Bartonella (Rochalimaea) Antibodies, Dementia, and Cat Ownership Among Men Infected with Human Immunodeficiency Virus

To determine the association between recent human immunodeficiency virus (HIV)-associated dementia and serum antibodies to Bartonella (Rochalimaea) henselae, we performed a nested case control study within the Multicenter AIDS Cohort Study in Los Angeles. We measured serum IgG and IgM antibodies to B. henselae with use of enzyme immunoassay in 369 HIV-seropositive and HIV-seronegative participants with and without recent neuropsychological deterioration. Data on pet ownership were also collected. IgM antibodies to B. henselae were strongly associated with neuropsychological decline or dementia (OR = 6.6; 95% CI = 1.4–31.9; P = .02). Those participants with IgM antibodies to B. henselae were 1.7 times more likely to develop HIV-associated dementia (HAD) or neuropsychological decline over the next 5 years. At least 4% of the new cases of HAD and neuropsychological decline were due to bartonella infection. Cat ownership was associated with the presence of IgM antibodies to B. henselae (OR = 6.4; 95% CI = 1.3–30.8; P = .02) and with neuropsychological decline and dementia (OR = 2.4; 95% CI = 1.2-5.1; P = .02). This finding suggests that some cases of HAD and neuropsychological decline are associated with potentially treatable B. henselae infections.