of Lutzomyia longipalpis, an important visceral leishmaniasis vector, suggested an increased range of this species in the Amazon Basin.
[80] Pregnant women infected with Zika virus are at a higher risk of giving birth to children with congenital malformations, including microcephaly.
[84] Furthermore, extreme climate patterns, including drought, floods and heatwaves are known to exacerbate the proliferation of mosquito breeding ground and as a result, escalate the rate of virus-borne diseases.
As of 2020[update], the World Health Organization summarized the current knowledge about the issue as follows: "There is no evidence of a direct connection between climate change and the emergence or transmission of COVID-19 disease.
[87] The authors found that climate-driven changes in the distribution and richness of bat species increased the likelihood of bat-borne coronaviruses in the Yunnan province, Myanmar, and Laos.
It has been observed that in the period of 2011–21, the "area of coastline suitable for Vibrio bacterial transmission has increased by 35% in the Baltics, 25% in the Atlantic Northeast, and 4% in the Pacific Northwest.
The emergence of Candida auris on three continents is proposed to be as a result of global warming and has raised the danger that increased warmth by itself will trigger adaptations on certain microbes to make them pathogenic for humans.
[96] The health of wild animals, particularly birds, is assumed to be a better indicator of early climate change effects because very little or no control measures are undertaken to protect them.
[96] Survival of Parelaphostrongylus tenuis, a brain worm of white-tailed deer that affects moose, could be increased due to the higher temperatures and milder winters that are caused by climate change.
Moose are already facing heat stress due to climate change, and may have increased susceptibility to parasitic and infectious diseases like the brain worm.
[96] Predicting the impact climate change might have on disease patterns in different geographic regions can be difficult, because its effects likely have high variability.
Therefore, climate change will also indirectly affect the health of humans through its multifaceted impacts on food security, including livestock and plant crops.
[97]While climate-induced heat stress can directly reduce domestic animals' immunity against all diseases,[98] climatic factors also impact the distribution of many livestock pathogens themselves.
[99] Without a significant improvement in epidemiological control measures, what is currently considered an once-in-20-years outbreak of bluetongue would occur as frequently as once in five or seven years by midcentury under all but the most optimistic warming scenario.
[101]: 747 Ixodes ricinus, a tick which spreads pathogens like Lyme disease and tick-borne encephalitis, is predicted to become 5–7% more prevalent on livestock farms in Great Britain, depending on the extent of future climate change.
[102] The policy implications of climate change and infectious diseases fall into two categories:[104] Addressing both of these areas is of importance, as those in the poorest countries face the greatest burden.
As is the case when responding to the effects of climate change, vulnerable populations including children and the elderly will need to be prioritized by any intervention.
The United Nations Environment Programme states that: "The most fundamental way to protect ourselves from zoonotic diseases is to prevent destruction of nature.
"[106] Significant progress has been achieved in terms of surveillance systems, disease and vector control measures, vaccine development, diagnostic tests, and mathematical risk modeling/mapping in recent decades.
[citation needed] Scientists are carrying out attribution studies, to find the degree to which climate change affects the spread of infectious diseases.
