Norovirus is a highly contagious infectious disease, which is transmitted from person-to-person via fecal-oral, or ‘vomitus-oral’ routes, or indirectly via contaminated food or environment. Airborne transmission of norovirus was implicated in an epidemiological study during an outbreak in a hotel restaurant , but only until recently was detection of norovirus RNA demonstrated in air samples collected in patient’s room and at the nurse’s station during hospital outbreaks , presumably due to projectile vomiting of patients, flushing of toilet, or during floor cleaning as described previously.
Detection of norovirus in air samples in patient without vomiting: implication of saliva testing for norovirus in immunocompromised host
We determined the persistence and excretion of a green fluorescent protein (GFP) expressing strain of S. Typhimurium from house flies. Individual male and female flies were fed either sterile Luria-Bertani (LB) broth (controls) or cultures of “high” (~105colony forming units [CFU]) or “low” (~104 CFU) doses of bacteria (treatments). Bacterial persistence was determined over 16 h by culturing whole-fly homogenate. Both sex and dose affected persistence between 6 and 12 h post-ingestion.
In a separate experiment, fly excretion events were monitored during this time interval and excreta droplets were individually cultured for bacteria. Female flies had more excretion events than males across treatments. We observed interactions of fly sex and bacterial abundance (dose), both on the proportion of Salmonella-positive droplets and the CFU shed per droplet (CFU/droplet). In the low-dose treatment, males excreted a greater proportion of positive droplets than females. In the high-dose treatment, males excreted more CFU/droplet than females. High-dose male flies excreted more CFU/droplet than low-dose males, but low-dose females excreted more CFU/droplet than high-dose females. Irrespective of sex, low-dose flies excreted a greater dose-adjusted CFU (CFU droplet/CFU fed) than high-dose flies.
This study demonstrates that both bacterial abundance and fly sex may influence excretion of bacteria from flies, and should be considered when assessing the risk of house fly transmission of pathogens.
Effects of bacterial dose and fly sex on persistence and excretion of Salmonella enterica serovar Typhimurium from adult house flies
11 April 2018
Journal of Medial Entomology
Dana Nayduch Klara Zurek Jessica L Thomson Kathleen M Yeater