Adapted for Ireland from Alley Cat Allies.

A Healthy Relationship

The Science Behind Why Feral Cats are Safe Members of Our Communities

(Download Alley Cat Allies' PDF version of this document)

Public health policies all over the world reflect the scientific evidence: community cats live healthy lives outdoors and don’t spread disease to people. But, advocates of catch and kill programs continue to justify this cruel practice by insisting that community cats represent a threat to public health because they do spread disease. 'There's simply no evidence to back up these claims,' says Deborah L. Ackerman, M.S., Ph.D., an adjunct associate professor of epidemiology at the UCLA School of Public Health.

More and more, public health officials are embracing Trap Neuter Return for community cats, and replacing outdated policies based on unfounded fears.

Most diseases that infect cats can only be spread from cat to cat, not from cat to human. You are much more likely to catch an infectious disease from the person standing in line with you at the grocery store than from a cat.¹ In fact, a 2002 review of cat-associated diseases published in the Archives of Internal Medicine concluded that, 'cats should not be thought of as vectors for disease transmission.'²

Infectious diseases can only spread from cats to humans via direct contact with either the cat or its faeces, and community cats often avoid humans. Statistics from the Centers for Disease Control and Prevention (CDC) show that cats are rarely a source of disease, and that it is unlikely for anyone to get sick from touching or owning a cat.³ 'Feral cats pose even less risk to public health than pet cats because they have minimal human contact, and any contact that does occur is almost always initiated by the person,' says Ackerman.

Science Shows Community Cat Colonies Pose No Disease Risk to Humans

The health risks that catch and kill advocates most often blame on cats are intestinal parasites, toxoplasmosis, rabies and flea-borne typhus (the latter two not an issue in Ireland anyway). Yet the spread of these diseases has never been conclusively linked to community cats.

Parasites are Species Specific

Ackerman says that the risk of catching an intestinal parasite like Cryptosporidium and Giardia from cats has been vastly over-hyped. Molecular studies show that these parasites are usually species specific - meaning that the type that infects cats does not infect humans - and 'some studies even suggest that cats and other animals are more likely to catch these parasites from humans than vice-versa,' according to Ackerman.

Most Cases of Toxoplasmosis Stem from Undercooked Food, Not Cats

Catch and kill advocates sometimes argue for killing community cats because they can transmit toxoplasmosis, a parasitic disease that spreads via Toxoplasma oocysts shed in the faeces of an infected animal. But studies show that the overwhelming majority of toxoplasmosis cases actually result from eating undercooked meat. According to CDC statistics, toxoplasmosis is the third leading cause of food-borne illness-related death in the U.S.⁹ In Ireland toxoplasmosis is reported relatively rarely, with an average of 42 cases annually between 2004 and 2010¹¹. However, as symptoms in healthy people are generally mild and non-specific, a significant proportion of cases probably go unnoticed. Studies in the UK have estimated that between 7-34% of people have been infected with T. gondii. In an Irish study, around 13% of children were shown to have been infected. However, the vast majority of these people will not have noticed any symptoms.

Pregnant women and their foetuses face a higher risk from the disease - a fact that catch and kill advocates often abuse to incite public paranoia - but a study published in the Archives of Internal Medicine in 2002 concluded that pregnant women were unlikely to catch toxoplasmosis from a cat.¹⁰ 

It's rare for anyone to catch toxoplasmosis from a household pet (cats are not the only carriers; dogs, birds and other mammals can also carry the parasite), let alone a community cat with whom they have no contact. Even if a cat is infected with Toxoplasma, it typically only sheds the disease-spreading oocysts for a few weeks. To catch an infection, a person would need to have direct contact with these infected faeces. Most people go out of their way to avoid touching the contents of their pet cat's litter box, and they're even less likely to touch feral cat faeces. In other words, even if a community cat leaves faeces in your garden, you would need to touch it and then somehow ingest the faeces to get toxoplasmosis.

For more information on toxoplasmosis in Ireland see the Health Protection Surveillance Centre's (HPSC) factsheet here.

No Danger from Rabies

Rabies isn't an issue in Ireland, but even if it were, the notion that community cats spread rabies is another empty argument used by advocates of catch and kill programs, according to Ackerman. The last confirmed cat-to-human transmission of rabies occurred in 1975 and the risk of catching rabies from a community cat is almost non-existent. Statistics from the CDC show that as a source of rabies infections in the US, cats rank way behind wild animals like bats, skunks and foxes who account for more than 90% of reported cases of the disease.⁴

And, where rabies is an issue, Trap Neuter Return is a safeguard against it where vaccinations are introduced, because 'the vaccination component of TNR programs ensures that the cats in managed colonies cannot catch or spread rabies,' says Ackerman.

Even in the unlikely event that a community cat develops rabies, it can't spread the disease to people without biting them, and community cats rarely seek direct contact with humans. The idea that cats will unexpectedly jump out of alleys and bite children is just as ridiculous as it sounds. A 1998 analysis showed that about 90% of cat bites were provoked, and the vast majority of cat bites are caused by pets.⁵

Cash says that since Atlantic City began its TNR program, he hasn't had a single complaint about feral cat bites or scratches. Learn more from Alley Cat Allies about why community cats do not spread rabies.

Flea-borne Typhus is Rare and Cats Don't Play a Part in the Fleas Arrival or Growth

Flea-borne typhus, again not a risk in Ireland anyway, is another infectious disease sometimes erroneously blamed on community cats. The disease is caused by Rickettsia bacteria that infect fleas, and most U.S. cases occur in Texas, Hawaii and California. Although infected fleas may hitch a ride on community cats, the chance of becoming infected with flea-borne typhus via such a cat is extremely low. In fact, Ackerman says, 'flea-borne typhus is rare even in areas such as Southern California, where the disease is endemic.' For instance, in 2009, Orange County, California reported 12 cases of flea-borne typhus out of a population of 3 million residents⁶, making the chance of infection just 1 in 250,000—about the same as the risk of being hit by an asteroid.⁷

Removing cats does not halt the spread of flea-borne typhus, because cats don't spread the disease - the fleas themselves do. Cats are merely a host for fleas and if the cats are eliminated, the fleas simply find another host like squirrels and raccoons. 'Fleas are very versatile. They live on cats, dogs, opossums, rats, and mice,' Ackerman says.

For this reason, public health officials in Texas, where flea-borne typhus is endemic, have focused their efforts on controlling fleas, rather than their hosts. Outbreaks are rarely traced to cats. In 2008, the CDC and Texas health authorities examining a cluster of flea-borne typhus in Austin found the Rickettsia bacteria in only 18% of cats, as compared to 44% of dogs and 71% of opossums, near the homes of people infected with the disease.⁸

Colony Caregivers are as Healthy as Everyone Else

Maybe the best proof that community cats pose no health risk to people is that community cat caregivers are healthy. 'If feral cats transmitted disease to humans,' says Ackerman, 'colony caregivers, who spend more time around feral cats than most people, would experience a heightened rate of disease, and this simply isn't the case.' None of the many caregivers she's interviewed have ever reported becoming sick from their work with community cats. No study has ever shown that colony caregivers have any increased risk of disease, despite their regular contact with cat colonies.

Catch and Kill doesn’t Improve Public Health

'Catch and kill policies are fear-based and rely on old wives' tales and flawed research to justify prejudice against cats,' says Ackerman. Removing community cats is never a sustainable solution, because that only opens up new territory for other cats to use. Learn more about this vacuum effect. According to Ackerman, there's absolutely no evidence that catch and kill policies reduce the incidence of human disease.

Trap Neuter Return Programs Protect Public Health and Prevent the Spread of Disease

Trap Neuter Return programs help to stabilise community cat populations and, if used, the vaccination component ensures that cats are protected against disease. These programs also allow cat caregivers and public health officials to monitor the health of cats in the community and ensure that they're immunised - and that 'protects the health of cats and humans alike,' says Cash.

Catch and kill programs offer no such similar benefits, because cats are simply removed without regard to their health.

'TNR is good public health policy,' says Cash. Atlantic City has been collaborating with Alley Cat Allies for the past ten years to manage feral cat colonies under the city's famous boardwalk. The TNR program that Atlantic City developed with Alley Cat Allies has never posed any health problems to the community, says Cash.

'Before our relationship with Alley Cat Allies, I was getting numerous complaints about feral cats,' he said. But since Alley Cat Allies began managing these colonies with TNR, the problems have ceased entirely, he says. 'The [cat] population that's here is much healthier,' says Cash. 'They're coexisting with people very well now. Most people don't even know the cats are there.'

While catch and kill advocates cling to outdated thinking and hyped-up stories, the people studying, teaching, and defending public health recognize that community cats do not spread disease to people. Policies based on fear, hype and hysteria serve neither the public nor the cats, and will only end in more cats being killed.

Instead, community cat policies should reflect the science and the facts - community cats are healthy animals. From a public health standpoint as well as a humane one, the best approach for community cats is Trap Neuter Return because it benefits the cats and the community.

---

[1] American Association of Feline Practitioners and the Cornell Feline Health Center, Cornell University, College of Veterinary Medicine.Zoonotic Disease: What Can I Catch From My Cat? 2002. See full information here.
[2] Kravetz, Jeffrey D., and Daniel G. Federman. “Cat-Associated Zoonoses.” Arch. Intern Med 162, no. 17 (2002): 1945-1952.
[3] Centers for Disease Control and Prevention. Diseases from Cats. July 28, 2010.http://www.cdc.gov/healthypets/animals/cats.htm (accessed October 25, 2010, link no longer live).
[4] Centers for Disease Control and Prevention. Rabies - Epidemiology. September 18, 2007.http://www.cdc.gov/rabies/epidemiology.html.
[5] Patrick, G.R., and KM O'Rourke. “Dog and Cat Bites: Epidemiologic Analyses Suggest Different Prevention Strategies.” Public Health Report, 1998: 252-257.
[6] Notifiable Diseases in Animals: Joint Meeting of the CCLHO Communicable Disease Control and Environmental Health Committees, April 15 (2010) (written statement of Deborah L. Ackerman, M.S., Ph.D., Adjunct Associate Professor of Epidemiology, UCLA School of Public Health on Free-Roaming Cats and the Public Health).
[7] Britt, Robert Roy. The Odds of Dying. January 5, 2005. Updated 2019.
[8] Adjemian, Jennifer, et al. “Murine Typhus in Austin, Texas, USA, 2008.” Emerging Infectious Diseases, 2010: 412-417.
[9] Centers for Disease Control and Prevention. Toxoplasmosis. January 11, 2008. http://www.cdc.gov/toxoplasmosis/ (accessed October 25, 2010).
[10] American Association of Feline Practitioners and the Cornell Feline Health Center, Cornell University, College of Veterinary Medicine.Zoonotic Disease: What Can I Catch from My Cat? 2002.
[11] Health Protection Surveillance Centre, Epidemiological Data, 26/03/12, http://www.hpsc.ie/hpsc/A-Z/Zoonotic/Toxoplasmosis/EpidemiologicalData/