Can brucella cause 'brain problems'?
Q - A patient in his 60s has a history of brucellosis. He has memory loss which shows up on neuro-psychiatric testing. No vascular cause has been found, he is not depressed or demented. His wife says they were told the brucellosis could cause 'brain problems' later. Is this likely?
A - Now almost exclusively acquired abroad, brucella is an unlikely cause of his symptoms. An intracellular parasite that is difficult to eradicate, brucella is characteristically associated with chronic relapsing infection, due to a reservoir of brucellae in tissues including lymphatics, bones and liver.
Essential questions to ask include when and how the diagnosis was made, the treatment length months of rifampicin and doxycycline are the norm and the particular species of brucella implicated.
A diagnosis of chronic brucellosis can be considered after 12 months' duration of symptoms, cyclical depression, malaise and fever, with persistently high levels of IgG. Complaints of short-term memory loss with no cognitive deficit were common in Gulf War veterans, in whom brucella screening formed part of the medical assessment.
In 5-10 per cent of chronic brucellosis, manifestations of chronic neurobrucellosis such as depression, mental inattention and memory disturbances develop. There are reports of dementia and psychoneurosis in a minority.
Histology includes arachnoid thickening, demyelination, meningo-vascular syndrome, thecal inflammation and granulomata. Although no single titre is diagnostic, serum and CSF IgG should be measured, and a level of >1/160 would be suggestive.
Proposed as a cause of chronic fatigue syndrome, we receive regular requests for brucella serology after a patient has visited alternative health practitioners. I have yet to see one serologically confirmed infection.
The other protean infection, syphilis, should be excluded.
Marina Morgan is consultant microbiologist at the Royal Devon and Exeter Hospital