Allergic rhinitis is an inflammation of the nasal membranes mediated by an allergic reaction. This is a very common condition, affecting about 20% of the population. The condition is characterized by inflammation of the mucous membranes of the nose, eyes, Eustachian tubes, middle ears, sinuses, and pharynx. The hypersensitive immune reaction is triggered by an IgE response to an environmental allergen. The IgE response enables the release of various immune system mediators, including histamine, tryptase, chymase, kinins, heparins, leukotrienes, and prostaglandins that are responsible for the characteristic clinical features of the condition. Major signs and symptoms include repetitive sneezing, runny nose, nasal congestion, nasal itching, post-nasal drip, itchy eyes, ears, nose or throat, sore throat, generalized fatigue, and impaired smell. The most common form of allergic rhinitis is hay fever, caused by an allergic reaction to pollen. Some forms of the condition are seasonal, and occur only during those times of the year when the corresponding allergen is present. For instance, tree, grass and ragweed pollen allergies are more common during hot, dry, and windy days. Similarly, mold spores are higher in early spring, late summer, and early fall. Other allergens like dust mites, cockroaches, and animal dander can be found all-year round.
A study of the clinical features is the first step towards diagnosing this condition. Confirmation of the diagnosis involves a skin test (scratch, patch, or other tests) with the allergen. The best form of treatment is to avoid the allergen. Drugs that are commonly used to treat an allergic attack include short and longer-acting anti-histamines, nasal corticosteroid sprays, and decongestants. In cases where it is impossible to avoid the allergen, allergy shots may be recommended, which slowly de-sensitize the body against the allergen. In children, the immune system may by itself become less sensitive to the allergen as time passes.
Paulose (1991) studied 43 patients diagnosed with chronic rhinitis and underwent turbinectomy. Of these patients, 11 (25.5%) were previously diagnosed with allergic rhinitis. Pre-operative findings included enlarged, pale turbinates with watery or mucoid nasal discharge. Since some of the patients in the study underwent surgical procedures, like septoplasty and nasal polypectomy in addition to the turbinectomy, it was not possible to truly assess the benefit of the procedure. The tissue resected by turbinectomy was examined histopathologically. Only nine of the cases (22%) showed polypoidal changes with eosinophilic infiltration in the submucosa, indicating a low incidence of allergic rhinitis in the series. In one of the patients, foreign body granuloma could be seen around disrupted seromucinous glands. Most of the turbinates showed mild to moderate mononuclear cell infiltrates. Polypoidal turbinates, however showed severe mononuclear cell infiltration.
[Paulose KO. Chronic rhinitis: pathology on focus. J Bahrain Med Soc. 1991; 3(3):151-6.]
As part of the ISSAC (international study of asthma and allergies in childhood) Phase I, Al-Riyami et al. (2003) conducted a nationwide study to determine the prevalence of allergic rhinitis in Oman. Data was collected from all pupils (divided into 6-7 age group and 13-14 age group) of a randomly selected class of a randomly selected school by filling up an Arabic version of the ISSAC questionnaire. Approximately 3000 children in each of the groups were interviewed, 99% of which were Omanis. The chi square test was used to compare between the two groups and the prevalence rates were calculated by dividing the number of positive responses to each question by the number of completed questionnaires. About 95.4% of the 6-7 years age group (3893 children), and 89.5% (3174 children) of the 13-14 years age group completed the questionnaire. Allergic rhinitis and eczema were found to be associated with significant sleep disturbance and limitation of activity in both age groups. On the other hand, the older age group had the higher cumulative prevalence rate of allergic rhinitis (10.5%) than that of the younger age group (7.4%). The 12-month prevalence rates of rhinitis symptoms, rhinitis with itchy eyes, and activity limited was also higher in the older group (23.8%, 13.4%, and 22.2%, respectively) when compared to the 6-7 years old group (15%, 7.2%, and 13.3%, respectively). In view of the high prevalence rates of reported symptoms and diagnosis of allergic rhinitis which was associated with high morbidity as indicated by limitation of activity, Al-Riyami et al. (2003) concluded that more studies needed to be done to determine the possible causes of under-diagnosis and under-management of this condition for better control.
Janahi et al. (2006) undertook the first ever study to determine the prevalence of allergic diseases among schoolchildren in Qatar. A total of 3,500 Qatari schoolchildren, aged between 6 and 14 years, were selected from both rural and urban areas, based on a stratified, random sampling technique. Parents of all selected subjects were asked to fill questionnaires based on ISAAC intending to diagnose asthma or allergic rhinitis in their child. The response rate was 93.8%, with 3,283 of the subjects returning properly filled questionnaires. Males constituted 52.3% of the study group. A high prevalence of allergic rhinitis (1,001 subjects; 30.5%) was diagnosed in the study population. This prevalence was higher than earlier reports from Saudi Arabia and the United Arab Emirates. Interestingly, the prevalence was found to decrease with increasing age. Males were found to be more susceptible to allergic rhinitis, especially among the youngest age group (6-8 years). Allergic rhinitis was found to be closely associated with other allergic conditions, with 56.3% of the affected subjects also having either asthma and/or eczema.
AlSaeed (2007) studied the spectrum of allergens causing allergic rhinitis in 42 adult patients (28 males, 14 females). Sera from the patients were assayed for IgE antibodies to 20 different allergens, including eight different pollen/aeroallergens, animal dander from six different species of animals, house dust mites, and four different species of moulds, using an allergen immunoblot assay kit. Positive sensitization was seen in 69% of the patients. Pollen/aeroallergens were found to be the group with the most frequent sensitization to (66.9%). Of these, the most prominent allergens were grasses (11%), and rye (10.2%). AlSaeed (2007) attributed this to the common utilization of plants in urban areas for greening purposes. A total of 22.8% of the patients were found to be sensitive to animal dander, of which cat (9.4%) and dog (7.9%) were the most common. In addition, 8.6% of the patients were sensitive to house dust mites, while only 0.8% were sensitive to moulds. Although the maximum number of patients showed sensitization to only one of the allergens (24.2%), combined sensitizations were also shown by patient subsets, and the largest subset of such combined sensitizations comprised of patients sensitive to both dander and pollen. [Al-Saeed A. Sensitization to allergens among patients with allergic rhinitis in warm dry climates. Bahrain Med Bull.2007; 29(1)]
Nayar et al. (2004) conducted a study to determine the prevalent patterns of allergens in 239 Omani patients (142 males and 97 females, with the majority in the third and fourth decades of life) with perennial and seasonal allergic rhinitis (1997-1999) by using skin prick test with 31 allergens. The patients were asked to stop any allergic oral medications for 72 hours and any topical medications for 24 hours before the test. Histamine was used as a positive control and saline was the negative control. The most common allergens with positive response were found to be house dust mites, cat fur, hay dust and mixed threshings, while the least commonly encountered allergens were cod and sardine. A total of 31 patients had no positive response to any of the allergens, while out of the remaining 208 patients who responded positively to either one or more allergens, 25 responded to more than 10 allergens (majority were in the 4th decade of life). [Nayar P, Al Amri MK, Al Khabori MJ. Skin testing in allergic rhinitis: experience in Oman. Oman Med J. 2004; 19(2):54-7.]