ADH Health Advisory

Rifampin/Penicillin-Resistant Strain of RB51 Brucella Contracted from Consumption of Raw Milk


The Texas Department of State Health Services, with assistance from CDC, is investigating Brucella RB51 exposures and illnesses that may be connected to the purchase and consumption of raw (unpasteurized) milk from K-Bar Dairy in Paradise, Texas. Investigation indicates that Arkansans were potentially exposed.  Symptoms of brucellosis can include: fever, sweats, malaise, anorexia, headache, fatigue, muscle & joint pain, and potentially more serious complications (e.g., swelling of heart, liver, or spleen, neurologic symptoms).  For persons potentially exposed, providers should use the included information to guide their management decisions.


Raw milk is milk from cows, sheep, or goats that has not been pasteurized to kill harmful bacteria. This raw, unpasteurized milk can carry dangerous bacteria such as Brucella, Campylobacter, Cryptosporidium, Salmonella, E. coli, and Listeria, which are responsible for causing numerous foodborne illnesses.  These harmful bacteria can seriously affect the health of anyone who drinks raw milk, or eats foods made from raw milk. However, the bacteria in raw milk can be especially dangerous to people with weakened immune systems, older adults, pregnant women, and children. In fact, a CDC analysis found that foodborne illness from raw milk especially affected children and teenagers.

A person who drank raw milk from K-Bar Dairy in Paradise, Texas, has been hospitalized with brucellosis. Milk samples from the dairy have tested positive for a Brucella strain called RB51. The Texas Department of State Health Services, with assistance from CDC, has been investigating additional exposures and illnesses that may be connected to the purchase and consumption of raw milk from this dairy between June 1 – August 7, 2017. During this investigation, it was determined that individuals who reside in Arkansas might have also purchased or consumed implicated raw milk or dairy products from K-Bar Dairy during the aforementioned timeframe. People who consumed raw milk or raw milk products from this dairy from June 1, 2017 to August 7, 2017, are at an increased risk for brucellosis and should receive appropriate post-exposure prophylaxis (PEP) as soon as possible.  They are advised to consult with their health care providers regarding PEP care and possible diagnostic testing. Please note: the incubation period for brucellosis can range from five days to six months.


  1. abortus RB51 is a strain of Brucella developed specifically for immunization of cattle against brucellosis to allow serological differentiation between naturally infected and vaccinated animals. Accidental human exposure to RB51, though uncommon, has resulted in development of symptoms consistent with brucellosis. Exposures have included needle sticks, eye and wound splashes, and contact with infected material, including raw milk.


Brucella strain RB51 is resistant to rifampin and penicillin. A combination of doxycycline and trimethoprim/sulfamethoxazole for 21 days is the recommended first-line PEP regimen for RB51 exposure. There is no serological test available to detect RB51 infection. Blood culture is the recommended diagnostic test for exposed symptomatic individuals. When ordering blood cultures to diagnose brucellosis, please advise the laboratory that blood culture may grow Brucella and that appropriate laboratory precautions should be observed. If brucellosis occurs despite prophylaxis, treatment regimens should be selected based on antimicrobial susceptibility results. Please see the diagram below for information on developing an evaluation and treatment plan for exposed patients. Women who are pregnant or breastfeeding should consult with their health care provider.

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