The common cold (acute coryza)
This highly infectious illness comprises a mild systemic upset and prominent nasal symptoms. It is due to infection by rhinoviruses, the majority of which belong to the picornavirus group and exist in at least 100 different antigenic strains. Infectivity from close personal contact (nasal mucus on hands) or droplets is high in the early stages of the infection, and spread is facilitated by overcrowding and poor ventilation. On average, individuals suffer two to three colds per year but the incidence lessens with age, presumably as a result of accumulating immunity to the causative virus strains. The incubation is from 12 hours to an upper limit of 5 days. The clinical features are tiredness, slight pyrexia, malaise and a sore nose and pharynx. Profuse, watery nasal discharge, eventually becoming thick and mucopurulent, persists for up to a week. Sneezing is present in the early stage. Secondary bacterial infection occurs only in a minority.
Sinusitis is an infection of the paranasal sinuses that often complicates upper respiratory tract infections, e.g. coryza and allergic rhinitis. Acute infections are usually caused by Streptococcus pneumoniae and Haemophilus influenzae. Symptoms include frontal headache and facial pain and tenderness, usually with nasal discharge, but are often difficult to differentiate from symptoms of the common cold.
Treatment is with antibiotics. Many strains of H. influenzae are now resistant to amoxycillin so co-amoxiclav or cefaclor are preferred. In addition nasal treatment with decongestants such as xylometazoline or antiinflammatory therapy with topical corticosteroids such as fluticasone propionate nasal spray should be given to reduce swelling of the mucosa and unblock the sinus openings. Rare complications include local and cerebral abscesses. Chronic sinusitis can be a cause of headaches, but often these headaches are due to tension.
Rhinitis is present if sneezing attacks, nasal discharge or blockage occur for more than an hour on most days for:
• A limited period of the year (seasonal rhinitis)
• Throughout the whole year (perennial rhinitis)
This is often called hay fever and is the most common of all allergic diseases. It is better described as seasonal allergic rhinitis. Worldwide prevalence rates vary from 2% to 10%. Prevalence is maximum in the second decade, when up to 20% of young people suffer symptoms in June and July.
Nasal irritation, sneezing and watery rhinorrhoea are the most troublesome symptoms but many also suffer from itching of the eyes and soft palate and occasionally even itching of the ears due to the common innervation of the pharyngeal mucosa and the ear. In addition, approximately 20% suffer from attacks of asthma. The common seasonal allergens are shown.
Patients with perennial rhinitis rarely have symptoms that affect the eyes or throat. Half have symptoms predominantly of sneezing and watery rhinorrhoea, whilst the other half complain mostly of nasal blockage. The patient may lose the sense of smell and taste. A swollen mucosa can obstruct drainage from the sinuses, causing sinusitis in half of the patients. Perennial rhinitis is most frequent in the second and third decade, decreasing with age, and can be divided into four main types.
PERENNIAL ALLERGIC RHINITIS. The major cause of this is an allergen called Der p l contained in the faecal particles of the house-dust mite Dermatophagoides pteronyssinus; these particles are approximately 20 /-Lm in diameter, not dissimilar in size to pollen grains. The house-dust mite itself is <0.5 mm in size, invisible to the naked eye, and is found in dust throughout the house, particularly in older, damp dwellings. They depend for nourishment upon desquamated human skin scales and are found in abundance (4000 mites per gram of surface dust) in human bedding. The next most common allergens come from domestic pets and are proteins derived from urine or saliva spread over the surface of the animal as well as skin protein. Allergy to urinary protein from small mammals is a major cause of morbidity amongst laboratory workers. Industrial dust, vapours and fumes are more likely to cause occupationally related perennial rhinitis than asthma.
The presence of perennial rhinitis makes the nose more reactive to non-specific stimuli such as cigarette smoke, washing powders, household detergents, strong perfumes and traffic fumes; these are not acting as allergens.
PERENNIAL NON-ALLERGIC RHINITIS WITH EOSINOPHILIA. No extrinsic allergic cause can be identified in these patients, either from the history or on skin testing but, as in patients with perennial allergic rhinitis, eosinophilic granulocytes are present in nasal secretions.
VASOMOTOR RHINITIS. These patients with perennial rhinitis have no demonstrable allergy or eosinophilia in nasal secretions. They may be suffering from non-specific nasal hyperreactivity due to an imbalance of the autonomic nervous system innervating the erectile tissue (sinusoids) in the nasal mucosa.
ASAL POLYPS. These are round, smooth, soft, semitranslucent, pale or yellow, glistening structures attachedto the sinus mucosa by a relatively narrow stalk or pedicle and occur in patients with both allergic and vasomotor rhinitis. They cause nasal obstruction, loss of smell and taste and mouth breathing, but rarely sneezing, since the mucosa of the polyp is largely denervated.