In a recent study published in Emerging Infectious Diseases, researchers developed an innovative method to diagnose respiratory viral infections (RVIs) in children using discarded facial tissues.
RVIs are common in children of all age groups, necessitating their early detection. They typically manifest as common colds and rhinorrhea with no fever but acute respiratory distress (ARD) in severe cases, resulting in death. Besides their clinical effects, RVIs are a major economic burden on healthcare. However, the worst is that doctors too often prescribe antibiotics for RVI treatment, so they have become a reason for increasing antimicrobial resistance.
With the advent of severe acute respiratory coronavirus 2 (SARS-CoV-2), it seems like some respiratory viruses could circulate all year round. However, most circulate more in winter when temperature and behavioral patterns favor their dissemination. Overall, research has not fully revealed the pattern of respiratory virus circulation.
However, advancements in the molecular biology domain have enabled their early detection. Several commercial assays with automated approaches easily detect common respiratory viruses. However, it is still challenging to correctly identify pathogens in RVIs. If that becomes feasible, it would have several advantages; it could help doctors limit the use of antibiotics and prevent onward transmission to the community and nosocomial infections.
Most patients consider nasal swab sampling invasive, though it most reliably fetches accurate results. The only limitation is that technicians do not extensively test these samples for all common respiratory viruses. Another problem is these samples are difficult to collect from children. Blaschke et al. first proposed using facial tissues to diagnose RVIs in children; their method attained 84% sensitivity (satisfactory); however, nasal aspirate, a more sensitive sample type, is still widely used for RVI diagnoses in children.
About the study
In the present study, researchers collected used tissues from two communities (daycare center and preschool) of children once a week for a year (pooled data) to document RVIs in different settings. In the first study, they collected all tissues from the daycare facility with 40 children in the age group of under 19 months to up to four years. The preschool had 20 students in each class, between three to four years of age.
The researchers also collected samples of 30 volunteers with influenza-like symptoms or a confirmed RVI, assessed via a standard nasal swab sample test, who served as positive controls. The team collected containers filled with used tissues (used only for nose blowing) each week and counted them. They used commercial kits to detect viral genomes in these tissues.
The researchers gathered a large amount of pooled data from the daycare center and the preschool. Collecting used tissues was noninvasive, so the professionals or the parents did not raise concerns. On the contrary, they awaited the weekly results.
Despite staying close by in preschool and daycare centers, older and younger children did not catch respiratory infections from the same viruses. First, it indicated that children's immunity varied with age, and so did their susceptibility to RVIs. Also, it showed that daycare centers adhered to hygiene rules strictly compared to preschools. Yet, pooled data collected throughout the year helped the researchers assess how prone these children were to RVIs.
As expected, rhinovirus circulated consistently among children year-round, showing children had weak immunity to this virus, but it caused relatively mild symptoms in young children. On the contrary, the researchers detected parainfluenza virus 3 in autumn in children from both communities, consistent with the findings of Horemheb-Rubio et al. The start of the academic year marks the first gathering of children. From that time and even after March break, researchers detected parainfluenza virus 3 activity consistently in used tissue samples for several weeks.
Interestingly, the researchers also detected cytomegalovirus (CMV) in the daycare center. Its detection in pooled material indicated that either it was perpetually circulating among children or one or a few infants infected by CMV before or at birth continuously shed the virus. The team did not perform individual analyses on ethical grounds, as even one CMV-infected child would have led to discrimination against that child or his/her eviction.
Earlier, propagating the virus(es) in cell culture was the reference for diagnosis. Recent advancements have made molecular detection of viral genomes possible, as demonstrated by this study. However, the information gained by each method is different. So while nucleic acid amplification methods are overall more sensitive, they give no insights into the viability or possible infectiousness of the detected virus. Yet, viral genomes detected in used tissue samples provide helpful information.
They provide a method of detecting any respiratory-transmitted virus early and intervene to prevent its onward transmission further. Athletes repeatedly tested during events could also benefit from this strategy. Most importantly, this method helps RVI diagnosis remotely. Someone could send a used tissue sample via mail and know about the potential dissemination of an infection in a population.
Furthermore, the study data could help predict the emergence of winter seasonal viruses (e.g., influenza virus) as these propagate efficiently among young children. Early detection gives time to caution parents who can mask their children to protect them from infection. As expected, the researchers detected the first influenza-positive used tissue collection in the daycare center, six weeks before the seasonal peak.
Though now it is just a proof-of-concept work, according to the authors, accumulating more data could help scale up the use of this novel method on a larger scale.