Feral cats in TNR colonies are no greater risk to human beings than pet cats

An interesting study dated 2003 titled: Prevalence of infectious diseases in feral cats in Northern Florida concluded that feral cats in TNR colonies are no more of a risk in terms of spreading disease to people or cats tban domestic cats. The basis for that statement is that feral cats cared for by volunteers in TNR colonies have infectious diseases to the same level or to a lower level than domestic cat sin the USA. Therefore, detractors of feral cats cannot claim, on the basis of this study, that feral cats in their community spread disease to people and therefore they should be eliminated.

TNR feral cats
TNR feral cats. Picture in the public domain.
Two useful tags. Click either to see the articles:- Toxic to cats | Dangers to cats

The scientists took blood samples or sera from 553 feral cats. The most common infections in the feral cats studied were:

  • Bartonella henselae, which causes cat scratch fever in people;
  • Feline Coronavirus (FCoV), which is a common viral infection in cats generally asymptomatic which can cause mild diarrhoea. Pathogenic oronavirus ccan lead to feline infectious peritonitis (FIP)
  • Mycoplasma spp., which is a bacterial infection usually of the respiratory system and urinary tract, as I understand it;
  • D. immitis, which is heartworm, a blood-borne parasite that resides in the heart or adjacent large blood vessels of infected animals;
  • T. gondii, which is toxoplasmosis, a well-known, usually asymptomatic disease in cats and in people which has been well discussed on the Internet.

In addition to the above, male cats were at a significantly higher risk for FIV which is Feline immunodeficiency virus, a bit like human AIDS. FeLV (Feline leukaemia virus) was also present but both FIV and FeLV were relatively low in prevalence when compared to infection rates reported for owned cat in the United States. For the feral cats studied the rates were as follows: FeLV 3.3%, FIV 5.2%. Prevalence of FeLV in pet cats ranges from 2% to 18%. Prevalence of FIV for pet cats ranges from 1.2% to 43.9% according to many studies.

ASSOCIATED PAGE: FeLV in plain language.

“Feral cats in this study had similar prevalence of infections compared to those published for pet cats in the United States. This suggests that feral cats assessed in this study appear to be of no greater risk to human beings or other cats than pet cats.”

TNR volunteer Toronto
Verena Besso working at a TNR colony in Toronto. Photo: Richard Lautens.

ASSOCIATED PAGE: Percentage of cats with FIV in various countries

Caveat: they say that ‘the results of this study should be interpreted with some caution as the samples were collected from feral cats that were trapped by caretakers for the purpose of neutering’ by which they mean these were feral cats under the care of volunteers in TNR programs. What they are hinting at is that the cats might be healthier than feral cats who are not within a colony which is part of a TNR program. This is because of various reasons such as neutering reduces aggression and fights, some TNR programs vaccinate, the cats are fed.

On that basis, by the way, this caveat should promote the concept of TNR in the USA. If under TNR programs the feral cats are healthier and less likely to carry disease than domestic cats then surely that is a strong argument to expand the TNR program.

I’ve deliberately kept this very short to get to the point quickly (as these studies are a hard read and complex) but if you want to read the entire study then please click the link below:

Infectious diseases in TNR colony feral cats in N. Florida

It is published on the Journal of Feline Medicine and Surgery (2004) 6, 287e296.


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