CBRNE - Brucellosis Clinical Presentation

History is the most helpful component in diagnosing brucellosis.

• Unless exposure is due to a weaponized attack, almost every case either directly or indirectly involves exposure to an affected animal.
• Elicit an occupational history (eg, farmer, veterinarian) that is suggestive of exposure to a source animal.
• Suspected biological attack should heighten awareness of potential infection.
• Because brucellae typically take 1-8 weeks to incubate, include in the history any possible exposures in the preceding few months.
• Obtain exposure to potentially contaminated foodstuffs or travel to an area where the disease is endemic.
• Symptoms of brucellosis are protean and nonspecific. Somatic complaints (weakness, fatigue, malaise, body aches, depression, anorexia) may often predominate.

  • Onset may be an abrupt acute febrile illness, chronic infection, or localized infection.
  • When case reviews were performed, certain symptoms were noted to be more prevalent. Fever was observed in 90-95% of patients, malaise in 80-95%, myalgias in 40-70%, sweats in 40-90%, and arthralgias in 20-40%. Except for fever and malaise, most symptoms were observed in half or fewer than half of patients. In the largest case series to date, fever, fatigue and malaise, and arthralgias were predominant. Other than fever, no one symptom occurred with enough frequency to be useful in ruling out brucellosis as a cause.
  • Neuropsychiatric complaints may include depression, headache, and irritability. In patients with advanced cases where meningoencephalitis is present, these complaints may include changes in mental status, coma, neurologic deficit, nuchal rigidity, or seizures.
  • Arthralgias may be diffuse or localized, with a predilection to bone ends and the sacroiliac joint. Although uncommon, acute monoarticular arthritis may be part of the presentation.
  • In respiratory infections, nonproductive cough and pleuritic chest pain predominate.
  • Patients with prolonged cases often experience weight loss, fatigue, and anorexia.
  • A significant percentage of patients may have GI complaints, primarily dyspepsia, although abdominal pain from hepatic abscesses may occur. Suspect hepatic abscesses in patients with signs of systemic toxicity and persistently elevated liver enzymes. The abscess can serve as a source of bacteremic seeding. There are also case reports of spontaneous bacterial peritonitis secondary to brucellosis infection.
• Genitourinary infections with brucellae have been reported and include orchitis, UTI, and glomerulonephritis. Frank renal failure or sepsis is rare.
• Endocarditis from brucellae is reported, with septic embolization a common complication from this form of brucellosis. Other cardiac complications, such as pulmonary edema or dysrhythmias, are rare. Brucellae endocarditis is the form most commonly associated with fatalities.

Physical examination findings in brucellosis, like history, often are nonspecific.

• Focal infection of bones, joints, or the genitourinary system may present with localized abnormal physical findings in the affected areas. Arthritis, joint effusions, urethritis, or, in patients with severe cases, costovertebral angle tenderness, may be observed. Epididymo-orchitis has been described in association with brucellosis. Testicular abscess, mimicking tumor, has also been reported. Focal osteomyelitis of the vertebrae, tibia, and, especially, the knee has also been associated with brucellosis infection even in the absence of other significant systemic symptoms.
• Some patients may present with hepatosplenomegaly, 10-30% with hepatomegaly, and 10-70% with splenomegaly. Right upper quadrant pain and jaundice may indicate hepatic abscess.
• In chronic infection (>3-6 mo), weight loss may be apparent.
• Infection of the nervous system may present with focal findings (abscesses) or nuchal rigidity (leptomeningitis). Of note, nuchal rigidity was present in fewer than half of patients with brucella leptomeningitis. Typical focal findings may steer toward an abscess. Global depression of cognition may occur. At least one case of spondylitis with resulting spinal cord compression has been documented.
• Dermal manifestations may include cutaneous ulcerations, petechiae, purpura, and erythema nodosum. Brucella may be cultured from these skin lesions.
• Endocarditis may present with murmurs, and mycotic aneurysms of ventricles, brain, and aorta have been observed.
• Although pulmonary complaints are frequently present, physical findings of this organ system are almost always normal.
• Generally, physical examination findings are normal, and diagnosis is made from history and serology.
• Immune thrombocytopenic purpura has been described as a sequelae of brucellosis infection.

Brucellosis is caused by exposure to the pathogen via the routes discussed above. Occupational exposures tend to be isolated. A large-scale outbreak of the infection should raise suspicion that a biological weapon has been released, most likely via an infectious aerosol.