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  • Updated 10.05.2021
  • Released 04.10.1998
  • Expires For CME 10.05.2024

Brucellosis of the nervous system



Brucellosis is a multisystem bacterial illness. It is one of the most common zoonotic diseases worldwide and is endemic in many Mediterranean and Middle Eastern countries. Globally, more than 500,000 new cases occur each year, with an estimated 2.4 billion people at risk (56). The disease is transmitted to humans through consumption of infected, unpasteurized animal milk; through direct contact with infected animals; or via inhalation of infected aerosol particles. Laboratory workers who handle patient specimens or prepare Brucellosis vaccines for animal use are also at risk of infection (109). Nonspecific complaints include irregular fevers, malaise, arthralgia, myalgia, weight loss, and night sweats. Infection of the nervous system, known as neurobrucellosis, occurs in 4% of patients (71). The neuropathology involves direct bacterial invasion, complicated by an inflammatory response. Isolation of Brucella in blood or CSF or positive bone marrow culture remain the gold standards for diagnosis (96), but serological tests, including point-of-care assays and polymerase chain reaction, aid in establishing the diagnosis. Forty-five percent of patients will have abnormal neuroimaging findings. Parenteral ceftriaxone in combination with doxycycline and rifampin is now recommended as first-line therapy to achieve eradication and reduce the risk of relapse (91).

Key points

• Brucellosis is an acute, subacute, or chronic zoonotic illness caused by nonmotile, unencapsulated, intracellular, gram-negative coccobacilli that involves the central and peripheral nervous systems in approximately 4% of patients.

• Neurologic disease is caused by infection with the bacterium, as well as the inflammatory response elicited by the infection.

• The diagnosis of neurobrucellosis is made definitively by isolation of the bacteria from brain or cerebrospinal fluid or presumptively in the context of a systemic infection with a neurologic syndrome.

• Forty-five percent of neurobrucellosis patients have abnormal neuroimaging findings, including inflammation of the dura, leptomeninges, cranial nerve and/or spinal nerve roots; white matter abnormalities; and vascular involvement through vasculitis, hydrocephalus, and cerebral edema (33; 89).

• Treatment of neurobrucellosis using combined antibiotics regimens with a minimum of 1 month of parenteral ceftriaxone is recommended to achieve eradication and reduce the risk of relapse.

Historical note and terminology

Brucellosis has been recognized for millennia (18). In 1859, JA Marston gave the first clinical account of the disease that he named “Mediterranean fever” (27). At that time, the condition was also known as “undulant,” “remittent,” “Malta,” or “Crimean fever.” Surgeon David Bruce was the first to isolate a “micrococcus” bacterium and identify it as the causative agent of Malta fever (17). This gram-negative coccobacillus was later renamed “Brucella” in his honor (108).

Some medical historians have proposed that the chronic headaches and severe weakness suffered by Florence Nightingale may be attributable to neurobrucellosis contracted while serving during the Crimean War (119).

Brucellosis was 1 of 5 infectious agents (including anthrax, tularemia, Q fever, and Venezuelan equine encephalitis) developed by the United States during the Cold War as a potential biologic weapon (50). The U.S. National Institutes of Health have classified Brucella melitensis as a category B priority pathogen and possible bioterrorist agent due to its potential for infection via aerosols (114).

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