Neurologic Infections in Travelers

Malveeka Sharma, MD, MPH; Joseph R. Zunt, MD, MPH


Semin Neurol. 2019;39(3):399-414. 

In This Article



Brucellosis is one of the most common zoonotic diseases, caused by the bacteria Brucella.[41]Brucella melitensis is the most commonly reported species causing human infection. Transmission occurs through direct contact with infected animals, ingestion of unpasteurized milk or cheese from infected animals, and rarely airborne transmission.[42] Brucellosis can be found worldwide, but most developed countries with adequate public health programs have extremely low rates of infection. High-risk areas include the Mediterranean Basin, South and Central America, Eastern Europe, Asia, Africa, the Caribbean, and the Middle East.[43] Of note, Brucella spp. have been implicated as potential agents of bioterrorism.

Life Cycle, Ecology, and Species

Brucella spp. are small, gram-negative bacteria that are nonmotile, nonencapsulated, facultative intracellular bacilli. Exposure to as few as 10 to 100 bacteria can lead to infection. The bacterium can survive in extreme environments. Other species implicated in human infection include B. abortus, B. ovis, B. suis, and B. canis.[43]

Clinical Manifestations

The classic presentation is an acute or subacute febrile illness characterized by intermittent fever, malaise, and anorexia. The bacteria can invade almost any organ system and lead to systemic illness. It may also produce relapsing, chronic localized or delayed infection.[44] Older host age and longer duration of infection are correlated with higher risk of developing neuroborreliosis.[41] Neurologic manifestations can develop at any stage of disease, and include encephalitis, meningoencephalitis, abscess formation, radiculitis, myelitis, peripheral and cranial neuropathies, subarachnoid hemorrhage, and neuropsychiatric issues.[42,45]


Along with appropriate clinical and exposure history, diagnosis requires identification of Brucella spp. on culture of blood, bone marrow, CSF, or an affected organ (e.g., liver). Culture is often negative during chronic infection. Serum agglutination and ELISA are also commonly used serologic studies. CSF analysis may reveal a mononuclear pleocytosis, elevated protein, low glucose, and decreased adenosine deaminase.[44,46]


Recommended treatment for neuroborreliosis includes a combination of doxycycline, rifampicin, or a third-generation cephalosporin for a minimum of 12 weeks.[41] Regimens that include ceftriaxone were more effective and required a shorter duration of therapy.[47] Treatment should be continued until CSF abnormalities normalize.[48] Prevention of human brucellosis targets multiple levels: providing education on occupational hygiene for farmers and migrant workers and food hygiene targeting the preparation and treatment of raw milk and meat. Vaccines are not generally available, but China and the former Soviet Republic have developed human vaccines for use in highly endemic regions that were well tolerated and effective.[44]