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Gajurel K.,Stanford University | Gomez C.A.,Stanford University | Dhakal R.,National Reference Center for the Study and Diagnosis of Toxoplasmosis | Vogel H.,Stanford University | And 2 more authors.
Transplant Infectious Disease | Year: 2016

The efficacy of primary prophylaxis with atovaquone in preventing Toxoplasma reactivation and disease in hematopoietic cell transplant (HCT) recipients is unknown. We describe 2 cases of atovaquone prophylaxis failure in pre-HCT Toxoplasma-seropositive (pre-HCTSP) recipients who underwent allogeneic HCT (allo-HCT) and review the literature on atovaquone prophylaxis in HCT recipients. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

Gajurel K.,Stanford University | Dhakal R.,National Reference Center for the Study and Diagnosis of Toxoplasmosis | Montoya J.G.,Stanford University | Montoya J.G.,National Reference Center for the Study and Diagnosis of Toxoplasmosis
Current Opinion in Infectious Diseases | Year: 2015

Purpose of review Toxoplasmosis in haematopoietic cell transplant (HCT) recipients is associated with high morbidity and mortality rates. Prophylaxis following HCT is recommended for high-risk pre-HCT toxoplasma-seropositive (pre-HCTSP) recipients. However, there is no agreement or consistency among programmes on whether to adopt prophylaxis or not, or if used, on the chosen antitoxoplasma prophylactic regimen. This review discusses the role of prophylaxis, and preemptive treatment, for toxoplasmosis in the setting of HCT. Recent findings Approximately two-thirds of toxoplasmosis cases following HCT are reported in allogeneic pre-HCTSP (allo pre-HCTSP) patients. This finding confirms a major role of reactivation of latent infection in the pathogenesis of toxoplasmosis in this patient population. Toxoplasma disease-related mortality in allo pre-HCTSP patients was reported at 62%, but it can be significantly decreased with early detection and treatment of toxoplasma infection. There are no randomized trials comparing the efficacy of different prophylactic agents to prevent toxoplasmosis after HCT. Several observational studies have demonstrated the efficacy of trimethoprim-sulfamethoxazole (TMP/SMX) in decreasing the incidence of toxoplasmosis following HCT. There is limited information regarding efficacy of other prophylactic agents. Preemptive treatment using routine blood PCR monitoring seems to be beneficial in detecting infection early and preventing disease in several observational studies and has been adopted for allo pre-HCTSP HCT patients when universal prophylaxis is not possible. Summary Universal prophylaxis with TMP/SMX in allo pre-HCTSP patients should be implemented by all transplant programmes. Preemptive treatment with routine blood PCR monitoring is an option if prophylaxis cannot be used. © 2015 Wolters Kluwer Health, Inc. All rights reserved.

Dhakal R.,National Reference Center for the Study and Diagnosis of Toxoplasmosis | Gajurel K.,Stanford University | Pomares C.,National Reference Center for the Study and Diagnosis of Toxoplasmosis | Pomares C.,Stanford University | And 6 more authors.
Journal of Clinical Microbiology | Year: 2015

A positive Toxoplasma immunoglobulinM(IgM) result is often interpreted as a marker of an acute infection. However, IgM can persist for several years, and Toxoplasma commercial IgM diagnostic test kits can yield a number of false-positive results. For these reasons, a chronic Toxoplasma infection can be erroneously classified as an acute infection, resulting in serious adverse consequences, especially in pregnant women, leading to emotional distress and unnecessary interventions, including termination of pregnancy. Interpretation of Toxoplasma serology at a reference laboratory can help differentiate a recently acquired infection from a chronic infection. Serological test results for 451 patients with positive Toxoplasma IgM and IgG test results obtained at nonreference laboratories (NRLs) that were referred to Palo Alto Medical Foundation Toxoplasma Serology Laboratory (PAMF-TSL) to determine whether the patient was acutely or chronically infected were retrospectively reviewed. PAMF-TSL results established that of the 451 patients, 335 (74%) had a chronic infection, 100 (22%) had an acute infection, and 7 (2%) were not infected, and for 9 (2%), results were indeterminate. Positive Toxoplasma IgM and IgG test results obtained at NRLs cannot accurately distinguish between acute and chronic infections. To do so, testing at reference laboratories is required, as mandated in 1997 in a letter from the Food and Drug Administration (FDA) to clinicians and laboratories in the United States. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

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