Toxoplasmosis, cryptosporidiosis, and isosporiasis in HIV-negative immunocompromised patients: A single-centre study, Ottawa, Ontario, Canada.

BACKGROUND

Historically, patients with HIV have been at the highest risk of infection with opportunistic protozoans such as Toxoplasma, Cryptosporidium, and Isospora. Among patients with HIV who are compliant with antiretroviral therapy, the likelihood of acquiring an opportunistic infection is low. The risk of infection is harder to mitigate in the growing number of HIV-negative immunodeficient patients, such as people with hematological malignancies or those who are post-transplantation.

METHODS

We conducted a retrospective case series of patients with documented Toxoplasma infections between 2008 and 2017 and with Cryptosporidium and Isospora infections between 2014 and 2017 at the Ottawa Hospital.

RESULTS

During the study period, there were 10 confirmed cases of toxoplasmosis, 20 cases of cryptosporidiosis, and 2 cases of isosporiasis. Cryptosporidiosis (95%) and toxoplasmosis (60%) occurred more frequently among HIV-negative patients, whereas isosporiasis cases were limited to HIV-positive patients. Among patients with cryptosporidiosis, the most common underlying cause of immunosuppression in HIV-negative individuals was solid organ transplantation (15.79%), followed by diabetes (10.53%), end-stage renal disease (5.26%), and hematologic malignancy (5.26%). Seventy percent of patients had no known cause of immunosuppression. The most common underlying condition associated with toxoplasmosis was hematological malignancy (50%), followed by solid organ transplantation (33.33%), and solid tumours (16.66%).

CONCLUSIONS

This study's results suggest that Cryptosporidium infections are more common among immunocompetent patients in Ottawa, whereas Toxoplasma infections are more common among HIV-negative patients with acquired immunodeficiencies. As the demographics of immunocompromised individuals continue to evolve, screening for protozoal infections in high-risk populations may become clinically important.