A double-blinded, prospective study to define antigenemia and quantitative real-time polymerase chain reaction cutoffs to start preemptive therapy in low-risk, seropositive, renal transplanted recipients. Transplantation. 2014;98:1077-1081. [PMID: 24839894 DOI: 10.1097/tp.0000000000000189]

QuantiFERON-CMV as a Predictor of CMV Events During Preemptive Therapy in CMV-seropositive Kidney Transplant Recipients

BACKGROUND

Prevention of cytomegalovirus (CMV) infection after kidney transplantation is costly and burdensome.

METHODS

Given its promising utility in risk stratification, we evaluated the use of QuantiFERON-CMV (QFCMV) and additional clinical variables in this prospective cohort study to predict the first clinically significant CMV infection (CS-CMV, ranging from asymptomatic viremia requiring treatment to CMV disease) in the first posttransplant year. A cost-effectiveness analysis for guided prevention was done.

RESULTS

One hundred adult kidney transplant recipients, CMV IgG + , were given basiliximab induction and maintained on steroid/mycophenolate/tacrolimus with weekly CMV monitoring. Thirty-nine patients developed CS-CMV infection (viral syndrome, n = 1; end-organ disease, n = 9; and asymptomatic viremia, n = 29). A nonreactive or indeterminate QFCMV result using the standard threshold around day 30 (but not before transplant) was associated with CS-CMV rates of 50% and 75%, respectively. A higher QFCMV threshold for reactivity (>1.0 IU interferon-γ/mL) outperformed the manufacturer's standard (>0.2 IU interferon-γ/mL) in predicting protection but still allowed a 16% incidence of CS-CMV. The combination of recipient age and type of donor, along with posttransplant QFCMV resulted in a prediction model that increased the negative predictive value from 84% (QFCMV alone) to 93%. QFCMV-guided preemptive therapy was of lower cost than preemptive therapy alone ( P  < 0.001, probabilistic sensitivity analysis) and was cost-effective (incremental net monetary benefit of 210 USD) assuming willingness-to-pay of 2000 USD to avoid 1 CMV disease.

CONCLUSIONS

Guided CMV prevention by the prediction model with QFCMV is cost-effective and would spare from CMV surveillance in 42% of patients with low risk for CS-CMV.

Significant Increase in Cytomegalovirus (CMV) Infection in Solid Organ Transplants Associated With Increased Use of Thymoglobulin as Induction Therapy?

BACKGROUND

Cytomegalovirus (CMV) infection remains one of the most common viral pathogens affecting solid organ transplants (SOT). In 10 years of following the outcome of transplants, we noticed an increased incidence of CMV infection, along with increased use of rabbit anti-thymocyte globulin (rATG). The study aims to assess the incidence of active CMV infection and disease, response to treatment, and recurrence in a cohort of SOT. Furthermore, we look for correlating the CMV incidence with the type of induction therapy: r-ATG or interleukin 2 receptor-blocking antibody (basiliximab).

METHODS

This was a single-center, retrospective 10-year study in patients submitted to kidney, kidney-liver, and kidney-pancreas transplants who used a preemptive therapy protocol for CMV.

RESULTS

Among the 476 enrolled transplant recipients, 306 (64.2 %) had at least one episode of CMV infection (replication), and 71/306 patients (23.2 %) presented CMV-related disease. The most frequent clinical conditions associated with CMV disease were gastrointestinal. Among the 476 transplant patients, 333 received immunosuppressive induction with rATG (69.9 %); 140 (29.4 %) received induction with interleukin 2 receptor-blocking antibody (basiliximab). The initial maintenance immunosuppressive therapy in the patients who presented CMV infection was primarily performed with prednisone, tacrolimus, and sodium mycophenolate (91.7 %). The induction with rATG increased from 35.2%-94.6% in 10 years. The incidence of CMV infection was 20.7 % in the first year of observation and gradually increased to 87.3 % in the last year.

CONCLUSIONS

The data suggest that the increase in the use of rATG in recent years could be responsible for the very expressive increase in the incidence of CMV infection/disease.

Cytomegalovirus Viral Load in Transplanted Patients Using the NeuMoDx™ (Qiagen) Automated System: A 1-Month Experience Feedback

Cytomegalovirus (CMV) reactivations represent a significant morbidity and mortality problem in transplant patients. Reliable and rapid measurement of CMV viral load is a key issue for optimal patient management. We report here the evaluation of NeuMoDx™ (Qiagen) in a routine hospital setting (University Hospitals of Marseille, France) in comparison with our classical reference technique R-GENE. During one month, 719 CMV viral loads from 507 patients were measured in parallel in both techniques. Using the ROC (receiver operating characteristic) curve and our biological experience we suggest that values <52 IU/mL (geometric mean) correspond to negative samples, values >140 IU/mL (Fowlkes–Mallows index) correspond to quantifiable positive results and values ranging from 52 to 140 IU/mL represent non-quantifiable positive results. Follow-up of 15 transplant patients who developed CMV reactivation during the study showed that NeuMoDx™ provided higher viral load measurement during the first two weeks of follow-up for three patients. These important intra-individual variations resulted in a significant median increase considering the whole data set (6.7 points of difference expressed as a percentage of the initial viral load). However, no difference between the two techniques was noticeable after two weeks of treatment. Subsequent to this first study we conclude that NeuMoDx™, used with optimized logistics and an adapted threshold, allows a rapid CMV viral load measurement and that its use does not lead to any difference in patient management compared to the reference technique R-GENE^®.

[Viral infections in urology]

Einleitung

Die COVID-19-Pandemie („coronavirus disease 2019“) hat eindrucksvoll gezeigt, dass Infektionskrankheiten enorme Auswirkungen auf das Gesundheitswesen und darüber hinaus haben können. In der Urologie spielen Viren bei spezifischen Entitäten eine Rolle, wo sich der Urologe mit Viruserkrankungen beschäftigen muss.

Methodik

Diese Übersichtsarbeit hat zum Ziel in der Urologie relevante Virusinfektionen zu beschreiben und insbesondere die Impfprävention hervorzuheben. Es erfolgte eine selektive Literaturrecherche zu den Themen „COVID und Urologie“, „Urogenitale Virusinfektionen“, „Virale urologische Infektionen in der Transplantationsmedizin“ sowie „Impfprävention von Viruserkrankungen“.

Ergebnisse

Coronaviren sind Viren, die bereits 2‑mal lokale Epidemien verursacht haben (SARS- [„severe acute respiratory syndrome“] und MERS-Epidemie [„middle east respiratory syndrome“]). Die Tatsache, dass die SARS-CoV-2-Erkrankung („severe acute respiratory syndrome coronavirus 2“) auch ohne Symptome ansteckend ist, hat im Wesentlichen zu der raschen Ausbreitung und weltweiten Pandemie geführt. Eine Vielzahl von Viren, die auch eine Virämie induzieren können, wurde im Ejakulat nachgewiesen und wird damit mit einer etwaigen urogenitalen Infektion in Verbindung gebracht. Hierzu zählen u. a. das Mumps‑, Coxsackie-Viren oder Enteroviren. Es wurde auch gezeigt, dass auch eine Zika-Virusinfektion sexuell über die Spermien als Carrier übertragen werden kann. Somit spielen Viren auch eine wichtige Rolle in der Reproduktion. Bei der Nierentransplantation sind Urologen häufig mit viralen Infektionen konfrontiert. Die effektivste Waffe gegenüber Viren stellt die Impfprävention dar.

Schlussfolgerung

Äthiopathogenetisch ist der Urogenitaltrakt im Rahmen einer Virämie oder über eine Reaktivierung durch eine Immunsuppression am häufigsten mitbetroffen. Therapeutisch kommt der Immunmodulation sowie der Impfprophylaxe eine führende Rolle zu.

Clinical validation of an in-house quantitative real time PCR assay for cytomegalovirus infection using the 1st WHO International Standard in kidney transplant patients

Introduction:

Cytomegalovirus (CMV) is one of the most common agents of infection in solid organ transplant patients, with significant morbidity and mortality.

Objective:

This study aimed to establish a threshold for initiation of preemptive treatment. In addition, the study compared the performance of antigenemia with qPCR results.

Study design:

This was a prospective cohort study conducted in 2017 in a single kidney transplant center in Brazil. Clinical validation was performed by comparing in-house qPCR results, against standard of care at that time (Pp65 CMV Antigenemia). ROC curve analysis was performed to determine the ideal threshold for initiation of preemptive therapy based on the qPCR test results.

Results:

Two hundred and thirty two samples from 30 patients were tested with both antigenemia and qPCR, from which 163 (70.26%) were concordant (Kappa coefficient: 0.435, p<0.001; Spearman correlation: 0.663). PCR allowed for early diagnoses. The median number of days for the first positive result was 50 (range, 24-105) for antigenemia and 42 (range, 24-74) for qPCR (p<0.001). ROC curve analysis revealed that at a threshold of 3,430 IU/mL (Log 3.54), qPCR had a sensitivity of 97.06% and a specificity of 74.24% (AUC 0.92617 ± 0.0185, p<0.001), in the prediction of 10 cells/10⁵ leukocytes by antigenemia and physician's decision to treat.

Conclusions:

CMV Pp65 antigenemia and CMV qPCR showed fair agreement and a moderate correlation in this study. The in-house qPCR was revealed to be an accurate method to determine CMV DNAemia in kidney transplant patients, resulting in positive results weeks before antigenemia.

Epidemiology, risk factors, and outcomes associated with cytomegalovirus in adult kidney transplant recipients: A systematic literature review of real-world evidence

Kidney transplant recipients (KTRs) have increased risk for cytomegalovirus (CMV) infection/disease given the necessity of drug-induced immunosuppression. A comprehensive review of published literature reporting real-world data on prevention strategies utilized and associated CMV burden outcomes is limited. Such data could help inform future clinical practice and identify unmet needs in CMV management. We conducted a systematic review of observational studies published in Medline or EMBASE from January 2008 to November 2018 to identify current real-world CMV management approaches, CMV infection/disease risk factors, and outcomes associated with CMV infection. Descriptive statistics and pooled quantitative analyses were conducted. From 1608 records screened, 86 citations, including 69 803 adult KTR, were included. Prophylaxis and preemptive therapy (PET) were predominant approaches among D+/R- and R + CMV serostatus transplants, respectively. Valganciclovir and ganciclovir were frequently utilized across CMV risk strata. Despite prevention approaches, approximately one-fourth of KTR developed CMV infection. Age and D+/R- CMV serostatus were consistent risk factors for CMV infection/disease. CMV infection/disease was associated with increased mortality and graft loss. CMV was similarly associated with acute rejection (AR) risk, but with high heterogeneity among studies. Limited data were available on CMV and opportunistic infections (OIs) risk. CMV remains a significant issue. New strategies may be needed to optimize CMV management.

A split strategy to prevent cytomegalovirus after kidney transplantation using prophylaxis in serological high-risk patients and a pre-emptive strategy in intermediate-risk patients: Combining the best of two options?

BACKGROUND

Cytomegalovirus (CMV) remains an important challenge after kidney transplantation. Current Transplantation Society International Consensus Guidelines recommend antiviral prophylaxis or pre-emptive therapy for high-risk CMV-seronegative recipients with a CMV-seropositive donor (D+/R-) and moderate-risk CMV-seropositive recipients (R+). However, a split strategy according to CMV serostatus is not specifically mentioned.

METHODS

We evaluated a split strategy to prevent CMV infection after kidney transplantation in which D+/R- patients received valganciclovir (VGC) prophylaxis for 200 days, and R + patients were treated pre-emptively according to CMV DNAemia. Patients were followed until 1-year post-transplant.

RESULTS

Between April 2014 and March 2018, 40 D+/R- and 92 R + patients underwent kidney transplantation. Forty-six percent received antithymocyte globulin (ATG) induction, and 98% was treated with calcineurin inhibitors, mycophenolic acid (MPA), and steroids. No D+/R- patient developed CMV disease during prophylaxis (median 200 days), but 15% developed post-prophylaxis or late-onset disease. Fifty-three percent developed neutropenia during prophylaxis, including 16/40 (40%) grade 3 or 4 neutropenia requiring reduction/discontinuation of MPA (30%) and/or VGC (35%), and an occasional need for granulocyte colony-stimulating factor (5%). In the R + group, 40% received antiviral therapy for a median duration of 21 days; 5% developed early-onset CMV disease. Only 5% developed neutropenia. D+/R + status (hazard ratio (HR) 2.09,P = .004) and ATG use (HR 2.81, P < .0001) were risk factors for CMV reactivation.

CONCLUSIONS

Prophylaxis leads to acceptable CMV control in high-risk patients but comes with a high risk of neutropenia. Pre-emptive therapy is effective and limits drug exposure in those at lower risk of CMV.

Use of Viral Load as a Surrogate Marker in Clinical Studies of Cytomegalovirus in Solid Organ Transplantation: A Systematic Review and Meta-analysis

Symptomatic cytomegalovirus (CMV) disease has been the standard endpoint for clinical trials in organ transplant recipients. Viral load may be a more relevant endpoint due to low frequency of disease. We performed a meta-analysis and systematic review of the literature. We found several lines of evidence to support the validity of viral load as an appropriate surrogate end-point, including the following: (1) viral loads in CMV disease are significantly greater than in asymptomatic viremia (odds ratio, 9.3 95% confidence interval, 4.6-19.3); (2) kinetics of viral replication are strongly associated with progression to disease; (3) pooled incidence of CMV viremia and disease is significantly lower during prophylaxis compared with the full patient follow-up period (viremia incidence: 3.2% vs 34.3%; P < .001) (disease incidence: 1.1% vs 13.0%; P < .001); (4) treatment of viremia prevented disease; and (5) viral load decline correlated with symptom resolution. Based on the analysis, we conclude that CMV load is an appropriate surrogate endpoint for CMV trials in organ transplant recipients.

Colon perforation due to antigenemia-negative cytomegalovirus gastroenteritis after liver transplantation: A case report and review of literature

BACKGROUND

Cytomegalovirus (CMV) remains a critical complication after solid-organ transplantation. The CMV antigenemia (AG) test is useful for monitoring CMV infection. Although the AG-positivity rate in CMV gastroenteritis is known to be low at onset, almost all cases become positive during the disease course. We treated a patient with transverse colon perforation due to AG-negative CMV gastroenteritis, following a living donor liver transplantation (LDLT).

CASE SUMMARY

The patient was a 52-year-old woman with decompensated liver cirrhosis as a result of autoimmune hepatitis who underwent a blood-type compatible LDLT with her second son as the donor. On day 20 after surgery, upper and lower gastrointestinal endoscopy (GE) revealed multiple gastric ulcers and transverse colon ulcers. The biopsy tissue immunostaining confirmed a diagnosis of CMV gastroenteritis. On day 28 after surgery, an abdominal computed tomography revealed transverse colon perforation, and simple lavage and drainage were performed along with an urgent ileostomy. Although the repeated remission and aggravation of CMV gastroenteritis and acute cellular rejection made the control of immunosuppression difficult, the upper GE eventually revealed an improvement in the gastric ulcers, and the biopsy samples were negative for CMV. The CMV-AG test remained negative, therefore, we had to evaluate the status of the CMV infection on the basis of the clinical symptoms and GE.

CONCLUSION

This case report suggests a monitoring method that could be useful for AG-negative CMV gastroenteritis after a solid-organ transplantation.

Cytomegalovirus prophylaxis in seropositive renal transplant recipients receiving thymoglobulin induction therapy: Outcome and risk factors for late CMV disease

BACKGROUND

Anti-thymocyte globulin (ATG) therapy is a risk factor for cytomegalovirus (CMV) disease in renal transplant (RTx) recipients and therefore antiviral prophylaxis is commonly used. We evaluated the outcome of our current policy of 90 days of CMV prophylaxis in seropositive recipients given ATG and the risk factors for the occurrence of CMV disease after prophylaxis.

METHODS

We studied a retrospective cohort of 423 RTx (2010-2014) CMV-seropositive adults given ATG induction therapy.

RESULTS

54 (13%) patients developed CMV disease at a median of 163 days after transplant, of which 29 (54%) had viral syndrome and 25 (46%) had invasive disease. Median prophylaxis time (94 days) and immunosuppressive drugs were similar between groups (CMV vs no-CMV). Those with CMV disease had more deceased donors and higher donor age, lower lymphocyte count, and lower median eGFR at day 90. Multivariable logistic regression analysis at day 90 and 180 found that eGFR ≤40 ml/min/1.73 m² (but not acute rejection) was associated with late CMV disease. In a separate validation cohort of 124 patients with 8% late CMV disease, eGFR ≤45 and lymphocyte count ≤800 cells/mm³ at the end of prophylaxis remained predictive of late CMV disease occurrence.

CONCLUSIONS

These data indicate that antiviral prophylaxis adequately prevented CMV in seropositive recipients given ATG, but late disease still occurred. Low eGFR and low lymphocyte count at the end of prophylaxis may help identify patients at higher risk of CMV disease.

The effect of anti-thymocyte globulin and everolimus on the kinetics of cytomegalovirus viral load in seropositive kidney transplant recipients without prophylaxis

BACKGROUND

The use of mTOR inhibitors is associated with lower incidence of CMV infections but its effect on viral load has not been investigated.

AIMS, MATERIALS AND METHODS

This post-hoc analysis included data from 273 CMV seropositive kidney transplant recipients randomized to receive anti-thymocyte globulin and everolimus (rAGT/TAC/EVR, n = 81), basiliximab and everolimus (BAS/TAC/EVR, n = 97) or basiliximab and mycophenolate (BAS/TAC/MPS, n = 95). All patients received tacrolimus (TAC) and corticosteroids. Preemptive CMV therapy based on weekly pp65 antigenemia test was used during the first 6 months. Blinded weekly CMV DNAemia was compared among the groups.

RESULTS

The proportion of patients with undetectable CMV DNAemia (23.4% vs 56.7% vs 22.1%, P < .001) was higher in the BAS/TAC/EVR. The median number of study visits with positive CMV DNAemia (2.0 vs 0.0 vs 4.6, rATG/EVR vs BAS/MPS, P = .354; BAS/EVR vs BAS/MPS, P < .0001; rATG/EVR vs BAS/EVR, P < .001) were lower in the BAS/TAC/EVR. The proportion of patients with positive CMV DNAemia who were not treat for CMV infection/disease based on pp65 antigenemia was higher in rATG/TAC/EVR group (74.1% vs 36.1% vs 44.2%, P < .001) but mean CMV DNAemia was comparable to BAS/TAC/EVR and lower than BAS/TAC/MPS (8536 ± 15 899 vs 7975 ± 17 935 vs 16 965 ± 37 694 copies/mL, P < .05), respectively. The proportion of patients with CMV DNAemia below 5000 copies/mL was higher in patients receiving EVR (74.1% vs 83.5% vs 50.0%, P = .000), respectively.

DISCUSSION AND CONCLUSION

These data suggest that mTOR inhibitors reduce the incidence of CMV infection by limiting CMV viral replication.

Pp65 antigenemia and cytomegalovirus diagnosis in patients with lupus nephritis: report of a series

Introduction:

In contrast to organ transplantation, few studies correlate the monitoring of pp65 antigenemia with a diagnosis of cytomegalovirus (CMV) in patients with systemic lupus erythematosus (SLE).

Objective:

To highlight the importance of CMV outside transplantation, we monitored pp65 antigenemia in a series of SLE patients.

Methods:

From March 2015 to March 2016, SLE patients presenting kidney involvement, fever, and an unclear infection at hospital admission were monitored through pp65 antigenemia. The pp65 antigenemia assay, revealed by immunofluorescence, was correlated with clinical and laboratory findings.

Results:

We included 19 patients with a suspected unclear infection. A positivity for pp65 antigenemia was found in seven patients (36.8%). The mean age was 33.5 ± 11.2 years, 16 (84%) were females, and 16 (84%) were black. Lymphopenia, anemia, and higher scores of SLEDAI were significantly more common in pp65-positive patients. Five patients received antiviral therapy with ganciclovir. Although receiving specific CMV treatment, one patient died because of suspected CMV disease.

Conclusions:

Pp65 antigenemia might be relevant in SLE patients, and studies with a greater number of patients are needed in order to establish sensitivity and specificity of pp65 antigenemia in different clinical contexts of SLE patients.

Prevalence of cytomegalovirus disease in kidney transplant patients in an intensive care unit

OBJECTIVES

To define the frequency of cytomegalovirus disease among kidney transplant patients in an intensive care unit in which this complication was suspected and to identify predisposing factors and their possible impact on clinical outcome.

METHODS

Retrospective observational study in which kidney transplant patients over the age of 18 years were hospitalized for any reason in an intensive care unit with at least one collection of samples to test for the presence of antigenemia or cytomegalovirus via polymerase chain reaction during hospitalization. Cytomegalovirus disease was defined as positive antigenemia or polymerase chain reaction above 500 copies/mL in the presence of symptoms and in the appropriate clinical setting, as judged by the attending physician.

RESULTS

A total of 99 patients were included (age: 53.4 ± 12.8 years, 71.6% male). Cytomegalovirus disease was diagnosed in 39 patients (39.4%). Respiratory symptoms (51%), non-specific clinical worsening (20%) or gastrointestinal symptoms (14%) were the main reasons for exam collection. Transplant time was lower in those with cytomegalovirus disease than in those without this diagnosis (6.5 months and 31.2 months, p = 0.001), along with pulse therapy in the last 6 months (41% and 16.9%, p = 0.008) and previous use of thymoglobulin in the last year (35.9% and 6.8%, p < 0.001). In the logistic regression model, only the transplant time and the use of thymoglobulin were associated with a higher frequency of cytomegalovirus. There was no difference in clinical evolution between patients with and without cytomegalovirus disease.

CONCLUSION

In kidney transplant patients suspected of cytomegalovirus disease, the prevalence was high. Transplant time less than 6 months, and the use of thymoglobulin in the last year should increase the intensivist's suspicion for this complication.

Clinical correlates of pp65 antigenemia monitoring in the first months of post kidney transplant in patients undergoing universal prophylaxis or preemptive therapy

Introduction

Human cytomegalovirus is a major cause of morbidity in kidney transplant patients.

Objectives

We aimed to study viral replication and serological response in the first months post kidney transplant in patients undergoing universal prophylaxis or preemptive therapy and correlate the findings with the clinical course of Human cytomegalovirus infection.

Patients and methods

Independent from the clinical strategy adopted for managing Human cytomegalovirus infection, prophylaxis versus preemptive therapy, the pp65 antigenemia assay and serological response were assessed on the day of transplantation, and then weekly during the first three months of post-transplant.

Results

From the 32 transplant recipients, 16 were positive for pp65 antigenemia, with a similar incidence rate in each group. There were no positive results in the first three weeks of monitoring; the positivity rate peaked at week eight. There was a trend for a higher and earlier frequency of positivity in the universal prophylaxis group in which the course of the Human cytomegalovirus infection was also more severe. Despite the differences in clinical picture and in the initial immunosuppressant schedule, the serological response was similar in both groups.

Conclusion

Routine monitoring during the first three post-transplant months has a positive impact on the early detection of Human cytomegalovirus viral replication allowing for timely treatment in order to reduce morbidity of the disease. The strategy of universal therapy employing intravenous ganciclovir was associated to a worse clinical course of the Human cytomegalovirus infection suggesting that the use of >10 cells/2 × 10⁵ leukocytes as a cut-off in this setting may be inappropriate.

Targeted preemptive therapy according to perceived risk of CMV infection after kidney transplantation

Background

Methods

Results

Conclusion

Cytomegalovirus infection in transplant recipients

Cytomegalovirus infection is a frequent complication after transplantation. This infection occurs due to transmission from the transplanted organ, due to reactivation of latent infection, or after a primary infection in seronegative patients and can be defined as follows: latent infection, active infection, viral syndrome or invasive disease. This condition occurs mainly between 30 and 90 days after transplantation. In hematopoietic stem cell transplantation in particular, infection usually occurs within the first 30 days after transplantation and in the presence of graft-versus-host disease. The major risk factors are when the recipient is cytomegalovirus seronegative and the donor is seropositive as well as when lymphocyte-depleting antibodies are used. There are two methods for the diagnosis of cytomegalovirus infection: the pp65 antigenemia assay and polymerase chain reaction. Serology has no value for the diagnosis of active disease, whereas histology of the affected tissue and bronchoalveolar lavage analysis are useful in the diagnosis of invasive disease. Cytomegalovirus disease can be prevented by prophylaxis (the administration of antiviral drugs to all or to a subgroup of patients who are at higher risk of viral replication) or by preemptive therapy (the early diagnosis of viral replication before development of the disease and prescription of antiviral treatment to prevent the appearance of clinical disease). The drug used is intravenous or oral ganciclovir; oral valganciclovir; or, less frequently, valacyclovir. Prophylaxis should continue for 90 to 180 days. Treatment is always indicated in cytomegalovirus disease, and the gold-standard drug is intravenous ganciclovir. Treatment should be given for 2 to 3 weeks and should be continued for an additional 7 days after the first negative result for viremia.