Standardization of a UV LED Peak Wavelength, Emission Spectrum, and Irradiance Measurement and Comparison Protocol.

Standard protocols for the measurement of irradiance, peak wavelength, and emission spectra have not yet been established for UV LED devices. This lack of standardization creates an uneven field for comparison between products. A detailed protocol was developed and tested in 14 facilities spanning manufacturers of UV LEDs and devices and research institutions in seven different countries. This protocol includes equipment calibration specifications, methods for the measurement and comparison calculations of irradiance and emission spectra, methods for the determination of peak wavelength, quality control and quality assurance steps, and industry-wide tolerances to error for each type of measurement. Measurements of the same source by operators using different equipment resulted in 2-10× the error found when measurement equipment provided as part of the study was used by each participant. The data were used to identify outliers, determine prediction intervals, and define acceptable tolerances to error. With this protocol, manufacturers have a means to report their UV LED specifications with verifiable quality control and quality assurance steps. The protocol and data generated from this study will create more confidence in the industry and standardize the comparison of UV LEDs by consumers, researchers, designers, and regulators.

Cholera prevention training materials for community health workers, Haiti, 2010­2011.

Stopping the spread of the cholera epidemic in Haiti required engaging community health workers (CHWs) in prevention and treatment activities. The Centers for Disease Control and Prevention collaborated with the Haitian Ministry of Public Health and Population to develop CHW educational materials, train >1,100 CHWs, and evaluate training efforts.

Pulsed and continuous light UV LED: microbial inactivation, electrical, and time efficiency.

Ultraviolet light emitting diodes (UV LEDs) have increasing applications in the inactivation of microorganisms in water, air, food, and on surfaces. System designers currently have metrics for comparison of the microbial and energy efficiency of UV LEDs, but these have not included a time component. Without including the time efficiency of a UV LED, neither the fluence-basis nor the electrical-basis of comparison clarifies which UV LED wavelength and operating condition is optimal for a design space. This research explores microbial inactivation of UV LEDs at various wavelengths under continuous and pulsing operating conditions. Planktonic microorganisms of relevance to public water supplies and UV system design are included: E. coli and MS-2 for benchmarking against previous studies and P. aeruginosa which has not been studied in pulsed systems or for continuous and combined UV LED wavelengths. Pulsing UV LEDs at various duty rates (percent of cycle spent on) and frequencies (number of cycles per second) does not result in a statistically significant disinfection performance difference over the continuous light operation at that respective wavelength. UV LEDs emitting at peak wavelengths corresponding to the peak action spectrum of a microorganism are optimal on a fluence-basis, but these are typically less electrically efficient UV LEDs. System designers can compare the normalized microbial inactivation, electrical, and time efficiencies (ENETO) of various UV LEDs; ENETO ≥1 for a pulsing condition ensures equal or improved efficiency compared to the continuous light condition while expanding the lifetime of the UV LED and decreasing the size or cost of associated power supplies.

Comparison of ultraviolet light-emitting diodes and low-pressure mercury-arc lamps for disinfection of water.

Ultraviolet (UV) light-emitting diodes (LEDs) emitting at 260 nm were evaluated to determine the inactivation kinetics of bacteria, viruses, and spores compared to low-pressure (LP) UV irradiation. Test microbes were Escherichia coli B, a non-enveloped virus (MS-2), and a bacterial spore (Bacillus atrophaeus). For LP UV, 4-log10 reduction doses were: E. coli B, 6.5 mJ/cm(2); MS-2, 59.3 mJ/cm(2); and B. atrophaeus, 30.0 mJ/cm(2). For UV LEDs, the 4-log10 reduction doses were E. coli B, 6.2 mJ/cm(2); MS-2, 58 mJ/cm(2); and B. atrophaeus, 18.7 mJ/cm(2). Microbial inactivation kinetics of the two UV technologies were not significantly different for E. coli B and MS-2, but were different for B. atrophaeus spores. UV LEDs at 260 nm are at least as effective for inactivating microbes in water as conventional LP UV sources and should undergo further development in treatment systems to disinfect drinking water.

US outbreak of human Salmonella infections associated with aquatic frogs, 2008-2011.

OBJECTIVE: Although amphibians are known Salmonella carriers, no such outbreaks have been reported. We investigated a nationwide outbreak of human Salmonella Typhimurium infections occurring predominantly among children from 2008 to 2011. METHODS: We conducted a matched case-control study. Cases were defined as persons with Salmonella Typhimurium infection yielding an isolate indistinguishable from the outbreak strain. Controls were persons with recent infection with Salmonella strains other than the outbreak strain and matched to cases by age and geography. Environmental samples were obtained from patients' homes; traceback investigations were conducted. RESULTS: We identified 376 cases from 44 states from January 1, 2008, to December 31, 2011; 29% (56/193) of patients were hospitalized and none died. Median patient age was 5 years (range <1-86 years); 69% were children <10 years old (253/367). Among 114 patients interviewed, 69 (61%) reported frog exposure. Of patients who knew frog type, 79% (44/56) reported African dwarf frogs (ADF), a type of aquatic frog. Among 18 cases and 29 controls, illness was significantly associated with frog exposure (67% cases versus 3% controls, matched odds ratio 12.4, 95% confidence interval 1.9-infinity). Environmental samples from aquariums containing ADFs in 8 patients' homes, 2 ADF distributors, and a day care center yielded isolates indistinguishable from the outbreak strain. Traceback investigations of ADFs from patient purchases converged to a common ADF breeding facility. Environmental samples from the breeding facility yielded the outbreak strain. CONCLUSIONS: ADFs were the source of this nationwide pediatric predominant outbreak. Pediatricians should routinely inquire about pet ownership and advise families about illness risks associated with animals.