Climate: long-term patterns of weather, including temperature and precipitation, in a region

Climate change refers to changes in those long-term patterns of weather, temperature, precipitation, etc.

Natural cycles of climate change have occurred throughout Earth's history.

• • For example, there have been periods, known as Ice Ages, interspersed with periods of warming.

Human activities have accelerated climate change to unprecedented rates.

Climate factors, including temperature and precipitation, affect where pathogens, vectors, and hosts can survive.

• • Changes in climate factors change the geographic range of pathogen vulnerability.

"Climate limits the spatial range, timing, and magnitude of malaria" (Colón-González et al. 2021)

• • Increasing temperatures will "exponentially" increase (Colón-González et al. 2021):

    • • Biting

      • Development and maturation

      • Incubation

      • "Capacity to produce more offspring” (Afrane et al. 2012)

  • Increasing precipitation will increase:

    • • "Creation of mosquito breeding sites" (Colón-González et al. 2021)

  • Increasing drought conditions may also increase the availability of mosquito breeding sites

    • • Efforts to increase water storage may inadvertently supply mosquitoes with standing water, perfect for laying eggs

The effects of climate change on the life cycle of Anopheles "translat[es] to an increased disease transmission efficiency” (Afrane et al. 2012)

The effects of climate change on the environment predict that the geographic range of Anopheles will expand, both in latitude and altitude.

• • Temperate regions of North America, Central Europe, and Northern Asia

  • Highland regions of Africa

There is “clear evidence that Anopheles mosquitoes have undergone rapid range shifts over the twentieth century” (Carlson et al. 2023)

In the past, the majority of malaria infections in Africa were via Anopheles gambiae vectors. Recently, foreign Anopheles species have been expanding their ranges, particularly into the East African Highlands. These new species are "major potential threat[s] to malaria control in the region” (Ryan et al. 2021).

• • An. stephensi--which is native to South Asia and the Middle East--now has "established populations in Djibouti, Ethiopia, and Sudan" (Ryan et al. 2021).

    • • This species is known to be "resilient to habitat extremes” and may significantly increase malaria risk in urban areas (Ryan et al. 2021).

  • An. arabiensis has been observed "breeding in the central Kenyan highlands...for the first time" (Afrane et al. 2012).

    • • Anopheles mosquitoes had not been reported in this high elevation region before. The appearance of An. arabiensis suggests that climate change has made the area "conducive to the proliferation of malaria vector species” (Afrane et al. 2012).

In 2023, a case of locally-acquired malaria was reported in Maryland for the first time in 40 years. That summer, at least eight other cases were reported in Florida and Texas (Dillinger).

Malaria cases in northwest Pakistan tripled from 2022 to 2023. Researchers blame this sharp increase on "climate-induced disasters, in the shape of devastating floods and excessive rains" (Saeed 2024)

There is a lot of concern regarding climate change and malaria

Climate change is considered to be making malaria worse by producing conditions that favor the spread of malaria-carrying mosquitoes

Increasing rates of malaria infection are increasing burdens on local healthcare systems.

• • This will disproportionately impact underdeveloped countries and regions with under-resourced healthcare systems.