A Veterinarian's Needle Stick With the RB51 Brucella Cattle Vaccine: Oregon, 2017

The case

On December 7, 2017, a previously healthy, middle-aged male veterinarian went to an Oregon emergency department with 4 days of cough, malaise, muscle aches, fever and joint pain. He had stuck himself with a needle while giving cattle the Brucella abortus strain RB51 vaccine, 3 weeks before he fell ill.

• First visit: brucellosis was considered, but no Brucella test was done. After a chest X-ray he was sent home with doxycycline for pneumonia in the right upper lung.
• December 11: he returned with worse pneumonia and was admitted, and the Oregon Health Authority's Public Health Division was told of a probable brucellosis case. He was started on rifampin, ceftriaxone and azithromycin alongside the doxycycline.
• Public health stepped in with RB51-specific advice on treatment and testing, and, with the Oregon State Public Health Laboratory, on lab safety. The hospitalist stopped rifampin, kept doxycycline, and added trimethoprim-sulfamethoxazole (TMP/SMX).
• Within 3 days he was better and went home on doxycycline and TMP/SMX for 60 days, the recommended treatment for human RB51 infection. Blood and sputum cultures taken on admission later came back negative for Brucella.

He confirmed the needle stick was his only known exposure. Though he gave the vaccine regularly and knew it could infect people, he had not taken the recommended 21 days of doxycycline and TMP/SMX after the exposure.

Why RB51 is tricky

Brucellosis is a bacterial disease shared by people and many animals, and it takes very few bacteria to infect a person. Work-related exposures most often affect veterinarians, health care workers and laboratory staff.

• RB51 is a live, weakened vaccine, approved in the mid-1990s for the Brucellosis Eradication Program.
• It is resistant to rifampin, a first-line drug for human brucellosis.
• It does not produce antibodies that commercial blood tests can detect, so confirming infection takes a culture.
• Human infections usually come from needle sticks, which are fairly common among veterinarians and underreported. Of 26 RB51 exposures reported to CDC in 1998–1999, seven (27%) led to lasting illness with symptoms like this patient's.
• Pasteurization kills RB51, and it is rarely shed in milk, but it drew national attention recently when cases and exposures followed drinking raw milk in Texas and New Jersey — cases that exposed how little is known about diagnosing and treating it in people.

The lesson

Occupational RB51 exposure is a real risk for veterinary staff. Clinicians, laboratory staff and public health officials should know the difficulties of diagnosing and treating it and be ready to manage cases and exposures. State and local health departments can keep in regular touch with veterinary and laboratory communities about RB51 and advise clinicians unfamiliar with it. More: CDC's brucellosis reference guide.

Sources

Based on Sarah M. Hatcher, David Shih, Jacobey Holderman and others, "Notes from the Field: Adverse Event Associated with Unintentional Exposure to the Brucella abortus RB51 Vaccine — Oregon, December 2017," MMWR, Centers for Disease Control and Prevention; a work of the United States government in the public domain. The report's "TMX/SMX" is corrected to TMP/SMX.