Smallpox was not notably infectious in the prodromal period and viral shedding was usually delayed until the appearance of the rash, which was often accompanied by lesions in the mouth and pharynx. The virus can be transmitted throughout the course of the illness, but this happened most frequently during the first week of the rash when most of the skin lesions were intact. Infectivity waned in 7 to 10 days when scabs formed over the lesions, but the infected person was contagious until the last smallpox scab fell off.Smallpox was highly contagious, but generally spread more slowly and less widely than some other viral diseases, perhaps because transmission required close contact and occurred after the onset of the rash. The overall rate of infection was also affected by the short duration of the infectious stage. In temperate areas, the number of smallpox infections was highest during the winter and spring. In tropical areas, seasonal variation was less evident and the disease was present throughout the year. Age distribution of smallpox infections depended on acquired immunity. Vaccination immunity declined over time and was probably lost within thirty years. Smallpox was not known to be transmitted by insects or animals and there was no asymptomatic carrier state. Mechanism
Once inhaled, the variola virus invaded the mucus membranes of the mouth, throat, and respiratory tract. From there, it migrated to regional lymph nodes and began to multiply.
Nasal obstruction – bilateral nasal stuffiness alternates from one site to other; this is more marked at night, when the dependent side of nose is often blocked. Postnasal drip. Complications
Nonallergic rhinitis cases may subsequently develop polyps, turbinate hypertrophy and sinusitis. Pathophysiology
Nasal mucosa has a rich blood supply and has venous sinusoids or "lakes" surrounded by smooth muscle fibers. These smooth muscle fibers act as sphincters and control the filling and emptying of sinusoids. Sympathetic stimulation causes vasoconstriction and shrinkage of mucosa, which leads to decongestion of the nose. Parasympathetic stimulation causes not only excessive secretion from the nasal gland but also vasodilatation and engorgement, which lead to rhinorrhoea and congestion of the nose. The autonomic nervous system, which supplies the nasal mucosa, is under the control of the hypothalamus. Diagnosis
Nose examination: The mucosa is usually boggy and edematous with clear mucoid secretions. The turbinates are congested and hypertrophic.Pharynx examination: Mucosal injection and lymphoid hyperplasia involving tonsils, adenoids and base of tongue may be seen. Investigations
Absolute eosinophil count, nasal smear, skin and in vitro allergy tests to rule out allergic rhinitis, acoustic rhinometry for measuring nasal patency, smell testing, CT scan in cases of sinus disease and MRI in case of mass lesions. Classification
Treatment
Medical
The avoidance of inciting factors such as sudden changes in temperature, humidity, or blasts of air or dust is helpful. Intranasal application of antihistamines, corticosteroids, or anticholinergics may also be used for vasomotor rhinitis. Intranasal cromolyn sodium may be used in patients older than two years.