Hepatitis B and the Incidence of Astham
Other Title
B型肝炎和氣喘發生率的相關
Date Issued
2004
Date
2004
Author(s)
DOI
zh-TW
Abstract
Asthma is the most common chronic disease in childhood and accounts for substantial morbidity and health care costs. During the last thirty years, an increase in the prevalence of asthma as been documented in many countries. As the human genotype would not have changed drastically over a relatively short time period, these phenomena are not easily ascribed to genetic changes in populations. Hence, environmental factors has become the focus of medical research. For a long time, allergen exposure early in life was considered to be a major risk factor for the development of asthma and other allergic diseases. No intervention studies, however, showed that reduced exposure to allergens has a significant impact on the development of asthma and allergic disease.
Because of the consistent observations of an inverse association between family size and risk of atopy, allergic rhinitis, and eczema., the so-called “hygiene hypothesis” was proposed, suggesting changes in the type and degree of stimulation from the microbial environment associated with improvements in public health and hygiene may increase the predisposition to chronic allergic conditions during childhood. This hypothesis is explained by shifts in the pattern of infectious diseases in early life, affecting the maturation of the immune system. Thus, at birth the immune system is skewed towards a Th2 cytokine profile which is characteristic of allergic individuals, but during infancy and early childhood this profile is normally shifted towards a non-allergic Th1 profile, perhaps through exposure to infections and other environmental stimuli. Some epidemiological studies support the hypothesis by showing that exposure to measles, rubella, varicella, mumps, and environmental endotoxin in childhood may protect against the development of allergy, while for mycobacteria, measles and respiratory viruses, there are studies that demonstrate an enhancement rather than prevention of allergic disease. The available epidemiological evidence in supportive of hygiene hypothesis is thus controversial.
Recently, it is increasingly apparent that asthma phenotype could probably programmed before birth. The interactions between mother, placenta and fetus in influencing the development of fetal and infant immune responses to allergens during gestation have emerged as a focus of intense research. Despite the laboratory work, few clinical studies on the effect of maternal infection on the development of childhood atopy have been inconsistent. Positive association between maternal use of antibiotics during pregnancy and childhood asthma and negative association between probiotics use during pregnancy advocate the hygiene hypothesis, while inverse relation between maternal vaginitis and febrile infection episodes during pregnancy defied the hypothesis.
In this study, we retrospectively investigated the relationship between maternal and personal chronic hepatitis B virus (HBV) infection and its subsequent influence on the development of asthma of the child, because HBV is the most prevalent chronic maternal and neonatal infection in Taiwan before the implementation of universal neonatal HBV vaccination program. An estimated 15 to 20% of child-bearing age women are affected and approximately 40% to 50% of their children were infected perinatally. Besides, we hypothesized that chronic infection rather than episodic infection might play more roles in the maturation of the immune system. The carriage status between mother and child was also analyzed to see if there is any synergistic role on the development of asthma in later life.
The study population consisted of randomly selected 2931 1980~1982 birth cohort in northern Taiwan, who participated in the national survey of asthma prevalence in 1995~1996. Asthma was defined by using International Study of Asthma and Allergies in Childhood (ISSAC) self-reported and video questionnaires and physician diagnosis. Detailed information on history of wheezing episodes, early age rural life and nursing status, pet-keeping, sibship size, and family history of allergy were acquired with standardized questionnaires. Maternal and personal Hepatitis B virus carrier status was obtained from self-reported questionnaires or telephone interview records and secondarily confirmed by reported hospital health records.
An individual with a mother of HBV carrier was associated with a decreased cumulative incidence of asthma in the 20th ~21st year than with a mother of non-HBV carrier (OR 0.71, 95% CI 0.51 to 0.98). There was no association between asthma and personal HBV carrier status in the first 20th ~21st years of life, regardless of maternal carrier status. When maternal HBV carrier status was controlled, postnatally acquired HBV carrier was associated with an increased cumulative incidence of asthma at the age of 20 to 21 (OR 1.48, 95% CI 1.01 to 2.16).
Our results showed that maternal carriage of HBV served as protective factors against the development of childhood asthma, and post-natally acquired HBV infection was positively associated with the incidence of asthma. The results may lend support to the view that that immune deviation as a critical factor against atopic disease may start before birth. Post-natally chronic HBV carrier state may reflect the Th2 nature of immunity and the propensity of asthma development. Further studies are required to clarify the underlying immunological mechanism. Studies on relationship between other maternal chronic infections on the risk of childhood atopy are also required.
Subjects
氣喘
TH1/TH2反應
清潔理論
B型肝炎
TH1/TH2 response
Hepatitis B
Asthma
Hygiene hypothesis
SDGs
Type
text