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Story of the Aedes mosquito

  • Published at 05:15 pm August 22nd, 2019
aedes
Photo : Courtesy

A short history of ‘the most dangerous animal in the world’

Professor Jeffrey R Powell of Yale University called Aedes mosquito ‘the most dangerous animal in the world’ in his paper titled ‘New contender for most lethal animal’ (Nature, 2016). And it’s not difficult to see why.

Recently, dengue has been wreaking havoc across South Asia. Philippines has declared a national epidemic after more than 600 people died from the fever. Malaysia too is facing an all-time high dengue crisis with around 80,000 people affected. 

In Bangladesh, thousands of people are being hospitalized, with hundreds of new dengue patients being admitted every day. 

The notorious dengue virus is transmitted by its notorious carrier: the Aedes mosquito. 

Precisely, Aedes aegypti is the mosquito responsible for spreading dengue. Dengue spreads through a vicious cycle. According to the WHO, the virus passes to humans through the bite of an infected female Aedes mosquito which acquires the virus by feeding on the blood of an infected person. 

It’s usually people rather than the mosquito itself that cause the virus to spread widely. This is because the Aedes mosquitoes usually breed in or near dwellings and fly no more than 400m. At this rate it is not possible for the mosquito alone spread the disease, without infected people also acting as carriers. 

Even though we associate dengue with Aedes, it is however, also capable of causing yellow fever, chikungunya and Zika virus infections. 

The Aedes mosquito first originated in West Africa. It was introduced to the New World 400-550 years ago via European slave trade.

The species was introduced by European ships to the Mediterranean region in 1800 and became established there by 1950. 

Aedes mosquito was introduced to Asia by the 1870s after the opening of the Suez Canal in 1869. It also made its way to Australia and the South Pacific, the scientific paper titled ‘Recent History of Aedes aegypti: Vector Genomics and Epidemiology Records,’ documents. The paper was authored by Jeffrey R Powell, Andrea Gloria-Soria, and Panayiota Kotsakiozi, and published in 2018 in the science journal BioScience. 

Historical reports of dengue and yellow fever are not all reliable as the names of the diseases and the mosquitoes that caused them differed from region to region. Until 1900, it was not even known that mosquitoes cause diseases. But some things are known about its history.

When the Aedes mosquito first existed in Africa they used tree holes and other natural pockets of water as larval breeding grounds and non-human mammals as blood source. 

Then this ‘wild’ breed of mosquitoes became “domesticated” and began to use household water containers as breeding grounds and humans as a blood source. This domestication of Aedes mosquitoes is the root cause of our woes today.