Human brucellosis is a reportable zoonotic disease characterized by undulating fever, malaise, and drenching sweats potentially complicated by meningitis, abscesses and endocarditis. It is caused by a facultative intracellular gram-negative cocobacillus that infects cattle, pigs, dogs, goat, and sheep. The RB51 live attenuated Brucella abortus vaccine was licensed in 1996 for immunization of cattle in the United States, as part of the State-Federal Brucellosis Eradication Program. Humans acquire the infection by consumption of contaminated dairy products or raw meat, direct contact with infected animal tissues, or by inhalation of contaminated aerosols. It is our duty as healthcare professionals to report these rare, yet serious brucellosis cases to increase acquaintance with the disease. To our knowledge, we present the first documented human brucellosis case in the United States confirmed by blood cultures, caused by the RB51 strain B. abortusused in cattle vaccine.
A 22 year-old veterinary technician presented with a 2-day history of fever, chills and profuse sweating. Blood cultures grew Brucella species that was confirmed by the center for disease control (CDC) as Brucella abortus, RB51 strain. Brucellaantibody titers revealed high immunoglobulin M and low immunoglobulin G levels indicating an acute infection. She was treated with doxycycline for 6 weeks and gentamycin for 2 weeks, with resolution of symptoms and sterilization of blood cultures.
The patient had no history of travel, ingestion of unpasteurized milk, or exposure to infected cattle. She reported multiple administrations of the RB51 Brucella vaccine, without any self-inoculation. This history raised the possibility of infection through aerosolization. The CDC passive registry recorded suspected brucellosis cases with possible accidental exposure to RB51 vaccine in the US particularly in Kansas in 1997, and in New York State in 2007.
Brucellosis is a bioterrorism agent and a threat that endangers animal and human health, economy, and tourism. Only 3.5% of US brucellosis infections are recognized due to disease unfamiliarity by US born physicians and the general population. Increased awareness of the population at risk and its healthcare providers is crucial to control disease spread in the United States.