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Acute Respiratory Infections (ARI) are some of the most common human diseases worldwide. However, they have a complex and diverse etiology, and the characteristics of the pathogens involved in respiratory infections in developing countries are not well understood. In this work, we analyzed the characteristics of 17 common respiratory pathogens in children (≤14 years old) with ARI in Guangzhou, southern China over a 3-year period using real-time polymerase chain reaction. Pathogens were identified in 2361/4242 (55.7%) patients, and the positivity rate varied seasonally. Ten of the 17 pathogens investigated showed positivity rates of more than 5%. The most frequently detected pathogens were respiratory syncytial virus (768/2361, 32.5%), influenza A virus (428/2361, 18.1%), enterovirus (138/2361, 13.3%), Mycoplasma pneumoniae (267/2361, 11.3%) and adenovirus (213/2361, 9.0%). Co-pathogens were common and found in 503 of 2361 (21.3%) positive samples. When ranked according to frequency of occurrence, the pattern of co-pathogens was similar to that of the primary pathogens, with the exception of human bocavirus, human coronavirus and human metapneumovirus. Significant differences were found in age prevalence in 10 of the 17 pathogens (p≤0.009): four basic patterns were observed, A: detection rates increased with age, B: detection rates declined with age, C: the detection rate showed distinct peaks or D: numbers of patients were too low to detect a trend or showed no significant difference among age groups (p>0.05). These data will be useful for planning vaccine research and control strategies and for studies predicting pathogen prevalence. [ABSTRACT FROM AUTHOR]

Ambient formaldehyde, acetaldehyde, and acetone are harmful air pollutants with potential carcinogenic effects on human health. They are considered as important photochemical products from photo-oxidation of atmospheric hydrocarbons. However, little is known on the effet of photodegradation of air pollutants on δC values. Here, we report the first C isotope evidence for the photochemical production of ambient formaldehyde, acetaldehyde, and acetone. Air samples were collected each day during early morning, noon, early afternoon, and late afternoon on 17-19 September 2008 in Guangzhou by drawing air through 2,4-dinitrophenylhydrazine-coated cartridges. The samples were analyzed using high-performance liquid chromatography for concentration analysis and then using gas chromatography-combustion-isotope ratio mass spectrometry for δC analysis. Our results show that ambient formaldehyde, acetaldehyde, and acetone were enriched by 1-5 ‰ in C in the early afternoon relative to other sampling durations, and they also exhibited the highest concentrations in the early afternoon. Measured δC values of formaldehyde, acetaldehyde, and acetone were in the range from −37.15 to −29.01 ‰. The observed enrichment in C implied important photochemical production together with the highest concentrations in the early afternoon. Especially, measured δC range from −37.15 to −29.01 ‰ was in accordance with forecasted δC range from −43 to −28 ‰ based on the mass balance in C between the carbonyls and its major hydrocarbon precursors, providing important C isotope evidence for the photochemical production of ambient formaldehyde, acetaldehyde, and acetone. [ABSTRACT FROM AUTHOR]