Table 1. Key foodborne pathogens currently ranked in Canada to consider in the context climate change (6).

Pathogen	Symptoms (42)	Current cases per 100,000 people (6)	Influence of climate on occurrence (20,43)
Norovirus	Symptoms include nausea, vomiting, diarrhea, stomach cramps, low-grade fever, chills, headache, muscle aches and fatigue	3,223.79	Extreme weather events (such as heavy precipitation and flooding) and decreased air temperature
Clostridium perfringens	Symptoms include diarrhea, pain and cramps, stomach bloating, increased gas, nausea, weight loss, loss of appetite, muscle aches and fatigue. In rare cases, severe dehydration, hospitalization, death	544.50	Uncertain
Campylobacter spp.	Symptoms include fever, nausea, vomiting, stomach pain, and diarrhea. In rare cases, hospitalization and long-lasting health effects, death	447.23	Changes in the timing or length of seasons, increased air temperatures, precipitation and flooding
Salmonella spp., nontyphoidal	Symptoms include chills, fever, nausea, diarrhea, vomiting, stomach cramps, and headache. In rare cases, hospitalization and long-lasting health effects, death	269.26	Changes in the timing or length of seasons, extreme weather events, increased air temperatures
Bacillus cereus	Symptoms include diarrhea or vomiting. In rare cases, hospitalization and long-lasting health effects, death	111.60	Changes in the timing or length of seasons, drought
Verotoxigenic Escherichia coli non-O157	Symptoms include diarrhea. In rare cases, hospitalization and long-lasting health effects, death	63.15	Changes in the timing or length of seasons, extreme weather events, increased air temperatures
Verotoxigenic Escherichia coli O157	Symptoms include diarrhea. In rare cases, hospitalization and long-lasting health effects, death	39.47	Changes in the timing or length of seasons, extreme weather events, increased air temperatures
Toxoplasma gondii	Symptoms include minimal to mild illness with fever. In rare cases, inflammation of the brain and infection of other organs, birth defects	28.10	Extreme weather events, increased air temperatures, precipitation (44)
Vibrio parahaemolyticus	Symptoms include diarrhea, stomach cramps, nausea, vomiting, fever and headache. In rare cases, liver disease	5.53	Extreme weather events, increased air temperatures, increased sea surface temperature
Listeria monocytogenes	Symptoms include fever, nausea, cramps, diarrhea, vomiting, headache, constipation, muscle aches. In severe cases, stiff neck, confusion, headache, loss of balance, miscarriage, stillbirth, premature delivery, meningitis, death	0.55	Extreme weather events, increased air temperatures, precipitation
Vibrio vulnificus	Symptoms include diarrhea, stomach cramps, nausea, vomiting, fever, headache. In rare cases, liver disease	<0.01	Extreme weather events, increased air temperatures, increased sea surface temperature

Abbreviations: spp., species; <, inferior to

Note: Currently, the five most common foodborne pathogens are norovirus, Clostridium perfringens, Campylobacter spp., Salmonella spp. and Bacillus cereus