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What Are The Diseases Caused by Microorganisms?

Team AckoJan 17, 2024

Microorganisms, also called microbes, are organisms of microscopic size. They may exist in single-celled forms or as a colony of cells. While many microorganisms are harmless to human beings, there are several varieties of microbes that can cause minor and major diseases in human beings. A microorganism that has the potential to cause disease is known as a pathogen.




What are the Various Types of Disease-Causing Microorganisms?

Diseases caused by microorganisms are quite common. They differ in severity and symptoms.

The various types of disease-causing pathogens can be categorised into the following:

1. Viruses

Viruses are microscopic pathogens containing genetic codes, such as DNA or RNA. They must invade a host in order to multiply.

Once an individual is infected, viruses invade the cells within the body and use the components of the host cell to replicate themselves, thereby creating more viruses.

The new viruses are released from the host cells after the process of replication is complete. This results in diseases caused by microorganisms.

Some variants of viruses can remain dormant for days or weeks before they start multiplying again. This is why sometimes a person appears to have recovered from a viral infection but ends up falling sick again.

Viral infections are difficult to treat as viruses are immune to antibiotics. Viruses can be transmitted through respiratory droplets via the air we breathe, or through contact with the blood or bodily fluids of a person with an infection. 

Diseases Caused by Viruses

Among the diseases caused by microorganisms, many are caused by viruses. Several viral diseases are contagious. They include:

  • Common cold

  • Flu

  • Warts, including genital warts

  • Oral and genital herpes

  • Meningitis

  • Measles

  • Viral gastroenteritis

  • Chickenpox/shingles

  • Many hepatitis variants   

  • Dengue fever

  • HIV and AIDS

  • Yellow fever

  • Coronavirus diseases

2. Bacteria

Bacteria are microscopic, single-celled organisms that exist almost everywhere on earth. They are very diverse and can live in various types of environments, including on and inside the human body.

Many bacteria are harmless, and some are actually beneficial to human health. However, several groups of bacteria also cause diseases and are called pathogenic bacteria. Out of the numerous diseases caused by microorganisms, several are caused by pathogenic bacteria. 

If your immune system is compromised by a virus, you become more prone to bacterial infections as well. Sometimes the diseases caused by viruses can lead to normally harmless bacteria becoming pathogenic.

Doctors usually recommend antibiotics to treat bacterial infections. However, overuse of antibiotics can also lead to bacterial strains becoming resistant to antibiotics. Bacteria can cause diseases by excreting or secreting toxins.

Diseases Caused by Bacteria

Bacteria can lead to several kinds of diseases in human beings. Bacterial diseases include:

  • Botulism

  • Typhoid

  • Tuberculosis

  • Cholera 

  • Diphtheria 

  • Bacterial meningitis 

  • Tetanus 

  • Lyme disease 

  • Gonorrhoea

  • Syphilis

  • Strep throat

  • Urinary tract infection (UTI)

  • Bacterial gastroenteritis

  • Salmonella food poisoning             

  • E.coli infection 

  • Cellulitis

3. Fungi

Fungi can refer to any member of a group of spore-producing organisms that feed on organic matter. There are millions of different fungal species, and some are microscopic.

Only a few fungi variants are pathogenic. When we talk about diseases caused by microorganisms, some of these are caused by pathogenic fungi.

Some fungal microorganisms live on and inside the human body and can cause sickness when they overgrow. Fungi cells have a nucleus protected by a membrane and a thick cell wall, making them hard to kill. 

Some fungal infections are easy to treat. However, some new strains of fungal infections are suspected to be more dangerous. Several fungal infections are contagious and can spread from one person to another through contact. 

Diseases Caused by Fungi

Fungal diseases are common in human beings. These diseases include:

  • Pneumocystis pneumonia

  • Blastomycosis

  • Histoplasmosis

  • Ringworm

  • Athlete’s foot

  • Jock itch

  • Cryptococcosis

  • Valley fever

  • Candidiasis

  • Aspergillosis

  • Vaginal yeast infections

  • Thrush

  • Fungal nail infections (onychomycosis)

4. Parasites

Parasites are organisms that live on or inside other organisms of another species (its hosts). They derive their nutrients from the hosts, causing them harm.

Of the various diseases caused by microorganisms, many are caused by parasites. Pathogenic parasites that can cause disease in humans can be of three main classes: protozoa, helminths, and ectoparasites.

  •  Protozoa

Protozoa are single-celled organisms found in different types of habitats. They can live on or inside human bodies and multiply.

Protozoa can cause infections and diseases in human beings. Transmission of protozoa from one individual to another can occur through a faecal-oral route or can be transmitted by an arthropod vector.

Protozoa that are infectious to humans are classified into four groups: Sarcodina, Mastigophora, Ciliophora, and Sporozoa.

  •  Helminths

Helminths are multicellular parasitic worms. Some adult helminths are visible to the human eye and are not microscopic.

However, helminths fall within the field of microbiology because their microscopic eggs and larvae are responsible for many diseases caused by microorganisms.

Helminth infections often occur when a person drinks water contaminated with worm eggs and larvae.

There are three main groups of helminths that cause disease in humans: flatworms (platyhelminthes), thorny-headed worms (acanthocephalans), and roundworms (nematodes). 

  • Ectoparasites

Ectoparasites are organisms that live on the skin of the host.

The term can broadly include blood-sucking arthropods, such as mosquitoes and organisms (fleas, lice, ticks, and mites) that attach themselves to or burrow into the skin of their hosts and stay there for a relatively long time.

They can cause diseases on their own and also act as transmitters of many different pathogens that, in turn, cause diseases.

Diseases Caused by Parasites

Different types of parasites can cause various diseases in human beings. Parasitic diseases include the following:

  • Dysentery

  • Malaria

  • African trypanosomiasis

  • Babesiosis 

  • Chagas disease 

  • Leishmaniasis 

  • Toxoplasmosis

  • Schistosomiasis 

  • Amebiasis

  • Cryptosporidiosis (Crypto) 

  • Giardiasis

How Health Insurance Can Protect You Against Diseases Caused by Microorganisms 

With so many disease-causing microorganisms present in our living environment, it becomes imperative to take precautions to protect ourselves.

Ensure that you maintain good hygiene, eat healthy foods, and get adequate physical exercise to maintain your health.

Investing in a good health insurance plan also helps protect you and your family in case you do end up getting diseases caused by microorganisms.

Medical emergencies are unpredictable and can cause major upheavals in your finances. It is advisable to be prepared so that you are ready to face unexpected costs of medical care, including hospitalisation fees.

A sound health insurance plan covers essential health benefits and makes it easier for you to access high-quality medical care in case of medical emergencies. Check out ACKO’s health plans for a hassle-free insurance experience.

Frequently Asked Questions



Which microorganism causes the most illnesses?

Bacteria and viruses that cause the most illnesses, hospitalisations, or deaths include campylobacter, clostridium perfringens, E. coli, listeria, norovirus, and salmonella.

Are all microorganisms harmful to humans?

Some microorganisms, including bacteria, fungi and viruses, can make you ill. But most microorganisms are not harmful to humans; many are actually beneficial to us.

What is the name given to disease-causing microorganisms?

Disease-causing microorganisms are collectively called pathogens.                                     

How does the immune system destroy microorganisms?

Antibodies help the body fight harmful microorganisms and the toxins they produce.

How do microorganisms enter our bodies?

Microorganisms usually enter our bodies through the mouth, nose, eyes, or urogenital openings. They can also enter through wounds or bites that breach the skin barrier.

What is the smallest of all microorganisms?

Viruses are the smallest of all microorganisms.

Disclaimer: The content on this page is generic and shared only for informational and explanatory purposes. Please consult a doctor before making any health-related decisions.


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