Infectious diseases

The information here is provided for general educational purposes. Always wise to consult professional medical care if you need advice.

Share on facebook
Share on twitter

The diseases which are caused by pathogenic microorganisms are known as infectious diseases and the pathogens are mostly viruses, bacteria, fungi and protozoa, and sometimes helminths and prions. The infection can be transmitted to an organism directly by the pathogens and by indirect methods as well like from one person to another by sneezing, coughing and touching.


Very small parasites, not considered alive or dead. Viruses need to infect a host in order to copy themselves


Single-celled microorganisms that belong to larger group of organisms called “prokaryotes”.


single-celled microscopic animals


Living organisms built of eukaryotic cells like yeast or mold

Viruses challenge our concept of what “living” means. A virus is genetic material contained within an organic particle that invades living cells and uses their host’s processes to produce a new generation of viral particles.

See here a list of viruses

Viral diseases

A virus is a tiny substance that can cause a deadly infection. Viral diseases occur when an organism’s body gets infected by a pathogenic virus. Viruses are not considered to be either living or dead, rather they can replicate only when inside another cell. As viruses cause different infections in different parts of the body, these infections can be categorized as;

  • Respiratory viral diseases
  • Gastrointestinal viral diseases
  • Hemorrhagic viral diseases
  • Neurological viral disease
  • Exanthematous viral infection

Respiratory viral diseases

Viruses cause respiratory infections which can be transmitted from one person to another. These infections usually infects the respiratory tract from the upper and lower sides. These diseases typically cause cold-like or flu-like symptoms.



  • Flu
  • Common cold
  • Parainfluenza
  • Severe acute respiratory syndrome

Transmission / symptoms / Treatment

These viral infections are spread out and transmitted by sneezing, coughing and touching objects with dirty hands of an infected person.

Symptoms of this infection are usually coughing and   sneezing.

These infections usually heal on their own after 2 or 3 days through proper care, washing hands, and covering nose and mouth while coughing or sneezing. Cough Elixir and pain killers are used to manage symptoms, while antiviral drugs can be prescribed by physicians for rapid cure. 

Hemorrhagic viral diseases

It is a viral disease that has a severe and harmful impact on the vascular system. These diseases are often characterized by bleeding (Hemorrhage).


  • Ebola
  • Dengue fever
  • Yellow fever
  • Congo hemorrhagic fever 


Transmission / symptoms / Treatment

These viral diseases can be transmitted through the bite of insects and by direct contact with infected blood or any fluid at any orifices (Such as the nose, eye and mouth) or through broken skin.
Dengue fever is spread by the Aedes mosquito.
High fever, weakness, bleeding from nose or mouth and body pain are common symptoms of this infection.

These viral infections do not have any special treatment and the simplest thing to do is to avoid these infections by taking precautionary measures. Treatments for these diseases focus on relieving symptoms.

Neurological viral diseases

These viral infections are concerned to infect the nervous system, such as the brain and spinal cord. 


  • Rabies
  • Poliomyelitis
  • Measles
  • Viral encephalitis

Symptoms / Transmission / Treatment

Fever, laziness, drowsiness, and unconsciousness are some main symptoms of these types of infections, although the exact symptoms can differ between neurological viral diseases. These infections are transmitted can be transmitted in many ways; for Rabies it can be transmitted by being bitten by an infected animal, Poliomyelitis, measles and viral encephalitis can be spread by coming into direct contact with feces or saliva of an infected person. The best way to prevent these diseases is to take vaccines. Vaccines exist for polio, measles and different types of viral encephalitis.

Hepatic viral disease

These disease cause inflammation and damage in the liver. This can cause severe problems in some cases because the liver may not be able to clear toxins out of the body.


Hepatitis A, B, C, D, and E

Transmission / Symptoms / Treatment

Infection can be transmitted in many different ways including: through contaminated food or water and through the feces, blood, semen, saliva or other fluids of an infected person. Common symptoms include yellowish, pale eyes and skin, severe fatigue, swelling in the abdomen and legs and dark yellow urine.     

Hepatitis can be prevented through basic sanitation and hygiene, such as washing ones hands and preparing food in a clean manner. Vaccines also exist for certain types of hepatitis to prevent infection. This is important for hepatitis A, since it has no special treatment options. Treatment for hepatitis varies depending on the type. These typically are aimed at relieving symptoms such as maintaining blood glucose and blood pressure. Some types of hepatitis have no medication therapies, whereas others have antiviral medication as an option. Hepatitis A and Hepatitis E do not have any medication options, but are manageable and typically resolve themselves; patients are advised to get rest, nutrition and hydration while their body fights off the infection.

Bacteria are small, single celled organisms that live in diverse environments. We cannot live without bacteria as we rely on bacteria for our own survival. Bacteria can live in soil, the ocean and inside the human gut. 

Bacterial diseases

Examples of infectious diseases caused by bacteria are:

  • Cholera
  • Tuberculosis
  • Plague
  • Anthrax
  • Syphilis 
  • Leprosy 
  • Food poisoning
  • Ulcers
  • Gonorrhea

Transmission / Symptoms / Treatment

Bacterial infections can be transmitted by unhygienic food, contaminated water, and unhealthy sexual practices.

Symptoms include weakness, diarrhea, vomiting, pain, bloody urine or difficulty in urination and high fever. To avoid these infections, precautionary measures should be taken like; preparing food in a sanitary and hygienic way, washing hands frequently and social distancing. 


single-celled either free-living or parasitic, which feed on organic matter. 

Protozoan infectious disease

Protozoa are responsible for infections in different types of animals, plants and also marine life. Some infections caused by protozoa are;

  • Sleeping sickness
  • Giardiasis
  • Chagas
  • Malaria


Transmission / Symptoms / Treatment

Protozoan infections can be transmitted by insects, unhealthy sexual practices and eating unhygienic food, like ingestion of cysts.

Symptoms can include fatigue, loss of appetite, weakness, dehydration, and vomiting and weight loss. Treatment depends on the type of protozoa causing the disease. Malaria can be treated with medication such as chloroquine and doxycycline. Other treatments can include anti-parasitic medications, such as benznidazole for Chagas.


multi-celled, plant-like organisms. Unlike other plants, fungi cannot make their own food from soil, water, and air. Instead, fungi get their nutrition from plants, people, and animals. Many fungi are not dangerous in healthy people. 

Fungal infectious diseases

Infections caused by fungi are common throughout the world.


  • Ringworm
  • Blastomycosis
  • Thrush in men and women
  • White-nose syndrome
  • Histoplasmosis
  • Aspergillosis

 Transmission / Symptoms / Treatment

Fungal diseases can be transmitted from person to person very easily, such as through skin to skin contact and inhalation of air where fungal spores may be present.

Symptoms from fungal diseases are different depending on the disease but can range from itching, red skin, rashes, cracks in the skin, hair loss from specific areas like in some places of mustaches, beards, etc.

Infection can be treated by taking antifungal medicines like antifungal drugs, creams, sprays, and liquids. Antifungal treatment can sometimes have serious side-effects, so fungal infection is best prevented by taking precautionary measures like taking care of the cleanliness of your body and changing clothes regularly.

How was this post?

Click on a star to rate it!

Average rating 5 / 5. Vote count: 1

No votes so far! Be the first to rate this post.

Please complete the required fields.

One Response

Leave a Reply

Your email address will not be published. Required fields are marked *