What are Pathogens? Give examples.

Hint:Microorganisms are unicellular or multicellular organisms that are widespread in nature and can either be beneficial to life or cause harm. Microorganisms, also known as microbes are classified into six major types, namely viruses, fungi, algae, protozoa, bacteria, and Archaea.

Complete answer: Pathogens are microorganisms that cause diseases, infections, or illnesses to the host. Many natural defenses are present against pathogens within the human body in the form of helpful bacteria and the human immune system. Pathogens continue to threaten human life even with the presence of numerous medical advances that have been introduced to safeguard against infections, diseases, or illnesses caused by pathogens. These medical advances include fungicides, vaccinations, and antibiotics.
Examples of pathogens include some species of algae, viruses, bacteria, viroids, fungi, and prions. Pathogenic varieties of algae that cause the disease protothecosis in dogs, cats, humans, and cattle are known as Prototheca wickerhamii. This is a type of green algae that lacks chlorophyll and is found in sewage and soil.
The vast majority of bacteria are beneficial or harmless to humans, however, a relatively small variety of pathogenic bacteria are responsible for causing infectious diseases. Mycobacterium tuberculosis is a bacterial strain that causes the disease tuberculosis. This disease alone was responsible for the demise of about 1.5 million people in the year 2013. Most of the people affected by this disease are indigenous to sub-Saharan Africa. Pneumonia is another bacterial disease caused by Streptococcus and Pseudomonas bacteria. Pathogenic bacterias such as Salmonella, Shigella, and Campylobacter are known to be the cause of foodborne illnesses. Infections such as Typhoid fever, syphilis, leprosy, tetanus, and diphtheria are also caused by pathogenic bacteria.

Note: Diseases such as malaria, amoebiasis, giardiasis, etc. are caused by pathogenic protozoa. Most viruses are pathogenic in nature and attach themselves to the host body to replicate and spread infections. Diseases or infections caused by viruses include chickenpox, measles, influenza, smallpox, EBOLA, COVID-19, and HIV to name a few.