Types of Bloodborne Pathogens

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

Bloodborne pathogens come in all sorts of shapes and sizes. Some are super small, like viruses, and others are much bigger, like parasites. Other than viruses and parasites, find out what other types of pathogens are associated with our blood.

What are Bloodborne Pathogens?

Your blood keeps you alive in many ways. It carries oxygen that is used in biochemical reactions that sustain life. It carries white blood cells that help prevent infection. It's full of platelets that ensure you don't bleed to death from a mild scratch. However, your blood may also harbor some serious problems. These are collectively known as bloodborne pathogens, infectious disease causing agents that are found in blood and can be transmitted via blood and, in some cases, other bodily fluids.

Let's go over some of the types of bloodborne pathogens.


Perhaps the most well-known bloodborne pathogens are viruses. These are essentially lifeless things that only come to life once they are inside of your body. And the most famous of these is HIV, the human immunodeficiency virus. This is the virus that leads to a disease called AIDS, acquired immunodeficiency syndrome, also called acquired immune deficiency syndrome. While we can get rid of many viruses, like the ones that cause us the cold or flu, we cannot get rid of HIV entirely. If left untreated, HIV can destroy the body's ability to fight off even minor infections, resulting in a person's death.

The green spheres are HIV cells in this image taken by a scanning electron microscope

Another virus that is an important bloodborne pathogen is called the Hepatitis B virus, one that causes, you guessed it, hepatitis B. In short, the Hepatitis B virus damages the liver. So much so, that it can result in cirrhosis. Cirrhosis is a condition where the liver is so scarred over that it doesn't function properly. If that wasn't bad enough, this virus can also lead to liver cancer.


Viruses are not the only type of bloodborne pathogen. Bacteria are as well. In fact, bacteria are a well-known contaminant of blood products used in blood transfusions. While being infected with a bloodborne virus may cause a person a life-long disorder, being contaminated with bloodborne bacteria found in blood products can cause a person a rather unpleasant and rapid end.

All sorts of bacteria can contaminate blood stored for transfusion at a later time. These include:

  • Staphylococcus aureus, also the bacterium responsible for MRSA, or a staph infection
  • Anaplasma phagocytophilum, also known as tick-borne fever
  • Staphylococcus epidermidis, which can be associated with endocarditis
  • Escherichia coli, also known as 'E. coli' and can be found in contaminated food products
  • Klebsiella, an infection usually seen in people with weakened immune systems

Parasites and Prions

If that wasn't bad enough, bloodborne pathogens aren't limited to just viruses and bacteria. Various parasites can be transmitted via the blood to cause disease. None are more famous than Plasmodium, which causes malaria. Other parasitic diseases that can be transmitted to via infected blood include:

  • Babesiosis
  • Leishmaniasis
  • Chagas disease

A microscopic image showing Plasmodium found in blood

Due to proper screening protocols in the U.S., transmission of these parasitic diseases via contaminated blood transfusion products is extremely rare, but not unheard of in other parts of the world.

On a final note, another kind of pathogen, or disease causing agent, can be transmitted via the blood. This is actually a weird protein for which there is no known cure. It's called a prion. It is the same prion famous for causing Mad Cow Disease and Creutzfeldt-Jakob disease in people. There is currently no way of destroying prions found in blood transfusion products. Luckily, prion disease is very rare and is nowhere near as big of a threat as bacteria are to blood transfusion products.

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