Salmonella, oh the places you'll go

Salmonella find unusual niches

Backyard Chickens can carry Salmonella. "Hen chicken" by Thegreenj

In medicine it is often said "To know Syphilis is to know medicine", then it must be that "To know Salmonella is to know society". 

Each year salmonella infects approximately 1.2 million in the US. It causes 23,000 hospitalizations and 450 deaths in the US. The disease usually involves diarrhea, abdominal cramps and fever, but can result in more serious disease with bacteria in the blood. Salmonella infections are caused by ingesting salmonella - either in food or by touching something with salmonella and putting one's hands to one's mouth.

Serious cases may require hospitalization and long antibiotic courses.

These different outbreaks throw light on how what we eat and how we interact with animals affect our health. Most outbreaks are associated with different animals - the animals people eat, those they keep as pets, and those that can contaminate nuts and vegetables.  Animals can contaminate plants we eat when crops are irrigated with water from near livestock waste run-off. Birds flying or roosting can contaminate food processing centers. This should remind us to be careful when handling animals. We should be careful to wash afterwards. We should be careful when preparing meat. We should listen for safety warnings on outbreaks in food.

The sleuths of the CDC, Public Health and Food Safety Bureaus track down the many epidemics caused by different strains (there are over 2000). Severity of disease and source may correlate with particular strains.

They show up in some surprising places:

New types of Pets

Bearded Dragons

Bearded dragons have grown in popularity as pet reptiles in the US. These reptiles are sociable with humans. They are more readily handled than many other reptiles. People will often touch their pet bearded dragons. This is what led to an outbreak in 2014.

There were 166 infections in 34 states from Salmonella Cotham and Salmonella Kisarawe. The reptiles are themselves healthy when they carry the bacteria. The reptile will not appear sick when carrying the bacteria. This is often true with infections animals carry that can harm us Owners of reptiles should remember to wash their hands with soap and water after touching their pets or their bedding and cages.

More pets

Salmonella can be spread by dogs and cats. In fact, one recent epidemic was spread by dry dog food. Very young children were at most risk. Homes where pet food was in the kitchen faced higher risks.

Recent epidemics of Salmonella Typhimurium, however, have been caused by more exotic pets. These pets include  hedgehogs and African dwarf frogs as well as  frozen rodents for reptile pets.

Backyard chickens

More Americans now have chickens in their backyards - a new source of Salmonella. In 2014 and 2015, there were multistate salmonella outbreaks. (There were lots of different strains involved from Salmonella Indiana to Salmonella Infantis, Salmonella Newport, Salmonella Hadar, and Salmonella Enteritidis).

In 2014, this outbreak caused 300 infections in 42 states. In 2015, there were 4 separate outbreaks. These were traced to backyard chickens, largely from a specific mail-order hatchery. The same mail order chickens were linked to outbreaks in 2012 and 2013. Other outbreaks were connected to other live poultry sent to backyard flocks

Poultry can be healthy but have Salmonella in droppings and on feathers. Healthy-appearing chickens then can spread infection.This should be a reminder to wash hands after touching chickens and make sure children wash their hands. We should avoid having young children (under 5) and immunocompromised adults and kids touch chickens. We should make sure to stop chickens entering kitchens or eating places. We also need to avoid kissing chickens - which is sometimes a cause of illness. We should also clean chicken equipment well.

Newly popular foods

Chia powder, non-dairy cashew cheese, and nut butters have led recently to salmonella outbreaks. Salmonella Stanley spread through non-dairy cheese from nuts, which are often stored longer than dairy cheeses. Almonds require substantial irrigation (which might be contaminated by livestock waste) and are an increasingly popular product (almond milk use has surpassed soy milk). Almond and peanut butter disseminated Salmonella Braenderup in 2014.  Chia powder, also increasingly popular, led to an outbreak of Salmonella Newport, Salmonella Hartford, and Salmonella Oranienburg in 2014.

Chicken Farming

Salmonella is standardly associated with chickens and eggs. It can be spread by chicken farming, rather than simply backyard chickens, and has been associated with multistate outbreaks in 2014, 2013, 2011, 2010. Multidrug resistance was seen in a 2013 outbreak though the antibiotics affected were not first line choices. Resistance in bacteria from livestock can be related to antibiotic use, which may be used as livestock growth promoters.


As our food and our interactions with animals change, our infections change as well. Salmonella will always sneak, it seems, into animals and our food.

It is always important to wash hands, surfaces, and utensils when using raw meat. Fruits and vegetables should be washed. Pets and their food should be kept away from food and its preparation. Hands should be washed after handling birds, reptiles, and other pets.

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