Disease transmission from animals to humans is possible for children who interact with pets or with wild or domestic animals. Important zoonoses that may be encountered in North America, the common animal source or vector, and major modes of transmission are reviewed in disease-specific chapters in Section 3 and are listed in Appendix X . Most households in the United States contain one pet or more. The number of families with nontraditional pets, defined as (1) imported, nonnative species or species that originally were nonnative but now are bred in the United States; (2) indigenous wildlife; or (3) wildlife hybrids (offspring of wildlife crossbred with domestic animals), has increased in recent years. Infants and children also come in contact with animals at many venues outside the home, including zoos, farms, shopping malls, schools, hospitals, animal swap meets, agricultural fairs, and petting zoos. Examples of nontraditional pets and animals commonly encountered in public settings are listed in Table 2.21.

Table 2-21

Exposure to animals can pose significant infection risks to all people, but children younger than 5 years of age, pregnant women, the elderly, and people of all ages with immunodeficiencies are at higher risk of serious infections. The increased infection risk for children younger than 5 years of age is attributable, in part, to children's less-than-optimal hygiene practices and developing immune systems. Children younger than 5 years of age also are at increased risk of injury from animals because of their size and behavior. Bites, scratches, kicks, falls, and crush injuries to hands or feet or from being pinned between an animal and a fixed object can occur.

Nontraditional pets pose a potential risk of infection and injury. Most imported nonnative animal species are caught in the wild rather than bred in captivity. These animals are held and transported in close contact with multiple other species, thus increasing the transmission risk of potential pathogens for humans and domestic animals. Some nonnative animals are brought into the United States illegally, thus bypassing rules established to reduce introduction of disease and potentially dangerous animals. In addition, as an animal matures, its physical and behavioral characteristics can result in an increased risk of injuries to children. The behavior of captive indigenous wildlife and wildlife hybrids cannot be predicted. These potential risks are enhanced when there is an inadequate understanding of disease transmission and methods to prevent transmission; animal behavior; or how to maintain appropriate facilities, environment, or nutrition for captive animals. Among nontraditional pets, reptiles pose a particular risk because of high carriage rates of Salmonella species, the intermittent shedding of Salmonella in their feces, and persistence of Salmonella organisms in the environment. The US Food and Drug Administration ban on commercial distribution of turtles with shells less than 4 inches long in 1975 resulted in a sustained reduction of human Salmonella infections. Salmonella infections also have been described as a result of contact with hedgehogs, hamsters, and rodents and with baby chicks and other baby poultry, including ducklings, goslings, and turkeys.

Infectious diseases, injuries, and other health problems can occur after contact with animals in public settings. Enteric bacteria and parasites pose the highest infection risk. Individual cases and outbreaks associated with Salmonella species, Escherichia coli O157:H7, Campylobacter species, Giardia species, and Cryptosporidium species have been reported. Ruminant livestock (cattle, sheep, and goats) are the major source of infection, but poultry, rodents, and other domestic and wild animals also are potential sources and often are asymptomatic carriers of potential human pathogens. Direct contact with animals (especially young animals), contamination of the environment or food or water sources, and inadequate hand hygiene facilities at animal exhibits all have been implicated as reasons for infection in these public settings. Unusual infection or exposure has been reported occasionally; rabies has occurred in animals in a petting zoo, pet store, and county fair, necessitating prophylaxis of adults and children.

Contact with animals has numerous positive benefits, including opportunities for education and entertainment. However, many pet owners and people in the process of choosing a pet are unaware of the potential risks posed by pets. Pediatricians, veterinarians, and other health care professionals are in a unique position to offer advice on proper pet selection, provide information about safe pet ownership and responsibility, and minimize risks to infants and children. Pet size and temperament should be matched to the age and behavior of an infant or child. Acquisition and ownership of nontraditional pets should be discouraged in households with young children. Information brochures and posters are available for display in physician and veterinarian offices so parents can be educated about the guidelines available for safe pet selection and appropriate handling (www.cdc.gov/healthypets/index.htm, www.cdc.healthypets/health_prof.htm and www.avma.org/animal_health/brochures/pet_selection.asp.

Young children should be supervised closely when in contact with animals at home or in public settings, and children should be educated about appropriate human-animal interactions. Parents should be made aware of recommendations for prevention of human diseases and injuries from exposure to pets, including nontraditional pets and animals in the home and animals in public settings (Table 2.22).

Questions regarding pet and animal contact should be part of well-child evaluations and the evaluation of a suspected infectious disease.

Table 2-22