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World Mosquito Day

20th August

World mosquito day is celebrated on the 20th August every year to raise awareness around the importance of mosquito control

Mosquito-borne diseases have been recorded in human history for thousands of years as major causes of disability and death. No one, however, realised mosquitoes were vectors of the diseases until the end of the 19th century. The first breakthrough came in 1877 when British doctor Patrick Manson discovered that a Culex species of mosquito could carry the human filarial roundworm.

Over the next two decades he and other researchers from France, Italy, Russia and the USA turned to malaria, a major killer in both tropical and temperate countries. They slowly completed the complex jigsaw of malaria transmission and biology in humans and mosquitoes. 

In 1894, Manson persuaded Ronald Ross, a medical officer in the Indian Medical Service, to study mosquitoes as the likely vector of the malaria parasite. After years of fruitless research Ross finally proved in 1897 that Anopheles mosquitoes could carry the malaria parasite. He called the day of his discovery, 20 August, 1897 “Mosquito Day”. The London School of Hygiene and Tropical Medicine later named 20th August World Mosquito Day to mark the significance of his discovery, which is celebrated annually. 

This critical link to the Anopheles mosquito also showed that practical measures to prevent mosquito bites and control mosquito populations — vector control — could be used to prevent malaria.

The importance of mosquito control

Andy Ransom, CEO of Rentokil Initial, discusses the threat from mosquitoes worldwide and Rentokil’s commitment to protecting people and enhancing lives through our vector control work.


The need for mosquito vector control

Many mosquito-borne diseases such as malaria, dengue, Zika, chikungunya and West Nile fever have been undergoing a resurgence in recent years. According to the WHO’s Communicable disease threats report dated February 2022 “Chikungunya virus disease and dengue are vector-borne diseases transmitted by Aedes mosquitoes. Outbreaks of dengue and chikungunya virus diseases have been reported globally in the Americas, Asia, Africa, Oceania, and Europe. Chikungunya virus disease and dengue are not endemic in mainland Europe, despite autochthonous outbreaks having been reported during the summer and autumn months in recent years.”

Rapid urbanisation, increases in international trade and travel and changing agricultural practises are all contributing to the increases in mosquito and other vector-borne diseases. History shows that vector control efforts need to be continuously supported by all countries to maintain expertise and capacity. This is essential to detect threats, prevent resurgence of deadly diseases and cope with new outbreaks of diseases.

Mosquito-borne diseases 

More than one million people around the world die from mosquito-borne diseases every year, and hundreds of millions more experience pain and suffering from illnesses transmitted by mosquitoes.



Malaria is the deadliest mosquito-borne disease. In 2020 there were an estimated 241 million cases of malaria worldwide with the estimated number of deaths standing at 627000 according to the World Health Organisation. Malaria is caused by Plasmodium parasites transmitted by Anopheles mosquitoes. There are five species of the parasite that cause malaria and over 40 species of Anopheles mosquitoes that are important vectors of the disease. Each species of Anopheles has distinct ecology and behaviour, which makes malaria vector control more complex than other mosquito-borne diseases. Rentokil is proud to be part of the global Malaria No More effort to drastically reduce the risks posed by this deadly disease.


The Zika virus is primarily spread through bites of infected Aedes species of mosquito, including Ae. aegypti and Ae. albopictus, but many regions have local Aedes species that can transmit the virus. The virus can also be transmitted from a pregnant mother to her foetus, through blood transfusions and through sex. Experience in past Zika outbreaks showed the importance of an integrated approach in controlling the outbreak that should include integrated vector management, risk communication, sexual and reproductive health services, health education and healthcare.


Dengue is considered to be the most virulent mosquito-borne disease worldwide because of its rapid spread in recent decades, resulting in it now being endemic in more than 100 countries. According to the WHO: “The global incidence of dengue has grown dramatically with about half of the world's population now at risk. Although an estimated 100-400 million infections occur each year, over 80% are generally mild and asymptomatic.” Dengue thrives in the poor urban areas of the tropics and subtropics because of poor sanitation and the many sites suitable for breeding. Aedes mosquitoes only need a small quantity of water for the larvae to develop, such as gutters, puddles, drains, bottles, cans, tyres and uncovered water containers.

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