Shedding of norovirus in symptomatic and asymptomatic infections.

Norovirus is the most frequent cause of acute infectious gastroenteritis and it is difficult to control in crowded environments like hospitals and nursing homes. Transmission depends on oral intake of virus deposited in the environment by infectious subjects. Data from volunteer studies indicate that virus concentrations in stool are highly variable, but systematic studies of the time-course of shedding and its individual variation are lacking. This paper quantifies norovirus shedding in a large population of 102 subjects, including asymptomatic shedders, and uses a longitudinal model to generalize shedding patterns. Enhanced surveillance for studies of transmission of norovirus in hospital outbreaks has yielded a considerable number of faecal samples from symptomatic and asymptomatic shedders, both from patients and staff. Norovirus concentrations were determined by real-time PCR. A quantitative dynamic model was fitted to the shedding data, in a multilevel Bayesian framework, to study the time-course of shedding and its variation. The results indicate that shedding in asymptomatic subjects is similar to that in symptomatic infections, both showing considerable variation in peak levels (average 105-109 /g faeces) as well as duration of virus shedding (average 8-60 days). Patients appear to shed higher numbers of virus than staff, for slightly longer durations, but the differences are too small to be significant. Given equal shedding, the greater contribution of symptomatic cases to transmission must be caused by their higher efficiency in spreading these viruses. The results of this study will be helpful for risk studies that need to quantify the deposition of virus in the environment.

Leflunomide as part of the treatment for multidrug-resistant cytomegalovirus disease after lung transplantation: case report and review of the literature.

Treatment of cytomegalovirus (CMV) disease in transplant patients is challenging and, with antiviral resistance to first-line drugs, it remains uncertain which treatment algorithm to follow. Some data suggest that leflunomide, a pyrimidine synthesis inhibitor, can be used to treat resistant CMV infections. We report a 57-year-old CMV immunoglobulin-G (IgG)-seronegative woman, who received a bilateral lung transplant (LuTx) from a CMV IgG-positive donor with CMV primary disease. The CMV strain was genotypically resistant to ganciclovir, foscarnet, and cidofovir. After starting leflunomide as add-on therapy to a multidrug anti-CMV regimen, viral load declined substantially in 2 months without adverse events. This experience is discussed against the background of existing literature on the use of leflunomide as an anti-CMV agent in LuTx recipients.

Evaluation of the antiviral response to zanamivir administered intravenously for treatment of critically ill patients with pandemic influenza A (H1N1) infection.

A retrospective nationwide study on the use of intravenous (IV) zanamivir in patients receiving intensive care who were pretreated with oseltamivir in the Netherlands was performed. In 6 of 13 patients with a sustained reduction of the viral load, the median time to start IV zanamivir was 9 days (range, 4-11 days) compared with 14 days (range, 6-21 days) in 7 patients without viral load reduction (P = .052). Viral load response did not influence mortality. We conclude that IV zanamivir as late add-on therapy has limited effectiveness. The effect of an immediate start with IV zanamivir monotherapy or in combination with other drugs need to be evaluated.

Quantification of viral DNA and liver enzymes in plasma improves early diagnosis and management of herpes simplex virus hepatitis.

Herpes simplex virus (HSV) hepatitis is a rare and potential life-threatening disease. The diagnosis of HSV hepatitis is hampered by its indifferent clinical presentation, which necessitates confirmatory laboratory data to identify HSV in the affected liver. However, liver biopsies are often contraindicated in the context of coagulopathy, are prone to sampling errors and have low sensitivity in mild HSV hepatitis cases. There is an unmet need for less invasive diagnostic tools. The diagnostic and therapeutic value of HSV DNA load and liver enzyme level kinetics was determined in five patients with HSV hepatitis and twenty disease controls with HSV-DNAemia without hepatitis. At time of hospitalization, patients with HSV hepatitis had a higher median (± interquartile range) HSV DNA load (6.0 × 10(6) ± 1.2 × 10(9)) compared to disease controls (171 ± 2845). Viral DNA load correlated with liver transaminase levels and disease severity. Antiviral treatment led to rapid decline of HSV DNA load and improvement of liver function of patients with HSV hepatitis. The data advocate the prompt and consecutive quantification of the HSV DNA load and liver enzyme levels in plasma of patients suspected of HSV hepatitis as well as those under antiviral treatment.

Norovirus in a Dutch tertiary care hospital (2002-2007): frequent nosocomial transmission and dominance of GIIb strains in young children.

We report a retrospective analysis of norovirus (NoV) infections occurring in patients of a tertiary care hospital during five winter seasons (2002/03 to 2006/07). Data were compared with national surveillance data and with corresponding data for rotavirus. Between July 2002 and June 2007, faecal specimens from 221 (9.0%) of 2458 hospital patients with diarrhoea tested positive for NoV. The incidence in children varied from 2.52 per 1000 admissions in 2004/05 (when testing began to be performed routinely) to 11.9 per 1000 admissions in 2006/07, while the incidence in adults remained stable (mean: 1.49 per 1000 admissions). Two genotypes predominated during the study period: GIIb strains occurred mainly in children below the age of two-and-a-half years [odds ratio (OR): 14.7; P<0.0001] whereas GII.4 strains affected all age groups. Compared with rotavirus infections, NoV infections in children were more often hospital-acquired (59% vs 39%, OR: 2.29; P<0.01). Among these cases we identified 22 clusters of NoV infection among inpatients. Twelve of 53 patients from whom follow-up samples were available demonstrated long-term virus shedding. We report a dynamic pattern of sporadic NoV infections in large hospitals, with frequent nosocomial transmission and with the predominance of GIIb-related strains in children. Effective prevention strategies are required to reduce the impact of sporadic NoV infection in vulnerable patients.

Clinical relevance of quantitative varicella-zoster virus (VZV) DNA detection in plasma after stem cell transplantation.

Detection of Varicella-Zoster virus (VZV) DNA in plasma can facilitate the early recognition of complicated VZV-infection in immunocompromised hosts. The correlation of VZV-DNA in plasma with clinical presentations of VZV-infection and subsequent aciclovir treatment in allogeneic stem cell transplant (allo-SCT) recipients was studied. In 81 consecutive VZV-IgG positive allo-SCT recipients, VZV-DNA was measured at regular time points (1, 2 and 4 months) following allo-SCT and patient records were screened for VZV-related symptoms and aciclovir treatment. Subsequently, possible VZV-cases were studied in detail for the course of VZV-DNA and treatment effects. During the initial screening, VZV-DNA was detectable in seven patients. The survey of VZV-related symptoms revealed five additional possible VZV-cases. In cases where suitable plasma samples were available (10 out of 12), VZV-DNA was present almost simultaneously with the first clinical manifestations. No evidence of a preceding phase detectable by VZV-DNA only could be observed. Treatment with aciclovir was associated with a prompt reduction of VZV-DNA load. Detection of VZV-DNA in plasma in allo-SCT recipients accurately reflected the clinical presentation of VZV-infection and treatment with aciclovir. VZV-DNA detection in plasma of allo-SCT recipients appears clinically relevant as this may support early recognition and therapeutic management of VZV-infections following allo-SCT.

Diagnosis of human metapneumovirus and rhinovirus in patients with respiratory tract infections by an internally controlled multiplex real-time RNA PCR.

BACKGROUND: Adequate laboratory diagnosis of human rhinoviruses (hRV) and human metapneumoviruses (h MPV) requires molecular methods as viral culture lacks sensitivity. However, setting up individual PCRs for all respiratory viruses is not practical so preferentially multiplex PCRs are used. OBJECTIVES: To develop for routine diagnosis a rapid real-time PCR assay for detection of hRV and h MPV including an internal control in a single tube multiplex reaction using probes carrying different fluorophores to discriminate targets. STUDY DESIGN: The multiplex real-time RNA PCR was optimized to include the internal control virus and a total of 358 respiratory samples from 239 patients taken over a one-year period were analyzed by the multiplex assay. RESULTS: The multiplex assay with co-amplification of the internal control was as sensitive and specific as the individual assays. Application of this assay on clinical samples from 239 patients in a one-year period resulted in an incidence of hRV and h MPV of 41/239 (17.1%) and 6/239 (2.5%), respectively. Inhibition, defined as poor internal control amplification, was detected in 8 (2.2%) samples. Culture was performed on these samples and only four hRV were detected. CONCLUSIONS: This real-time PCR method enables sensitive diagnosis of these two respiratory pathogens with the potential to expand the assay as part of a full molecular respiratory viral screen.

Adenovirus infection in children after allogeneic stem cell transplantation: diagnosis, treatment and immunity.

Human adenoviruses (HAdV) are a frequent cause of potentially fatal infections in patients after allogeneic stem cell transplantation, especially in children. Monitoring of serum/plasma by real-time quantitative PCR is a sensitive tool for the recognition of patients at risk of a potentially fatal infection and for the evaluation of the efficacy of treatment. Data from a retrospective study and from a prospective study demonstrate that recovery of immunity after transplantation is essential for the elimination of HAdV infection. The feasibility of several approaches for the manipulation of immunity in the immunocompromised host to prevent a fatal course of the infection is discussed.

Effect of ribavirin on the plasma viral DNA load in patients with disseminating adenovirus infection.

Adenovirus (AdV) infections are an increasingly frequent and potentially fatal complication in allogeneic stem cell transplant recipients. To determine the antiviral potential of ribavirin in an unbiased way, 4 patients without immune recovery were prospectively analyzed by quantitative measurement of plasma AdV DNA load. Administration of ribavirin at the first signs of AdV dissemination was not accompanied by a decrease in the plasma AdV DNA load in any of these patients, and an increase in the AdV load was even documented in 3. These observations question the potential of ribavirin to improve the outcome for patients with disseminating AdV infection and support a critical evaluation of antiviral treatments for AdV infection that involves the kinetics of virus DNA load as an objective parameter of viral replication.