Although the majority of rhinovirus infections occur in children, our knowledge of the symptomatology is mainly acquired from adults. Accurate determination of symptoms is a challenge in children because symptoms are reported second-hand by parents trying to interpret what their child may feel. Two studies have evaluated the expression of cold symptoms in children who were brought to the doctor. A recent study evaluated cold symptoms in normal school-age children who actively participated with the parent in recording their symptoms (Winther, 2002). Cough, nasal congestion, and runny nose were present in roughly 60% of school-age children and continued for more than 10 days in uncomplicated colds. Feverishness was reported in 15% during the early phase. Rhinovirus was detected in 46% of these reported colds, and one or more bacterial pathogens were isolated in 29%. Symptom profiles for rhinovirus illnesses versus those with bacteria isolated were not different. In adults, 60% of those with colds report sore throat, sneezing, nasal discharge and obstruction, while cough and malaise are reported in approximately 40%. Fever is rare in uncomplicated colds, and feverishness is reported in less than 10% of adults with colds. Most cold symptoms in adults have diminished by day 7, with sneezing, congestion, and runny nose reported in less than 20%, whereas cough is still reported as present in roughly 40%.
Different serotypes of rhinovirus are thought to cause a similar symptom profile, although the symptom severity may vary due to the influence of stress and the status of the immune system and host responsiveness. Experimental rhinovirus infections with two different rhinovirus serotypes have demonstrated that approximately 20% of antibody-free adults become infected following rhinovirus challenge but do not report symptoms. The reason for this is unknown, but a similar trend has been found in children. Roughly 30% of children may have a rhinovirus infection without the signs or symptoms of a cold. This may be caused by infection without symptom expression, or that the cold symptoms are not recognized by the parents.
Signs Of Rhinovirus Infection
Examination of the nasal cavity in adults with rhinovirus infection reveals an increase in nasal secretions but is otherwise unspecific, since abnormal erythema and swelling of the turbinates is seldom observed. Rhinovirus infection causes abnormalities in the Eustachian tube and middle ear. Eustachian tube dysfunction results in intermittent negative middle ear pressure and fluid accumulation. Abnormal middle ear pressure can easily be measured by tympanometry and is present in 40–75% of rhinovirus infections in both children and adults. Approximately 40% of young children have changes in middle ear pressure prior to the time when the parent or caretaker realizes that the child has a cold (Moody et al., 1998). The causes of abnormal middle ear pressure during colds are unknown. Rhinovirus infection of the adenoid in the nasopharynx may result in Eustachian tube dysfunction, or rhinovirus infection may spread into the Eustachian tube and middle ear.
Abnormalities of the paranasal sinuses are also very common during the course of rhinovirus infection, as evidenced by computed tomographic scanning (CT scan). Image studies have shown sinusitis during the first week of illness in up to 75–87% of children and young adults, suggesting that sinus involvement is an inherent feature of a cold. It has recently been shown that nose blowing can generate intranasal pressure sufficient to propel nasal secretions into the sinus cavity. The majority of the abnormalities observed by CT scans during colds are likely due to accumulation of sinus secretions rather than mucosal swelling. Stagnant secretions in the sinuses may be due to blockage in the ostiomeatal complex, a narrow opening from the sinus to the nose, or it may be due to decreased ciliary clearance in the sinuses.
Clinical Diagnosis
Colds in adults are usually self-diagnosed, as everyone is familiar with the symptoms of a cold. Adults may commonly misdiagnose the involvement of a viral infection in the sinuses and middle ear as a bacterial complication, when in fact it is part of the rhinoviral infection.
Differential diagnoses to common colds are allergic rhinitis and vasomotor rhinitis, both of which will usually produce more prolonged sneezing attacks than the common cold. Rhinovirus infection can be distinguished from classic influenza in adults based on the more acute onset of malaise and frequently occurring fever present with influenza. However, milder cases of influenza cannot be easily distinguished from rhinovirus infection, especially in children.
Clinical Implications
Following introduction into the nose, rhinovirus can first be recovered from the adenoid area in the nasopharynx. Over several days, newly produced rhinovirus is excreted into the nasal mucus and may be distributed to other areas of upper respiratory mucosa. Adults seem more prone to paranasal sinus involvement, whereas young children seem more prone to otitis media during colds. The paranasal sinuses are not fully developed until about age 12, but other factors may also influence these differences. Children are not good nose blowers and thus may be less likely to spread rhinovirus into the sinuses. On the other hand, children spend more time asleep, and a horizontal position may facilitate the spread of mucus (and thus rhinovirus) into the middle ear cavity. Rhinovirus has been demonstrated in fluid obtained from the maxillary sinus/ear cavity of 40–50% of patients with acute sinusitis and otitis media (Pitkaranta et al., 1997, 1998). Multiple rhinovirus infections may cause hypertrophic adenoids (lymphatic glands in the posterior oropharynx) in children with blockage of the nasal passages, and consecutive rhinovirus infections in children without a wellness period in between may create a clinical picture simulating the chronic sinusitis seen in adults (chronic nasal discharge for more than 6 weeks).
It is very difficult to distinguish an acute viral otitis media or sinusitis from an acute bacterial otitis media or sinusitis. It is generally accepted that acute bacterial sinusitis complicates an estimated 0.5–2.2% of viral colds. The complication rate of acute bacterial otitis media following colds is not clear (Hendley, 2002). Suppurative otitis media, defined as a bulging tympanic membrane with purulent middle ear fluid or purulent otorrhea from a perforated tympanic membrane, occurs in only 2–15% of young children, but mild otitis media may occur in 40–50%. One problem may be that viruses and bacteria gain entrance to the sinus and ear cavities and are trapped without causing real mucosal invasion or infection.
In addition to the sinuses and middle ear, rhinovirus may also spread to the lower airways. Young children commonly develop bronchiolitis/reactive airway disease during rhinovirus infections (Heymann et al., 2005). The mechanism by which rhinovirus infection induces wheezing is not well understood. Adults with chronic bronchitis frequently develop exacerbation of their illness during rhinovirus infections with transient decreased pulmonary function. Rhinovirus is also an important precipitant for asthma attacks in both children and adults. The severity of cold symptoms is not greater in allergic patients with rhinovirus infection than in normal individuals, but patients with allergic rhinitis have increased airway responsiveness to histamine during rhinovirus infections.