Introduction:
The drastic climatic changes, especially the rapid warming of the earth's surface due to the emission of greenhouse gasses, have a widespread negative effect on the control and prevention of vector-borne diseases. Since many vectors grow rapidly in warm conditions, the transmission of disease in such conditions occurs rapidly and poses a great challenge in controlling the spread. The greenhouse gas effect has led to a rise in temperature by one degree Celsius above pre-industrial levels, which has led to more warm days and nights and a decrease in cold days and nights. Hence, these climatic changes majorly impact the transmission, pathogenicity, and intensity of the spread of vector-borne diseases.
What Are Vector-Borne Diseases?
The diseases spread through animals and insects, which act as vectors (mode of transport) in transmitting the viral infection, where they act as hosts and transmit the infection to another host once the vector has become ineffective.
What Are the Examples of Vector-Borne Diseases?
Dengue, Malaria, Zika virus, Lyme disease, West Nile river fever, plague, and human sleeping sickness are some examples of vector-borne diseases. These diseases involve arthropods (invertebrate animals) as vectors for transmission of the diseases.
How Does Climatic Changes Impact Vector-Borne Diseases?
According to the Intergovernmental Panel on Climate Change, the prevalence rates of various vector-borne diseases have increased with climatic changes. The panel also has predicted that climate-sensitive vector-borne diseases like malaria, dengue, Lyme disease, and West Nile virus infection are about to increase in the next 80 years under the influence of climatic changes if appropriate measures are not taken.
1. Impact on Malarial Infection:
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Malaria is one of the most commonly encountered climate-sensitive vector-borne diseases.
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Malaria is a vector-borne disease caused by the plasmodium parasite, which is transmitted between humans by the female anopheles mosquitoes acting as a vector and is one of the most deadly and most studied climate-sensitive vector-borne diseases.
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Due to the changes in temperature, humidity, rainfall, low socioeconomic status, and failure in the proper disease control measures, the disease spreads rapidly.
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The disease is more evident in tropical climates (considerably higher temperature regions).
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Temperate regions also have seen a rise in malaria cases. However, socio-economic development in these regions has led to a decrease in numbers.
2. Impact on Dengue Infection:
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Dengue is the most common mosquito-borne viral infection seen in tropical and subtropical regions. It is transmitted by Aedes aegypti.
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Recent times have seen an exponential rise in dengue cases due to an increase in trade and travel globally in the absence of disease control measures.
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The tropical climates, which usually get affected by drought conditions, see a rise in the cases as people are curbed from getting water on a daily basis, making them store water in containers in and around their homes.
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The stored water containers become a favorable breeding environment for Aedes aegypti mosquitoes, causing the spread of the infection.
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In case of heavy rainfall, the pooling of water around the houses in containers and other outdoor substances causes favorable breeding sites for the Aedes albopictus and spreads the infection in urban areas.
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Both the species Aedes aegypti and Aedes albopictus have the potential to adapt to higher temperatures, and hence, precautions should be taken to prevent outbreaks in such climatic conditions and their roles in future outbreaks.
3. Impact on Lyme Disease:
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Lyme disease is a tick-borne (vector) disease prevalent in the temperate regions.
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This disease typically becomes active and spreads rapidly in warm temperatures.
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If not treated immediately, the disease may lead to multisystemic complications.
4. Impact on West Nile Virus Infection:
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West Nile virus infection is caused by flavivirus which spreads through horses and humans (vectors).
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This is a potentially fatal neuroinvasive disease that has widespread occurrence.
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Although the infection is asymptomatic, it can lead to life-threatening complications in old patients and immunocompromised individuals.
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The spread of infection is influenced by warmer climatic changes and land-usage changes. Also, the virulence of the flavi virus, mosquito breeding environments contributes to the increased spread of the infection.
How Does Public Health Intervene to Control the Spread of Climate-Sensitive Vector-Borne Diseases?
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The surveillance control measures and investments in public awareness programs have led to the early detection, treatment, and prevention of vector-borne disease and also aided in devising measures to prevent further outbreaks resulting from climatic changes.
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Access to mosquito control programs, insecticides, and personal protective measures to face the newer trends of diseases owing to climatic changes has shown improved results in controlling the spread and prevention of vector-borne diseases.
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Although many countries worldwide have made efforts to prevent the mortality and prevalence rates in the past, this vector-borne disease with newer disease trends is posing challenges to the public health services in devising advanced strategies to eliminate the disease.
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Due to the development of drug and insecticide resistance and the improper availability of services during the COVID-19 pandemic, the cases have increased globally.
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Public health services need to come up with providing better socio-economic benefits to the underserved and improved access to personal protective measures to protect the people living in remote places from rapidly spreading vector-borne diseases.
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The dengue and the West Nile River virus infection can be prevented by conducting various community mosquito-control programs.
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Providing improved access to insect-repellent sprays and protective clothing to susceptible individuals majorly helps in preventing the spread.
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Vaccines against vector-borne diseases like yellow fever, Japanese encephalitis, and tick-borne encephalitis have been successful in preventing the diseases.
Conclusion:
The climatic changes in vectors, pathogens, and reservoir hosts have been negatively impacting public health services. Due to the abrupt climatic conditions, vector-borne diseases are seeing an increase in the rise in the ecosystem. As there is an imbalance in the climatic conditions with warmer temperatures, the vector becomes more active and involved in spreading the diseases at significantly higher rates. Hence, to prevent vector-borne diseases, the public health sector needs to take appropriate measures to reduce the prevalence and spread of vector-borne diseases and should come out with various vaccination programs. However, if measures are not taken to reduce the global temperatures and ill effects of global warming, the public health measures taken go in vain.
