This Month's Feature Review:

Vasomotor Rhinitis (VMR) or idiopathic non-allergic rhinitis

Vincent St Aubyn Crump

Rhinitis is defined as an inflammation of the nasal mucosa and it is characterised by nasal obstruction, runny nose (rhinorrhea), sneezing, and (itching) pruritus.

The causes of rhinitis can be broadly categorised into 3 headings:

1. Allergic Rhinitis

• Seasonal - Hay Fever
• Persistent (perennial) eg House dust mite-induced

1. Infectious Rhinitis (eg the common cold). Children, particularly young children in school or day care centres, may have from eight to 12 colds each year. Viral infections are self-limiting and usually last 7-10 days.
   
   
2. Non-allergic, Non-Infectious eg Vasomotor Rhinitis (or Irritant rhinitis). "Vaso" means blood vessels and "motor" refers to the nerves, which innervates nasal tissue and the blood vessels. This is sometimes referred to as idiopathic non-allergic rhinitis. It is estimated that up to 10% of the population suffers from non-allergic rhinitis.

Mixed Allergic and Non-allergic Rhinitis probably account for the majority of cases. This is an important category to recognise, as allergen avoidance measures only, will give sub-optimal improvements&

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New and Interesting Allergy Studies:

Farm residence and exposures and the risk of allergic diseases in New Zealand children.

Does heredity modify the association between farming and allergy in children?

Farm residence and exposures and the risk of allergic diseases in New Zealand children.

Wickens K, Lane JM, Fitzharris P, Siebers R, Riley G, Douwes J, Smith T, Crane J.

BACKGROUND: Studies in Europe have reported a reduced prevalence of allergy in farmers' children. We aimed to determine if there is a similar reduction in allergy among New Zealand farm children.

METHODS: Two hundred and ninety-three children participated (60%) aged 7-10 years, from selected schools in small towns and the surrounding rural area. Skin prick tests (SPT) to eight common allergens were performed. Parents completed questionnaires about allergic and infectious diseases, place of residence, exposure to animals, and diet, and they provided dust from the living-room floor. Endotoxin was measured using a Limulus amoebocyte lysate (LAL) assay and Der p 1 using enzyme-linked immunoassay (ELISA).

RESULTS: Current farm abode was found to increase the risk of having symptoms associated with allergy, but not SPT positivity. Independent inverse associations were found for early-life exposures: at least weekly consumption of yoghurt with hayfever (odds ratio (OR) = 0.3, 95% confidence intervals (CI) 0.1-0.7) and allergic rhinitis (OR = 0.3, 95% CI 0.2-0.7); any unpasteurized milk consumption with atopic eczema/dermatitis syndrome (AEDS) (OR = 0.2, 95% CI 0.1-0.8); cats inside or outside with hayfever (OR = 0.4, 95% CI 0.1-1.0) and AEDS (OR = 0.4, 95% CI 0.2-0.8); dogs inside or outside with asthma (OR = 0.4, 95% CI 0.2-0.8); and pigs with SPT positivity (OR = 0.2, 95% CI 0.1-0.9).

CONCLUSIONS: Despite finding a protective effect of early-life animal exposures, we found a greater prevalence of allergic disease on farms.

REFERENCE: Allergy 2002 Dec; 57(12): 1171-9

Does heredity modify the association between farming and allergy in children?

Reme ST, Pekkanen J, Soininen L, Kajosaari M, Husman T, Koivikko A.

Department of Paediatrics, Kuopio University Hospital, Kuopio, Finland. Sami.Remes@ktl.fi

AIM: It has been suggested that living on a farm decreases the risk of childhood allergy, especially if farming involves livestock. The aim of this study was to examine the association between farming and allergy in children, and the influence of atopic heredity in this association.

METHODS: The cross-sectional data of the 7981 children aged 13-14 y who participated in the Finnish ISAAC study between the years 1994 and 1995 were used to evaluate the association between farming and allergy.

RESULTS: Living on a farm was associated with a decreased risk of current symptoms of allergic rhinoconjunctivitis among all children (aOR 0.79; 95% CI 0.63, 0.99), and with a decreased risk of hay fever, especially among those children with a parental history of hayfever (aOR 0.60; 95% CI 0.40-0.89, p = 0.072 for interaction). The children of farmers with a history of hay fever also had a decreased risk of current wheeze (aOR 0.38; 95% CI 0.12-1.24, p = 0.040 for interaction). No significant association was found between farming and either asthma or eczema. Children living on a farm with livestock had the lowest risk of allergic rhinoconjunctivitis (aOR 0.69), followed by those living on a farm without livestock (aOR 0.89) compared with the non-farming children (p-value for trend 0.024).

CONCLUSION: Our results support the recent findings on a decreased risk of allergy among the children living on farms. A possible differential effect of parental history of hay fever on the relation of farming environment and the risk of allergic symptoms warrant further investigation.

REFERENCE: Acta Paediatr 2002; 91(11): 1163-9