الفهرس 
AsthmaOnly 14 pages are availabe for public view
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Abstract
SUMMARY
The current medical consensus definition of asthma is a chronic inflammatory disorder of the airways with an associated increase in airway responsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness and coughing particularly at night or in the early morning, that is often reversible either spontaneously or with treatment (Global Initiative for Asthma, 2006).
Environmental exposure to microorganisms has repeatedly been found to be inversely related to the manifestations of a topic diseases such as asthma and hay fever. This observation has been made in various contexts, including the studies conducted in the Republic of Karelia (Russia) and North Karelia (Finland), in which two populations in geographically adjacent areas live under different environmental conditions. In the present study, the prevalence of asthma and atopy were assessed to investigate rural-associated microbial exposure in school children living in predominantly rural area in Kaliopia Governorate, (Kaliope area and among other children living in the same governorate in an urban area, (Shoubra El Khema), when the diversity of microbial exposure was measured in both groups and related the diversity of exposure to asthma and atopy.
The present study was designed to determine the prevalence of childhood asthma and atopy in rural versus urban environments and to compare dust microbiological contamination and Endotoxin levels in rural and urban areas.
Skin testing was done using Bencard prick test (UK), to detect allergenicity to various area allergens. Atopy was defined by the presence of positive wheal > 2mm in diameter larger than the negative control. Dust analysis: Airborne dust samples from bedrooms and other rooms in the house were collected with the use of air sampler pump with electrostatic dust collectors, (Nomand et al., 2009).
These collectors are plastic sample holders equipped with an electrostatic cloth, with the potential to capture dust from the air. The collectors were placed in children’s bed rooms and other rooms in the house by field worker and left for 24 hours.
The cloths were washed with polysorbete 80, and dilutions of the washing solution were plated on five different growth media and after incubation for 48 hours, the colonies were counted.
The endotoxin activity of dust samples was determined by the limulus Amoebocyte lysate (LAL) gel clot method, (Noss et al, 2008).
Air pollutants were obtained by Miran IB2 instrument which was sited to measure urban and rural SOR2R and NOR2R. Ozone (OR3R) concentrations were measured by ultraviolet absorbance technique. Particulate matter, (PM 10), concentrations were measured using black smoke method which measure only particles of < 10 Mm in diameters (Schwartz et al, 1996).
Air pollutant levels were compared to Egyptian Air Quality Standards (Government of Egypt Law Nr. G., 2009).
Statistical analysis was performed using SPSS version 10 software. Variations in air pollutants and microorganisms in different
areas were evaluated by one-way ANOVA comparisons were also performed using t-test and chi squares.
It was shown that children living in rural area, (Kaliope) had a lower prevalence of asthma, (8%), compared to those living in urban area, (Shoubra El Khema), (11%), P < 0.05.
Differences were also greater for the prevalence of atopy among childhood asthmatics living in rural versus urban areas when it was found that aeroallergen sensitization to house dust mite (HDM) was lower in Kaliope area, (6.26%) compared to those in Shoubra El Khema, (16.36%), P < 0.01, (table 4).
Also, sensitization to fungi was lower in childhood asthmatics in Kaliope, (14.58%), compared to Shoubra El Khema, (23.64%), P < 0.05).
When the severity of asthma was compared in asthmatics living in rural and urban areas, it was shown that severe asthma was more prevalent in Shoubra El Khema, (18%) compared to those in Kaliope, (10.4%), (P< 0.05).
Air pollutant levels measured during the study period are shown in table 5. concentrations of SOR2R in both Shoubra El Khema and Kaliope areas were generally below the ambient air quality guideline in Egypt, 46.3 μg/mP3P and 38.8 u.g/m3 respectively. Also NOR2R levels in both areas were below Egyptian guidelines, 70.8μg/mP3P and 58.1 μg/mP3P respectively.
High levels of PM10 were recorded in both Shoubra El Khema and Kaliope areas, (140 μg/mP3P and 120 μg/mP3P) respectively which exceeded Egyptian air quality standards.
Although levels of OR3R were significantly higher in Shoubra El Khema compared to Kaliope, (118 μg/mP3P versus 79 μg/mP3P respectively,
(P < 0.001), the levels were within the accepted levels, (120 μg/mP3P). Levels of SOR2 Rand NOR2R were significantly higher in Shoubra El Khema compared to Kaliope, (P < 0.05), although there was insignificant difference between levels of PM10 in both areas, (P = 0.36).
The findings indicate that indoor microbial exposure is much more common in rural versus urban environment. As shown in table 6, total bacterial contamination of dust samples from Kaliope, (5.15 CFU/m3) was significantly higher than total bacterial count in Shoubra El Khema, (2.3 CFU/mP3P), P < 0.05.
Also mean concentrations of gram negative (G-ve) bacteria in dust samples were significantly higher in Kaliope, (3.51 CFU/mP3P) compared to Shoubra El Khema, (1.89 CFU/mP3P), P<0.5, (table 6).
Although mean concentrations of moulds were higher in Kaliope, (1.97 CFU/mP3P) compared to Shoubra El Khema, (1.88 CFU/mP3P), the levels were insignificant.
Out of 12 dust samples taken from each area, endotoxin levels above 100 endotoxin unit (EU) were found in 11 (91.7%) sample from calliope area, which was significantly higher compared to Shoubra El Khema where only one sample (8.3%) was above 100 EU, (P < 0.000), (Table 7).
Moreover, air pollutant levels were decreased in rural environment especially PM10 which may be an additional factor for the low prevalence of asthma and atopy in rural areas compared to urban areas with high levels of air pollutant levels.
These findings are consistent with other studies which suggest that poor air quality is associated with increased mortality from asthma.
The author reported that fluctuations in air pollutant levels especially particulate air pollution was associated with acute severe exacerbations of asthma