Luís Tavares Veterinarian Professor , Faculdade de Medicina Veterinária, Universidade de Lisboa The benefits for humans of their interaction with pets are widely known, namely to their health, for example: Psychological , as pets contribute to overcome loneliness, fight stress, depression, affective or emotional needs; Physical , for counteracting a sedentary lifestyle, thus contributing to prevent obesity, cardiovascular diseases, among others. Interaction with animals is more and more used as therapeutic , preventive and rehabilitation tool in several psycho-motor diseases. The benefits of interaction with pets are also demonstrated: In the development and educational process of children and young people; In the quality of life of the elderly, due to its usefulness in delaying intellectual and cognitive capacities decline in geriatric ages. Potential problems of living with animals The close contact with different species of companion animals can represent an increased risk of exposure to infectious agents to Man, namely those that are responsible for causing zoonoses , that is, diseases that are transmitted from animals to Man and and from Man to animals. This issue is even more relevant when the people involved have a vulnerable health, as is the case of immunocompromised people (who have their immune defenses reduced); Several clinical situations may be responsible for decreasing immune defenses, such as infections by the human immunodeficiency virus (HIV), patients undergoing cancer treatments, with cytostatic drugs, or those transplanted undergoing immunosuppressive treatments. The perception of this increased risk can lead to decisions or advice that the relationship with pets should be ended or not started. If this happens: The reciprocal benefits of living with animals are lost; Psychological vulnerability can be increased in people who, due to their illness, already have weaknesses and who would really have an emotional benefit from living with their animals. Thus, we must be aware of the real risks and the ways to minimize or even eliminate it, so that, whenever possible, those patients are not hindered of interacting with their animals. What are the diseases transmissible to man by animals There are hundreds of diseases with known zoonotic potential , some with a viral cause and many with bacteria, fungi, or parasite causes. Despite this multiplicity of possible situations of imminent risk of contagion from animals, the cases in which this contagion effectively resulted in serious illness or even death of the intervening are proportionally scarce. Diseases caused by viruses Except for rabies, most viruses that cause disease in dogs or cats are not, as a rule, transmitted to humans. Viruses that are common in dogs and, as such, are covered in vaccination programs - infectious gastroenteritis, canine distemper, hepatitis, para-influenza, among others -, are specific to dogs, are not transmitted to humans and do not pose any risk, even for immunocompromised patients. However, there are some viral diseases transmissible by rodents to humans , such as the virus that causes lymphocytic choriomeningitis, or the Hanta virus that can cause a serious illness in humans. Diseases caused by bacteria, fungi, or parasites Most zoonoses caused by bacteria, fungi or parasites are an effective risk of potential transmission from pet animals. This transmission can occur : By direct contact with the infected animal or with their feces, urine and other excretions; Contamination of water or food consumed by humans with biological material from infected animals. It turns out that this second type of contamination can occur even in people who do not have any pets , for example: By stepping on the street feces of an infected animal it is possible to contaminate the environment and the people who live in the same house; Through vector insects, for example flies that land on food, after having landed on feces, urine and other excretions of infected animals. For most of these zoonoses there are effective treatments both for animals and people, if the diagnosis is made early. An exception are multidrug-resistant bacteria, which are currently a very serious public health concern. However, there are many other situations in which there is a greater risk of contamination with a multidrug-resistant bacteria, than the contact with a pet. In addition, anyone who contacts an immunocompromised patient may pose a risk as great or greater than that of a pet animal. How to prevent disease transmission Most of the transmissions from pets to people can be completely avoided or minimized by complying with some basic hygiene and safety rules . These rules are usually advised by veterinarians assisting animals and include: Do not buy a pet in places where there are a lot of animals and different species and do not bring them into the family environment before taking them to the veterinarian; Keep the animal properly cleaned, regularly dewormed, and vaccinated according to the prevention plan defined by the veterinarian; Never feed animals with raw meat (because it is a potential source of contamination with several pathogens), cook food and, whenever possible, use a correctly formulated and processed commercial feed; Plan an animal training or education plan focused on preventing the animal from becoming aggressive, as the transmission of many of the potential zoonoses may be associated with scratches or animal bites. The training should also aim to counter the tendency that animals, especially dogs, have to eat things they pick up in the street, like food scraps, other animal feces, or to drink in ponds of stagnant water; Avoid direct contact with animal feces and urine and use gloves and a protective mask whenever it is necessary to manipulate or clean it; Never allow pets to share a bed or even a bedroom with people and avoid any direct contact of your face or mouth with the animal; Wash your hands carefully whenever you contact the animal and especially before eating; Particularly in the case of cats, keep their nails properly cut to avoid wounds resulting from playing with the animal; If any family member is immunocompromised, avoid having exotic animals, namely reptiles, rodents of unknown origin or any animal of a species whose behavior with their owners may be unpredictable. These rules are intended to keep pets healthy and should be followed whenever animals live in the same house with people, regardless whether someone is immunocompromised in the family. If strictly carried out, these rules will make dispensable the radical measures related with contact between immunocompromised people and animals , which can be much more harmful to both than prevent any possible contagion. The prevention of disease transmission from animals to man is currently based on measures and policies of One Health , which ideally should increasingly involve a joint work of doctors and veterinarians. You should also know that The relationship between man and animals is ancient and has been happening for the entire history of human civilization since the most primitive times. Man has used animals to help him with different tasks, to transport him, to feed him, to dress him and as companions. In modern times, although there is a tendency to decrease some of these uses, there has been an huge increase of people who seek the company of animals and keep them as pets. Although dogs and cats were by far the most chosen animal species as pets, today there is a growing number of other species used as “new companion animals” which include the rabbit, the hamster, the guinea pigs and other rodents and also exotic animal species such as ferrets, different birds, reptiles, such as turtles and iguanas, among others. Take all the precautions and continue to enjoy the company of animals. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
