Human rhinoviruses and enteroviruses are, taxonomically speaking, the same thing. Rhinoviruses were reclassified years ago as members of the Enterovirus genus within the Picornaviridae family, making every rhinovirus technically an enterovirus. Yet the two groups behave so differently in the body that clinicians, researchers, and diagnostic labs still treat them as distinct problems. The split between them is less about what they are on a genetic level and more about where they thrive, how they spread, and what kind of illness they cause.
How Rhinoviruses Became Enteroviruses
When rhinoviruses were first isolated in the 1950s, they were placed in their own genus, separate from the enteroviruses that included poliovirus and coxsackieviruses. The reasoning seemed obvious: rhinoviruses caused colds, enteroviruses caused gut and neurological infections, and the two groups looked different enough under the classification systems of the time. But as genome sequencing technology advanced, a different picture emerged. Rhinoviruses turned out to be enterovirus-like by every genomic comparison available, and the two groups shared too much genetic architecture to justify separate genera.
Today rhinoviruses are formally classified as three species within the Enterovirus genus: RV-A, RV-B, and RV-C. There are more than 160 known types across those three species.1PubMed Central. Rhinoviruses and Their Receptors They sit alongside the non-rhinovirus enteroviruses (species EV-A through EV-D), which include polioviruses, echoviruses, coxsackieviruses, and the numbered enteroviruses like EV-D68. The reclassification was genomically correct but created an odd situation: the term “enterovirus” now technically includes rhinoviruses, but in everyday medical shorthand people still say “enterovirus” to mean the non-rhinovirus members of the genus.2PubMed Central. Classification and Evolution of Human Rhinoviruses
Temperature Preferences and Where They Replicate
The most practical difference between rhinoviruses and non-rhinovirus enteroviruses is where in the body they set up shop. Rhinoviruses replicate best at the cooler temperatures found inside the nasal passages, around 33 to 35 °C, which is a few degrees below core body temperature.3PubMed Central. Temperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cells This is why they are primarily a respiratory pathogen: the nose and upper airways give them the thermal environment they need. At 37 °C, rhinovirus replication drops off. The body’s core temperature acts as a kind of natural barrier, which is part of why rhinovirus infections usually stay in the airways rather than spreading systemically.
Non-rhinovirus enteroviruses have no such temperature limitation. They replicate efficiently at core body temperature and typically begin their infection cycle in the gastrointestinal tract, entering through the gut lining before potentially spreading to the bloodstream and other organs.4PubMed Central. Enteroviruses: A Gut-Wrenching Game of Entry, Detection, and Evasion This is why classic enteroviruses can cause meningitis, myocarditis, hand-foot-and-mouth disease, and paralytic illness: they can travel well beyond their initial entry point. Rhinoviruses, confined to the cooler respiratory tract, almost never do that.
How They Get Inside Cells
Rhinoviruses and non-rhinovirus enteroviruses also use different doorways to enter host cells, which partly explains their different tissue preferences. Among rhinoviruses, the majority of RV-A types and all RV-B types latch onto ICAM-1, an adhesion protein found on respiratory epithelial cells. A smaller group of RV-A types uses members of the low-density lipoprotein receptor family. The relatively recently discovered RV-C species uses a receptor called CDHR3, which is expressed primarily in airway tissue.1PubMed Central. Rhinoviruses and Their Receptors
Non-rhinovirus enteroviruses, by contrast, rely on a wider range of receptors including the poliovirus receptor (CD155), decay-accelerating factor, and various others depending on the species and serotype. Some of these receptors are found on gut epithelial cells, neurons, or heart muscle cells, which is why enteroviruses can cause such a wide range of disease beyond respiratory illness.
Transmission Routes
The classic teaching is that enteroviruses spread primarily through the fecal-oral route, entering through contaminated hands or water, while rhinoviruses spread through respiratory droplets and contaminated surfaces. This broad distinction holds, but the real world is messier. Rhinoviruses can survive on surfaces like doorknobs and phone screens, and you can pick them up by touching your nose or eyes after touching a contaminated object. Non-rhinovirus enteroviruses also spread through respiratory secretions in addition to the fecal-oral route, which is how EV-D68 (discussed below) manages to cause outbreaks of respiratory illness.
Basic hand hygiene makes a meaningful dent in both transmission pathways. Research on alcohol-based hand sanitizer use in households found that it reduced the risk of rhinovirus infection by roughly half to nearly completely, depending on how much virus was initially on the hands.5PubMed Central. Impact of the use of an alcohol-based hand sanitizer in the home on reduction in probability of infection by respiratory and enteric viruses The same study found similar reductions for enteric viruses, reinforcing that hand hygiene works against both groups.
What Illness Looks Like
For most people, a rhinovirus infection means a common cold: runny nose, sneezing, sore throat, maybe a mild cough. This is the prototypical rhinovirus illness and accounts for more than half of all cold-like episodes.6PubMed Central. Human rhinoviruses The illness is usually self-limiting and relatively mild, though it still costs billions of dollars annually in medical visits and missed work.
But rhinoviruses can cause more than sniffles. In hospitalized children, rhinovirus and enterovirus infections (grouped together in many diagnostic panels) were associated with increased work of breathing in about two-thirds of cases, along with wheezing and crackles on lung examination at rates significantly higher than influenza.7Elsevier / PubMed Central. Rhino/enteroviruses in hospitalized children: a comparison to influenza viruses The encouraging finding in that same study was that hospital stays were shorter for rhinovirus/enterovirus than for influenza: a median of two days versus three.
Non-rhinovirus enteroviruses, meanwhile, produce a much broader clinical spectrum. The mildest infections cause a generic fever-and-rash illness or hand-foot-and-mouth disease. More serious infections can lead to viral meningitis, encephalitis, myocarditis, or the paralytic illness associated historically with poliovirus. Certain enterovirus types like EV-A71 are strongly linked to neurological complications. In a surveillance study of pediatric patients in Catalonia, nearly two-thirds of EV-A71 infections were associated with neurological problems, most commonly a form of brainstem inflammation called rhombencephalitis.8PubMed Central. Surveillance of enteroviruses from paediatric patients attended at a tertiary hospital in Catalonia from 2014 to 2017
Rhinovirus C and Childhood Asthma
Among the three rhinovirus species, RV-C has attracted the most clinical concern because of its tight association with asthma attacks in children. In a study of children presenting with acute asthma, RV-C was detected in about 59% of cases and was linked to higher severity scores compared with RV-A or RV-B infections.9PubMed Central. Association between human rhinovirus C and severity of acute asthma in children A separate study in Taiwan found that the prevalence of RV-C was far higher in children with asthma exacerbations than in children hospitalized for non-asthma respiratory illness, a pattern not seen with RV-A or RV-B.10Journal of Microbiology, Immunology and Infection. High correlation between human rhinovirus type C and children with asthma exacerbations in Taiwan
Part of the explanation lies in the receptor RV-C uses. The CDHR3 protein that serves as RV-C’s entry point is expressed in airway epithelium, and a specific genetic variant of the CDHR3 gene has been linked both to increased susceptibility to RV-C infections and to a higher risk of severe asthma exacerbations in young children.11PubMed Central. CDHR3 Asthma-Risk Genotype Affects Susceptibility of Airway Epithelium to Rhinovirus C Infections Children who carry this variant may be genetically primed for worse outcomes when they encounter RV-C, which helps explain why some kids end up in the emergency room while others shake off the same virus with mild symptoms.
Enterovirus D68 and the Blurry Line
If rhinoviruses are the enteroviruses that act like respiratory pathogens, EV-D68 is the non-rhinovirus enterovirus that decided to do the same thing. First isolated in the United States in 1962, EV-D68 is primarily a respiratory pathogen whose illness spectrum ranges from mild upper respiratory infections to severe disease requiring intensive care and mechanical ventilation.12PubMed Central. Enterovirus D68 and Human Respiratory Infections It gained widespread attention during a large outbreak in North America in 2014 that was linked to a spike in severe respiratory illness and a rare neurological condition called acute flaccid myelitis, a polio-like paralytic illness.
In the Catalonia surveillance data, the vast majority of EV-D68 cases (88%) presented with lower respiratory tract infections, and one case was associated with acute flaccid paralysis.8PubMed Central. Surveillance of enteroviruses from paediatric patients attended at a tertiary hospital in Catalonia from 2014 to 2017 EV-D68 is an important reminder that the rhinovirus/enterovirus boundary is not a clean line between “respiratory” and “everything else.” Some enteroviruses are very much respiratory pathogens, and some rhinoviruses can cause lower airway disease severe enough to land a child in the hospital.
Seasonality
In temperate climates, rhinoviruses tend to peak in autumn and spring, while non-rhinovirus enteroviruses are more active in summer and early autumn.13Oxford Academic (Military Medicine). Seasonality and Climatic Factors Associated With Human Rhinovirus/Enterovirus Nasopharyngeal Sample Positivity on Oahu, Hawai’i, 2016-2019 This matters clinically because a summer respiratory illness in a child is more likely to be an enterovirus than a rhinovirus, and that shifts the differential diagnosis. In tropical climates the picture is less clear, with both virus groups thought to peak during rainy seasons, though data remain limited.
The autumn rhinovirus surge is famously linked to school reopenings. Young children returning to classrooms in September seed a wave of rhinovirus transmission that ripples outward through families and communities. Enteroviruses circulating in summer can overlap with this wave in early fall, which partly explains why that period is such a miserable season for pediatric respiratory illness.
Why Diagnostic Panels Often Lump Them Together
If you have ever seen a lab result that says “rhinovirus/enterovirus detected” without specifying which, that is not sloppiness. It reflects a genuine technical challenge. Because rhinoviruses and enteroviruses share significant stretches of nucleotide sequence, many standard PCR-based tests cannot reliably distinguish between them. One study evaluating different rhinovirus detection strategies found that a broader picornavirus detection protocol was more sensitive but less specific, and a semi-nested protocol designed to differentiate rhinoviruses from other enteroviruses was less sensitive and ultimately could not reliably tell them apart.14PubMed Central. Rhinovirus detection using different PCR-based strategies
Specialized multiplex PCR assays have been developed to both detect and differentiate the two groups in respiratory samples, but these are not part of standard rapid panels in most clinical settings.15PubMed. Detection of rhinovirus and enterovirus in upper respiratory tract samples using a multiplex nested PCR For a typical patient with a cold, the distinction rarely matters for treatment. But in a hospitalized child or an immunocompromised adult, knowing whether the pathogen is a rhinovirus or a non-rhinovirus enterovirus can change the clinical picture and the list of complications to watch for. The gap between what the test reports and what clinicians want to know remains a frustration in pediatric and infectious disease medicine.
How They Evolve Differently
Both rhinoviruses and non-rhinovirus enteroviruses are RNA viruses with high mutation rates, but they differ in how they shuffle their genomes through recombination. Recombination within a species (intraspecies recombination) is common among non-rhinovirus enteroviruses and is considered a major driving force of their evolution. Among rhinoviruses, intraspecies recombination occurs but appears to be much more sporadic.16PubMed. Experimental human rhinovirus and enterovirus interspecies recombination
Recombination between different species is rarer still for rhinoviruses. When evidence of interspecies recombination is found, it typically traces back to ancient events that contributed to the original divergence of rhinovirus species, rather than ongoing exchanges in the current viral population.17PubMed Central. Chimeric rhinoviruses obtained via genetic engineering or artificially induced recombination are viable only if the polyprotein coding sequence derives from the same species Lab experiments have shown that artificially engineered chimeric rhinoviruses are only viable when the protein-coding sequence comes from the same species, hinting at strict compatibility requirements that limit rhinovirus recombination in nature. Non-rhinovirus enteroviruses face fewer such barriers, which partly explains their greater diversity and their ability to produce new pathogenic variants over time.
Antiviral Research Targeting Both Groups
There are no approved antiviral drugs for either rhinoviruses or non-rhinovirus enteroviruses, but several candidates are working through preclinical and early clinical stages. The most promising approaches target conserved features shared across the broader genus, which means a single drug could potentially work against both rhinoviruses and enteroviruses. Capsid-binding agents and monoclonal antibodies aim to block the virus from attaching to its host cell receptor, while protease inhibitors disrupt the processing of viral proteins needed for replication.18PubMed Central. Advances in the Treatment of Enterovirus-D68 and Rhinovirus Respiratory Infections
Two viral targets have attracted the most attention. VP1, a protein on the outer capsid shell, is relatively conserved and mediates the initial attachment and uncoating steps. The 3C protease, essential for viral replication, is highly conserved across different serotypes and offers a target for broad-spectrum drugs that could work against many enterovirus types at once.19PubMed Central. Selective human enterovirus and rhinovirus inhibitors: An overview of capsid-binding and protease-inhibiting molecules The shared biology here is a rare instance where the reclassification of rhinoviruses into the Enterovirus genus has direct therapeutic implications: drug developers can exploit the genomic similarities that motivated the reclassification in the first place.
Your Nose Bacteria May Influence What Happens Next
An emerging area of research suggests that the community of microbes already living in your nose helps determine how severe a rhinovirus infection becomes. In experimental rhinovirus challenge studies, the composition of the nasal microbiome before infection was associated with different levels of inflammatory response during the illness. Subjects whose nasal bacteria were dominated by Moraxella species showed the largest increases in inflammatory markers, while those with Staphylococcus-dominated profiles had the smallest changes.20Scientific Reports. Nasal microbiota clusters associate with inflammatory response, viral load, and symptom severity in experimental rhinovirus challenge
A more recent study in school-age children added another layer: the nasal phageome, meaning the viruses that infect the bacteria in your nose. A baseline microbiome profile dominated by commensal bacteria like Staphylococcus epidermidis was protective against subsequent respiratory viral infections, while profiles enriched in bacteriophages were associated with roughly four times the risk of infection. Certain phages appeared to work against children by reducing the population of beneficial S. epidermidis.21PubMed Central. Nasal microbiome and phageome profiles are associated with prospective respiratory viral infection risk in school-age children This research is still early, but it raises the possibility that the nose’s resident microbial ecosystem acts as a gatekeeper for respiratory viral infections, influencing whether a rhinovirus encounter becomes a bad cold or barely registers.