In my opinion: Tularemia and pet food

There are many problems within the pet food industry: Salmonella, pentobarbital, substandard ingredients, unsanitary production environments, to name a few.

Pet food blogger Susan Thixton would like you to believe that tularemia should be added to the list.

In her post titled The Deadly Pet Food Bacteria Cover-up dated September 6, 2019, Thixton alleges that the US Food and Drug Administration (FDA) and the US Centers for Disease Control and Prevention (CDC) are covering up a deadly outbreak of tularemia linked to a defunct Mars PetCare production facility in Joplin, Missouri.

According to Thixton, the most recent diagnosis was in August 2019.

The facility was closed down in 2013.

The article alleges that “multiple individuals have been diagnosed (confirmed through blood testing) with tularemia that either worked for, delivered to, or is a family member (of someone who worked for or delivered to) the closed Mars Petcare pet food plant located in Joplin, MO.” (emphasis hers)

According to Thixton, “the Centers for Disease Control (CDC) and the Kansas Health Department confirmed to multiple individuals they were exposed to the deadly bacteria at the pet food plant(emphasis hers)

She has published these allegations without providing any data or other substantiating information to support her claims.

Thixton claims that the exposure to Francisella tularensis, the bacterium that causes tularemia, was through “…exposure to rendered pet food ingredients”. She also states that  the microbe “…can survive for decades in soil and water.”

Let me shine the light of science on these allegations.

A few facts about tularemia and Francisella tularensis

  1. The incubation period (the time between exposure and onset of illness) for this disease is typically 3-5 days in most cases, although infections can take up to 14 days to develop.
  2. Francisella tularensis is endemic in the rabbit and small rodent population in parts of the United States and elsewhere around the world. The most common source of transmission is via bites from ticks and deer flies.
  3. Francisella tularensis also can be transmitted in food and water, by contact with infected sick or dead animals, and by exposure to aerosols (notably during grass cutting and haying operations)
  4. Francisella tularensis can survive for weeks (not decades) in water and soil.

How common is tularemia in the United States?

  • There were 198 diagnosed cases of tularemia in the United States in 2018. There have been 144 cases so far this year.
  • The incidence of tularemia in the US has been dropping since 1950 (the first year for which data are readily available), during which 927 cases were reported to CDC.
  • The five states with the highest incidence of tularemia (reported as cases per 100,000 population) during the period 2000-2017 are: South Dakota (1.49), Oklahoma (1.04), Arkansas (1.03), Kansas (1.00), and Montana (0.57).

Is tularemia likely to be transmitted by rendered pet ingredients?

  1. Francisella tularensis can be killed by heating to 50ºC (122ºF) for 15 minutes.
  2. Temperatures used in the rendering process typically reach 115-145ºC (245-290ºF) for 40-90 minutes.


  1. Francisella tularensis does not survive rendering.
  2. Francisella tularensis survives weeks – not decades – in soil and water.
  3. Francisella tularensis has an incubation period of 1-14 days.
  4. Francisella tularensis is a rare disease that has been relatively stable in its incidence for several decades.

Thixton’s allegations do not hold water on several fronts.

  • She claims the problem to be ongoing, yet states that the exposure was at the Mars PetCare plant that closed down in 2013. Anyone exposed to Francisella tularensis in 2013 would have developed symptoms within two weeks of exposure – not six years later.
  • She claims – without supporting data – that the source of the exposure was rendered pet food ingredients. Yet, Francisella tularensis cannot survive temperatures far milder than those used in rendering.
  • She claims the bacteria survive in soil and water for decades, whereas the scientific literature reports survival in terms of weeks.

Don’t take my word for this. Go to the sources

I have spent four decades working in and writing about food safety, including pet food safety.

I am always prepared to call out misbehavior on the part of companies large and small. I did so in the pentobarbital scandals.

I am not prepared to stand by while the credibility of food safety advocates such as myself is damaged by the publication of allegations not supported by documentation or scientific research.



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