Harmful microorganisms, called pathogens, cause infections like polio, cholera, mumps, rabies, and malaria. Some pathogens require carriers to spread diseases; for example, Anopheles mosquitoes transmit Plasmodium, which destroys red blood cells, causing anaemia and hypoxia.
- Microorganisms can enter the body through contaminated food, water, air, or cuts on the skin. For example, Streptococcus can infect wounds and, in rare cases, cause severe conditions like necrotising fasciitis.
- Mould like Aspergillus and bacteria like Pseudomonas cause food spoilage by forming scum or mould on items like pickles and jams.
- Bacteria like Salmonella and Clostridium botulinum cause food poisoning by releasing toxins called enterotoxins.
- Most pathogenic diseases are contagious and infect the host by using its nutrients and attacking its immune system. This has led to the development of vaccines and antibiotics.
- Certain pathogens affect only animals, such as anthrax, but can also infect humans. Others, like crown nerve disease, harm plants, reducing their quality and yield.
- Pathogens also harm food by growing on it and releasing toxins, which can cause serious health problems. Food preservation methods like boiling, purification, and filtration are used to prevent such harm.
Though less than 1% of microorganisms are harmful, they cause infectious diseases like influenza and measles and may contribute to chronic conditions like cancer and heart disease. Controlling microbial growth is essential to protect humans, animals, plants, and food from harmful effects.
