Introduction
Allergic diseases have been increasing in the last decades, particularly
in developing countries 1. This increase is likely a
consequence of environmental factors that heightens the risk of allergic
diseases in genetically susceptible individuals 2. To
date, allergy birth cohort studies are from western countries3,4 and modern Asian countries 5-8.
The generalizability of these results to the context of developing Asian
countries may not be relevant since the environment, feeding patterns
and lifestyles are largely different.
Positive family history of atopy is one of the important predisposing
factors of allergic diseases 9,10. Maternal atopy is
associated with allergic diseases than paternal influence11. The protective effects of breast feeding against
allergy remain a debating issue 12. Environmental
factors related to hygiene hypothesis theory, such as high socioeconomic
status, extended family, antibiotics exposure during infancy period,
farm environment and household furry pets, have been proposed to be
associated with allergic diseases 13. The rationale
behind this theory is that families with hygienic lifestyles are less
exposed to microorganisms. So the immature immune system of the young
infants might be driven towards allergic inflammation.
The atopic march refers to the progression of allergic diseases during
infancy and childhood 14. Classically, the atopic
march begins with atopic dermatitis (AD) or food allergy (FA) then
progresses to asthma or allergic rhinitis (AR) 14. The
co-occurrence between the diseases are also common15,16. These data support the existence of a shared
set of polymorphisms in allergic patients. However, previous literature
has shown that only one-third to half of the subjects with AD and FA
developed atopic march later in life 17. Besides, not
every subject with asthma and AR preceded with AD or FA17.
Using a population-based birth cohort manner, our study aimed to
describe the incidence, and natural course including of atopic march and
to identify factors associated with allergic diseases in Thai
population, which reflects developing Asian countries.