Pet ownership in immunocompromised children—A review of the literature and survey of existing guidelines

ARTICLE IN PRESS European Journal of Oncology Nursing (2006) 10, 117–127

www.elsevier.com/locate/ejon

Pet ownership in immunocompromised children—A review of the literature and survey of existing guidelines S. Hemsworth, B. Pizer Oncology Unit, Royal Liverpool Children’s NHS Trust, Eaton Road, Liverpool, UK

KEYWORDS Animals-domestic; Zoonoses; Animals; Immunocompromised-host; Disease; Risk

Summary Pet ownership has been associated with both emotional and physical health benefits. However, owning pets may also pose health risks to immunocompromised patients through zoonotic transmission of disease. Our initial impression was that there is a lack of any evidence base in information given by health care professionals regarding these risks. We therefore aimed to produce evidence-based guidelines addressing this issue. A Pubmed search was undertaken and a variety of literature on zoonoses reviewed. Existing guidelines were evaluated and a survey of all Paediatric Oncology Centres in the UK performed. There is a paucity of level 1 and 2 data addressing this issue and clearly more studies, particularly Randomised Controlled Trials (RCTs), are required. Nevertheless, general themes emerged and certain specific guidance was produced based on that produced by the Centres for Disease Control and Prevention in the US. Animal-associated pathogens of concern include Toxoplasma gondii, Cryptosporidium spp., Salmonella spp., Campylobacter spp., Giardia lamblia, Rhodococcus equi, Bartonella spp., Bordetella bronchiseptica, Chlamydia psittaci and dermatophytes. Despite this, the literature would suggest that with the exception of Bartonella henselae and dermatophytes only a relatively small number of infections in people are likely to be associated with pet contact. The majority of pet species do not appear to pose a major risk to immunocompromised children. Some animals, particularly reptiles, should be avoided because of the high risk of salmonellosis. Guidelines include general advice on good hygiene practices, veterinary care, pet foods, purchasing of new pets and age restrictions. Health care professionals should actively enquire about household pets and provide accurate information and practical advice on how to minimise the risk of infection. However, the overall benefits of the human–animal bond must be considered and with proper handling and husbandry immunocompromised patients should be able to continue to enjoy the significant benefits of pet ownership. & 2005 Elsevier Ltd. All rights reserved.

Corresponding author. Tel.: 0151 252 5971; fax: 0151 252 5676.

E-mail address: [email protected] (S. Hemsworth). 1462-3889/$ - see front matter & 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.ejon.2005.08.001

ARTICLE IN PRESS 118

S. Hemsworth, B. Pizer Zusammenfassung Der Besitz eines Haustieres hat offenkundig positive Auswirkungen auf den psychischen und ko ¨rperlichen Gesundheitszustand des Haustierbesitzers. Bei Patienten mit abgeschwa ¨chtem Immunsystem stellen Haustiere jedoch ¨ bertragungen zoonotischer Krankheitserreger potentielle aufgrund mo ¨glicher U Gesundheitsrisiken dar. Wir haben festgestellt, dass es fu ¨r Informationen, die von Medizinern bezu ¨glich dieser Risiken erteilt werden, bislang nahezu keine wissenschaftlichen Belege gibt. Daher haben wir uns zum Ziel gesetzt, evidenzbasierte Richtlinien zu dieser Fragestellung zu entwickeln. Es wurde eine PubMed-Recherche durchgefu ¨hrt und die Fachliteratur u ¨ber Zoonosen gesichtet. Des weiteren wurden vorhandene Richtlinien evaluiert, und es erfolgte ein Survey sa ¨mtlicher kinderonkologischer Zentren in Großbritannien. Es besteht ein Mangel an Level-1- und Level-2-Daten zu dieser Fragestellung. Ohne Zweifel sind weitere Studien erforderlich, insbesondere randomisierte kontrollierte Studien. Nichtsdestoweniger kristallisierten sich einige allgemeine Leitgedanken heraus, und es wurden relativ pra ¨zise Anleitungen erarbeitet, welche auf denjenigen der US-amerikanischen Centers for Disease Control and Prevention basieren. Zu den Infektionserregern, die bei Tierkontakten u ¨bertragen werden ko ¨nnen, za ¨hlen Toxoplasma gondii, Cryptosporidium spp., Salmonella spp., Campylobacter spp., Giardia lamblia, Rhodococcus equi, Bartonella spp., Bordetella bronchiseptica, Chlamydia psittaci sowie Dermatophyten. Aus der Fachliteratur geht jedoch hervor, dass abgesehen von Infektionen durch Bartonella henselae und Dermatophyten wahrscheinlich nur wenige menschliche Infektionen durch Kontakte mit Haustieren verursacht werden. Die Mehrzahl der Haustierarten stellt fu ¨r Kinder, die an einer Immunschwa ¨che leiden, kein gro ¨ßeres Risiko dar. Auf einige Tiere, insbesondere Reptilien, sollten jedoch wegen des relativ hohen Salmonellose-Risikos verzichtet werden. Die Richtlinien enthalten unter anderem Informationen zu Hygienefragen, tiermedizinischer Versorgung, Futter fu ¨r Haustiere, den Kauf neuer Haustiere sowie Alterseinschra ¨nkungen. Mediziner mu ¨ssen gezielt danach fragen, ob in dem betreffenden Haushalt Haustiere vorhanden sind. Sie mu ¨ssen pra ¨zise Informationen und praktische Ratschla ¨ge erteilen, wie das Risiko von Infektionen mo ¨glichst gering gehalten werden kann. Dabei sind jedoch die Vorteile der emotionalen Bindung zwischen Mensch und Tier zu beru ¨cksichtigen. Bei ada ¨quatem Verhalten und korrekter Tierhaltung ko ¨nnen auch Patienten mit Immunschwa ¨che die signifikanten Vorteile nutzen, die sich aus dem Besitz eines Haustieres ergeben. & 2005 Elsevier Ltd. All rights reserved.

Introduction Pet ownership has been associated with both emotional and physical health benefits. The bond between humans and animals has been recognised for many years. It has now been widely accepted that pets bring a unique sense of stability, love and continuity to people’s lives and some studies indicate that pets can have a positive influence on the quality of life (Spencer, 1992). There has also been an increase in the popularity of urban (city) farms and petting zoos; the aim of which is to enable city-dwelling children to become involved with animals. Whilst the emotional benefits of pet ownership are recognised, it is also known that some animals can transmit zoonotic diseases and these may pose serious health risks especially in young children, the elderly, pregnant women, organ recipients and immunocompromised

patients. The World Health Organisation defines ‘‘zoonoses’’ (Zoonosis, singular) as ‘‘Those diseases and infections, which are naturally transmitted between vertebrate animals and man’’ (WHO, 1959). With regards to cancer patients, both children and adults, there are no formal guidelines in the UK for safe pet handling whilst on chemotherapy and historically much advice seems to be ‘‘physician’s preference’’, with little evidence behind such decisions. We therefore decided to review the literature on zoonoses and whether they posed any threat to immunocompromised patients and to look for any guidelines produced. From our review we aimed to identify any risks to immunocompromised patients associated with pet ownership and to produce guidelines, evidence-based where possible, for staff and families on reducing the risks of animal acquired infections.

ARTICLE IN PRESS Pet ownership in immunocompromised children

Methods Literature search: A Pubmed search was undertaken on zoonoses and studies of zoonotic infections in immunocompromised patients. UK survey: A survey of paediatric oncology units in the UK was carried out to establish if there were any existing written evidence-based guidelines in use in these units. Expert advice: In recognition of the importance of veterinary advice, communication took place with veterinarian specialists based in the UK and USA. Existing guidelines: We looked to see if any evidence-based guidelines already existed.

Results Whilst a wealth of information is available on general zoonoses, there appear to be no randomised controlled trials on the subject. Zoonotic infections encompass a wide range of viral, bacterial, parasitic and fungal infections. Over 250 organisms are known to cause zoonotic infections (Greene, 1995) and whilst this list is formidable, many of the diseases are rare and the chances of humans contracting a zoonotic disease are small. The vectors of many zoonoses are not necessarily household pets, only approximately 30–40 vectors (Wong and Feinstein, 1999). These may include humans, farm animals, feral and exotic animals sold as pets; however, of these only a selective few have been reported with greater frequency in people with immunodeficiency and AIDS (Greene, 1995). The various modes of transmission are shown below:



  

Ingestion route. J Faeces. J Urine. J Saliva. J Milk. Inhalation. J Aerosol. Direct contact with animals, bedding, etc. Blood-borne.

The most common mechanisms of transmission are by inhalation or ingestion, but transmission may also occur following bites or scratches or by direct contact with arthropods. Many zoonotic agents are found naturally in soil, water or vegetation. Animals may contaminate the environment but in

119 most cases, people and animals acquire infections simultaneously and independently of each other (thus they may not strictly be zoonoses but diseases that man and animals have in common). Therefore, it is likely that most zoonotic infections in immunocompromised patients are acquired from environmental exposure rather than contact with pets (Grant and Olsen, 1999). Table 1 shows an overview, by no means allinclusive, of the more common zoonotic diseases that may be acquired from pet animals. The following infections may be of greatest concern to immunosuppressed people (USPHS, 1997):

     

Campylobacteriosis. Bartonellosis (Cat Scratch Disease (CSD)). Cryptosporidiosis. Giardiasis. Salmonellosis. Toxoplasmosis.

Campylobacteriosis is a disease caused by a group of Gram-negative rods—Campylobacter spp., that are commensal flora of animals. Campylobacter jejuni is frequently isolated from dogs or cats acquired from pet shops, kennels and animal shelters. However, uncooked meat, particularly poultry, is probably the main source of infection. The disease is transmitted via the faecal–oral route from food or water sources. Contaminated water supply, from migrating waterfowl or herbivores may be a source of infection for outdoor pets. Children less than 5 years old with a newly acquired puppy have the highest risk of infection (Salfield and Pugh, 1987). Signs of infection may include intense abdominal pain, bloody diarrhoea, pyrexial, tenesmus and faecal leukocytosis. Immunocompromised patients develop recurrent diarrhoea, dehydration and bacteraemia. Bartonellosis (CSD) is a bacterial infection caused by Bartonella henselae. Cats can spread B. henselae to people by bites and scratches. Lymph nodes, especially those around head, neck and upper limbs become swollen. Headaches, fatigue and poor appetite are also reported. Kittens are more likely to be infected and pass the bacterium to humans (Angelu et al., 1994; Zangwill et al., 1993). About 40% of cats carry the bacterium and do not show signs of illness. Immunosuppressed patients are more likely to have complications of CSD. Although B. henselae has been found in fleas, there is no evidence that a bite from an infected flea may lead to CSD (Koehler et al., 1994; Regenery et al., 1992). Cryptosporidiosis is an intestinal infection caused by a parasite Cryptosporidium parvum. It

Animal Species

Rabbits, rodents

Dogs Cats

Cats

Cats, dogs, ferrets, farm animals, horses

Wild birds (pigeons)

Cats, dogs, farm animals, ferrets, horses

Arthropod infections (Skin mites and ticks)

Ascaridiasis (Roundworm infection)

Bartonellosis (Cat scratch disease)

Campylobacteriosis

Cryptococcosis

Cryptosporidiosis

Mycotic

Cryptococcus neoformans

Parasite

Bacteria

Campylobacter

Faecal–oral route

Isolated from the soil, usually in association with bird droppings Inhalation of airborne yeast cells and/or basidiospores

Generally spread by eating or drinking contaminated food or water, unpasteurised milk, and by direct or indirect contact with faecal material from an infected person, animal or pet (especially puppies and kittens)

Cat scratch, bite

Ingestion of infective eggs in environment

Direct contact with infected animals

Transmission

Watery diarrhoea, accompanied by abdominal cramps. Nausea, vomiting, fever, headache and loss of appetite may also occur. Rarely, the parasite can cause an inflammation of the gall bladder or infect the lining of the respiratory tract causing pneumonia

Initial pulmonary infection is usually asymptomatic. Most patients present with disseminated infection, especially meningoencephalitis

Mild to severe infection of the gastrointestinal system, watery or bloody diarrhoea, fever, abdominal cramps, nausea and vomiting. A rare complication of Campylobacter infection is Guillain–Barre syndrome

Skin Lesions, infection at point of injury, lymphadenopathy

Dependent on organ damaged during larval migration—visual, neurologic or tissue damage

Temporary dermatitis Human infestation is transitory as mites do not reproduce on human skin

Signs and Symptoms

120

Cryptosporidium

Bacteria

Parasite

Parasite

Category

Bartonella henselae

Toxicara canis Toxicara catis Toxascaris leonina

Sarcoptes mange mite Cheyletidae Dermanyssidae Macronyssidae Trixacarus caviae

Organism

Zoonoses potentially transmitted by pets and petting/farm animals.

Disease

Table 1

ARTICLE IN PRESS S. Hemsworth, B. Pizer

Cats, cows, dogs, goats, horses, pigs, rabbits, rodents

Cows

Dogs, ferrets

Cats, dogs

Ferret

Fish

Rabbit rodents

Birds

Horses

Dermatophytosis (ringworm)

E. coli

Giardiasis

Hookworm

Influenza

Mycobacteriosis

Pasteurellosis

Psittacosis

Rhodococcus equi

Rhodococcus sp

Chlamydia psittaci

Pasteurella multocida

Mycobacterium marinum

Influenza virus

Ancylostoma caninum Ancylostoma braziliense Ancylostoma tubaeform Uncinaria stenocephala

Giardia intestinalis (Giardia lambia)

Escherichia coli 0157

Microsporum cani Trichophyton mentagrophytes

Bacteria

Bacteria

Bacterial

Bacteria

Viral

Parasite

Parasite

Bacteria

Mycotic

R. equi is readily found in soil, especially where domesticated livestock graze. Infection in humans derives from environmental exposure

Inhalation of dried secretions from infected birds

Bites/scratches (bacteria found in mouth of animals)

Aquarium water localised infections following access through broken skin

Via aerosol from infected ferret

Ingestion of infective eggs or contact with contaminated soil

Ingestion of contaminated water or food, faecal–oral route

Ingestion of contaminated food, faecal–oral route

Direct or indirect contact with asymptomatic animals or with skin lesions of infected animals,contaminated bedding

Pneumonia, pulmonary abscesses

Fever, headache, muscle aches, and a dry cough. Pneumonia

Cutaneous infections, bacteraemia

Skin Lesions, disseminated disease in immunocompromised patients

Fever, muscle aches, headache

Pruritic skin lesions Intestinal bleeding, swelling and pain

Diarrhoea, fever, severe abdominal cramps

Severe, bloody diarrhoea Kidney failure

Often mild, self limiting; scaling, redness, and occasionally vesicles or fissures

ARTICLE IN PRESS

Pet ownership in immunocompromised children 121

Reptiles, birds, cats, chicks, dogs ducklings, ferrets, fish, horses, rabbits,

Cats, dogs, rabbits, rodents

Cats

Salmonellosis

Tapeworm

Toxoplasmosis

Toxoplasma gondii

Parasite

Parasite

Bacteria

Salmonella

Dipylidium

Category

Organism

Ingestion of raw or undercooked infected meat, especially pork, lamb, or raw milk containing parasite. The parasite is shed primarily in the faeces of infected cats. Humans can become infected by the ingestion of food, water, or dirt contaminated with cat faeces. Toxoplasmosis can also be acquired through a transplacental infection, when an infected mother passes the infection to her foetus

Ingestion of infected flea

Ingestion of foods contaminated with animal faeces. Faecal–oral route

Transmission

Flu-like symptoms, lymphadenopathy

Proglottids are passed in faeces or are found round anus causing itching

Acute gastroenteritis with sudden onset of abdominal pain, diarrhoea, nausea, and fever. May lead to septicaemia

Signs and Symptoms

Data contained within this table has been obtained predominantly from the following references: Chomel (1992), University of California Institutional Animal Care and use Committee (1996), Centers for Disease Control. National Center for Infectious Diseases (2004).

Animal Species

Disease

Table 1 (continued )

ARTICLE IN PRESS

122 S. Hemsworth, B. Pizer

ARTICLE IN PRESS Pet ownership in immunocompromised children may be acquired from young domestic herbivores (calves, lambs, kids and piglets) with diarrhoea or less commonly pets such as cats and dogs. Environmental exposure is usually from drinking water contaminated by animal or human sewage (Greene, 1995). Immunocompetent people show signs of abdominal pain and self-limiting diarrhoea of 5–10 days, whilst immunocompromised patients may have severe water debilitating chronic diarrhoea which may be refractory to therapy (Glaser et al., 1998). Giardiasis is a gastrointestinal infection caused by the parasite Giardia intestinalis (Giardia lamblia). The parasite survives outside the body and in the environment for long periods of time. It is found in the intestine of animals and is passed on by the faecal–oral route and is also a common cause of waterborne disease. Symptoms include watery, foul-smelling diarrhoea, flatus and stomach cramps. Salmonellosis is a gastrointestinal infection typically from food-borne exposure. Severe recurrent diarrhoea and bacteraemia may result. Contaminated meat and eggs account for many exposures but animals can carry salmonella and pass it in their faeces. Reptiles including both wild and pet lizards, snakes, frogs and terrapins (turtles) are particularly likely to pass salmonellosis to people (Chomel, 1992; Mermin et al., 1997; Bren, 2004). Salmonella infection can also be acquired from farm animals including horses, baby chicks and ducklings (Bren, 2004). Toxoplasmosis is caused by single cell parasite— Toxoplasma gondii. Toxoplasmosis can affect all mammals, including man, as well as birds, amphibians and other reptiles. Certain species appear to be more likely to transmit the disease e.g. the pregnant sheep at the time of birth. Immunocompetent people may carry the toxoplasma parasite but have few symptoms. However, in pregnant women and immunocompromised patients toxoplasma infections can cause serious infection (Guay, 2001; CDC, 2004). The cat is the definitive host most commonly responsible for disease transmission where the disease is acquired by ingestion of oocysts shed by infected cats. However, shedding of cysts is unlikely except when the cat has ill health such as feline leukaemia; cat AIDS, severe diarrhoea or other debilitating illnesses (it can also be a cryptic infection in cats where they shed when first infected). Isolated outbreaks have also been reported following handling or inhaling of soil dust contaminated by cat faeces or contact with cat faeces from a litter tray or flowerbed. It may also be transmitted by eating raw vegetables, salad or fruit contaminated by infected material which has

123 not been washed thoroughly, ingestion of raw or undercooked meats, especially pork, through contamination of utensils, cutting boards and other foods which have been in contact with raw meat, drinking water contaminated with toxoplasma. Manifestations of the disease include ‘‘flu’’-like symptoms, swollen lymph glands, muscle aches and pains. Toxoplasmosis in the immunocompromised may cause damage to the brain or eyes (Riordan and Tarlow, 1996; Kravetz and Federman, 2002). Toxoplasmosis can be transmitted transplacentally if a woman is infected with toxoplasmosis while she is pregnant. Depending on the age of the foetus when it is infected and the virulence of the Toxoplasma, this can result in a spontaneous abortion, a stillborn child, or a child that is born with some degree of mental or physical retardation. In those foetuses that survive the lesions observed are predominantly cerebral, caused by cerebral vasculitis and necrosis. Whilst each of these infections, with the possible exception of Bartonella spp, may be acquired from sources other than pets, these zoonoses are often identified as affecting common pets and have the potential to cause severe and potentially fatal illnesses.

Other considerations Allergies Allergens from the hair, saliva or urine of household pets can cause an allergic reaction in sensitive individuals affecting the eyes and the airways, like hay fever, and can potentiate asthma. The allergens may also cause atopic dermatitis. Unfortunately, the only way to avoid pet allergies is to avoid those animals that provoke them, although this may be difficult in practice. Allergic reactions may also occur from other peoples’ pets or from allergens carried by humans who have been in contact with animals. Studies suggest that animal exposure during infancy actually reduces subsequent allergic sensitisation (Ownby et al., 2002). Parvovirus B19 can cause severe illness in people with certain blood disorders or immunodeficiency. However, Parvovirus B19 only infects humans; it is not the same as the animal parvoviruses. Animal parvoviruses are not transmissible to humans.

Bites and scratches Whilst most bites and scratches are not thought to be life threatening, they can cause pain, anxiety,

ARTICLE IN PRESS 124 wound disfigurement, and wound infections. Many organisms are capable of infecting animal bite wounds including Pasteurella spp., Capnocytophaga canimorsus, Bartonella henselae and quintana, Clostridium tetani, Streptobacillus moniliformis, Spirillum minus, Tularemia, and rabies. Education on wound hygiene is therefore important.

Pet vaccines Administration of live vaccines in immunocompromised and siblings of immunocompromised patients (except MMR and BCG) should be avoided (RCPCH, 2002). However, with regard to pet vaccines, none of the live attenuated vaccines used in the conventional dog and cat vaccines should cause any problems for immunocompromised human patients. In addition other vaccines such as those for leptospirosis, rabies and feline leukaemia are killed vaccines so are non-transmissible and as such poses no risk of infecting people (Bennett, 2002).

Survey of existing advice in oncology centres In February 2003, a written survey was performed of all 22 paediatric oncology centres within the UK to establish if they already had written guidelines for pet ownership and, if they did, on what evidence those guidelines were based. Twenty (91%) surveys were returned. Of these, only four centres said that they used published or locally developed guidelines. These guidelines are, however, limited to brief information in FamilyHeld Record (two centres) or Bone Marrow Transplant (BMT) booklets (two centres). Four additional centres stated that, although they did not have any formal guidelines on their unit, they did give out verbal advice regarding pet ownership. The advice given did not consider specific zoonoses, age of pet or animals which may/may not be kept but concentrated mainly on good hygiene practices such as washing hands, avoiding contact with excreta and promotion of vaccination/deworming programmes. In response to the question of whether they gave different advice for their BMT patients, two of the centres without formal guidelines advised that they did have such advice. This included not obtaining a new pet for 6–12 months post-transplant (one centre) and avoiding reptiles and birds (two centres). Two centres gave written advice about pets in their family held record and two included such advice as part of their post-BMT

S. Hemsworth, B. Pizer advice. Most centres admitted that advice was usually based on ‘‘physician’s preference’’ and such advice varied depending on Consultants and Units. All respondents said they would welcome national guidelines.

Available guidelines The only written evidence-based guidance was produced by the Centres for Disease Control and Prevention (CDC, 1999, 2002). http://www.cdc.gov/mmwr/preview/mmwrhtml/ rr5108a1.htm The CDC produced guidelines for the prevention of opportunistic infections in persons infected with Human Immunodeficiency Virus (HIV) and opportunistic infections among haematopoietic stem cell transplant recipients. The CDC is a Federal Health Agency based in the USA and is part of the Department of Health and Human Services. Other American organisations have produced written advice for people with HIV/AIDS infection (Humane Society of the United States, 1998; Pets are Wonderful Support, 1998; Pet Owners with HIV/AIDS Resource Services, 1995) but these also appear to be based on CDC guidelines or include the same advice.

Royal Liverpool children’s NHS Trust guidelines The 1999 CDC USPHS/IDSA guidelines for the prevention of opportunistic infections in persons infected with HIV (Centers for Disease Control Division of HIV/AIDS prevention, 1999) and CDC 2000 Guidelines for Preventing Opportunistic Infections among haematopoietic stem cell transplant recipients were the most comprehensive set of evidence-based guidance we found. We have, therefore, implemented these at the Royal Liverpool Children’s NHS Trust along with some additional ‘‘local’’ advice. Evidence-based rating system used to determine strength of recommendations is available on the CDC website.

Pet-related risks Health-care providers should advise immunocompromised persons of the potential risk posed by pet ownership. However, they should be sensitive to the possible psychological benefits of pet ownership and should not routinely advise patients to part with their existing pets. Specifically, health

ARTICLE IN PRESS Pet ownership in immunocompromised children care professionals should advise immunocompromised patients of the following precautions. Summary of CDC guidelines (reproduced with kind permission of the CDC).

125



 New pets











New pets should be checked by veterinarian before introducing them to the home as hygienic and sanitary conditions can vary considerably between pet stores, animal breeders and animal shelters. When obtaining a new pet, immunocompromised patients should avoid animals aged less than 6 months (or less than 1 year for cats) especially those with diarrhoea. Animals aged less than 6 months, especially those with diarrhoea, should always be examined by a veterinarian for cryptosporidium, salmonella, and campylobacter. Immunocompromised patients should avoid stray animals, reptiles (snakes, lizards, geckos and terrapins), wild birds and non-human primates such as monkeys. When visiting other households with pets, the same precautions should be taken with those pets. It is important to let friends/family know about these precautions.



 

Pet bedding such as blankets should be cleaned at least once a week and hutches/cages cleaned regularly by immunocompetent persons in order to reduce risk of exposure to faeces. Pet faeces should be placed in plastic bags and put in the household rubbish. Litter trays should be kept away from eating areas and kitchens and changed daily (bearing in mind it takes toxoplasmosis 24 h to become infectious). An immunocompetent person should change trays. Trays should be disinfected at least once a month by filling with boiling water and leaving to stand for 5 min, which will kill any toxoplasma organism.

Diet

  

Pets should not be allowed to hunt or feed from rubbish bins but maintained on a commercial diet for their species. If supplementary food is given, ensure that all egg, poultry and meat products have been adequately cooked before feeding. Pets should be given water that is fit for human consumption.

Pet health care

Animal-specific advice

 

Cats



All new pets should be examined by a vet. Families need to know what vaccinations and worming/flea control programmes are needed and these programmes must be kept up to date. Veterinary care should always be sought whenever a pet develops diarrhoea or respiratory illness. Immunocompromised persons should always avoid contact with animals that have diarrhoea. A faecal sample should be obtained from animals with diarrhoea and examined for Cryptosporidium, Salmonella, and Campylobacter.

 



Hygiene

  



Pets should be kept cleaned and brushed in order to keep the skin and coat healthy. Nails should be clipped short, to minimise risk of scratches (de-clawing is not recommended). Patients should wash their hands after handling pets (especially before eating) and avoid contact with pets’ faeces to reduce the risk for cryptosporidiosis, salmonellosis, and campylobacteriosis. Hand washing for immunocompromised children should always be supervised.





Patients should be aware that cat ownership increases their risk for toxoplasmosis and Bartonella infection, as well as enteric infections. Families who choose to obtain a cat should adopt or purchase an animal that is aged greater than 1 year and in good health to reduce the risk for cryptosporidiosis, Bartonella infection, salmonellosis, and campylobacteriosis. To reduce the risk for toxoplasmosis, immunocompromised patients should keep cats indoors, not allow them to hunt, and not feed them raw or undercooked meat. Some of the highly publicised infections shown in AIDS patients such as toxomplasmosis are due to reactivation of previous infections acquired from meat and do not relate to current pet exposures (Greene, 1995). Although declawing is not generally advised, immunocompromised patients should avoid activities that might result in cat scratches or bites to reduce the risk for Bartonella infection.

ARTICLE IN PRESS 126

  

Patients should wash sites of cat scratches or bites promptly and should not allow cats to lick the patients’ open cuts or wounds. Care of cats should include flea control to reduce the risk for Bartonella infection. Testing cats for toxoplasmosis or Bartonella infection is not recommended.

Birds

   

Screening healthy birds for Cryptococcus neoformans, Mycobacterium avium, or Histoplasma capsulatum is not recommended. Any bird that looks unwell should be checked out immediately by a veterinary surgeon. Contact with wild birds and their droppings should be avoided. Immunocompetent person should clean the linings of birdcages daily.

Other

  

Contact with reptiles (e.g., snakes, lizards, iguanas, and turtles) should be avoided to reduce the risk for salmonellosis. Immunocompromised persons should not clean out aquaria to reduce the risk for infection with Mycobacterium marinum. Contact with exotic pets (e.g., non-human primates) should be avoided.

Additional local advice

S. Hemsworth, B. Pizer

Conclusions Zoonosis among immunocompromised patients is an important issue. There is, however, a paucity of levels 1 and 2 evidence addressing the risks and clearly further research is required. General themes have emerged from the available evidence and certain specific guidance, based on CDC guidelines, has been produced. The majority of pets do not appear to pose any greater risk to immunocompromised patients than would interaction with other people or the environment. Misconceptions about pet-acquired illnesses may cause newly diagnosed families to get rid of their pets unnecessarily. It may be more detrimental to the well being of the immunocompromised patient to lose a beloved pet than to potentially risk acquiring a zoonotic infection. Potential risks are made greater by the unique organisms some animals carry and by poor hygiene measures. The vectors of many zoonoses are not necessarily pets but may include humans, farm animals, exotic and wild animals and whilst there is no way to completely eliminate exposure or transmission of zoonotic diseases there are ways to reduce the possibility of transmission. Educating pet owners on zoonosis prevention can help them make more informed decisions about risks and benefits of owning a pet. However, the overall benefits of the human–animal bond must be considered and in general immunocompromised patients should be able to continue to enjoy the significant benefits of pet ownership.

Acquisition of new pets

Acknowledgements

Whilst we would not advise families to get rid of existing pets, we would generally recommend that new pets are not acquired after diagnosis. If families do choose to adopt a new pet, an adult animal is safer. Families should always consult their Consultant Oncologist and veterinarian before adopting any new animal.

The authors would like to acknowledge the expert help of the following people:

First aid If bitten or scratched by any animal, the wound or scratch must be washed straightaway with plenty of cool running water. The area should be cleaned with Hibiscrubs (chlorhexidine glucconate which has both antibacterial/antifungal properties) and dried with clean dry gauze. The Oncology Unit should be informed.

Dr Lisa Conti, Director, Division of Environmental Health, Florida, USA. Dr Malcolm Bennett, Faculty of Veterinary Science, University of Liverpool, England. Dr Ashley Robinson, Associate Dean (Preclinical Programs), College of Veterinary Medicine, Western University of Health Sciences, California, USA.

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