Contents
The Biology Topics of biotechnology involves using living organisms to develop new products or solve problems.
Diseases that can be Transmitted by Mosquitoes and Prevention of Mosquito-Borne diseases
Mosquito is another insect which spreads diseases by transmitting disease-causing micro-organisms (or microbes) (see Figure). Mosquito acts as a carrier of disease-causing micro-organisms and spreads diseases from one person to another.
Please note that housefly carries the disease- causing microbes on the hair (outside its body) but the mosquito carries microbes inside its body. Mosquitoes breed in stagnant water of ponds, dirty drains, pools, ditches, and shallow lakes, etc.
The most common disease spread by mosquitoes is ‘malaria’. Actually, it is the female Anopheles mosquito which carries the parasite of malaria. The malarial parasite (called Plasmodium) causes malaria disease. It is called a parasite because it lives on the blood of a person as its food on entering his body. We will now describe how female Anopheles mosquito spreads malaria disease.
(i) When a female Anopheles mosquito bites a person suffering from malaria disease, it sucks the blood of that person which contains the malarial parasite microbes (see Figure) (Malarial parasite is a protozoan called Plasmodium).
(ii) And when this infected Anopheles mosquito now bites a healthy person to suck his blood, it transfers the malarial parasite microbes into his blood stream alongwith saliva.
(iii) By receiving malarial parasite microbes in blood, the healthy person also gets malaria disease.
Please note that only the female Anopheles mosquito sucks blood, so only the female Anopheles mosquito carries malarial parasite and spreads malaria. The male Anopheles mosquito does not suck blood of a person and hence does not spread malaria disease.
Another disease spread by mosquitoes is ‘dengue’. Dengue is caused by a virus. The female Aedes mosquito acts as a carrier of dengue virus and spreads the dengue disease from person to person.
Prevention of Diseases Spread by Mosquitoes
We can prevent (or control) the spreading of diseases like malaria and dengue caused by mosquitoes in the following ways :
- All the mosquitoes breed in water. So, the pools of stagnant water around the houses should be drained out so that mosquitoes may not breed in them. We should not let water collect in coolers, tyres, flower pots, etc. By keeping our surroundings clean and dry, we can prevent mosquitoes from breeding. And when there are no mosquitoes, there will be no malaria or dengue.
- The windows and doors of the house should have fine iron wire mesh so that mosquitoes cannot enter the house.
- Insecticides should be sprayed in houses periodically to kill mosquitoes.
- Oil should be sprayed on the surface of water in dirty water drains to kill the larvae of mosquitoes.
- Mosquito repellant cream should be applied on the exposed parts of the body before sleeping at night. Mosquito repellant devices can also be used.
- Mosquito net should be used over beds while sleeping to prevent mosquito bites.
Please note that the micro-organism which causes a disease is known as causative micro-organism of that disease. For example, tuberculosis disease is caused by bacteria, so the causative micro-organisms of tuberculosis are bacteria. Some of the common human diseases, their causative micro-organisms, modes of transmission and general methods of prevention are given below.
Some Common Human Diseases Caused by Micro-Organisms
Disease-Causing Micro-Organisms in Animals
Just like human beings, several micro-organisms cause diseases in other animals (such as cow, buffalo, sheep, goat and poultry birds). Some of the examples of diseases caused in animals by the micro-organisms (or microbes) are : Foot and mouth disease ; Anthrax and Aspergillosis.
(i) Foot and mouth disease of animals (like cattle) is caused by a virus. Thus, foot and mouth disease is a viral disease of animals. The causative micro-organism of foot and mouth disease is virus. The cattle suffering from this disease get blisters on feet and mouth.
(ii) Anthrax is a dangerous disease of animals (like catde) whichis. caused by a bacterium. Thus, anthrax disease is a bacterial disease of animals. The causative micro-organism of anthrax disease is a bacterium (known as Bacillus anthracis). The bacterium Bacillus anthracis which causes anthrax disease in animals was discovered by Robert Koch in 1876.
(iii) Aspergillosis is a disease of animals (like poultry birds) which is caused by a fungus. Thus, aspergillosis is a fungal disease of animals.’The causative micro-organism of aspergillosis disease is a fungus.
Disease-Causing Micro-Organisms in Plants
Just like human beings and other animals, micro-organisms also cause diseases in plants. For example, several micro-organisms (or microbes) cause diseases in plants like wheat, rice, potato, sugarcane, orange, apple, and others. Some of the common plant diseases caused by micro-organisms are : Rust of wheat; Citrus canker and Yellow vein mosaic of bhindi (Okra).
(i) The plant disease called ‘rust of wheat’ is caused by fungi. Thus, the causative micro-organism of ‘rust of wheat’ disease is fungus. The rust of wheat disease is transmitted through air and seeds. This means that the modes of transmission of the ‘rust of wheat’ disease are : Air and Seeds. As the name suggests, the rust of wheat disease occurs in wheat plants.
(ii) The plant disease called ‘citrus canker’ is caused by bacteria. So, the causative micro-organisms of‘citrus canker’ disease are bacteria. The ‘citrus canker’ disease is transmitted through air. This means that the mode of transmission of citrus canker disease of plants is : Air. As the name suggests, the citrus canker disease occurs in citrus trees such as those of lemon, lime, orange, etc.
(iii) The plant disease called ‘yellow vein mosaic of bhindi (or Okra)’ is caused by a virus.. So, the causative micro-organism of this plant disease is virus. The ‘yellow vein mosaic of bhindi’ disease is transmitted through insects. Thus, the mode of transmission of yellow vein mosaic of bhindi disease is : Insect.
The diseases of plants caused by micro-organisms reduce the yield and quality of various crops. The plant diseases can be controlled by the use of certain chemicals which kill the disease-causing micro-organisms (or insects). We will now discuss food poisoning and preservation of food.