Influenza diagnosis and treatment: a view from clinical practice

Common laboratory organic solvents are better medium for molecular detection of RNA viruses using PCR

PURPOSE

The unavailability of recommended viral transport medium during epidemics of respiratory viral infections is a substantial healthcare concern. It may prompt the use of alternatives, which may give rise to results with questionable validity. The present study was carried out to assess and validate the utility of commonly available solvents in the hospital/healthcare set-ups which may be used as ready and economical alternatives to commercial VTMs.

METHODS

To evaluate the readily available solvents as an alternative to VTM, cell culture supernatant of pH1N1 2009 isolate with HA titres of 1:4 and extracted viral RNA of SARS-CoV-2 were spiked in a 1:10 ratio in ethanol, acetone, methanol and were compared to commercially available VTM for detection of influenza virus by real time RT-PCR (qRT-PCR). The tubes were kept at room temperature 24 h, 48 h and 72 h. Ct values of the various solvents at different time points were compared and statistical analysis was performed using Python.

RESULTS

The Ct values of the Influenza and SARS-CoV2 viral genes in each solvent were maintained for 3 days at room temperatures, suggesting viral samples were stably preserved in the solvent for 3 days.

CONCLUSION

Methanol was found to be the most promising solvent for increasing the stability of viral RNA thereby enhancing the molecular diagnosis of the concerned pathogen.

Verdinexor Targeting of CRM1 is a Promising Therapeutic Approach against RSV and Influenza Viruses

Two primary causes of respiratory tract infections are respiratory syncytial virus (RSV) and influenza viruses, both of which remain major public health concerns. There are a limited number of antiviral drugs available for the treatment of RSV and influenza, each having limited effectiveness and each driving selective pressure for the emergence of drug-resistant viruses. Novel broad-spectrum antivirals are needed to circumvent problems with current disease intervention strategies, while improving the cytokine-induced immunopathology associated with RSV and influenza infections. In this review, we examine the use of Verdinexor (KPT-335, a novel orally bioavailable drug that functions as a selective inhibitor of nuclear export, SINE), as an antiviral with multifaceted therapeutic potential. KPT-335 works to (1) block CRM1 (i.e., Chromosome Region Maintenance 1; exportin 1 or XPO1) mediated export of viral proteins critical for RSV and influenza pathogenesis; and (2) repress nuclear factor κB (NF-κB) activation, thus reducing cytokine production and eliminating virus-associated immunopathology. The repurposing of SINE compounds as antivirals shows promise not only against RSV and influenza virus but also against other viruses that exploit the nucleus as part of their viral life cycle.

Predictors of influenza among older adults in the emergency department

Background

Diagnosis of influenza in older adults may be complicated by atypical presentations or when patients present with complications of an underlying illness. We aimed to identify clinical characteristics and epidemiological factors associated with influenza among community-dwelling adults aged ≥60 years presenting to emergency departments.

Methods

We identified patients with influenza-compatible chief complaints presenting to emergency departments of six acute care hospitals in Ontario, Canada during the 2011/12 and 2012/13 influenza seasons. Clinical characteristics, medical history and demographics were collected by patient interview, chart review and by contacting vaccine providers. Nasopharyngeal swabs were tested for influenza using polymerase chain reaction. We modeled predictors of influenza using multivariable logistic regression models that compared individuals with and without influenza.

Results

Of 1318 participants, 151 (11 %) had influenza (98 A/H3N2, 12 A/H1N1, 4 A [not sub-typed], 37 B). In the multivariable model, clinical symptoms associated with influenza were cough (OR 6.4, 95 % CI 3.2, 13.0), feverishness and/or triage temperature ≥37.2 °C (OR 3.0, 95 % CI 2.0, 4.7), 2–5 days from symptom onset to the emergency department visit (OR 2.2, 95 % CI 1.5, 3.2), and wheezing (OR 2.1, 95 % CI 1.3, 3.3). The effect of cough on influenza increased with older age. Epidemiological factors associated with increased odds for influenza included weeks when ≥10 % influenza tests from provincial laboratories were positive (OR 5.1, 95 % CI 1.2, 21.7) and exposure to a person with influenza-like illness (OR 1.9, 95 % CI 1.3, 2.8). Among participants with influenza, only 47 (31 %) met the U.S. Centers for Disease Control and Prevention criteria for influenza-like illness (temperature ≥37.8 °C and cough and/or sore throat).

Conclusions

As in younger adults, cough and feverishness are the two symptoms most predictive of influenza in the elderly. Current influenza-like illness definitions did not adequately capture influenza in older adults.

Factors affecting the success of influenza laboratory diagnosis

Influenza is one of the most common human infectious diseases, and has profound health and economic consequences. The laboratory diag- nosis of influenza virus infections plays an important role in the global surveillance of influenza. Therefore, there is a growing demand for highly sensitive and rapid methods for detecting influenza. The performance of particular diagnostic methods is affected by various factors. In this study, we assess the effects of patients' age and time to diagnosis on the probability of detecting influenza using four diagnostic methods (virus isolation, rapid test, RT-PCR and real-time RT-PCR). We examined 3,546 samples from central and eastern Slovakia during the influenza seasons from 2005-2006 to 2010-2011. In general, the probability of influenza detection significantly decreased with the time from onset of illness to sample collection (T1) as well as with patients' age (AGE). On the contrary, time from sample collection to delivery (T2) did not play a role in the prob- ability of influenza detection. As judged by odds ratios, the virus isolation method was most sensitive to T1, followed by the rapid test and RT-PCR methods. For the effect of AGE, the rapid test and virus isolation methods were more sensitive than PCR-based methods. The effects of T1 and AGE were independent of each other. Laboratories which participate in inifluenza surveillance should use several methods to enable rapid and accurate influenza A and B virus detection.

Prevalence of influenza and adherence to the anti-flu vaccination among elderly

INTRODUCTION: The flu, a condition that can affect the elderly by increasing the risk of serious complications can be prevented through vaccination. Estimate the prevalence of signs and symptoms suggestive of influenza in a group of elderly either vaccinated or unvaccinated against influenza was the objective this study. METHODS: This is a cross-sectional study performed in a Brazilian City. A structured questionnaire was employed to identify the presence of signs and symptoms of influenza in individuals aged 60 years or over. For analysis of associations between variables the prevalence ratio (PR) and its 95% confidence interval (95% CI) were used. RESULTS: One hundred ninety-six participants were interviewed, of whom 57.7% were female. The average age was 69.7 years. About 25% of the vaccinated and 20% of the unvaccinated in 2009, and 25% of the vaccinated and 22.5% of the unvaccinated in 2010 reported having the flu. Among the vaccinated and unvaccinated in 2009 and 2010, there was no verified association between vaccination and influenza (PR=1.24; [95% CI: 0.63-2.43] and PR=1.11; [95% CI: 0.59-2.09], respectively). CONCLUSIONS: This study suggests that, among the elderly selected, the vaccination coverage for influenza is below the ideal, even with projection of the best indices for 2011 (~ 84%). The data on vaccination and disease protection needs further research; however, the results point to the need for measures to better clarify to this population about the disease, its complications and the benefits of vaccination, in addition to combatting the stigma related to low adherence.

Critical analysis of deaths due to atypical pneumonia during the onset of the influenza A (H1N1) virus epidemic

BACKGROUND

The ongoing influenza A (H1N1) pandemic stroked Mexico and posed a huge challenge to the medical care and public health systems. This report analyzes the clinical course and process of care of patients who died due to atypical pneumonia and fulfilled the clinical criteria of suspected case of novel influenza A (H1N1) virus infection.

METHODS

We conducted a retrospective analysis of a series of 38 patients who died between April 7 and April 28, 2009 at Instituto Mexicano del Seguro Social (IMSS) hospitals due to severe pneumonia and respiratory distress. These cases coincided with the beginning of the outbreak, so patients did not undergo laboratory testing to diagnose influenza. According to IMSS and CDC criteria, post-hoc analysis allowed considering the presumptive diagnosis of S-OIV infection. A multidisciplinary group analyzed the information from the clinical charts, laboratory tests, radiographic studies and death certificates, using descriptive statistics.

RESULTS

Most cases were middle-aged (mean 33 years, range: 4-62 years) and previously healthy; 18.4% had an underlying chronic disease, 23.7% were obese and 7.9% were current smokers. None had received the seasonal influenza vaccine; they had cough (92%), fever (86.8%), and malaise (73.7%). The median time from disease onset to hospital admission was 6 days (range 0-8 days). All were admitted to the intensive care unit with pneumonia and/or respiratory distress. Average time from disease onset to death was 8 days (range 4-18 days).

CONCLUSIONS

An increased number of severe cases of atypical pneumonia in previously healthy adults highlight the importance of the availability of a timely surveillance system able to identify sudden increases in the number of cases or presentation of apparently known diseases.

Preclinical in vitro activity of QR-435 against influenza A virus as a virucide and in paper masks for prevention of viral transmission

Prophylaxis against influenza is difficult, and current approaches against pandemics may be ineffective because of shortages of the two proven classes of antivirals in the face of a large-scale infection. Herbal/natural products may represent an effective alternative to conventional attempts to protect against infection by avian influenza virus. QR-435, an all-natural compound of green tea extract and other agents, has been developed to provide protection against a wide range of viral infections. The antiviral activities of several QR-435 preparations as well as QR-435 (1) green tea extract were tested against A/Sydney/5/97 and A/Panama-Resvir 17 strains of avian influenza virus H3N2 by means of an assay based on Madin-Darby canine kidney cells. Toxic effects of QR-435 formulations on these cells were also evaluated as were the virucidal properties of a commercially available mask impregnated with QR-435. The efficacy of a QR-435/mask combination was compared with that of the QR control/mask combination, an untreated mask, and no mask. QR-435 had significant in vitro activity against H3N2 at concentrations that were not associated with significant cellular toxic effects. The antiviral activity of QR-435 (1) was similar to that of QR-435. Masks impregnated with QR-435 were highly effective in blocking the passage of live H3N2 virus. These preclinical results warrant further evaluation of the prophylactic use of QR-435 against viral infection in humans.

In vivo prophylactic activity of QR-435 against H3N2 influenza virus infection

BACKGROUND

Prophylaxis against influenza infection can take several forms, none of which is totally effective at preventing the spread of the disease. QR-435, an all-natural compound of green-tea extract and other agents, has been developed to protect against a range of viral infections, including the influenza subtype H3N2.

METHODS

Several different QR-435 formulations were tested against the two influenza A H3N2 viruses (A/Sydney/5/97 and A/Panama/2007/99) in the ferret model. Most experiments included negative (phosphate-buffered saline) and positive (oseltamivir 5 mg/kg, twice daily) controls. QR-435 and the control were administered 5 minutes after intranasal delivery of the virus as prophylaxis against infection resulting from exposure to infected but untreated ferrets and for prevention of transmission from infected and treated ferrets to untreated animals. Effects of QR-435 on seroconversion, virus shedding, and systemic sequelae of infection (weight loss, fever, reduced activity) were evaluated.

RESULTS

QR-435 prevented transmission and provided prophylaxis against influenza virus H3N2. Prophylaxis with QR-435 was significantly more than with oseltamivir in these experiments. Optimal in vivo efficacy of QR-435 requires a horseradish concentration of at least 50% of that in the original formulation, and the benefits of this preparation appear to be dose dependent.

CONCLUSIONS

QR-435 is effective for both prevention of H3N2 viral transmission and prophylaxis. These preclinical results warrant further evaluation of its prophylactic properties against avian influenza virus infection in humans.

Field performance and new uses of rapid influenza testing in Thailand

OBJECTIVES

Rapid influenza tests are increasingly used in surveillance systems and for clinical care in Southeast Asia. However, the performance and utility of rapid influenza tests under field conditions in rural Southeast Asia has not been evaluated.

METHODS

In the context of a larger study on the causes of respiratory illness in rural Thailand, we used a rapid test to collect data on influenza burden, seasonality, and cost of illness. We compared the performance of the QuickVue Influenza Test to tissue cell viral culture and reverse transcriptase-polymerase chain reaction (RT-PCR) among 1092 Thai patients meeting the World Health Organization case definition for influenza-like illness over a 12-month period.

RESULTS

The sensitivity and specificity of the QuickVue test compared to viral culture were 77% and 96%, respectively. Rapid influenza tests were useful to describe the seasonality of influenza, estimate the cost of illness, increase the sensitivity of surveillance, conduct outbreak responses, and guide evaluation of suspected avian influenza virus infections.

CONCLUSIONS

Despite their high cost, rapid influenza diagnostic tests are useful tools for influenza research, surveillance, and outbreak investigations in Southeast Asia.

Evaluation of PCR testing of ethanol-fixed nasal swab specimens as an augmented surveillance strategy for influenza virus and adenovirus identification

Viral culture isolation has been widely accepted as the "gold standard" for laboratory confirmation of viral infection; however, it requires ultralow temperature specimen storage. Storage of specimens in ethanol at room temperature could expand our ability to conduct active surveillance and retrospective screenings of viruses with rapid and inexpensive real-time PCR tests, including isolates from remote regions where freezing specimens for culture is not feasible. Molecular methods allow for rapid identification of viral pathogens without the need to maintain viability. We hypothesized that ethanol, while inactivating viruses, can preserve DNA and RNA for PCR-based methods. To evaluate the use of ethanol-stored specimens for augmenting surveillance for detection of influenza viruses A and B and adenoviruses (AdV), paired nasal swab specimens were collected from 384 recruits with febrile respiratory illness at Fort Jackson, S.C., in a 2-year study. One swab was stored at ambient temperature in 100% ethanol for up to 6 months, and the other swab was stored at -70 degrees C in viral medium. For viral detection, frozen specimens were cultured for a variety of respiratory viruses, and ethanol-fixed specimens were tested with TaqMan (TM) probe and LightCycler SYBR green (SG) melting curve assays with at least two different PCR targets for each virus. The sensitivities of the TM and SG assays on specimens stored in ethanol for 1 month were 75% and 58% for influenza A, 89% and 67% for influenza B, and 93 to 98% and 57% for AdV, respectively. Lower specificities of the real-time assays corresponded to the increased detection of PCR-positive but culture-negative specimens. Influenza virus RNA was detected as well or better after 6 months of storage in ethanol.