Epidemiology and Prevention of Healthcare-Associated Infections Related to Animals in the Hospital

David J. Weber

William A. Rutala

Americans keep a wide variety of animals as household pets. Common pets include cats, dogs, birds, and fish; however, increasingly more exotic animals are being kept as pets, including other felines, ferrets, monkeys and other primates, rabbits, reptiles, rodents, and wolves. In addition, a variety of farm animals may be kept as pets, such as cattle, chickens, horses, pigs, and sheep. In 2006, 37.2% of households owned a dog, 32.4% owned a cat, 3.9% owned a pet bird, and 1.8% owned a horse (1). The total number of animals owned was 72.1 million dogs, 81.7 million cats, 11.2 million birds, and 7.3 million horses. An estimated 9 million American homes had an aquarium. The average veterinary expenditures per household for all pets was $366 (1). Retail trade in pet food alone totaled $41.2 billion in 2007 (2).

Hospitalized patients may come into contact with animals for two main reasons: the use of animals for animal-assisted interventions (also known as pet therapy or pet-assisted therapy) and the use of service animals, such as guide dogs for the blind and primates for persons with impaired motion. This chapter focuses on the benefits and potential risks of animal use in the hospital, especially pet therapy. This chapter covers only the most common animals kept as pets and the major zoonotic diseases. Readers interested in a comprehensive review of zoonotic diseases or in rare and exotic zoonotic diseases are referred to several comprehensive monographs (3,4,5, 6,7,8 and 9,10,11,12,13,14,15) and review articles (16,17 and 18). Several excellent reviews of infections associated with pets have appeared in the general medical literature (19,20,21,22,23,24,25,26,27,28,29,30,31 and 32,33). The frequency of type of allergic reactions to pets has also been reviewed (26,27,34,35 and 36). Finally, the infectious hazards associated with the use of animals in medical research have also been reviewed (37,38 and 39). The clinical diseases associated with specific zoonotic agents and their therapy are well covered in infectious diseases textbooks (40,41).

Multiple recent outbreaks of zoonotic diseases that have occurred as a result of petting zoos have called attention to the risks of human-animal contact, especially for young children (42,43,44 and 45). Recommendations to prevent such outbreaks have recently been published (46). In recent years, there has been a growing appreciation that most emerging infectious diseases are of zoonotic origin (47,48,49 and 50,51,52). Finally, with the exception of smallpox, virtually all potential bioterrorist agents are zoonotic pathogens including Bacillus anthracis (anthrax), Coxiella burnetii (Q fever), Francisella tularensis (tularemia), and Yersinia pestis (plague) (53,54,55,56,57,58,59,60,61 and 62). Bioterrorist agents are discussed in Section XVII Bioterrorism. In the future, zoonotic pathogens may be introduced into humans via the use of xenotransplantation (63,64,65 and 66,67,68).

POTENTIAL HAZARDS OF ANIMALS IN THE HOSPITAL

A comprehensive literature survey of human pathogens listed more than 1,400 infectious agents capable of causing human infection (47). Of these, more than half are known to be zoonotic (i.e., able to infect other host species). However, strictly speaking, zoonoses refer only to those diseases that are transmitted from vertebrate animals to humans. In most cases, humans are accidentally infected and are dead-end hosts. Other pathogens also share maintenance of their life cycle with both animals and humans. In addition, the ectoparasites of some domestic animals carry pathogenic microorganisms, which may spread to humans through close association with infested animals.

Humans may come into contact with animals through many activities, including pet ownership; leisure pursuits such as camping, hunting, and hiking; travel to remote regions; and via occupations such as animal husbandry, medical research, veterinary medicine, animal control, and handling of agricultural products or animal hides. This chapter reviews only the diseases most likely to be transmitted by domesticated animals that serve as pets or service animals, because these animals are most likely to be encountered in the hospital (Table 94-1). These common pets include birds; cats; dogs; rodents such as mice, rats, gerbils, and hamsters; and fish, turtles, snakes, and rabbits. Nonhuman primates that may be used to aid disabled persons are also discussed.

Potential Pathogens

Animals commonly used as pets can serve as the reservoir or source for a significant number of diseases that potentially could be transmitted to humans in the healthcare
setting (Table 94-2). These animals are also involved in the life cycles of an even wider variety of diseases in which healthcare-associated transmission is either rare or impossible (e.g., echinococcosis, leishmaniasis, schistosomiasis, and trypanosomiasis). New zoonotic pathogens continue to be recognized either because the microbial agent is newly isolated or because its potential to cause human disease is newly recognized (47,48,49,50,51 and 52). Newly discovered zoonotic pathogens discovered outside the United States include Nipah virus (69), Hendra virus (70), and SARS-coV (71), whereas newly discovered pathogens in the United States include Sin Nombre virus (72) and Southern Tick-Associated Rash Illness (73). Zoonotic diseases endemic outside the United States may spread to the United States, leading to sporadic infections or outbreaks such as dengue (74), monkeypox (75), and West Nile disease (76).

TABLE 94-1 Diseases Potentially Transmitted by Pets in the Healthcare Setting

*Infectious Disease*		*Cats*	*Dogs*	*Fish*	*Fowl/Birds*	*Primates*	*Rabbits*	*Reptiles*^a	*Rodents*^b
Viral
	Simian herpes B virus					+
	Influenza A (avian)				+
	Lymphocytic choriomeningitis								+++
	Monkeypox					+	+		+
	Rabies	+	+
	Simian immunodeficiency virus					+
Bacterial
	Aeromonas			+				+
	Anthrax	+	+
	Brucellosis		+
	Campylobacteriosis	+	++		++			++	++
	C. canimorsus sepsis	+	+++
	Cat scratch disease	+++	+
	Ehrlichiosis		+
	Erysipeloid			+	+				+
	Leptospirosis		+		+		+		+
	Listeriosis		+		+		+	+
	Murine typhus								+
	Mycobacteriosis (M. marinum)			+++
	Pasteurellosis	+++	++			+	+++		+
	Plague	+							+
	Psittacosis				+++
	Q fever	++
	Rat bite fever								+++
	Rocky Mountain spotted fever		++
	Salmonellosis	+	+		+++	+	+++	+++	+++
	Tuberculosis	+	+			+	+
	Tularemia	++	+				++		+
	Vibriosis			+
	Yersiniosis				+	+	++	++	++
Parasites
	Cryptosporidiosis	+	+			+
	Dipylidiasis		+
	Dirofilariasis		+
	Echinococcosis		+
	Fleas	+	+
	Giardia lamblia		+			+
	Mites (scabies)	+	+
	Toxocariasis	++	+
	Toxoplasmosis	+++
Mycotic
	Dermatophytosis	+	++				+++		+++
^aReptiles include lizards, snakes, and turtles. ^bRodents include hamsters, mice, and rats.
+, rare zoonoses; ++, occasional zoonoses; +++, most common zoonoses.
(Adapted from references 4,16,18,19,20.)

TABLE 94-2 Medically Important Zoonotic Diseases

*Pathogen*		*Disease*	*Medical Illness(es)*
Viral
	Coronavirus	SARS	Pneumonia (mortality 10-15%)
	Herpesvirus simiae (B virus)	B virus infection	Erythema, vescicles, ulcers, and local pain at site of inoculation Rapidly progressive ascending neuropathy and encephalitis
	Lymphocytic choriomeningitis (LCM)	LCM meningitis	Influenza-like illness and occasional meningitis
	Orbivirus	Colorado tick fever	Biphasic disease: sudden onset of fever, prostration, headache, photophobia, muscle and joint pains; followed by 2- to 3-d remission; then second episode of fever and rash (10%)
	Orthopoxvirus	Monkeypox	Variola-like skin eruption with lymphyadenopathy (mortality ˜10%)
	Rhabdovirus	Rabies	Encephalitis (mortality ˜100%)
	Rotavirus	Rotavirus	Enteritis
Bacterial
	Aeromonas spp.	Aeromonas	Gangrenous wound infection, gastroenteritis, and pneumonia
	Bacillus anthracis	Woolsorter’s disease	Localized skin lesions; mediastinal or intestinal infection (rare) leading to sepsis
	Borrelia burgdorferi	Lyme arthritis	Three stages: (a) localized characterized by skin rash (erythema chronicum migrans); (b) disseminated characterized by musculoskeletal symptoms, neurological, or cardiac abnormalities, arthritis; (c) persistent infection with chronic skin, nervous system, or joint involvement
	Borrelia spp.	Relapsing fever	Systemic disease marked by periods of fever alternating with afebrile episodes; erythema, petechia, jaundice may occur
	Brucella spp.	Brucellosis	Systemic disease with acute or insidious onset, characterized by fever, headache, weakness, sweating, chills, arthralgia, and weight loss
	Campylobacter jejuni	Campylobacteriosis	Gastroenteritis
	Capnocytophaga canimorsus	Septicemia	Sepsis with multiorgan failure and cutaneous gangrene
	Rochalimaea henselae	Cat scratch disease	Lymphadenitis, Parinaud’s syndrome, meningo-encephalitis, and bacillary angiomatosis in HIV-infected patients
	Chlamydia psittaci	Psittacosis	“Atypical” pneumonia
	Ehrlichia spp.	Ehrlichiosis	Multisystem disease; may have rash
	Erysipelothrix insidiosa	Erysipeloid	Skin infection (localized pain, erythema, edema surrounding wound); arthritis; and sepsis (rare)
	Francisella tularensis	Tularemia	Indolent ulcer and adenopathy (ulceroglandular); pneumonia; systemic symptoms (typhoidal); pharyngitis, abdominal pain, diarrhea, and vomiting (gastrointestinal); conjunctivitis; and adenopathy (oculoglandular)
	Leptospira interrogans	Leptospirosis	Variable disease; biphasic illness—sudden onset with fever, headache, severe myalgias, conjunctival suffusion, rash, meningitis, hepatorenal failure, and CNS involvement
	Listeria monocytogenes	Listeriosis	Variable disease, meningitis, and abortion
	Mycobacterium marinum	Skin granulomas	Local ulcerative disease
	Mycobacterium tuberculosis	Tuberculosis	Pneumonia, disseminated infection, and meningitis
	Pasteurella multocida	Pasteurellosis	Cellulitis, septic arthritis, osteomyelitis; pneumonia; meningitis; endocarditis; sepsis; and intra-abdominal infection
	Pseudomonas pseudomallei	Melioidosis	Fever, pneumonia, gastroenteritis; chronic cases may have necrotic and granulomatous soft tissue or bone lesions
	Coxiella burnetti	Q fever	Variation in severity and duration; onset may be sudden with chills, headache, weakness, and malaise; pneumonitis and endocarditis may occur
	Rickettsia rickettsii	Rocky Mountain spotted fever	Systemic illness with fever, headache, rash, meningitis, multiorgan failure
	Salmonella enteriditis	Salmonellosis	Gastroenteritis, sepsis (occasionally), and osteomyelitis Staphylococcus aureus Staphylococcal infection Skin and soft tissue infections, osteomyelitis, endocarditis, toxic shock syndrome, and gastroenteritis (toxin mediated)
	Streptococcus pyogenes	Streptococcal infection	Pharyngitis and cellulitis; streptococcal toxic shock syndrome
	Streptobacillus moniliformis	Haverhill or rat bite fever	Systemic illness characterized by sudden onset fever and chills, headache and muscle pain, followed by rash, polyarthritis, and rarely endocarditis
	Vibrio parahemolyticus	Vibriosis	Acute gastroenteritis
	Yersinia enterocolitica	Yersiniosis	Acute ileitis; peritonitis may occur; rarely septicemia, reactive arthritis
	Yersinia pestis	Plague	Systemic disease with multiple manifestations: lymphadenitis (bubonic), pneumonia (pneumonic), and sepsis
Fungal
	Dermatophytes	Ringworm	Skin disease (ringworm)
Parasitic
	Babesia microti	Babesiosis	Sepsis with fever, shaking chills, headache, gastrointestinal symptoms, and arthralgias; hemolytic anemia
	Cryptosporidia spp.	Cryptosporidiosis	Gastroenteritis (self-limited in normal host, may become chronic in immunocompromised host)
	Ehrlichia risticii	Ehrlichiosis	Systemic illness similar to Rocky Mt. spotted fever without rash
	Giardia lamblia	Giardiasis	Chronic diarrhea
	Toxoplasma gondii	Toxoplasmosis	Usually asymptomatic, lymphadenopathy, chorioretinitis, and encephalitis (immunocompromised host)
(Adapted from references 4–6,8,9,27,28.)

Healthcare-Associated Hazards of Animals in the Hospital

Zoonotic diseases can be transmitted to humans through animal trauma (bites, scratches, and stings); direct contact; arthropod vectors; aerosols; and contamination of food, water, or milk (4,77) (Table 94-3). Physicians should be aware of the major clinical syndromes associated with zoonotic diseases and their potential to cause healthcareassociated infection (78,79,80) (Table 94-2).

Hospitalized patients often have altered host defenses that may increase their susceptibility to a zoonotic infection and/or increase the severity of clinical disease (81,82,83,84,85 and 86) (Table 94-4).

In addition to direct transmission from animal to human, healthcare epidemiologists and infection preventionists should be aware that some zoonotic diseases may be transmitted from human to human, whereas others may represent a hazard in the microbiology laboratory (Table 94-4) (see Chapter 77). Several recent papers have provided recommendations for the management of animals in public settings and healthcare facilities (46,87,88 and 89,90).

Unfortunately, few scientific studies have addressed the potential risks of animal-to-human transmission in the healthcare setting. Furthermore, because animals have, in general, been excluded from hospitals, experience gained by means of case reports and outbreak investigations is minimal. However, Lefebvre et al. (91) assessed 102 healthy visitation dogs for the presence of zoonotic pathogens. Zoonotic agents were isolated from 80% of animals including toxigenic Clostridium difficile (40.1%), Salmonella spp. (3%), extended spectrum β-lactamase (ESBL)- or cephaloporinase-producing Escherichia coli (4%), Pasteurella spp. (29%), Malassezia pachydermatis (8%), Toxocaria canis (2%), and Ancylostoma caninum (2%). Scott et al. (92) described an epidemic of methicillin-resistant Staphylococcus aureus (MRSA) on a rehabilitation geriatric ward. The paws and fur of a cat that roamed the ward were heavily colonized by MRSA, and the cat was considered to be a possible vector for the transmission of MRSA. Lyons et al. (93) described an outbreak of Salmonella heidelberg in a hospital nursery that was traced to infected calves on a dairy farm where the mother of the index patient lived. An outbreak of Rhodococcus (Gordona) bronchialis sternal surgical site infections after coronary artery bypass surgery was linked to a nurse whose hands, scalp, and vagina were colonized with the epidemic pathogen (94). Although cultures of neck-scruff skin of two of her three dogs were also positive, whether the animals were the source for colonizing the nurse or whether both the animals and nurse were colonized from an environmental reservoir could not be determined. An evaluation of a large outbreak of M. pachydermatis in an intensive care nursery discovered that the isolates from all 15 case patients, 9 additional colonized infants, 1 healthcare worker, and 3 pet dogs owned by healthcare workers had identical patterns of restriction fragment length polymorphisms (95). The authors believed that M. pachydermatis was likely introduced into the intensive care nursery from the healthcare worker’s hands after being colonized from pet dogs at home and then persisted in the nursery through patient-to-patient transmission. Patient infections were not benign and included eight bloodstream infections, two urinary tract infections, one case of meningitis, and four asymptomatic colonizations. Multiple healthcare-associated outbreaks of Microsporum canis (ringworm) with person-to-person transmission have been described in newborn nurseries (96,97) or neonatal intensive care units (98). In the latter case, the source of infection was a nurse, likely infected from her pet cat.

TABLE 94-3 Transmission of Important Zoonotic Diseases

*Disease*		*Aerosol*	*Ingestion*	*Contact*	*Animal Trauma*	*Arthropod-Vector*
Viral
	B virus infection		Saliva		Primate bite
	LCM meningitis	Infected aerosols	Food, water
	Colorado tick fever					Tick
	Rabies	Probably bat caves, laboratory		Secretions, corneal tranplant	Wild animals, dog, cat
Bacterial
	Aeromonas spp.	Fresh water drowning	Food, water	Water	Fish, reptile
	Anthrax	Spores in hides, spores in raw wool	Spores in contaminated meat	Spores in hides or environment	Contact with lesions on animals
	Brucellosis	Inhalation while handling animals or products	Goat cheese and milk products	Animal and food products
	Campylobacteriosis		Meat, poultry, milk, water	Puppies with diarrhea
	C. canimorsus sepsis				Dog bite
	Cat scratch disease				Cat scratch
	Ehrlichiosis					Tick
	Erysipeloid			Fish slime, shell-fish	Lobster or crab pinch
	Leptospirosis	Secretions, wild and domestic animals	Water, milk	Contaminated water
	Listeriosis		Vegetables, water, cheese
	Lyme arthritis					Tick
	Melioidosis				Rodents
	Monkeypox	From infected animals		Primates, rodents
	Mycobacteriosis (M. marinum)			Water, fish tanks
	Pasteurellosis	Respiratory secretions		Cat, dog secretions	Feline bites and scratches, dog bites
	Plague	Inhalation-infected material		Infected animals	Cat scratch	Rodent flea
	Psittacosis	Dried excreta from birds
	Q fever	Endospores from animal-contaminated soil, cat afterbirth		Infected animals
	Rat bite fever		Water, milk contaminated by infected urine		Lab and wild rodents
	Rocky Mountain spotted fever	Laboratory accident		Engorged tick		Tick
	Relapsing fever					Tick
	Salmonellosis		Food esp. poultry, eggs, shellfish, water	Fecal material reptile/amphibians		Cockroaches, bed bugs
	Tuberculosis	Respiratory secretions	Milk (M. bovis)
	Tularemia	Droplet particles, dead birds, animals	Food including meat	Dressing squirrels, muskrats, etc.	Cat bite (rare)	Tick
	Vibriosis		Shellfish
	Yersiniosis		Milk, water	Farm animals
Fungal
	Dermatophytes			Dogs, cats
Parasitic
	Babesiosis					Tick
	Cryptosporidiosis		Cysts in water, ice
	Ehrlichiosis					Tick
	Giardiasis		Cysts in water
	Toxoplasmosis		Oocysts from cat feces, tissue cysts from uncooked meat
(Adapted from references 4,30,37,41.)

Outbreaks of Q fever have been described in a secondary school in which infected goats were maintained for teaching purposes (99), in a psychiatric institution in which patients and staff worked with goats on a farm (100), and in a university department in which sheep placentas were used for fetal respiratory studies (101). There are two reports of postmortem examinations that lead to the transmission of C. burnetii to pathologists, mortuary technicians, doctors, and a medical student (102,103). Person-to-person transmission of Q fever within a family that affected five members has been reported (104). Healthcare-associated transmission has also been reported. There have been several reports of hospital staff who acquired Q fever via exposure to infected patients (102,105,106). In the latter case, Q fever developed in an obstetrician 7 days after he cared for a woman undergoing a spontaneous abortion at 24 weeks. C. burnetii was identified in the fetal spleen and kidney, and the placenta, but not the lung. Probable patient-to-patient transmission has also been described (107).

ANIMAL USE IN THE HOSPITAL

Service Animals as Aids for Disabled Persons

The Americans with Disabilities Act (ADA) of 1990 is a federal civil rights law that protects persons with disabilities from discrimination in areas of employment, public services, public accommodations, services operated by private entities, and telecommunications (78). Title III of the ADA mandates that persons with disabilities accompanied by service animals generally must be allowed access with their service animals into places of public accommodation, including restaurants, public transportation, and healthcare facilities. The responsibilities of healthcare institutions under the Act have been extensively reviewed in a guidance document by the Association for Professionals in Infection Control and Epidemiology (78). Disability, as defined in the ADA, is any physical or mental impairment that substantially limits one or more major life activities such as breathing, hearing, or caring for oneself. Service animal is a legal term defined in the ADA. A service animal is a dog individually trained to do work or perform tasks for the benefit of a person with a disability. A service animal is not considered a “pet,” because it is specially trained to help a person overcome the limitations caused by his or her disability (78).

Dogs are most often trained for service work (78). In the United States, an estimated 5,000 working dogs guide the visually impaired, more than 2,500 working dogs assist the hearing impaired, and more than 2,500 working dogs aid the physically challenged persons (108). Service animals provide several valuable services, including enhanced mobility, dignity, decreased anxiety, improved confidence, and independence (109). Not surprisingly, visually challenged persons have a close relationship with their dogs. The importance of guide dogs is well recognized, and they are often exempt from public health regulations governing dogs in general. Animals may also be used to aid the hearing disabled and physically disabled patient; however, these uses are less well described than those of guide dogs.

TABLE 94-4 Zoonotic Diseases with Special Healthcare-Associated Concern

			*Important Laboratory Hazard*	*Compromised Hosts with Increased Susceptibility*^a
*Disease*		*Human-to-Human Transmission*	*Important Laboratory Hazard*	*At-Risk Population*	*Disease*
Viral
	LCM meningitis	Not described	Yes	Not described
	Colorado tick fever	Not described	No	Not described
	Rabies	Anecdotal reports; corneal transplants	Yes	Not described
Bacterial
	Aeromonas infection	Yes (contact, fecal-oral)	No	Not described
	Anthrax	Yes (contact)	Yes	Not described
	Brucellosis	Not described	Yes	Not described
	Campylobacteriosis	Yes (fecal-oral)	No	Not described
	C. canimorsus sepsis	Not described	No	Asplenia	Sepsis
	Cat scratch disease	Not described	No	HIV infection	Bacillary angiomatosis, Bacillary peliosis
	Erysipeloid	Not described	No	Not described
	Leptospirosis	Not described	Yes	Not described
	Listeriosis	Not described	No	Organ transplant	Sepsis, meningitis
				Chemotherapy	Sepsis, meningitis
	Lyme disease	Not described	No	Not described
	Melioidosis	Yes (contact)	No	Not described
	M. marinum granuloma	Not described	No	Not described
	Monkeypox	Yes	Yes	Not described
	Pasteurellosis	Not described	No	Lung disease	Pneumonia
				Prosthetic joint	Septic arthritis
	Plague	Yes (aerosol)	Yes	Not described
	Psittacosis	Yes (aerosol)	Yes	Not described	Chronic infection
	Q fever	Yes (aerosol during birth)	Yes	Cancer
	Rat bite fever	Not described	No	Not described
	Relapsing fever	Not described	Yes	Not described
	Rocky Mountain spotted fever	Not described	Yes	G6PD deficiency	Death from infection
	Salmonellosis	Yes (contact, fecal-oral)	Yes	Achlorhydria	Sepsis
				HIV infection	Prolonged infection, sepsis
				Hemoglobinopathy	Osteomyellitis
	Tuberculosis	Yes (aerosol)	Yes	Organ transplant	Pneumonia, disseminated disease
				HIV infection disease	Pneumonia, disseminated disease
	Tularemia	Not described	Yes	Not described
	Vibriosis	Yes (fecal-oral)	No	Cirrhosis (V. vulnificus)	Sepsis
	Yersiniosis	Yes (fecal-oral)	No	Not described
Fungal
	Dermatophytes	Yes (contact)	Yes	Not described
Parasitic
	Babesiosis	Yes (transfusion)	No	Asplenia	Sepsis (death)
	Cryptosporidiosis	Yes (fecal-oral)	No	HIV infection	Chronic gastroenteritis
	Ehrlichiosis	Not described	No	Not described
	Giardiasis	Yes (fecal-oral)	No	Not described
	Toxoplasmosis	Yes (transfusion)	Yes	Organ transplant	Pneumonia
				HIV infection	Encephalitis
^aLack of a described risk should not be taken to imply that immunocompromised patients are not in fact at higher risk for disease acquisition or progression.

Healthcare facilities as places of public accommodation are required to permit the use of service animals by a person with a disability as defined by the ADA, unless doing so would create a fundamental alteration or a direct threat to the safety of others or the facility (78). It is not permissible to require that a service animal wear special equipment or tag nor is it permissible to require “certification” or proof of an animal’s training or a person’s disability.

To ensure compliance with the ADA, healthcare facilities should have a written policy regarding the use of service animals by employees, patients, and visitors. This policy should ensure that service dogs and their owners have general access to the institution. The service animal policy should include the following topics (78,110). First, the locations in the hospital from which the service animal is prohibited. Such areas would include those that pose a risk to patients, especially areas that require the use of sterile or clean precautions such as operating rooms, pharmacy, and kitchens. Also, the service animal should be prohibited from areas that pose a risk to the animal such as pathology and radiology. Second, facilities should not permit handlers with service animals to act as selfappointed animal-assisted therapy (AAT) (“pet therapy”) providers. Third, employees, visitors, and patients should be educated to understand that service animals should not be allowed to come in contact with any patient’s nonintact skin (e.g., surgical wounds and drainage tube). Fourth, there should be a mechanism to screen persons other than the handler (e.g., roommate) who may come into contact with the service animal for allergies or fears regarding the service animal. Fifth, the policy should define conditions on which the service animal may be removed, restricted, or denied access to an area. Such conditions might include aggressive behavior (i.e., biting), inability to contain excretions, or apparent illness. Evaluation of a potentially ill animal should be made by a veterinarian. Sixth, care and feeding of the service animal should be the responsibility of the owner or the handler or their designee rather than healthcare personnel. The facility may elect to provide temporary care such as during a short operative procedure but would need to have available trained personnel. Legal services should be consulted regarding any formal consent needed when the handler transfers responsibility for service animal stewardship to a facility representative. Finally, a mechanism should be in place for determining the appropriate use of a service animal on a case-by-case basis.

Differences Between Service Animals and Therapy Animals

Therapy animals and their handlers are trained to provide specific human populations with appropriate contact with animals (111). They are usually personal pets of the handlers and accompany their handlers to the sites they visit, but they may also reside at a facility. Animals must meet specific criteria for health, grooming, and behavior. Therapy animals are usually not service animals. Federal law, which protects the rights of qualified persons with disabilities, has no provision for people to be accompanied by therapy animals in places of public accommodation that have “no pets” policies. AAT is a goal-directed intervention in which an animal is incorporated as an integral part of the clinical healthcare treatment process. Animal-assisted activities (AAAs) provide opportunities for motivational, educational, and/or recreational benefits to enhance a person’s quality of life. Both AAT and AAA are delivered by a trained person.

Animal-Assisted Therapy

AAT is designed to promote improvement in the physical, psychosocial, and/or cognitive function of people who are being medically treated (112). Other terms used in the literature for AAT are “pet therapy” or “pet-facilitated therapy.” In a review of pet-facilitated therapy as an aid to psychotherapy, Draper et al. (113) noted that a literature review conducted in 1987 revealed more than 1,000 articles on the human-animal bond. As of 1983, however, only six studies of the therapeutic value of pets in which controls were used had been reported. They concluded that the benefits of pet therapy rely heavily on anecdotal reports and the widespread attachment of persons with animals. More recently, Allen (114) performed a critical appraisal of the literature from 1986 through 1997 and concluded that most reports describing the effects of human-canine interactions fell into the lowest category of scientific studies (i.e., descriptive studies and expert opinion). Newer research, sometimes using controlled trials, has provided evidence that companion animals provide health benefits in the home setting (115). However, there continues to be a paucity of well-designed clinical trials evaluating the benefits of AAT in the hospital.

The benefits of AAT have been reviewed (116,117,118,119,120,121 and 122). AAT has been most commonly reported to be beneficial among the chronically mentally ill (118,123,124 and 125), geriatric patients (126,127,128,129 and 130), patients with hypertension or coronary artery disease (131,132), and human immunodeficiency virus-infected persons (133).

Several recent articles have reviewed the potential risks associated with AAT in healthcare facilities (87,134,135 and 136). Risks fall into four general areas: reservoir of multidrugresistant human pathogens, animal bites or scratches, allergies, and transmission of a zoonotic infection. The potential risks of bites or acquisition of a zoonotic disease are reviewed later. However, to date, there have been no reports of illness or disease among hospitalized patients associated with a well-designed program that provides AAT.

ANIMALS USED IN HOSPITALS AS RESERVOIRS OF MULTIDRUG-RESISTANT PATHOGENS

Since the last revision of this chapter, there has been a growing literature that animals commonly used as pets or for AAT may be colonized with multidrug-resistant pathogens and that these animals may transmit such pathogens to human contacts (137,138,139). Of particular concern are MRSA, C. difficile, and ESBL-producing gram-negative bacilli (140).

MRSA first emerged as a serious pathogen in human medicine in the late-1970s and has been increasingly reported in animals in the last 10 years (141). Human strains of MRSA have increasingly been described in cats, dogs,
horses, and pigs. A cross-sectional study demonstrated a high prevalence of concurrent MRSA colonization as well as identification of indistinguishable strains in humans and pet dogs and cats in the same household (142). Owners of MRSA-colonized dogs are more likely than owners of non-MRSA-colonized pets to be colonized with MRSA (143). A positive correlation has been demonstrated between the presence of a cat in the home and isolation of MRSA from surfaces (144,145). Recently, 2 of 11 resident cats of a longterm care facility were found to be colonized with MRSA (146). It appears that humans are generally the vector for animal colonization (141). For example, a pet therapy dog appears to have been colonized by MRSA after visiting the geriatric wards (147). In a longitudinal study of dogs involved in AAT in healthcare facilities, Lefebvre et al. (148) demonstrated a rate of MRSA acquisition that was 4.7 times higher than in dogs involved in other animal-assisted interventions. However, animal-to-human transmission has been suggested. For example, Manian reported recurrent MRSA infection in a patient with diabetes and in his wife. The nares of the family dog were colonized with an identical strain of MRSA. Recurrence of MRSA infection and nasal colonization in the couple was halted only following successful eradication of MRSA from the dog’s nares (149). Similarly, Cefai et al. described a colonized dog that was implicated as reservoir for reinfection of two nurses after their treatment to eliminate MRSA carriage (150). To date, the available data on MRSA transmission between humans and companion animals are limited, and the public health impact of such transmission needs to be the subject of more detailed epidemiologic investigations (151).

The incidence of C. difficile infection in the United States has been noted to be increasing over the last decade in association with the emergence of a new, hypervirulent stain (NAP1/BI/O267) (152). C. difficile is both a commensal microorganism and a pathogen in domestic and food animals (153). Recent studies have found considerable overlap among bovine, equine, porcine, canine, and human isolates (153,154). Toxigenic strains of C. difficile have been isolated from companion dogs, and dog colonization with C. difficile was associated with living with an immunocompromised individual (155). Human strains of C. difficile have been isolated from the stool (156) and paws (157) of pet therapy dogs.

ESBL-producing gram-negative bacilli have been isolated from animals (140). Recently, acquisition of a multidrug-resistant E. coli from a dog bite was reported (158).

DISEASES TRANSMITTED BY ANIMAL BITES

Animal bites are a major public health problem (159,160). National estimates based on a 1994 national telephone survey of randomly selected households revealed 4.7 million dog bites, of which approximately 799,700 necessitated medical attention (161). These numbers corresponded to an annual incidence rate of 18 per 1,000 and bites requiring medical attention 3 per 1,000 (adults 2 per 1,000 vs. children 6.4 per 1,000). A follow-up survey from 2001 to 2003 revealed that an estimated 4.5 million people were bitten each year (162). Compared with 1994, the incidence of dog bites among adults remained relatively unchanged whereas the incidence among children declined by 47%. Overall, 19% of dog bites required medical attention. Although most bite wounds are trivial and most victims do not seek medical attention (162), bite wounds have been reported to account for approximately 1% to 2% of all emergency department visits in the United States (162,163,164,165,166 and 167). More precise population-based estimates are available from a 1992 to 1994 National Center for Health Statistics survey, which reported that 334,000 dog-related injuries were seen in US emergency departments for a rate of 129 per 100,000 persons (164). More recent data from the National Electronic Surveillance System-All Injury Program for the year 2001 revealed that an estimated 368,245 persons were treated in US emergency departments for dog bite-related injuries (rate: 129.3 per 10,000 population) (168). This is slightly lower than the rate of 158 per 10,000 population reported from the 2001 to 2003 national cross-sectional telephone survey (162). Although most bites produce only minor injury, at least 10% require suturing (169), and 1% to 5% required hospitalization (164,167,169,170,171,172 and 173). An estimated 5,991 hospitalizations resulted from dog bites in 1994 (173). Between 1991 and 1998, 6,676 hospitalizations in California resulted from dog bites (174). Attacks by dogs resulted in at least 25 deaths between 1995 and 1996 (175) and 27 deaths between 1997 and 1998 (176). Between 1979 and 2005, an average of 19 deaths were reported annually from dog bites (177). In summary, dog bites result annually in an estimated 17 to 19 deaths, 6,000 to 13,000 hospitalizations, and more than 330,000 emergency department visits, with the total costs of treating these injuries being $235,600,000 to $253,700,000 (173,177). Because of its medical importance, the epidemiology, clinical management, and prevention of bite wounds have been extensively reviewed (165,171,178,179,180,181,182,183,184,185,186,187,188,189 and 190).

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Tags: Hospital Epidemiology and Infection Control

Jun 22, 2016 | Posted by drzezo in GENERAL & FAMILY MEDICINE | Comments Off

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