This rare form of meningoencephalitis is included here because of the current interest in Bacillus anthracis as a bioweapon. Lanska was able to collect from the literature 70 patients with meningeal infection, most of whom were encephalopathic. He has estimated that fewer than 5 percent of infected individuals will acquire a meningoencephalitis; in a 2001 U.S. outbreak, only 1 of 11 cases with anthrax pneumonitis developed this complication. Reflecting the main site of natural infection, the majority of cases originated in cutaneous anthrax. In addition to a typically fulminating course after a prodrome of one or several days, the exceptional feature was a hemorrhagic and inflammatory spinal fluid formula. Subarachnoid hemorrhage was prominent in autopsy material, presumably reflecting necrosis of the vessel walls as a toxic effect of B. anthracis.
Treatment Although natural isolates are sensitive to penicillin, bioengineered strains are resistant; therefore, combined treatment with ciprofloxacin with clindamycin, rifampin, or meropenem has been recommended initially. The benefit of specific antitoxin is uncertain once meningoencephalitis has occurred.
Recently, very similar overwhelming cases with meningitis and subarachnoid hemorrhage caused by Bacillus cereus have appeared in immunosuppressed patients.
This worldwide disease of domesticated livestock is frequently transmitted to humans in areas where the infection is enzootic. In the United States, it is distinctly rare, with 200 cases or fewer being reported annually since 1980, some in abattoir workers. During the 1950s it was a fashionable explanation for chronic fatigue. In the Middle East, infection with Brucella is still frequent, attributable to the ingestion of raw milk. In Saudi Arabia, for example, al Deeb and coworkers reported on a series of 400 cases of brucellosis, of which 13 presented with brain involvement (acute meningoencephalitis, papilledema and increased intracranial pressure, and meningovascular manifestations). The CSF showed a lymphocytic pleocytosis and increased protein content. Blood and CSF antibody titers to the organism were greater than 1:640 and 1:128, respectively. There is also a tuberculous-like osteomyelitis that may cause compression of the spinal cord.
Treatment Prolonged treatment with doxycycline with streptomycin or gentamicin; an alternative is doxycycline plus rifampin to suppress the infection.
This is a rare but often-discussed disorder, predominantly of middle-aged men. Weight loss, fever, anemia, steatorrhea, abdominal pain and distention, arthralgia, lymphadenopathy, and hyperpigmentation are the usual systemic manifestations. Less often, infection is associated with a number of neurologic syndromes. It is caused by a gram-positive bacillus, Tropheryma whipplei, which resides predominantly in the gut. Biopsy of the jejunal mucosa, which discloses macrophages filled with the periodic acid-Schiff (PAS)-positive organisms, is diagnostic. PAS-positive histiocytes have also been identified in the CSF, as well as in periventricular regions, in the hypothalamic and tuberal nuclei, and diffusely scattered in the brain.