What do you think is the deadliest animal in the world? Answer choices are: a lion, a shark, a black mamba snake, or a mosquito?
If you guessed the last answer choice, you are correct!
Typically, when we think of deadly animals, we think of animals like lions, sharks, or snakes. But the mosquito is the deadliest animal in the world because of how many people it kills every year. Though the origin of the name “mosquito” is a Spanish/Portuguese word meaning “little fly”, the impact these animals have on people all over the world is not ‘little;’ they transmit many infectious diseases including Zika, Dengue, Chikungunya, yellow fever and malaria.
Mosquito-borne diseases are most prevalent in Sub-saharan Africa, India, South America, Central America, and Asia. Since mosquitoes typically thrive in warm and humid climates with high rainfall, these tropical and sub-tropical regions encourage their breeding and multiplication.
Taking a closer look at what supports the survival of these deadly animals, it turns out that the changing climate, specifically global warming, has a pretty big role to play.
Global warming is caused by many things such as carbon emissions from power plants, greenhouse gases, deforestation, etc. The earth is changing and we humans are all guilty, one way or the other as our activities have interfered with the protective layers of the atmosphere, causing warming and other changes. For example, the ozone, which absorbs most of the sun’s ultraviolet radiation, is being depleted by things like vehicle emissions, byproducts of industrial processes, and aerosols. The effects of this depletion are that we are exposed to diseases and other health complications.
We can see the effects of our interference in the changes in frequency and intensity of some extreme weather events, rising sea levels, and a change in global temperature, which makes the environment more suitable for certain organisms and parasites to migrate and expand from one region to the other. In fact, mosquitoes have historically thrived in tropical regions due to the natural warm climate. However, we are now seeing more new cases of infectious diseases caused by mosquitoes in the temperate regions of the world.
It’s a vicious cycle: the more the ozone layer gets depleted, the warmer the climate becomes, which encourages the survival of mosquitoes; they love it!
Higher temperatures increase the development rate of the mosquito and affect the development of the Plasmodium parasite which causes malaria within the mosquito. At an ambient temperature of 23℃, the parasite will develop in 16 days, but at 27℃, it takes the parasite only 10 days to mature and become infectious. This means that a 2-3℃ rise in temperature can increase the number of people at risk of malaria by 3-5%, or more than 100 million worldwide.
It’s clear that human-induced global warming is likely to increase the infection rates of mosquito-borne diseases by creating more mosquito-friendly habitats, especially in parts of the world where mosquitoes normally do not thrive. It is inevitable that the prevalence, distribution, and seasonality of these mosquito-borne diseases will change. In fact we have already seen these changes:
- 2007: Chikungunya cases in Italy for the first time
- 2007: Outbreak of Zika virus on Yap Island (considered the first Zika emergency in the Pacific Ocean)
- 2014: A large outbreak of Chikungunya in the Caribbean, where it had not been seen before
- 2014: Re-emergence of Dengue in France, Croatia, and Central and South America
- 2014: Re-emergence of Chikungunya in France, Northern Italy, and Central and South America
- 2016: Malaria in Greece for the first time in decades
- 2017: Re-emergence of Zika virus in the US after the disease initially emerged in 2014
We all have a role to play to reduce the prevalence of mosquitoes in the environment, and therefore curb the spread of the organisms transmitted by these deadly little creatures. We must pay attention to how our actions and activities are contributing to climate change or global warming and understand these changes so we can better predict and prepare for future infectious disease outbreaks.
