Clinical Features

Brucellosis, also known as "undulant fever," typically appears as a nonspecific illness with a fever resembling influenza. Fever, headache, muscle aches, joint pain, back pain, sweats, chills, generalized weakness, and malaise are common complaints. Cough, lung congestion, and chest pain occur in up to 20% of cases, but acute pneumonia is unusual, and pulmonary symptoms may not correlate with radiographic findings.

The Brucellosis-positive chest x-ray is often normal, but may show lung abscesses, single or small lesions, bronchopneumonia, enlarged lymph nodes, and fluid in the chest cavity. Gastrointestinal symptoms (anorexia, nausea, vomiting, diarrhea and constipation) occur in up to 70% of adult cases, but less frequently in children. Ileitis, colitis, and chronic inflammatory lesions or hepatitis may occur in 45-63 % of cases.

Low back pain and tenderness can occur in up to 60% of brucellosis cases and are sometimes due to various bone and joint infections. Vertebral osteomyelitis, an infection of the spine and disc space, and sacroiliac infection occur in a minority of cases, but may be a cause of chronic symptoms.

Joint involvement in brucellosis may vary from pain to joint immobility and fluid build up. While the sacroiliac joints are most commonly involved, peripheral joints (notably, hips, knees, and ankles) may also be affected. Meningitis complicates a small minority of brucellosis cases. Behavioral disturbances and psychoses appear to occur out of proportion to the height of fever, or to the amount of overt Central Nervous Symptom disease, which raises questions about an ill-defined neurotoxic component of brucellosis.

Diagnosis

Because most cases of brucellosis present as non-specific fever illnesses, diagnostic hallmarks are lacking, and the disease is often unsuspected. Maintenance of a high index of suspicion is thus critical if one is to firmly establish a diagnosis of brucellosis.

A history of animal contact, consumption of unpasteurized dairy products, or travel to areas where animals are infected with brucellosis, should prompt consideration of brucellosis infection as a diagnosis. The white cell count in brucellosis patients is usually normal but may be low; anemia and bleeding may also occur.

Medical Management

Standard Precautions are adequate in managing brucellosis patients, as the disease is not generally transmissible from person-to-person.

Oral antibiotic therapy alone is sufficient in most cases of brucellosis. Exceptions involve uncommon cases of localized disease, where surgical intervention may be required (e.g., heart-valve replacement for endocarditis).

A combination of Doxycycline 200 mg/d PO + Rifampin 600 mg/d PO is recommended. Both drugs should be administered for six weeks. Doxycycline 200 mg/d PO for six weeks in combination with two weeks of Streptomycin (1 g/d IM) is an acceptable alternative. Doxycycline + Gentamicin, TMP/SMX + Gentamicin, and Ofloxacin + Rifampin have also been studied and shown effective. For patients with meningoencephalitis or endocarditis, long-term triple-drug therapy with rifampin (a tetracycline) and an aminoglycoside is recommended by some experts.

Prevention

Vaccines have eradicated brucellosis from most domestic animals in the United States. However there is probable risk that animals could be deliberately infected with brucellosis by terrorist (agro-terrorism).

Drug therapy is not generally recommended following possible exposure to endemic disease. A 3-6 week course of therapy (with one of the regimens discussed above) should be considered following a high-risk exposure such as a in a biological warfare context.