Day 8: Salmonella

Consuming water contaminated with Salmonella can cause diarrhea, nausea, fever, and, in severe cases, typhoid fever.  Although commonly mistaken for a specific species of bacteria, Salmonella is actually the name of a genus that encompasses 2 distinct species of bacteria Salmonella enterica (or Salmonella choleraesuis), Salmonella bongori and Salmonella typhi.  They typically enter water systems through faecal contamination from sewage discharges, runoff from livestock and wild animals, and they can have devastating public health implications.  Because salmonella contamination is generally accompanied by contamination from other bacteria associated with faecal contamination, they are usually monitored via testing for E. Coli or other Coliform Bacteria, which provide a baseline index for detection.  Salmonella can survive for weeks without a host and are not destroyed by freezing – they are however sensitive to UV light and heat, which is why boiling is recommended for protection.


Salmonella was discovered in 1885 through a USDA research program that was searching for the cause of hog cholera, and identified the genus as a possible cause.  Although Salmonella was not the actual cause they were looking for, later research identified that different bacteria within the genus were the root cause of several infectious diseases in both animals and humans.  Where classification of Salmonella eventually led to the identification of over 2000 different species, it was eventually concluded that these classifications focused on distinctions at the sub-species level, and that there are in fact only 3 species.  

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