Disease Vector Control: Mosquito

World Health Organisation defines health as “a state of complete physical, mental and social well-being, and not merely the absence of a disease.”

A disease is an abnormal condition of an organism’s body or its part due to infection or environmental condition.

An organism that acts as an agent or intermediate carrier of disease causing pathogen is called disease-carrier or vector.Vectors breed in insanitary conditions and spread diseases.  

Vectors like flies and rats come in contact with infected person, garbage, faeces or sewage.Germs like bacteria, virus and other parasites adhere to the body parts of the vector.These vectors transfer the germs by brushing legs or exuding saliva and fluid to host body or uncovered food.

Tropical climate of countries like India encourages the development of disease vectors. The spreading of the diseases can be controlled by the eradication of disease carriers or vectors.

Insects such as mosquito, housefly, cockroach, rodents etc. act as vectors.

Three kinds of mosquitoes are commonly found in India, namely Anopheles, Culexand Aedes.

The life cycle of a mosquito is divided into 4 stages, namely egg, larva, pupa and adult.

Culexmosquitoes lay their eggs one at a time, sticking them together to form a raft while anopheles eggs have distinct lateral floats. Aedesmosquitoes lay their eggs singly on damp soil which hatch only when flooded with water.

Anopheles larvae must lie parallel to the water surface in order to get a supply of oxygen through a breathing opening. Culex and Aedes larvae lie at an angle to the surface of water as they obtain oxygen through a breathing tube called a siphon.
Some mosquito-borne diseases are filaria, dengue, malaria, yellow fever etc.

Many people worldwide die because of mosquito-borne diseases. Mosquito control is thus very necessary throughout the world.
The various methods for controlling mosquitoes include spraying chemicals like DDT, fumigation of dwelling places with sulphur dioxide, destruction of their breeding places, biological control etc.

Using repellants and mosquito nets help in the protection against mosquitoes.

Certain fish like Gambusia feeds on mosquito larvae and is thus used to control mosquitoes.

The Government of India has undertaken many projects for the control of mosquitoes,which include survey of malaria hit areas, spray of insecticides and distribution of drugs to the affected patients.

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  • Q1

    A man is recovered from malaria completely. Can he transmit malaria to others still now?

    Marks:1
    Answer:

    Yes

    Explanation:

    Yes, he may transmit malaria to others after he has fully recovered

    as an asymptomatic carrier of a malaria infection. After having recovered from the primary attack of Plasmodium vivax or Plasmodium ovale malaria subsequently suffer a relapse. Antimalarial drugs such as chloroquine and mefloquine that are given to cure malaria do not eliminate mature sexual forms of parasites from the bloodstream and may remain infective for on average two months.

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  • Q2

    Petrik suffering from high fever with shivering but fever comes after every 48 hours. Can you predict the type and cause of this fever?

    Marks:1
    Answer:

    Malaria; formation of new merozoites

    Explanation:

    Plasmodium vivax causes malaria in which fever comes after every 48 hours due to formation of new generation of merozoites. Its incubation period is 14 days.

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  • Q3

    Which fish is used in biological control of mosquitoes?

    Marks:1
    Answer:

    Gambusia is used in biological control of mosquitoes.

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  • Q4

    Name any two disease vectors that spread disease.

    Marks:1
    Answer:

    Mosquitoes and houseflies are the disease vectors that spread disease.

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  • Q5

    Mention any two kinds of mosquitoes commonly found in India.

    Marks:1
    Answer:

    Anopheles and Culex are the two types of mosquitoes commonly found in India.

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