The New York City Health Department issued a health alert Friday after two recent imported cases of the zoonotic bacterial infection, Brucella melitensis were reported in the city.
In April and May 2015, two laboratory-confirmed cases of Brucella melitensis were reported, exposing dozens of health workers to the serious bacterium.
Health officials are reminding clinicians to get travel histories and risk exposures from patients presenting with fever and infectious disease symptoms. If brucellosis or infection from another highly infectious agent is suspected, inform the clinical laboratory so that laboratorians can take special precautions to prevent exposure.
The NYC Health Department describe the two incidents in great detail:
In the first incident, a male patient in his 40s presented to a NYC hospital with debilitating neck pain. He had been living in Africa for 6 – 9 months. On presentation, he was afebrile, though he developed fever, chills and sweats after he arrived at the emergency department (ED). His CBC was normal, and transaminases were not tested. Two days after admission, a consultant elicited a history of recurrent fever, weight loss, and anorexia while he was in Africa. He ultimately was diagnosed with extensive cervical prevertebral and retropharyngeal phlegmons.
After 4 days of incubation, 2 sets of blood cultures were flagged as positive by the instrument. Blood culture bottles were vented and Gram stained in a biological safety cabinet, and small, Gram negative coccobacilli were observed. Colony growth on subculture was apparent after roughly 24 hours of incubation. The following laboratory work was done on an open bench: subculturing; catalase test; a qualitative method for identifying Neisseria and Haemophilus spp. that requires inoculation with standardized suspensions of bacteria; and spotting bacterial growth on a steel plate for analysis with matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).
MALDI-TOF MS could not identify the organism, because Brucella is not included in the instrument’s reference database. Approximately 1 week after the blood cultures initially demonstrated growth, the isolate was sent to an outside laboratory for additional testing which identified a presumptive Brucella sp. pathogen of voles and sea mammals, and the NYC Health Department was notified. The patient was reinterviewed when this information was received, and he reported weekly consumption of unpasteurized cow, goat, and camel milk in Africa. The clinical isolate was sent to CDC and confirmed as B. melitensis.
A laboratory risk assessment was conducted. (For information about assessing laboratory risk after exposure to Brucella spp., see http://www.cdc.gov/brucellosis/laboratories/risk-level.html) A total of 35 persons were classified as having had either high or low risk exposures in the microbiology laboratory during the week that laboratorians worked with the unidentified isolate on an open bench.
In the second incident, a patient in his 20s presented to a NYC hospital with a 2-month history of recurrent fever, dry cough, night sweats, weight loss, myalgia, arthralgia, and fatigue. He had returned recently from a stay of 2-3 months in the Middle East. On evaluation, he had fever (T 102 ◦ F), anemia, and elevated transaminases. Chest x-ray was negative; chest CT showed hepatosplenomegaly.
The initial concern was that the patient might have tuberculosis, but this was ruled out. After 5 days, 2 sets of blood cultures that were collected on admission were flagged as positive for microbial growth. All 3 microbiology laboratory work, including blood culture bottle venting, Gram staining, and vortexing, was conducted on an open laboratory bench. The blood culture Gram stains were read as tiny, Gram positive cocci in pairs and chains. After subculture and incubation for 2 days, colony growth of tiny, Gram negative cocci was observed. An automated microbial identification system identified a presumptive B. melitensis the following day, and the NYC Health Department was contacted. A MALDI-TOF MS instrument undergoing validation at the facility also failed to identify the isolate, because Brucella is not in the instrument’s reference database.
The patient was re-interviewed by clinical staff, and he reported drinking unpasteurized sheep milk during his time in the Middle East. The NYC Public Health Laboratory confirmed the isolate as B. melitensis.
A laboratory risk assessment was conducted by the hospital’s infectious disease department and infection control program. Because multiple potential aerosol-generating procedures and other manipulations of Brucella cultures were performed on an open laboratory bench, 18 people were classified as having had either high or low risk exposures.
The incidents also highlight aspects of clinical and laboratory practice requiring greater attention like handling suspect clinical isolates in a biological safety cabinet until highly infectious agents have been ruled out and ensuring “slow-growing” small Gram negative organisms are also handled under the appropriate conditions.
Brucellosis is a contagious disease of animals that also affects humans. The disease is also known as Bang’s Disease. In humans, it’s known as Undulant Fever.
Brucellosis is one of the most serious diseases of livestock, considering the damage done by the infection in animals. Decreased milk production, weight loss, loss of young, infertility, and lameness are some of the affects on animals.
The Brucella species are named for their primary hosts: Brucella melitensis is found mostly is goats,sheep and camels, B. abortus is a pathogen of cattle, B. suis is found primarily in swine and B. canis is found in dogs.
There are two common ways people get infected with brucellosis. First, individuals that work with infected animals that have not been vaccinated against brucellosis. This would include farmers, slaughterhouse workers and veterinarians.
They get infected through direct contact or aerosols produced by the infected animal tissue. B. abortus and B. suis are most common.
The second way is through ingesting unpasteurized dairy products. This is seen in people who travel to areas of the Middle East or Latin America (B. melitensis) where brucellosis is endemic in ovine ad bovine animals. “When in Rome” is an attitude many foreign travelers take to experience aspects of a foreignculture.
There have been several cases of domestically acquired brucellosis from people who have eaten Mexican cheese made from unpasteurized goat milk.
In the U.S., brucellosis has decreased over the decades due to vaccination of young animals and the slaughter of the sick ones.
Brucellosis is also an occupational hazard to laboratory workers who inappropriately handle specimens or have an accident or spill. Brucella is highly infectious in the aerosolized form.
If someone gets infected with Brucella, the incubation period is about 2-3 weeks, though it could be months. Fever, night sweats, severe headache and body aches and other non-specific symptoms may occur.
Acute and chronic brucellosis can lead to complications in multiple organ systems. The skeletal, central nervous system, respiratory tract, the liver, heart, gastrointestinal and genitourinary tracts can all be affected. Untreated brucellosis has a fatality rate of 5%.