Harmful Microorganisms

Harmful Microorganisms: -

When a child suffers from a common cold or cough he/she is asked by the school to stay at home. The reason for this is to prevent other children from being exposed to harmful, infectious and contagious microbes.

Disease-causing Microbes: -

The disease-causing microbes are known as pathogens. Microbes can spread through the air, water, soil, or from an infected person to a healthy person. Thus the diseases caused by them are called communicable diseases.

Some microbes, their spreading source and the disease caused:-

Bacteria:

Source: - Disease caused: - Food, water Cholera Water Typhoid Infectious food material Anthrax Air Citrus canker (in plants).

Virus:

Source:- Disease caused:- Air Common cold, measles Water Hepatitis A, polio Contact Chickenpox Intimate contact/blood transfusion AIDS (caused by HIV) Infected food matter Foot and mouth disease (cattle).

Insect vector TMV, yellow vein mosaic (plants)

Protozoa: -

Source: - Disease caused: - Insect vector Malaria Water/soil Dysentery.

Fungi: -

Source: - Disease caused: - Air, seeds Rust of wheat (plants).

Food Poisoning: -

When bacteria or fungi act on food material, a toxic chemical by-product is sometimes formed. When this infected food is consumed, this toxin may produce several ill effects in our body including nausea, vomiting and even death. This is called food poisoning.

Some Definitions to Remember:

Communicable Diseases: These are microbial diseases (diseases caused by microbes) that spread from one infected person to a healthy person through the air, water, food, or physical contact,  such as cholera, chickenpox, common cold and tuberculosis.
Carriers: Insects and animals that carry disease-causing microbes and transfer them from one place to other are called carriers or vectors, such as houseflies and mosquitoes.

How do houseflies transfer pathogens?

A housefly may sit on the garbage and animal excreta and the pathogens stick to their body. When they sit on uncovered food, these pathogens get transferred to the food. When someone eats this contaminated food, he or she may fall sick. To avoid this, we must keep the food covered.

Name the carriers of:

Malaria

Female Anopheles mosquito (carries the parasite of malaria called Plasmodium)

Dengue

 Female Aedes mosquito (carries the dengue virus called Flavivirus)

Common Diseases and their Modes of Transmission

 

How do prevent diseases that spread through air or contact?

To prevent diseases that spread through the air, keep the patient in complete isolation and keep his or her personal belongings away from others. Vaccination at a suitable age can prevent the onset of tuberculosis, chickenpox, polio, and measles.

How to prevent diseases that spread through water or food?

To prevent the spread of polio, cholera, typhoid and hepatitis A, vaccination is effective. One should also maintain personal hygiene and good sanitary habits and drink boiled drinking water. One should also eat properly cooked food to avoid diseases like cholera.

How to prevent diseases that spread through mosquitoes?

We can stop the spreading of diseases caused by mosquitoes (such as malaria and dengue) by not allowing the mosquitoes to breed. We should keep our surroundings clean and dry, and not let water collect anywhere - in coolers, tires, and flower pots etc. We should also spray insecticides and use mosquito repellents and mosquito nets to protect ourselves from mosquito bites.

Common Diseases and the Microorganisms that cause them

Diseases Caused by Microorganisms in Animals

Anthrax: A dangerous disease that affects humans and cattle is caused by a bacterium called Bacillus Anthracis.

Foot and mouth disease in Cattle: It is caused by a virus called the Foot-and-mouth-disease Virus (FMDV) of Picornavirus.

Diseases Caused by Microorganisms in Plants

Microorganisms can cause diseases in plants and reduce crop yield. Some of the plants in which they cause diseases are:

The plants can be protected by using chemicals that kill these microbes.

Common Diseases in Plants caused by Microbes

Citrus Canker is caused by Bacteria and spreads through Air.

Rust of Wheat is caused by Fungi and spreads through Air or Seeds.

Yellow Vein Mosaic of Okra (Bhindi) is caused by viruses and spreads through Insects.