Introduction
Climate change has an important influence on the transmission of vector-borne diseases. One-sixth of the population worldwide suffers from illness due to vector-borne diseases, as estimated by the World Health Organisation (WHO). The risk of vector-borne disease increases as the climate changes, which alters temperature and weather patterns around the globe. Temperature and rainfall are climate variables that directly influence vector-borne diseases. These changes may cause the displacement of insects to regions that are more favorable to them.
Insects such as ticks, mosquitoes, and flies can transmit vector-borne diseases. The impact of climate change leads to malaria and dengue, which have become the big five: malaria, dengue, Zika, chikungunya, and yellow fever. Globally, these diseases may lead to morbidity and mortality. The mortality rate yearly due to vector-borne diseases is more than 700,000 deaths. These diseases are now transmitted from human to human, although they are zoonotic in origin in tropical and subtropical regions through mosquitoes. There is a huge impact on socioeconomic status. Health inequities increase due to vector-borne diseases.
What Are Vector-Borne Diseases?
Vector-borne diseases have three elements: The pathogen, the vector, and the host. Pathogens that cause infection can be viruses, bacteria, or parasites. Vectors that transmit the pathogen to the host are mosquitoes, ticks, and flies. Hosts like humans or other animals are infected and fall sick. It is caused by a vector, a living organism like mosquitoes or ticks, that transmits infectious agents from an infected animal to humans or other animals.
How Do Climate Variables Influence Vector-Borne Diseases?
Temperatures are the simple connections that affect the biting vectors via survival and reproductive rates and pathogens that they carry via survival and developmental rates. Precipitation is by disease transmitted by vectors that have aquatic developmental stages, such as mosquitoes, and also via humidity, where vectors transmit diseases without such stages, such as ticks or sandflies. The indirect effects of climate and weather conditions are on the natural environment and human systems. The geographic spread of vectors such as mosquitoes and ticks increases in warmer temperatures where they can survive and breed. Stagnant water due to increased rainfall and droughts creates more vector breeding areas. Warmer climates extend the disease transmission season. The behavior of vectors is affected by temperature changes.
What Are the Risks Of Vector-Borne Diseases?
The Aedes mosquito is a vector responsible for spreading infectious diseases that are dangerous and life-threatening, such as zika, chikungunya, and dengue fever. The mosquito-borne viral infection dengue is found in tropical and subtropical regions that cause flu-like illness. Dengue, in severe cases, can lead to hospitalization and sometimes death.
Mosquitoes, to survive, are found in cement tanks, tires, and household pitchers. Another concerning vector is the ticks. They can transmit many pathogens and also zoonotic viruses. Ticks number has increased during warm winters in the last decade. In subarctic regions of Asia and Europe, tick-borne encephalitis is found. They are also found in Germany in the winter months.
The extrinsic incubation period is when a vector ingests the pathogen, and when the vector is ready to transmit the pathogen to another host strongly depends on the temperature. The transmission of vector-borne diseases has a direct impact on temperature. Temperature affects the biting behavior and survival of vectors.
What Are the Common Illnesses Caused by Mosquitoes Due to Climate Change?
The common illness caused due to climate change is malaria, dengue, and West Nile virus infection. The most deadly and studied climate-sensitive vector-borne disease is malaria. Malaria is caused by plasmodium species and is transmitted between humans through female anopheles mosquitoes. Malaria usually responds to rainfall, humidity, and temperature. In the highlands of Colombia and Ethiopia, there is an increase in temperature of 0.2 degree Celsius, which leads to the spread of malaria in these countries. Dengue is also the most common mosquito-borne viral disease.
To decline dengue, various vector-control programs have increased globally. The four serotypes of the dengue virus are transmitted between humans. The cause of dengue is water storage containers used with inadequate piped water supply and in areas with rainfall-filled containers. These can become mosquito breeding sites. The neuroinvasive disease in humans and animals is caused by West Nile virus. It is centered around a bird-mosquito transmission cycle. It mostly infects humans and horses. When it occurs in humans, they are asymptomatic but sometimes can cause life-threatening illness, mostly in elderly and immunocompromised persons. Preventing this disease in humans is essential as there are no medications or vaccines to treat it. This disease is mostly seen in warming temperatures in the North and already exists in Europe and Germany.
How Does Tick-Borne Illness Influence Climate?
The most common tick-borne disease worldwide is Lyme disease. It is highest in temperate regions of Western Europe and East Asia. The infection can cause debilitating multisystemic chronic disease when not treated early. Humans have no role to play in the ongoing transmission of disease. There is an increase in human-tick interaction during summers when climate change occurs. Warming temperatures are associated with ticks in Canada and Norway, where there is an increase in cases of Lyme disease.
Conclusion
Climate change will increase the impact of vector-borne diseases on humans and animals by direct and indirect effects. The direct effect is on the biology of vectors and transmission cycles. The indirect effects are through socioeconomic mechanisms. Rainfall and humidity of the environment also strongly influence vector-borne transmission diseases. Heat-trapping gasses such as carbon dioxide release should be reduced, which decreases impacts on climate change, thereby helping to protect our health and well-being. The insect repellent cream can be used to avoid bed bug bites. Mosquito control programs should be conducted to control the spread of illness.
