Bacterial Diseases in Humans

There are various diseases that are caused by bacteria in humans. Some of the common bacterial diseases in humans are tuberculosis, pneumonia, typhoid, tetanus, etc. Bacteria that cause various diseases in humans are known as pathogenic bacteria. We are able to sustain the growth of many bacteria due to the innate immunity provided by the body’s defence system. Bacteria that cause diseases are able to invade the body tissues and fluid by surpassing the natural defence mechanisms of the body. Bacteria can either damage cells directly, release toxins, affect cellular functions or can initiate an immune response, which can damage the cells.

Bacteria are present everywhere, they are an important part of the ecosystem and help in maintaining a sustainable environment. There are less than a hundred species of bacteria that are known to cause diseases in humans.

What are Bacterial Diseases?

Bacterial diseases are diseases caused by bacteria. There are a number of bacteria found in the human body. A variety of these do not cause any infections and are known as “good bacteria”. The bacteria that cause diseases in humans are called “harmful bacteria”. There are thousands of bacteria present in the gut that are beneficial for humans. The pathogenic bacteria in humans account for less than a hundred species.

Bacterial diseases are communicable diseases and spread from one person to another. Bacterial diseases are infectious diseases and are transmitted through water, air, food, vectors, body fluids, etc.  Bacterial disease in humans is one of the major causes of death to humans, even after so much advancement in medical research.

Read on to explore the bacterial diseases in humans caused by the harmful bacteria along with the causes and symptoms.

Also Read: Human Diseases

Bacterial Diseases


Bacterial Diseases in Humans

There are a variety of bacteria that cause diseases in humans. These include:

Bacterial Diseases in Humans Causative Agent
Pulmonary Tuberculosis Mycobacterium tuberculosis


Corynebacterium diptheriae


Vibrio cholerae


Mycobacterium leprae


Bordetella pertussis


Clostridium tetani


Yersinia pestis

Neisseria gonorrhoeae


Treponema pallidum

Salmonella enteritis

Bacterial Diseases Causes

The bacteria enter the human body through various sources and cause bacterial diseases. Bacterial diseases are communicable diseases. Bacteria can be transmitted through direct contact or through food, water, air, etc. These sources include:

  • Through contaminated food and water.
  • By having sexual contact with an infected person.
  • By sharing contaminated needles, or needles for tattooing or infected surgical equipment.
  • Through infected faeces or body fluids.

Bacteria can either directly affect the host cell or can cause a heightened immune response that damages the cells. Humans that have weak immunity are more susceptible to bacterial infections. Bacteria cause damage by following mechanisms:

  • Direct – Bacteria may cause direct damage to the host cell. Bacteria may attach to the cells and derive nutrients from the host tissue. They release waste products that damage the tissues.
  • Toxin Production – Endotoxins are present in the outer lipopolysaccharide membrane of Gram -ve bacteria and it is released with lysis of bacterial cell membrane when they die.
  • Indirect – Bacteria may induce an inappropriate or excessive immune response that causes damage to host tissues.

Bacterial Disease Symptoms

Following are the major symptoms of bacterial diseases:

  • Bloody and painful urine
  • Irritability
  • Diarrhoea
  • Vomiting and nausea
  • Weakness
  • Stiffness in neck
  • Flu-like symptoms
  • Rashes and lesions

Risk Factors Involved

  • Infants and children.
  • Eating raw or undercooked egg and meat.
  • Malnutrition.
  • Chronic diseases.
  • Genetic factors.
  • Immunodeficiency disorders.

Treatment of Bacterial Diseases in Humans

Bacterial infections can be treated by the use of antibiotics. Bacteriocidal medicines kill bacteria, whereas bacteriostatic medicines inhibit the further growth of bacteria. Bacteriophages are also used to treat certain bacterial infections. It is known as phage therapy.

Although antibiotics are available to treat various bacterial diseases in humans, constantly evolving bacteria and developing resistance to antibiotics is the major cause of concern. Excessive use of antibiotics for treating bacterial diseases in humans as well as for other use like intensive farming has contributed largely to the increasing antibiotic resistance in bacteria.

Prevention of Bacterial Diseases

Managing and preventing bacterial diseases is much easier compared to viral diseases. Bacterial diseases in humans can be prevented by maintaining proper hygiene. Bacterial diseases can be prevented by taking the following measures:

  • Timely vaccination.
  • Use of surface disinfectants of bleach to kill pathogenic bacteria.
  • Cooking food properly.
  • Consuming hygienically prepared food.
  • Proper sterilisation of needles and other surgical equipment.
  • Washing and sanitizing hands at regular intervals.
  • Avoiding unprotected sexual intercourse.
  • Be mindful and avoid going out in public places if infected.
  • Avoid sharing personal items like toothbrushes, razors, soap, utensils, etc.

Also Read: Infectious Diseases

To know more about bacterial diseases in humans, their causes, symptoms, keep visiting BYJU’S website or download BYJU’S app for further reference.


Test your Knowledge on Human Bacterial Diseases


  1. A 70 yr old lady housewife developed stomach cancer – now in stage 4 which was diagonised after tests on 4th June 2019. She was normal traveled in and out of the country. Never had any symptoms of pain. She had a mental tension over a litigation that did not go in her favor due to an alleged lapse of the legal practitioner. This was in Oct / Nov 2018 . She is a non veg. She underwent a uterus removal operation some years ago. Presently on medication. Chemotherapy or surgical operation risky according to medical practitioners advice. Could this be classified as a bacterial disease. Suggestions for diet and treatment.

    1. Cancer can have many causes- ranging from hereditary to even pathogenic. However, in this case, it seems to be a combination of several factors. There is no definitive evidence that stress leads to cancer, but many theories do exist supporting the same. One of the most popular theories is that continuous exposure to stress and associated hormones may promote growth and spread of tumours. Coming to the question, this case cannot conclusively be classified as a bacterial disease due to the involvement of several factors.

      Stage 4 stomach cancer is usually not curable, but it is certainly treatable. The primary goal is to ease the symptoms and control the spread of cancer. Furthermore, the treatment depends on the specific characteristics of the disease. Usual treatments for stage 4 stomach cancer may include radiation therapy, chemotherapy or even targeted drug therapy.

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