What are harmful microorganisms?

Harmful microorganisms are microbes that cause diseases in humans, animals, and plants, or spoil food and water. While many microorganisms are useful, some are pathogens (disease-causing organisms) that negatively affect health, agriculture, and the environment. The major harmful microorganisms include bacteria, viruses, fungi, and protozoa.

Disease in Humans and Animals

• Bacteria: Some bacteria cause diseases such as tuberculosis, cholera, typhoid, and pneumonia.
• Viruses: They are responsible for illnesses like influenza, polio, measles, HIV/AIDS, and COVID-19. Viruses can spread quickly from person to person.
• Protozoa: Parasites such as Plasmodium cause malaria, while Entamoeba histolytica causes amoebic dysentery.
• Fungi: Fungal infections like ringworm and athlete’s foot affect the skin, while some fungi attack internal organs in weak immune systems.

Disease in Plants

Harmful microorganisms also attack crops and reduce yield, leading to food shortages. For example:

• Xanthomonas bacteria cause citrus canker.
• Puccinia fungi cause rust disease in wheat.
• Tobacco mosaic virus (TMV) damages tobacco, tomato, and other crops.

These plant diseases lead to major economic losses for farmers.

Food Spoilage and Contamination

Microorganisms such as fungi and bacteria spoil food items by growing on them, especially in warm and moist conditions. Mold on bread, fungal growth on fruits, and souring of milk are common examples. Contaminated food and water containing harmful microbes can lead to food poisoning and diarrhea.

Environmental Harm

Some microbes contaminate water sources and spread water-borne diseases. Others release toxins that affect animals and humans. Excess microbial growth in water bodies can cause oxygen depletion, killing fish and aquatic life.

Harmful microorganisms are disease-causing microbes such as bacteria, viruses, fungi, and protozoa. They cause infections in humans and animals, damage crops, spoil food, and pollute water. Unlike beneficial microbes, these microorganisms pose serious threats to health, agriculture, and the environment.