Download Zoonotic disease issues

Summary for Animal Care Expo
“Rabies, FIV and Parasites: Managing Public and Feline Health Concerns”
Zoonotic disease issues
Animals and people living in the same environment can present zoonotic disease issues. A zoonotic
disease is classically defined as a disease that is passed from animal to humans. Technically, it can work
both directions, but the most commonly accepted definition is transmission of an infectious agent or
disease process from an animal to a person. An estimated 2/3 of infectious agents are zoonotic and ¾ of
new and emerging diseases have an animal origin.
As community cat management and trap-neuter-release (TNR) programs continue to develop in cities and
towns across the country, opponents will often raise the issue of zoonotic disease as a reason not to
institute TNR/community cat management programs into exiting animal control structures. The fear of
disease spread in the human population among the community cats can be used as a scare tactic with
public officials and skeptical citizens. The use of common-sense biosecurity and scientific fact can help
alleviate any fear of potential disease problems. That makes knowledge of potential risk important to
proponents of community cat programs so they can assess risk and promote biosecurity to minimize
exposure to these infectious agents.
Rabies is always at the top of the list of zoonotics of concern. Rabies is a viral disease of mammals that
has been with us since ancient times. The virus is transmitted from one mammal to another by a bite.
The bite allows the virus to be buried in the tissue and travel up nerve pathways, affecting the sensory
nervous system and eventually the brain. The cat is the most common domestic species diagnosed with
rabies in this country. The feral cat population is most susceptible as they have the most contact with
wildlife. Wildlife is the primary source of rabies in the United States. Bats, raccoons, fox, skunk and
coyotes are all rabies vector species that live in our urban and suburban environments. The community
cat population has the opportunity to interact with all of these species, so their susceptibility to rabies will
always be an issue. Vaccination for rabies should be a requirement for all TNR programs to show interest
in supporting public health.
Endoparasites generally refers to intestinal parasites and protozoa which can be transmitted from cats to
people or from a common environment to both people and animals. Nematodes such as roundworms and
hookworms may be transmitted to people via oral ingestion or contact with the skin. Baylisascaris is the
roundworm of raccoons and, since these animals thrive in our urban and suburban environment, the soil
can be infested with eggs that can be ingested and migrate to the brain causing damage and death. Cats
can be carrier for this particular parasite. Hookworm larvae can burrow into human feet, as they contact
infected soil, and cause tracks in the skin.
Protozoan infections such as giardia are acquired by people and animals, usually from a common water or
other source. Giardia causes cramping and diarrhea in people and animals and can be difficult to
diagnose because the cystic stage is difficult to find in the stool. Toxoplasmosis is caused by an organism
carried by the cat, but also contracted from eating poorly cooked meat. It can cause brain damage in the
human fetus if the mother contracts the organism in the first trimester. Many people have been exposed
to the Toxoplasma gondii organism and have a titer against infection. Pregnant women should either not
clean out the litter box, to avoid contact with eggs, or use gloves when doing that task.
Ecto parasites such as fleas, ticks and mosquitos have the cat as their natural host, so they will be around,
but prefer the cat or dog to the human. These external parasites can carry several diseases, but not many
of them are transmissible to humans. Vector-borne diseases such as West Nile virus and Lyme disease are
not passed from the cat to human but are acquired by people through exposure to an infected insect. Cats
acquire heartworms from contact with an infected mosquito and are less susceptible than dogs. Humans
do not get the canine/feline heartworm at all in this country. Plagues has been associated with fleas and
cats in certain parts of the country. Cat scratch disease has been associated with cats and fleas also. This
is a bacterial disease carried by cats but also associated with susceptible humans. Tularemia and plague
can be carried by cats to people after being acquired from other rodents. Cats can be implicated in other
disease outbreaks but their role in spread is not proven.
Bacterial and fungal infection can be passed from animals to humans, but less likely as the types of
bacteria that infect people are generally in a different group than those that affect animals. Animals can
be unapparent carriers of bacteria that can then pass with contact to people. Since our feral cats generally
avoid contact with people, in spite of a high risk of exposed animals, they present a low risk of contact
with humans.
Fungal infections, especially skin infections like superficial dermatophytosis or “ringworm,” can be very
contagious to people, especially children who snuggle with their kitten or puppy. These organisms
include Sporthrix sp and Microsporum sp. Deep fungal infection such as blastomycosis and
histoplasmosis are geographically defined and the person acquires them from the same source as the cat.
Some are found in bird droppings while others are associated with rodents.
Feline immunodeficiency virus (FIV) belongs to the same retroviral group as HIV (humans) and EIA
(horses). These viruses do not cross species lines and are not transmitted between cats and people. There
is no risk to people from FIV infected cats, only to other cats and it usually is spread by fighting and bite
wounds to other animals.
Zoonotic diseases are more likely carried by unhealthy cats, although cats can be inapparent carriers of
disease in other cases including toxoplamosis and some bacterial infections. Immunocompromised
people are most susceptible to these infections because of their inability to fight infection. These include
children, pregnant women and people who have gone through chemotherapy along with those with
chronic medical conditions. This population has grown and may be part of your volunteer corps. Proper
biosecurity procedures should be in place to avoid infection.
Education of local officials is important in showing that management of community cats can minimize the
spread of disease among the cats and potential transmission to people. By vaccinating cats for rabies we
protect the most vulnerable population exposed to rabies vector species. By feeding in one area, we stop
the destructive foraging behavior that is common in feral cats. Attention to medical issues of feral cats
keep these cats healthier and less likely to spread disease.
Community cat groups need to engage veterinarians, public health officials, animal control officials,
university experts and the public to understand their program. They also need to be aware that the disease
risk is present with community cats and ensure they can provide protection to volunteers and workers.
Veterinarians need to be aware of these possible diseases and try to identify cats that may be sources of
infection. Biosecurity procedures should be in place for volunteers to minimize possible transmission.
Zoonotic disease transmission is not common but is a risk factor in dealing with community cats. Every
TNR program needs to acknowledge the issue and address the ways to minimize exposure. Working with
the community and officials can help alleviate fears and allow community programs actually help
minimize zoonotic disease spread.