Quantitative PCR as a marker for preemptive therapy and its role in therapeutic control in Trypanosoma cruzi/HIV coinfection

Abstract

Background: Trypanosoma cruzi and HIV coinfection can evolve with depression of cellular immunity and increased parasitemia. We applied quantitative PCR (qPCR) as a marker for preemptive antiparasitic treatment to avoid fatal Chagas disease reactivation and analyzed the outcome of treated cases.

Methodology: This mixed cross-sectional and longitudinal study included 171 Chagas disease patients, 60 coinfected with HIV. Of these 60 patients, ten showed Chagas disease reactivation, confirmed by parasites identified in the blood, cerebrospinal fluid, or tissues, 12 exhibited high parasitemia without reactivation, and 38 had low parasitemia and no reactivation.

Results: We showed, for the first time, the success of the timely introduction of benznidazole in the non-reactivated group with high levels of parasitemia detected by qPCR and the absence of parasites in reactivated cases with at least 58 days of benznidazole. All HIV+ patients with or without reactivation had a 4.0-5.1 higher chance of having parasitemia than HIV seronegative cases. A positive correlation was found between parasites and viral loads. Remarkably, treated T. cruzi/HIV-coinfected patients had 77.3% conversion from positive to negative parasitemia compared to 19.1% of untreated patients. Additionally, untreated patients showed ~13.6 times higher Odds Ratio of having positive parasitemia in the follow-up period compared with treated patients. Treated and untreated patients showed no differences regarding the evolution of Chagas disease. The main factors associated with all-cause mortality were higher parasitemia, lower CD4 counts/μL, higher viral load, and absence of antiretroviral therapy.

Conclusion: We recommend qPCR prospective monitoring of T. cruzi parasitemia in HIV+ coinfected patients and point out the value of pre-emptive therapy for those with high parasitemia. In parallel, early antiretroviral therapy introduction is advisable, aiming at viral load control, immune response restoration, and increasing survival. We also suggest an early antiparasitic treatment for all coinfected patients, followed by effectiveness analysis alongside antiretroviral therapy.

Fig 1. Parasitemia by qPCR in the first and second samples of HIV seronegative, HIV+ untreated (UT), HIV+ treated (T) non-reactivated + reactivated groups in the first and second samples.

Fig 2. Evolution of qPCR (T. cruzi Eq/mL) in blood samples before and during the follow-up in treated and untreated patients.

A) Untreated patients (UT)–no significant reduction of parasitemia during the period; B) Treated non-reactivated patients showing reduction of pre-treatment high levels. Some patients had high levels 2–12 months before the treatment which decreased at the beginning of treatment (T0); C: Treated and reactivated patients showed very high levels of parasitemia before the treatment and reduction of parasitemia.

Fig 3. Comparison of qPCR (T. cruzi Eq/mL) in cerebrospinal fluid (CSF) and blood samples before and after the treatment in three patients.

A) Patient resistant to antiretrovirals, with a viral load of 26,050 HIV copies/mL, 10 CD4 cells/μL, and in CSF, 19,530.0 par Eq/mL. After the antiparasitic treatment, undetectable levels of parasites in CSF and survival; B) Reduction of parasites but a moderate level was detected in the CSF before death; C) Reduction of parasites level to undetectable (blood, cerebrospinal fluid, and necropsy) after treatment, followed by death, possibly due to immune reconstitution syndrome, based on histopathologic findings, early ART introduction, and no confirmed causes of death.

Fig 4. Kaplan-Meier survival estimates for untreated patients (UT), treated patients without Chagas disease reactivation (TNR) and treated patients who reactivated (TR).

Ticks on each curve represent censored individuals.