Shigella: Explaining the Latest CDC Health Advisory and Disinfection with UVC LEDs
Per the CDC’ Health Advisory in late February 2023, extensively drug-resistant (XDR) Shigella infections (shigellosis) are rising in the United States (CDC, 2023). Shigella is already a significant public health concern in Europe and Asia (WHO, 2022, Muzembo et al., 2023). Only a tiny amount of this organism in water or on surfaces (10-100 organisms) is required to cause disease once ingested (Benjamin, Griggs, & Fitz, 2015). Drug resistance makes treatment options limited once ill (Lefèvre et al., 2023). The symptoms due to the acute enteric infection from Shigella cause inflammatory diarrhea (can be bloody!), abdominal cramping, fever, and tenesmus (change in bowel habits where one feels like they need to pass stool, although their bowels are already empty).
The two Shigella strains responsible for most outbreaks are Shigella dysenteriae and Shigella sonnei. The most common species in the USA is Shigella sonnei. With a peak-effect wavelength of 265 nm (Lindblad, Tano, Lindahl, & Huss, 2020), the highest disinfection level observed utilized UVC, requiring only between 3 and 8 mJ/cm2 to obtain 4 Log Reduction Value (LRV) against Shigella dysenteriae and Shigella sonnei respectively. The Klaran WR water reactor using LEDs between 260 nm and 270 nm provides a dosage of 10 mJ/cm2 against Shigella dysenteriae and Shigella sonnei at 2 L/min of water flow rate. Modules using Klaran UVC LEDs between 260 nm and 270 nm could also provide over 10 mJ/cm2 against Shigella dysenteriae and Shigella sonnei on surface in the matter of seconds.
Source: (CDC, 2023)