November 04, 2016
1 min read

Toxoplasma infection associated with neurocognitive impairment in HIV

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Toxoplasma gondii infection was associated with neurocognitive impairment among patients with HIV, according to a study recently published in Clinical Infectious Diseases. The association was particularly strong in those with higher CD4 counts, the researchers reported.

“[HIV]-associated neurocognitive disorder (HAND) is a well-recognized complication of HIV-1 infection that can impede employment, activities of daily living and ultimately survival. ... Recent evidence from animal and human studies suggests that [latent Toxoplasma infection] can result in behavioral changes, including increased impulsivity, aggression and suicide attempts; difficulties with learning in mice; and with memory, reaction time and higher risk of traffic accidents in humans,” Ajay R. Bharti, MD, of the department of medicine at the University of California, San Diego, and colleagues wrote.

Researchers performed neurocognitive assessments on 263 patients with HIV and tested them for latent Toxoplasma infection. Seventy percent were receiving ART, most participants were white (59%) and 90% were men. Mean age was 42 years, and mean duration of education was 12.6 years. Median CD4 count was 387 cells/µL (interquartile range, 231-582 cells/µL).

Thirty (11.4%) participants had latent Toxoplasma infection, Bharti and colleagues reported, with no differences in race or ethnicity associated with infection (P > .8). Undetectable levels of HIV RNA were present in fewer than half of patients in the study. However, the percentage of participants with detectable HIV-RNA was higher among those with Toxoplasma than those without the infection (57% vs 44%; P = .18).

Fifty-seven percent of patients with Toxoplasma infection had neurocognitive impairment, compared with 34% of uninfected patients, indicating a significant association between the infection and neurocognitive impairment (OR = 1.67; 95% CI, 1.17-2.4), Bharti and colleagues reported. The probability of neurocognitive impairment increased alongside rising CD4 counts in Toxoplasma-infected patients (P = .001), and had an inverse relationship to CD4 counts in uninfected patients (P = .021).

“Longitudinal studies of patients before and after ART initiation could test our hypothesis that immune reconstitution plays a role in the pathogenesis of cognitive impairment in patients with [latent Toxoplasma infection]. Intervention trials with existing or investigational drugs active against Toxoplasma cysts would further strengthen our findings and could lead to new treatments for HAND in people living with [latent Toxoplasma infection],” Bharti and colleagues wrote. – by Andy Polhamus

Disclosure: The researchers report no relevant financial disclosures.