15
Brucellosis Reference Guide: Exposures, Testing, and Prevention
VETERINARY EXPOSURES
Vaccine Exposure
Accidental exposures to live, attenuated vaccine strains of
Brucella spp. in veterinarians have been reported via needle stick
injury, as well as through spray exposure to the conjunctiva and
open wounds. Personnel administering RB51, S19, and Rev-1
vaccinations should wear proper PPE, including gloves and eye
protection. Proper animal restraint should be used to minimize
needle sticks or conjunctival splashes.
Brucella abortus RB51 Vaccine
16, 24
The Brucella abortus RB51 vaccine is currently the only vaccine
used in the United States for prevention of brucellosis in cattle
herds. Although RB51 was developed to be less pathogenic
and abortifacient than the S19 strain in animals, it does
retain pathogenicity for humans. Local adverse events have
been reported less than 24 hours after exposure, and systemic
reactions may begin 1 to 15 days subsequent to exposure.
●
Risk Assessment: Vaccine exposures typically occur
through direct contact; therefore, all individuals exposed to
RB51 should be considered as having a high-risk exposure.
●
Symptom Monitoring: Symptom monitoring should
be emphasized following exposures to RB51 vaccine
because of the lack of serological tests available to
identify seroconversion. The symptom monitoring table in
Appendix 2 can be given to exposed individuals.
●
Antimicrobial Post-Exposure Prophylaxis (PEP): Antibiotic post-exposure prophylaxis has been
recommended for individuals accidentally exposed to B. abortus RB51 vaccine. Refer to Table 4 for PEP
guidance. Because RB51 was derived by selection in rifampin-enriched media and is resistant to rifampin
in vitro, rifampin should not be used for PEP. The strain is also resistant to penicillin.
●
Serological Monitoring: The RB51 vaccine is a modified live culture vaccine and there are currently no
serological assays available to detect an antibody response to RB51.
Brucella abortus S19 Vaccine and Brucella melitensis Rev-1 Vaccine
25, 26
The B. abortus S19 and the B. melitensis Rev-1 animal brucellosis vaccines are available outside the U.S. and
have been known to cause systemic disease in humans. With the scope of human travel and animal trading,
potential cases in the U.S. may arise in persons exposed to the vaccine or to animals previously vaccinated.
●
Risk Assessment: Vaccine exposures typically occur through direct contact; therefore, all individuals
exposed to S19 or Rev-1 strains should be considered as having a high-risk exposure.
●
Symptom Monitoring: Guidelines for symptom monitoring can be found in Appendix 2.
●
Antimicrobial Post-Exposure Prophylaxis (PEP): CDC recommends a concomitant prophylaxis regimen of
doxycycline and rifampin for three weeks following exposure to the S19 and Rev-1 vaccine strains. Refer to
Table 4 for PEP guidance. Rev-1 is resistant to streptomycin, and therefore this drug should not be used for
PEP or treatment courses.
25
●
Serological Monitoring: Serological monitoring is available for S19 and Rev-1 exposures. Quantitative
serological monitoring should be emphasized to detect a B. abortus S19 infection among veterinary workers,
as patients may present with mild clinical symptoms or as asymptomatic.
26
Clinical Exposure
Veterinarians and breeders have a higher risk of contracting brucellosis because of close direct contact with
infected animals, and in part because of inconsistency in the implementation of standard precautions in
veterinary practice.
Risk of exposure is greatest when veterinarians handle aborting animals or those undergoing parturition, though
high-risk activities may also include specimen draws during clinical examination, surgical procedures, or
disinfection and cleaning of contaminated environments. Inhalation of aerosolized Brucella organisms and
contamination of the conjunctiva or broken skin are common routes of exposure during the aforementioned
high-risk procedures.
Exposure to Brucella canis
While dogs can become infected with various Brucella spp., they serve
as the primary host for Brucella canis. B. canis is thought to be less
virulent than other strains of Brucella species and few human cases
have been documented, though this may be a result of difficulty in
diagnosis and underreporting.
27
●
Symptom Monitoring: Symptom monitoring should be
emphasized following exposures to dogs infected with brucellosis
because of the lack of serological tests available to identify
seroconversion. The symptom monitoring table in Appendix 2 can
be given to exposed individuals.
●
Serological Monitoring: While serological monitoring is not
available for B. canis exposures, it is recommended that baseline
serum is drawn for serological testing to rule out titers to other
Brucella spp., as veterinary personnel may be exposed to a variety
of species.
●
Antimicrobial Post-Exposure Prophylaxis (PEP): A prophylaxis
regimen should be considered for all personnel with high-risk
exposures. See Table 4 for PEP guidance.
Marine Mammal Exposure
28, 29
Multiple marine mammals that have been stranded in the Gulf of Mexico, Atlantic, and Pacific coasts since 2010
have had laboratory evidence of brucellosis infection. While marine-associated brucellosis in humans has not
been documented in the U.S., four human cases are known to have occurred worldwide. One individual was
exposed in a laboratory while handling samples from an infected dolphin, and three individuals became sick
after consuming raw fish or shellfish. Individuals who come in contact with marine mammals, particularly those
stranded or visibly ill, are potentially at risk for infection from B. ceti or B. pinnipedialis.
●
Risk Assessment: Higher-risk activities when working with infected marine mammals include aerosol-
generating procedures (use of saws) or cleaning of facilities with high-pressure equipment during and after
a necropsy. Failure to use PPE, including proper respiratory protection, during the aforementioned activities
places individuals at a greater risk for occupational exposure to Brucella spp. An excerpt of the Revised
Interim Marine Mammal Brucella Specific Biosafety Guidelines for the National Marine Mammal Stranding
Network is provided in Appendix 3, and may be used as a resource for post-exposure risk assessment.