Vet Times The website for the veterinary profession https://www.vettimes.co.uk AIDS, CANINES AND ZOONOSES: RISKS AND BENEFITS OF VISITS Author : Katharine M Evans Categories : Vets Date : April 20, 2009 Katharine M Evans explains how a few simple precautions can help to reduce some of the zoonotic risks when introducing dogs to patients with HIV/AIDS ACQUIRED immune deficiency syndrome (AIDS) is caused by the human immunodeficiency virus (HIV), a retrovirus. HIV infection causes a gradual decrease in the number and proportion of CD4+ T-lymphocytes, and thus severely compromises cell-mediated immunity. AIDS is the clinical condition of an immune system that is so compromised by HIV infection, there is an inability to protect against the growth of low-grade pathogens or viral-induced tumours. A 1991 study looked into the role of companion animals in the lives of people who had HIV/AIDS and concluded that animals provided the affection, support, nurturance and acceptance that were otherwise often totally absent in the lives of most of these individuals (Carmack, 1991). Many AIDS patients in a residential care centre will have had to give up much-loved pets to enter such a facility as their health deteriorated. Studies have shown that 20 to 30 per cent of people with HIV/AIDS may also have diagnosable depression (Olatunji et al, 2006). Other studies have found significant relationships between depressive symptoms and HIV disease progression, with depression associated with declines in CD4+ cell counts over time (Burack et al, 1993). 1 / 9
In a survey at the UCLA Medical Center, patients with diverse conditions reported that dog visits made them feel happier and calmer, more loved and less sad and anxious. Decreasing the prevalence of depression and anxiety can be viewed as increasing a patient s quality of life. As there is no cure, a key goal in the treatment of patients with HIV/AIDS is to maintain as high a quality of life as possible, and to address their emotional and social needs. However, the clear benefits of dog visits to AIDS patients must be balanced against the potential for transmitting infectious diseases. Zoonoses Opportunistic infections are a significant risk for people with HIV/AIDS, and zoonotic organisms are often involved. Indeed, it was the occurrence of five deaths due to overwhelming Pneumocystis carinii (a zoonotic fungus) pneumonia in Los Angeles in 1981 that first led to the recognition of AIDS. The risk of developing opportunistic infections increases as CD4+ counts decrease, especially when counts are less than 200 cells/5l. The most significant zoonoses in the UK that can be potentially acquired from dogs are shown in Table 1. Apart from several zoonoses that may be acquired from other companion animal species, other zoonotic infections reported in immunodeficient patients (such as pneumocystosis and cryptococcosis) are probably acquired from environmental exposure, rather than animal contact. It should be borne in mind that dogs can also act as mechanical vectors for non-zoonotic infectious agents, and thus have the potential to spread disease from patient to patient. Dogs should be kept away from patients who are in isolation and/or who are infected with certain organisms, such as methicillin-resistant Staphylococcus aureus (MRSA). Preventing infections It would be prudent to select a single individual to be aware of and record all animals entering the facility. Records should be kept to facilitate contact tracing in the event of potentially zoonotic patient infections, or handler and dog contact with contagious patients. The measures recommended for preventing zoonotic infections as a result of this dog visitation programme fall into two broad categories. The first consists of measures to minimise the risk of the dogs becoming infected with these organisms. The second consists of protocols to prevent the transmission of these organisms from dog to patient in the event of an infection occurring in a dog. Only adult dogs should be used, as their behaviour will be more predictable and they present a lower zoonosis risk. The dogs to be used in this programme should be screened and trained to ensure that they are able to tolerate the equipment and the environment, and should be trained not to lick, scratch or bite. 2 / 9
The dog should receive a health check from a veterinary surgeon every six months, and the veterinarian should be informed that the animal might visit immunocompromised patients. During the health check, particular attention should be given to dental health and eye, ear or nose conditions. Due to the vulnerability of AIDS patients to opportunistic infections, it would be worth performing faecal flotation and culture at these health checks to monitor for Cryptosporidium, Giardia species, Salmonella, Campylobacter and endoparasites. It is important that the owner of the dog adheres to an appropriate flea, tick and enteric parasite control programme for his or her pet. A suitable regime for endoparasite prophylaxis would include a combination of praziquantel, pyrantel and febantel every three months. Flea and tick control can be achieved by the monthly application of an ectoparasiticide, such as fipronil. Each dog should be vaccinated according to the current recommendations against canine distemper virus, canine adenovirus type one and two, canine parvovirus, canine parainfluenza virus, Leptospira interrogans serovars canicolaand icterohaemorrhagiae,and Bordetella bronchiseptica. Vaccination against B bronchiseptica requires detailed management. Currently, a live vaccine is used, and the dog may be able to transmit the vaccine strain during the period of active infection and viraemia after vaccination. For this reason, the manufacturers of the vaccine state that immunocompromised individuals should avoid any contact with the vaccine and vaccinated dogs for up to six weeks after vaccination (NOAH, 2006). Therefore, dogs must not take part in this programme for six weeks after vaccination against B bronchiseptica. It is recommended that dogs that have travelled abroad are not used in this programme, to prevent the introduction of more exotic pathogens, such as Leishmaniaspecies. For this reason, vaccination against rabies is considered unnecessary. It has been suggested that dogs that come into contact with immunocompromised people should receive routine dental prophylaxis with scaling or brushing. Any dog that has been unwell for any reason should be withdrawn from visiting for at least one week after the resolution of symptoms. If any dog develops diarrhoea, a faecal sample should be obtained for Salmonella and Campylobacterculture. It should also be examined for Cryptosporidium and Giardia species. The canine diets to be used in this programme are extremely important in limiting faecal-oral pathogens. Only commercial diets that have been cooked or pelleted should be fed. The dogs should not be allowed to scavenge, hunt or eat other animals faeces. They should be given water that is fit for human consumption and prevented from drinking outside surface water or toilet bowl water. Dogs should be bathed regularly with antiseptic shampoos. Their coats should be brushed before a visit to remove as much loose hair, dander and other debris as possible this is also a good time 3 / 9
to visually inspect for fleas and ticks. The dogs nails should be kept short and free of sharp edges. Dog handlers should only have one dog with them at a time, and should be instructed that patients should not be left unattended with their dog. They should approach the patient from the side that is free of any invasive devices, such as intravenous catheters. The dog should be prevented from contacting any insertion sites, open or bandaged wounds, surgical incisions or other breaches in the skin. The dog should also be prevented from licking or bumping against medical devices. The handler should discourage patients and staff from shaking the dog s paw. Obviously, the dog s paws will come into contact with areas such as the floor of the ward, the corridor and the ground outside the building and, as such, may carry a variety of different organisms. All visiting dogs should be prevented from entering areas where food and/or medication is prepared or stored. They should also not be allowed to enter patients bathrooms and lavatories. Handlers should be instructed not to visit patients while they are eating or drinking, and not to permit a patient to eat or drink while interacting with the dog. If a patient requests that a dog be placed on his or her bed, the handler should place a disposable, impermeable barrier between the animal and the bed this should then be thrown away after each patient interaction period. Perhaps the single most important infection-control procedure is strict hand washing, and the best method for this should be taught to any patients, visitors and staff who come into contact with the dogs, as well as to the handlers. All individuals should wash their hands thoroughly before and after each animal contact. This is especially important for AIDS patients before eating, smoking, cleaning their teeth or putting in contact lenses. It is recommended that handlers carry an alcohol-based hand rub with them, and that this is offered to anyone who has touched the dog. However, this is an adjunct to rather than a substitute for thorough hand washing. Any dog bites or scratches that occur should be reported to healthcare staff immediately, so that wounds can be cleaned and treated promptly. Antimicrobial prophylaxis may be considered. Any dog that has bitten or intentionally scratched a patient, visitor or staff member must be withdrawn from the programme. If a dog urinates or defecates in the ward, the material should be disposed of as clinical waste and the incident immediately reported to healthcare staff, so that the area can be properly disinfected promptly. The visit should be terminated and appropriate measures taken to prevent recurrence during future visits. After a dog visit, the routine cleaning of surfaces should be performed with an appropriate antiseptic. Conclusion 4 / 9
The clear benefits that dog visits to residential care facilities can offer to AIDS patients far outweigh the potential risks of zoonotic infection, as a number of relatively simple measures can be taken to minimise the risks that such visits entail. These measures also apply to dog visits to other immunocompromised individuals, such as some cancer patients, and this information could be modified to advise immunocompromised pet owners on how to minimise the risks they face. References Burack J H, Barrett D C et al (1993). Depressive symptoms and CD4 lymphocyte decline among HIV-infected men, Journal of the American Medical Association 270: 2,563-2,568. Carmack B J (1991). The role of companion animals for persons with AIDS/HIV, Holistic Nursing Practice 5: 24-31. Glaser C A, Angulo F J and Rooney J A (1994). Animal-associated opportunistic infections among persons infected with the human immuno deficiency virus, Clinical Infectious Diseases 18: 14-24. Gorbach S L and Bartlett J G (1998). Zoonotic diseases in immunocompromised patients. In Gorbach S L, Bartlett J G and Blacklow N R (eds), Infectious diseases(second edn) WB Saunders, Philadelphia: 1,542-1,545. Hemsworth S and Pizer B (2006). Pet ownership in immunocompromised children a review of the literature and survey of existing guidelines, European Journal of Oncology Nursing 10: 117-127. NOAH (2007). Compendium of Data Sheets for Animal Medicines. Olatunji O, Mimiaga M P H et al (2006). A review of treatment studies of depression in HIV, Topics in HIV Medicine 14(3): 112-124. 5 / 9
The benefits of dog visits to patients must be balanced against the potential for transmitting diseases, the author says. Photo: SXC/ILKER. 6 / 9
All individuals should wash their hands before and after each animal contact. Alcohol-based hand rubs are recommended. Photo: SXC/DANI TOTH. 7 / 9
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Powered by TCPDF (www.tcpdf.org) Table 1. Zoonoses potentially transmitted by dogs, shown in order of frequency of occurrence in HIV-infected patients 9 / 9