Which Bloodborne Pathogen Is Most Contagious?

Which Bloodborne Pathogen Is Most Contagious?

Bloodborne pathogens are microorganisms transmitted through the bloodstream, and various diseases are present in the human body due to their infection. If you work in close vicinity with substances known to carry these pathogens, you should arm yourself with a heightened awareness. Today’s article aims to do just that by examining the most common bloodborne pathogens, their transmission and acquisition frequency, and ways to prevent them.

The Most Common Bloodborne Pathogens

While the Occupational Safety and Health Administration (OSHA) lists at least 20 bloodborne pathogens known to cause human disease, three stand out as the most common and, therefore, could be construed as the most contagious. These three garner OSHA’s focus due to the significant mortality and morbidity associated with them (1).

Hepatitis B

Caused by the hepatitis virus (HBV), hepatitis B is a serious liver infection. It spreads through infected blood, semen, or other bodily fluids. Most people infected with HBV experience it as an acute infection lasting less than six months. Most adults with HBV recover completely, whereas infants and children are more likely to develop more severe symptoms. The medical community refers to this as chronic HBV (2).

This more severe version lasts longer than six months and can lead to liver failure, liver cancer, or cirrhosis (permanent scarring of the liver) (2).

Hepatitis B symptoms might include some, all, or none of the following (2):

  • Dark urine.
  • Abdominal pain.
  • Jaundice (yellowing of the skin and whites of the eyes).
  • Joint pain.
  • Weakness and fatigue.
  • Loss of appetite.
  • Nausea and vomiting.

Hepatitis C

Similar to HBV, Hepatitis C (HCV) is a viral infection that targets the liver causing inflammation. HCV spreads through contaminated blood. While it is rare for symptoms to accompany acute HCV infections, chronic HCV can have an immense impact on the liver and present with any of the following (3):

  • Bleeding or Bruising easily.
  • Loss of appetite.
  • Itchy skin.
  • Dark urine.
  • A buildup of fluid in the abdomen (ascites).
  • Weight loss.
  • Swelling of the legs.
  • Hepatic encephalopathy (nervous system disorder brought on by severe liver disease).
  • Spider Angiomas (red spider-like blood vessels on the skin).

Human Immunodeficiency Virus (HIV)

HIV targets and damages the immune system interfering with the body’s ability to fight diseases and infections. Most commonly associated with sexual transmission, the virus also spreads by contact with infected blood. Much like HBV and HBC, the symptoms of HIV largely depend on the phase of the infection. In the primary or acute HIV stage, flu-like symptoms consisting of the following may present (4):

  • Sore throat and mouth sores.
  • Joint pain and muscle aches.
  • Night sweats.
  • Swollen lymph glands.

As the virus damages the immune system, it will eventually become a chronic condition that lasts for years. With advancements in antiretroviral therapy, an individual can live symptom-free with HIV. However, untreated, HIV turns into Acquired Immunodeficiency Syndrome (AIDS) within an average of 8-10 years (4).

How Do Bloodborne Pathogens Spread?

As one might expect, the probability of transmission elevates with increased exposure to carriers of these pathogens. These transporters include but are not limited to the following (5):

  • Vaginal secretions.
  • Cerebrospinal fluid.
  • Synovial fluid.
  • Pleural fluid.
  • Peritoneal fluid.
  • Amniotic fluid.
  • Saliva (in dental procedures).
  • Any body fluid that is visibly contaminated with blood.

According to the Centers for Disease Control (CDC), the most common incidents that lead to the transmission of a bloodborne pathogen are the following (5):

  • From mothers to babies at or before birth.
  • Accidental puncture from broken glass, contaminated needles, or other sharps.
  • Sexual contact with infected individuals.
  • Sharing needles.
  • Contact between broken or damaged skin and infected bodily fluids.
  • Contact between mucous membranes and infected bodily fluids.

Risk of Transmission

Medical care professionals have the most frequent exposure to the entries on the list above and, therefore, run the greatest risk of transmission. The CDC estimates that 5.6 million healthcare workers and those in related industries are at risk of occupational exposure to bloodborne pathogens; additionally, 385,000 sharps-related injuries occur among healthcare providers every year (6).

Hepatitis B is the most infectious of the three most common bloodborne pathogens. Still, the risk of transmission depends largely on the presence of the hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg). If the source patient tests positive for both antigens and a percutaneous injury occurs, the risk of developing clinical hepatitis ranges from 22 to 31 percent. With HBsAg positive but HBeAg negative, the range drops from 1 to 6 percent (7).

According to a publication released in 2022, the number of HBV infections among healthcare professionals has declined by almost 98 percent since 1983, decreasing the incidence from 17,000 to 263 acute HBV infections in 2010. They attribute this to the increase in HBV immunization among healthcare providers (7).

Hepatitis C most commonly transmits due to injuries sustained from sharp objects. However, progression from infection to a detectable presence of HCV antibodies in the blood, also known as seroconversion, happens at a significantly lower rate than HBV (7).

According to the CDC, seroconversion of HCV after exposure from an infected source falls within the 0 to 7 percent range with a 1.8 percent average. Transmission due to mucous membrane exposure to blood is exceedingly rare (8).

Exposure to bodily fluid positive for HIV comes with a relatively low risk of transmission. According to a publication released in 2022, 58 confirmed cases of occupationally acquired HIV occurred between 1985 and 2013; only 1 occurred between 2000 and 2013. These rates change depending on the type of exposure as follows (9):

  • HIV transmission occurred in 20 out of 6135 cases, or 0.33 percent, following percutaneous exposure.
  • One case out of 1143 exposures or 0.09 percent of mucosa exposure.
  • No cases out of 2712 exposures to intact skin.

Ways to Prevent

OSHA requires all facilities and occupations that have the potential to come in contact with carriers of bloodborne pathogens to implement measures to ensure the safety of their workers. This includes mandating preventative measures such as the following (7):

  • HBV vaccine.
  • Use double-gloving.
  • Use of a safety zone.
  • Engineered sharps injury prevention devices.
  • Clear communications when passing sharps.
  • Personal protective equipment such as impervious gowns and face/eye shields.

While bloodborne pathogens can transmit from person to person, the right knowledge and preventative measures can lessen those risk percentages immensely. This begins with the proper training, such as the courses offered through our vast suite of training material. Make yourself and your workplace a safe environment with the completion of our bloodborne pathogen training course and certification found here.


  1. Denault D, Gardner H. OSHA Bloodborne Pathogen Standards. [Updated 2022 Apr 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Retrieved November 20, 2022 from: https://www.ncbi.nlm.nih.gov/books/NBK570561/
  2. Mayo Foundation for Medical Education and Research. (2022, September 24). Hepatitis B. Mayo Clinic. Retrieved November 21, 2022, from https://www.mayoclinic.org/diseases-conditions/hepatitis-b/symptoms-causes/syc-20366802
  3. Mayo Foundation for Medical Education and Research. (2021, August 31). Hepatitis C. Mayo Clinic. Retrieved November 21, 2022, from https://www.mayoclinic.org/diseases-conditions/hepatitis-c/symptoms-causes/syc-20354278
  4. Mayo Foundation for Medical Education and Research. (2022, July 29). HIV/AIDS. Mayo Clinic. Retrieved November 21, 2022, from https://www.mayoclinic.org/diseases-conditions/hiv-aids/symptoms-causes/syc-20373524
  5. Bloodborne diseases. BC Centre for Disease Control. (n.d.). Retrieved November 21, 2022, from http://www.bccdc.ca/health-info/disease-types/bloodborne-diseases
  6. Centers for Disease Control and Prevention. (2015, February 11). Sharps safety for healthcare settings. Centers for Disease Control and Prevention. Retrieved November 21, 2022, from https://www.cdc.gov/sharpssafety/index.html
  7. Weber, MD, MPH, D. J. (2022, October). Prevention of hepatitis B virus and hepatitis C virus infection among health care providers. UpToDate. Retrieved November 21, 2022, from https://www.uptodate.com/
  8. Updated U.S. Public Health Service Guidelines for the management of … Morbidity and Mortality Weekly Report. (2001, June 29). Retrieved November 22, 2022, from https://www.cdc.gov/mmwr/PDF/rr/rr5011.pdf
  9. Zachary, MD, K. C. (2022, October). Management of health care personnel exposed to HIV. UpToDate. Retrieved November 21, 2022, from https://www.uptodate.com/