The Short-term Effects of Temperature on Infectious Diarrhea among Children under 5 Years Old in Jiangsu, China: A Time-series Study (2015-2019).

The association between meteorological factors and infectious diarrhea has been widely studied in many countries. However, investigation among children under 5 years old in Jiangsu, China remains quite limited. Data including infectious diarrhea cases among children under five years old and daily meteorological indexes in Jiangsu, China from 2015 to 2019 were collected. The lag-effects up to 21 days of daily maximum temperature (Tmax) on infectious diarrhea were explored using a quasi-Poisson regression with a distributed lag non-linear model (DLNM) approach. The cases number of infectious diarrhea was significantly associated with seasonal variation of meteorological factors, and the burden of disease mainly occurred among children aged 0-2 years old. Moreover, when the reference value was set at 16.7°C, Tmax had a significant lag-effect on cases of infectious diarrhea among children under 5 years old in Jiangsu Province, which was increased remarkably in cold weather with the highest risk at 8°C. The results of DLNM analysis implicated that the lag-effect of Tmax varied among the 13 cities in Jiangsu and had significant differences in 8 cities. The highest risk of Tmax was presented at 5 lag days in Huaian with a maximum RR of 1.18 (95% CI: 1.09, 1.29). Suzhou which had the highest number of diarrhea cases (15830 cases), had a maximum RR of 1.04 (95% CI:1.03, 1.05) on lag 15 days. Tmax is a considerable indicator to predict the epidemic of infectious diarrhea among 13 cities in Jiangsu, which reminds us that in cold seasons, more preventive strategies and measures should be done to prevent infectious diarrhea.

[Impact of different temperatures and ambient PM2.5 on the cytotoxicity and cytophagocytic function of alveolar macrophages of rat].

OBJECTIVE: To investigate the interactive effects of different temperatures and ambient PM2.5 on the rat alveolar macrophages. METHODS: The rat alveolar macrophages were collected. The cells were exposed in vitro to 18℃, 24℃, 30℃, 37℃ and 43℃ with PM2.5 at the concentrations of 100 µg/ml, 50 µg/ml, 25 µg/ml and 0 µg/ml respectively. The cells were cultured in the different cases for 8 hours, then cytotoxicity was assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide(MTT)reduction assay and phagocytosis function of macrophages was assessed by neutral red absorption test. RESULTS: The relative survival rate and the cytophagocytic function of alveolar macrophages of rats among the different concentration groups decreased significantly (P<0.05) compared with the blank control group. Both were dose-dependent. The 37℃ group had the highest level of relative survival rate and the cytophagocytic function compared with other different temperatures groups. Interactive effect of different temperatures and ambient PM2.5 was not observed. But the lower temperature and the higher PM2.5 concentration group had stronger toxicity to alveolar macrophages. CONCLUSIONS: The results suggested that different temperatures and ambient PM2.5 have cytotoxicity on alveolar macrophages,injuring the phagocytosis. The two factors had some interaction.