Paper Reviewed
Wen, L., Zhao, K., Cheng, J., Wang, X., Yang, H., Li, K. Xu, Z. and Su, H. 2016. The association between diurnal temperature range and childhood bacillary dysentery. International Journal of Biometeorology 60: 269-276.

Introducing their study, Wen et al. (2016) write that bacillary dysentery or BD is "a bacterial infection of the mucosal surface of the intestines caused by different species of Shigella bacteria." It often results in severe and bloody diarrhea, as well as fever, abdominal cramps and tenesmus with an incubation period of 1 or 2 days, the transmission of which usually occurs "via polluted drinking water and contaminated food or through person-to-person contact."

Noting that "little is known about whether the within-day variation of temperature has any impact on bacillary dysentery," the eight researchers studied "the relationship between diurnal temperature range (DTR) and BD in Hefei, China," focusing on "daily data on BD counts among children aged 0-14 years from 1 January 2006 to 31 December 2012," which they obtained from the Hefei Center for Disease Control and Prevention," while daily data on temperature covering the same period were collected from the Hefei Bureau of Meteorology. And what did they thereby learn?

Wen et al. report that (1) "the DTR effect on childhood bacillary dysentery increased when DTR was over 8°C," that (2) "male children and children aged 0-5 years appeared to be more vulnerable to the DTR effect," and that (3) "the data indicate that large DTR may increase the incidence of childhood BD."

In this regard, we note that in a study of DTR that was conducted for the entirety of China based on data collected from 479 weather stations for the period 1962 to 2011, Shen et al. (2014) found that the country-wide DTR declined at a mean rate of 0.157°C/decade, which phenomenon they attributed to the fact that, in most parts of the world, daily minimum temperatures increased at a faster rate than daily maximum temperatures since the 1950s, citing the similar findings of Karl et al. (1993), Horton (1995), Easterling et al. (1997) and Zhou et al. (2009), while additionally noting that "DTR decreased significantly in China over the past several decades," citing Karl et al. (1991, 1993), Kukla and Karl (1993), Dai et al. (1997, 1999), Liu et al. (2004), Ye et al. (2010), Zhou and Ren (2011), Wang and Dickinson (2013), Xia (2013) and Wang et al. (2014).

In light of this host of DTR findings, it would appear that the global warming of the past century or so has likely helped to significantly reduce the occurrence of childhood BD, not only in Hefei, China, but everywhere that BD typically occurs.

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