Background: The transmission mode of severe acute respiratory syndrome coronavirus 2 is primarily known as droplet transmission. However, a recent argument has emerged about the possibility of airborne transmission. On June 17, there was a coronavirus disease 2019 (COVID-19) outbreak in Korea associated with long distance droplet transmission. Methods: The epidemiological investigation was implemented based on personal interviews and data collection on closed-circuit television images, and cell phone location data. The epidemic investigation support system developed by the Korea Disease Control and Prevention Agency was used for contact tracing. At the restaurant considered the site of exposure, air flow direction and velocity, distances between cases, and movement of visitors were investigated. Results: A total of 3 cases were identified in this outbreak, and maximum air flow velocity of 1.2 m/s was measured between the infector and infectee in a restaurant equipped with ceiling-type air conditioners. The index case was infected at a 6.5 m away from the infector and 5 minutes exposure without any direct or indirect contact. Conclusion: Droplet transmission can occur at a distance greater than 2 m if there is direct air flow from an infected person. Therefore, updated guidelines involving prevention, contact tracing, and quarantine for COVID-19 are required for control of this highly contagious disease.

No abstract

This study observed the effect of different LED light colour on the behaviour and fear responses of broilers. In experiment 1, 400 broilers were placed into eight different light treatments. In experiment 2, six different light colours with five different age groups were considered. In experiment 1, use of a red and red-yellow mixed light significantly increased walking behaviour. Consequently, sitting and standing behaviour were found to be wavelength dependent, whereby short wavelength (blue, green-blue) treated birds spent more time sitting and standing than that under long wavelength (red, red-yellow). Consistently in experiment 2, birds spent more time feeding under the green treatment than with other treatments. Walking behaviour was significantly decreased and sitting and standing behaviour was increased under the blue light. Age also influenced the behaviour of broiler: young birds were more active than older birds. In addition, ground pecking and wing stretching behaviour were influenced by the wavelength of the light. Time of day did not influence the behaviour of the broilers. Under the red and red-yellow light treatments, birds spent longer in tonic immobility. Thus, the results suggest that red and red-yellow light activated the broiler's movement and fear responses while blue and greenblue decreased the movement and they spent more time sitting.

We evaluated the effect of monochromatic and combined light emitting diode (LED) light colour on performance, ovarian morphology, and reproductive hormone and biochemical blood parameters in laying hens. A total of 600 Hy-line Brown pullets, 12 weeks of age, were divided (25×4×6 = birds × replications × treatments) as follows: red (R), green (G), blue (B), and combinations of R→G and R→G→B treatments. Fluorescent white light (W) was the control. The results showed that higher egg production was found under the monochromatic R and combination R→G treatments, and that heavier eggs were laid by the B and G treatments (P<0.05). Consequently, better feed conversion ratio was attained in the R→G treatment. Serum follicle stimulating hormone and 17 -estradiol levels were significantly higher in the R and R→G treatments. B treated birds came into production 15 days later than those treated with R light. Organ weight (ovary and stroma) and ovarian follicle numbers (1-3 and 4-6 mm) were significantly higher in R treated birds, as well as serum glucose and triglyceride contents. Serum IgG concentrations and the heterophil to lymphocyte ratio were not influenced by light colour. In these laying hens, 14 h R with 2 h G light in the later part of the day increased reproductive hormone levels, ovarian weight, and follicle number and hence increased egg production. Thus, these results suggest that a combination of R→G light may be comparable with monochromatic R light to enhance egg production in laying hens.

No abstract