Laboratory Risks for Brucellosis

What to know

Brucellosis is the most commonly reported laboratory-associated bacterial infection. If you work in a lab, take precautions when handling samples to prevent infection. If you are exposed, determine your risk and follow recommendations for symptom monitoring and possible post-exposure prophylaxis.

lab worker holding a test tube

Safe laboratory practices

In a laboratory setting, the risk for accidental exposure to Brucella is highest for procedures or manipulations that occur outside the class II biological safety cabinet (BSC) and that have the potential for creating aerosols or splashes, including:

  • Pipetting
  • Centrifuging
  • Grinding
  • Blending, shaking, vortexing, and mixing
  • Sonicating
  • Opening containers of infectious materials
  • Containers breaking during transport or manipulation

If an exposure occurs

Once a potential exposure is recognized, determine which activities led to the exposure. Then identify:

  • Who was in the laboratory during the suspected time(s) of exposure
  • Where they were in relation to the exposure
  • Whether surfaces or other materials or equipment are contaminated

Preventing Brucella lab exposure‎

If you don't know if the sample you're testing contains Brucella, work in a certified biosafety cabinet (BSC) and wear appropriate PPE to minimize exposure risks. If Brucella infection is suspected, BSL-3 practices are recommended when handling products of conception or clinical specimens.

This chart can help you determine if lab professionals are at minimal, low, or high risk, and how to proceed following a laboratory exposure:

If you're at minimal risk for Brucella infection after a lab exposure, find out what you need to do.
Brucella laboratory minimal risk assessment and PEP chart
If you're at low risk for Brucella infection after a lab exposure, find out what you need to do.
Brucella laboratory low risk assessment and PEP chart
If you're at high risk for Brucella infection after a lab exposure, find out what you need to do.
Brucella laboratory high risk assessment and PEP chart

Post-exposure prophylaxis

Workers with high-risk exposures should begin antimicrobial post-exposure prophylaxis (PEP) as soon as possible to prevent Brucella infection. Prophylaxis can begin up to 24 weeks after exposure. PEP is generally not recommended for low-risk exposures, though it may be considered on a case-by-case basis. PEP courses should include a minimum of 21 days of:

  • Doxycycline (100 mg) orally twice daily and
  • Rifampin (600 mg) once daily


If you're exposed to the rifampin-resistant B. abortus RB51 from vaccine, PEP should include doxycycline plus another antibiotic effective against Brucella, such as TMP-SMZ, for 21 days.

Discuss all PEP regimen and dosing decisions with your healthcare provider, especially if you can't take any of the recommended antibiotics. If you develop clinical symptoms while on the PEP and brucellosis is confirmed, the treatment will likely be extended.

Symptom Surveillance

An occupational health provider should arrange for regular (at least weekly) monitoring for fever or symptoms consistent with brucellosis for all exposed workers. In addition, plan to take your temperature daily for 24 weeks from the last known date of exposure. Be aware of brucellosis symptoms and call your healthcare provider if you develop these symptoms within 6 months of the exposure, even if you've already undergone PEP.

Serological Monitoring

If you had a low-risk or high-risk exposure, you should be tested using quantitative serological testing to detect infection early. Your blood should be drawn and submitted to the same laboratory at 0 (baseline), 6, 12, 18, and 24 weeks after exposure.

CDC's Zoonotic and Select Agent Laboratory (ZSAL) is able to perform serial serological monitoring at no cost. If you use other laboratories, we recommend an agglutination assay to quantify seroconversion.

Exposure to B. canis or RB51‎

Infection with B. canis or B. abortus RB51 cannot be identified through serological tests. If you were exposed, pay close attention to your symptoms using the symptom monitoring chart.