World mosquito day is celebrated annually on August 20. It is a commemoration of a British doctor, Sir Ronald Ross’s discovery in 1897 that ‘female mosquitoes transmit malaria between humans’. The London School of Hygiene and Tropical Medicine organizes world mosquito day celebrations every year, since the 1930s.
Mosquitoes are one of the deadliest animals in the world. Their ability to carry and spread diseases to humans causes millions of deaths every year. There are several different mosquitoes that can carry many different diseases. Aedes, Anopheles, Culex mosquitoes act as vectors (living organisms that can transmit infectious diseases between humans or from animals to humans) for the following diseases-
Aedes: Chikungunya, Dengue fever, Lymphatic filariasis, Rift Valley fever, Yellow fever, Zika
Anopheles: Malaria, Lymphatic filariasis (in Africa)
Culex: Japanese encephalitis, Lymphatic filariasis, West Nile fever
Facts about mosquito borne diseases:
· Female Anopheles culicifacies is the main vector of malaria and commonly feeds on cattle as well as humans.
· Anopheles (Vector of malaria) breeds in rainwater pools and puddles, borrow pits, river bed pools, irrigation channels, seepages, rice fields, wells, pond margins, sluggish streams with sandy margins.
· Anopheles mosquito mostly bites between dusk and dawn.
· Female Aedes aegypti transmits dengue, chikungunya, zika and yellow fever diseases to humans.
· Ae. aegypti bites most frequently during daytime, and peak biting periods are early in the morning and in the evening before dusk.
· Aedes aegypti mosquito breeds in any type of manmade containers or storage containers having even a small quantity of water.
· Eggs of Aedes aegypti can live without water for more than one year.
· Ae. aegypti usually fly an average of 400 metres, but it can be transported accidently by humans from one place to another.
· Only female mosquitoes require a blood meal and bite animals while male mosquitoes do not bite but feed on the nectar of flowers or other suitable sugar source.
Prevent mosquito borne diseases by ‘Integrated vector management (IVM)’: IVM includes:
(a) Vector surveillance- Larval surveys and adult surveys are important for early detection of mosquito population so that proper control measures can be initiated at an early stage.
(b) Vector management- It includes methods to eliminate mosquito breeding and adult mosquito population. These are –
(i) Environment management:
It includes efforts to reduce actual or potential larval (immature stages of mosquitoes) habitats in and around houses by:
· Covering all water containers in the house to prevent fresh egg laying by the vector.
· Emptying and drying water tanks, containers, coolers, bird baths, pets’ water bowls, plant pots, drip trays at least once each week.
· Removing discarded items that collect rainwater from open spaces.
· Regularly checking for clogged gutters and flat roofs that may have poor drainage.
(ii) Biological control-
· Introducing larvivorous fishes (Gambusia/ Guppy) in ornamental water tanks/garden.
· Using bacteria, Bacillus thuringiensis (Bt H-14) as biological larvicide in stagnant water. It poses no danger to humans, non-targeted animal species, or the environment when used according to directions.
(iii) Chemical control-
· Chemical larvicides (such as temephos) are used in permanent big water containers where water has to be conserved or stored because of scarcity of water or irregular and unreliable water supply.
· Adulticide- In areas where cases of dengue, chikungunya, and/or Zika virus infection are detected pyrethrum spray or malathion fogging or ultra-low volume (ULV) spray are recommended for the control of adult mosquitoes. Indoor residual spraying with insecticides is used to control malaria.
(c) Personal protective/preventive measures-
· using insect repellent;
· wearing clothes (preferably light-coloured) that cover as much of the body as possible;
· using physical barriers such as screening the windows and doors.
· sleeping under mosquito nets even during day time.
· patients infected with dengue, chikungunya, or zika virus, their household members, and community must follow personal preventive measures.
The National Vector Borne Disease Control Programme (NVBDCP)* It is one of the technical departments of the Directorate General of Health Services under the Ministry of Health and Family Welfare, Government of India and is the nodal agency responsible for the prevention and control of all vector-borne diseases in India.
WEDNESDAY, 12 AUGUST 2020