A Review of Zoonotic Disease Threats to Pet Owners: A Compendium of Measures to Prevent Zoonotic Diseases Associated with Non-Traditional Pets Such as Rodents and Other Small Mammals,Reptiles,Amphibians,Backyard Poultry,and Other Selected Animals

I. Salmonella

Salmonella bacteria can spread through many ways such as contact with feces of infected small mammals or contaminated surfaces. A diversity of NTP species were identified in the literature and ACOSS data, including rats, mice, guinea pigs, and hedgehogs, with multiple outbreaks or case reports associated with each of these. Rodents were associated with over half of the small mammal salmonellosis illnesses identified (refer to the Background section of this document on Salmonella for more detailed information on Salmonella).

Most of the outbreaks identified in the CDC literature review and ACOSS data request were multistate (Appendix C. Glossary), however, this may reflect the type of illness reports that get investigated and published versus a true reflection of frequency. Single state outbreaks or individual cases may not be as likely to be investigated or published. The distribution pathways of these species from breeder to distributor, retailer, and NTP owner affect geographic distribution of outbreaks (Appendix D. Industry layout).

II. Lymphocytic choriomeningitis virus (LCMV)

Lymphocytic choriomeningitis virus (LCMV) is a rodent-borne arenavirus and a rare cause of human illness. The primary reservoir for LCMV is the house mouse (Mus musculus) (Jay et al, 2005). Most human LCMV infections are associated with wild rodent exposure (Charrel et al, 2006; Foster et al, 2006; Talley, 2019); however, human LCMV infection has also been associated with exposure to pet or commercial rodent species that have been exposed to wild rodents, particularly hamsters (Amman et al, 2007; Biggar et al, 1975; Deibel et al, 1975; Gregg, 1975; Rousseau et al, 1997) and feeder mice (Knust et al, 2014). LCMV has also been detected in other pet rodent species, such as guinea pigs (Amman et al, 2007).

Zoonotic transmission of LCMV can occur via rodent bites, direct contact with rodents and their urine, feces, saliva, bedding or nesting materials, or inhalation of aerosolized infectious materials in the environment (Jay et al, 2005).

LCMV infections in people can be asymptomatic or cause a mild febrile illness; in high-risk groups more severe infections can cause meningitis, encephalitis, myelitis, or acute hydrocephalus (Charrel et al, 2006; Wilson and Peters, 2014). Person-to-person transmission can occur via organ transplantation (“Brief Report: Lymphocytic Choriomeningitis,” 2008; Fischer et al, 2009; MacNeil et al, 2012) or from a pregnant person to their fetus (Barton and Mets, 2001). Congenital infections can result in fetal death or severe neurologic and/or ophthalmologic birth defects (Barton and Mets, 2001; Barton et al, 1995; Wright et al, 1997). Congenital infection with LCMV has been reported in the infant child of a veterinarian with direct occupational exposure to pet rodents and indirect home exposure to wild rodents (J. Brown, personal communication, Indiana Department of Health). Contact between wild and domestic rodents was suspected as a potential source of previous outbreaks of LCMV infections in the United States (Knust et al, 2014; Talley, 2019).

III. Streptobacillus moniliformis (the cause of rat bite fever)

Rat bite fever (RBF) is a rare bacterial disease transmitted by bites or scratches from colonized rodents, typically rats, although mice, gerbils, guinea pigs, and squirrels can also carry the bacteria that cause it (Infection in Animals, Rat-Bite Fever (RBF), 2019). S. moniliformis can also spread through exposure to rodent urine or saliva, or surfaces contaminated with these fluids, including water or food. Ingestion of S. moniliformis causes the disease Haverhill fever (Abdulaziz et al, 2006). Rats colonized with the bacteria may appear healthy, although some may develop arthritis, skin infections, pneumonia, and swollen lymph nodes. Clinical signs in people include fever and joint pain or rash that can progress to systemic involvement of the heart, liver, lungs, or brain and sepsis if untreated (Hryciw et al, 2018; Kache et al, 2020). Children and young adults are more commonly affected (“Notes from the Field: Fatal Rat-Bite Fever in a Child,” 2013) and infection is increasingly associated with pet rodent ownership (Kache et al, 2020). RBF surveillance is not routinely conducted in the United States, and analysis of nationwide administrative datasets suggests that it may occur more commonly than is reported (Kache et al, 2020). Further research is needed to characterize the true prevalence and associated risk factors (Shvartsblat et al, 2004).

IV. Hantaviruses (Seoul virus and others)

Seoul virus is an Old World hantavirus with worldwide distribution. It is carried and spread by rodents, specifically the brown or Norway rat (Rattus norvegicus), including pet and wild rat populations. People can become infected through contact with infected rodents or their urine, feces, saliva, or contaminated nesting materials (Kerins, 2019). Infection in people can progress to hemorrhagic fever with renal syndrome (HFRS) which can be fatal.

Other hantaviruses include Sin Nombre virus (SNV), a New World hantavirus and rare cause of hantavirus pulmonary syndrome (HPS), a severe pulmonary disease associated with exposure to wild rodents (the SNV reservoir is the deer mouse Peromyscus maniculatus). SNV may be a concern in cases where wild rodents have contact with domestic rodents, such as those in breeding facilities. Contact between wild and domestic rodents is suspected as a potential source of previous outbreaks of Seoul virus in the United States (Kerins, 2019).

V. Monkeypox virus

Monkeypox is a rare viral disease usually found in central and western Africa (Baum, 2018). Monkeypox does not occur naturally in the United States, but cases have happened that were associated with international travel and importation of animals from places where the disease is more common. Monkeypox virus can infect rats, mice, rabbits, and prairie dogs, but may not cause clinical signs of disease in infected animals. A 2003 monkeypox outbreak in the United States highlights the effect that co-mingling wildlife and domestic animals can have on public health through the emergence of zoonotic diseases (monkeypox call out box) (Croft et al, 2007; Monkeypox in the United States, 2022; Reed et al, 2009). Exposures to infected prairie dogs occurred among several groups including 26 children attending in-home childcare, resulting in 5 confirmed infections (Kile et al, 2005). Healthcare workers attending to 3 patients were also exposed, with no cases reported.

VI. Leptospira species

Leptospirosis is a bacterial disease that affects people and animals and is widespread globally (Leptospirosis, 2019). It is caused by spirochete bacteria of the genus Leptospira, with 22 known species divided into more than 300 serovars (e.g., Leptospira interrogans serogroup Icterohaemorrhagiae) (Boey et al, 2019). The bacteria can spread through the urine of infected animals including rodents, cattle, pigs, horses, dogs, and other wild animals) (Leptospirosis, 2019). Wild rats (Rattus species), especially the Norway/brown rat (Rattus norvegicus) and the black rat (R. rattus) are the most important sources of Leptospira infection in humans and animals as they are abundant in urban and peridomestic environments (Gaudie et al, 2008; Himsworth et al, 2013). Leptospira incidence increases after heavy rainfall and has been associated with natural disasters with large outbreaks occurring after hurricanes, typhoons, and floods (Himsworth et al, 2013). Rodents may be infected with the bacteria and show no clinical signs of disease (Leptospirosis, 2019). Infected animals may excrete the bacteria into the environment continuously or periodically over a few months up to several years (Leptospirosis, 2019). Infections in people have been associated with pet mice and rats (Day, 2016; Friedmann et al, 1973; Gaudie et al, 2008).

People can become infected with the bacteria through coming in to contact with the urine (or other body fluids, except saliva) of infected animals or contact with water, soil, or food contaminated with the urine of infected animals. Drinking contaminated water can cause infection. Infection can also occur through contact with contaminated water via cuts in the skin or mucous membranes in the nose, eyes, or mouth. People may be asymptomatic or have non-specific clinical signs including high fever, headache, chills, muscle ache, rash, or jaundice.

To help prevent leptospirosis infection in pets, it is important to keep wild rodents (rats, mice, or other animal pests) from mingling with pet rodents, and to keep rodent pest problems under control (Leptospirosis, 2019). People should not keep wild rats as pets.

VII. Trichophyton, Microsporum, and other dermatophytes

Dermatophytosis, colloquially known as ringworm, is a fungal skin infection that can be transmitted from small mammals to people either through direct contact or contaminated items such as bedding. Caused by a variety of genera, including Trichophyton and Microsporum, these dermatophytes are commonly associated with rabbits and guinea pigs (Cafarchia et al, 2012; Day, 2016; Donnelly et al, 2000; Kraemer et al, 2013). Infections in small mammals are normally mild or asymptomatic and consist of areas of crusting alopecia (hair loss). Hair loss and other skin lesions on animals should be properly diagnosed and treated by a veterinarian, and all pets in an affected household should be examined for ringworm. In addition, areas where the animal has spent time should be appropriately disinfected, if possible.

I. Salmonella

The most common zoonotic disease acquired from pet reptiles is salmonellosis (Bosch et al, 2016). Salmonella bacteria can live in reptile gastrointestinal tracts, and generally do not cause signs of disease in reptiles (Bosch et al, 2016; Schlossberg, 2016). Reptiles can shed Salmonella bacteria intermittently in their feces, and some reptiles, such as snakes, may carry more than one serotype of Salmonella at a time (DuPonte et al, 1978; Goupil et al, 2012). Reptiles can acquire Salmonella strains in several was, including transovarially (transmission of the bacteria from the reptile to its offspring), via direct contact with other infected reptiles, or through contamination of their environment (Schlossberg, 2016; Schröter et al, 2006). Snakes and carnivorous reptiles may acquire Salmonella strains through food sources such as feeder animals, whether live or frozen, which can carry Salmonella bacteria (Section V. Feeder Animals) (“Notes from the Field: Infections with Salmonella,” 2012; “Salmonella Typhimurium Infections,” 2014).

Transmission of Salmonella strains from reptiles to people can occur through direct contact with the animal and indirect contact with a contaminated environment. Indirect contact can occur through cross-contamination of the environment, including the home, where animals roam, or where people cared for or stored animal supplies. Contact with contaminated terrarium or aquarium water can occur with aquatic reptiles, where splashes from tanks and touching the water have led to Salmonella infections in infants and children (Bosch et al, 2016). Salmonellosis has also been acquired through swimming in a pool housing turtles with a shell length less than 4 inches (10.16cm) (“Multistate Outbreak of Human Salmonella Infections,” 2008). Salmonella infections in infants and children have resulted from cross contamination of sinks and bathtubs used to bathe pet reptiles or to clean reptile supplies and also to clean household items such as baby bot tles or to prepare infant formula or other food (Kiebler et al, 2020; “Reptile-Associated Salmonellosis,” 2003)

Certain husbandry practices can increase the risk of contracting a Salmonella infection from reptiles, including housing multiple reptiles in the same enclosure and infrequently changing the water in the habitat (Corrente et al, 2017). Terrarium substrates may act as a reservoir for Salmonella bacteria, which are extremely resilient in the environment (Winfield and Groisman, 2003). Viable Salmonella specimens have been isolated from dried reptile stool in cages 6 months after removal of the reptile and from aquarium water 6 weeks after removal of a turtle (Corrente et al, 2017; Mermin et al, 2004; Schlossberg, 2016). Washing eggs in a detergent solution may reduce Salmonella burden in turtle hatchlings (Mitchell et al, 2007), however, these animals may be subsequently exposed to Salmonella through food, water, other animals, and the environment, therefore they may be re-infected at any time (Harris et al, 2010). Using antibiotics to treat or wash eggs is never recommended because of the potential for development of antimicrobial resistance in turtles and their environment (Mitchell et al, 2007). Multiple outbreaks of Salmonella infections in humans have been associated with turtles marketed as Salmonella-free but were still shedding the bacteria (Bosch et al, 2016; Walters et al, 2016).

II. Other zoonotic pathogens and causes of illness or injury to people

Less common potential zoonotic pathogens that can cause infections in reptiles include West Nile virus (WNV), Aeromonas spp., Mycobacterium spp., Vibrio spp., Chlamydia spp., Burkholderia pseudomallei (Melioidosis, 2021), and Armillifer (pentastomiasis) (Ebani et al, 2008). Reptiles have also been shown to be amplifying hosts for some arboviruses including chikungunya virus, WNV (crocodilians), and eastern equine encephalitis virus (snakes), with evidence of fecal shedding for WNV (Bosco-Lauth et al, 2018; Graham et al, 2012; White et al, 2011). There is some evidence that WNV might also spread from reptiles to other animals this way (Divers, 2020). Imported reptiles may harbor exotic ticks which can carry diseases that infect people. Four species of Amblyomma ticks, parasitizing lizards, and tortoises were introduced into Florida and were found to be infected with Ehrlichia ruminantium, which causes ‘Heartwater’ disease, and C. burnetti, the agent of Q fever (Mendoza-Roldan et al, 2020). Imported reptiles may also carry antimicrobial-resistant bacteria, contributing to the global spread of multidrug-resistant bacteria (Unger et al, 2017). Bites from reptiles can result in trauma and infection from a broad array of microbes, and some reptile species are venomous (Abrahamian and Goldstein, 2011). Large reptiles such as mature boa constrictors or crocodilians can pose a risk for severe injuries or even death if not housed or handled properly (Smith et al, 2012).

I. Salmonella

Amphibians have been linked to a multistate outbreak and case reports of Salmonella infection in the United States. A 2008 multistate outbreak of infections with Salmonella enterica serotype Typhimurium demonstrated the first known illnesses linked to African dwarf frogs in the United States (Zarecki et al, 2013). This outbreak spanned at least 3 years and caused illnesses predominantly among children (see call out box).

II. Mycobacterium species—the causative agent of “Fish-handlers disease”

“Fish-handlers disease,” also called “fish tank granuloma,” is caused by infection with environmental Mycobacterium bacteria (see box). Mycobacteriosis is a bacterial, systemic granulomatous disease that occurs in aquarium and cultured food fish and can be zoonotic. It can result from infection by several Mycobacterium species (Disease Information—Mycobacteriosis, 2020). Mycobacterium marinum is one of the most important species found in salt and freshwater. People, especially fish owners, can be exposed through direct contact with animals or their environment, including contaminated water sources, such as aquarium water. Cases of infection with Mycobacterium marinum in the United States are uncommon but are likely underreported (Disease Information—Mycobacteriosis, 2020). Progression of infection depends on immune competence of the patient, usually occurring due to injury or non-intact skin (Aubry et al, 2002; Hashish et al, 2018). Rare reports of dissemination such as joint and bone infection have been documented in severely immunocompromised patients (Bhatty et al, 2000; Hashish et al, 2018; Petrini, 2006). Infections have also been reported in reptiles housed in aquaria previously used for fish (Disease Information—Mycobacteriosis, 2020).

III. Other zoonotic diseases and causes of illness or injury to people

Wound infections can be caused by bacteria associated with aquatic animals and their environments. These bacteria may be associated with freshwater (Aeromonas spp., Comamonas spp., Edwardsiella ictaluri, E. tarda, Burkholderia pseudomallei); water sources with higher salinity, e.g., brackish or marine water, (Vibrio spp.) (Finkelstein and Oren, 2011)^; or water sources varying in salinity, e.g., fresh and salt water (Mycobacterium spp., Streptococcus iniae, Erysipelothrix rhusiopathiae) (Lowry and Smith, 2007; Weinstein et al, 2009; Weir et al, 2012b; Yacisin et al, 2017). In 2019, a freshwater home aquarium was recognized as the source of possible transmission of Burkholderia pseudomallei, the causative agent of melioidosis, to a person confirmed with the infection who had no history of travel to endemic areas (Dawson et al, 2021).

Bite or puncture injuries can also occur with aquatic species (Abrahamian and Goldstein, 2011). Some aquatic animals can produce venoms or toxins (Abrahamian and Goldstein, 2011; Warwick and Steedman, 2012). Palytoxin is an example of an emerging invertebrate toxin that has been associated with exposure to marine aquariums containing certain species of invertebrates such as Palythoa soft corals, Ostreopsis dinoflagellates, and Trichodesmium cyanobacteria. Palytoxin is unique in that exposure can occur through inhalation, ocular or skin contact, or ingestion and has caused human illnesses (Pelin et al, 2016). Palytoxin exposures commonly occur while cleaning aquaria or intentionally removing zoanthid corals to control populations from overrunning an aquarium.

Ingestion of bacteria including Vibrio spp., E. tarda, Lactococcus garvieae, and Plesiomonas shigelloides in untreated water from aquatic animal habitats can also cause illness (Lowry and Smith, 2007; Weir et al, 2012b).

I. Salmonella

Despite awareness of the risk of salmonellosis from handling raw poultry, some people are not aware that Salmonella can also spread between live poultry and people, and education is needed (Basler et al, 2016, 2014). Poultry are a known source of Salmonella infection in people, and transmission to people after contact with backyard poultry or their environment is a well-recognized public health problem (Basler et al, 2016; Gaffga et al, 2012; Loharikar et al, 2013; Loharikar et al, 2012). Baby poultry, particularly chicks and ducklings, have been linked to several recent and extensive outbreaks. Poultry can be infected with Salmonella through multiple routes, including by contact with infected birds, vertical transmission from infected hens to their eggs, or from contaminated feed (Anderson et al, 2016; Basler et al, 2014; Behravesh et al, 2014; Gaffga et al, 2012; Loharikar et al, 2013; Loharikar et al, 2012).

As the popularity of backyard flock ownership has increased, the number of reported outbreaks of infections with Salmonella in people from contact with backyard poultry has also dramatically increased. Human infections result from contact with infected poultry and their environment, including enclosures in which they are kept or transported. A recent study by the Michigan Department of Health and Human Services found that 26% of poultry shipping boxes over a 3-year period were contaminated with Salmonella, including four subtypes known to be previously associated with human illness (Habing et al, 2015; Sidge, 2019).

Outbreaks affecting adults and children have increased, with reported cases typically beginning in January and continuing through much of the year (Behravesh et al, 2014). During 2020, data reported to PulseNet, the national laboratory network for enteric disease surveillance in the United States, indicated the highest number of backyard poultry-associated outbreaks with Salmonella infections and outbreak-associated illnesses in a 1-year period on record for the United States. It is estimated that because only a small proportion of Salmonella infections are diagnosed and reported to public health departments, there are an additional unreported 29 infections for every reported case (Hale et al, 2012; Scallan et al, 2011).

The backyard poultry linked to previous outbreaks traced back to several sources including multiple hatcheries, agricultural feed stores, and internet sites. Facilities with people at higher risk for serious illness from Salmonella infection have experienced outbreaks, including school classrooms, daycare centers, and nursing homes.

II. Campylobacter

Poultry often carry Campylobacter bacteria in their intestinal tract and can appear healthy. In the United States, most illnesses in people occur from eating raw or undercooked poultry or coming in contact with surfaces contaminated by raw or undercooked poultry (Campylobacter and Pets, 2021). Other risk factors for contracting Campylobacter infection from poultry-related sources include keeping backyard poultry, butchering poultry for meat, and contact with contaminated eggs (Campylobacter and Pets, 2021). Occupational exposures and resulting infections have been documented in abattoir workers and people working in poultry processing facilities (de Perio et al, 2013).

Campylobacter infection in people tends to occur sporadically, with outbreaks rarely reported. A summary of 934 sporadic Campylobacter infections in Minnesota residents during 2012–2016 who reported an animal agriculture exposure before their illness revealed that 54% had contact with poultry or their environment (Minnesota Department of health, unpublished data; Klumb et al, 2020). Campylobacter infection in people are likely to be underdiagnosed, in part due to changes in laboratory testing (e.g., increase in culture-independent diagnostic testing [CIDT]) (Marder et al, 2017) and difficulty growing and isolating the organism. Campylobacter infection in people may also be underreported because it is not a reportable condition in many jurisdictions.

III. Avian influenza

Avian influenza refers to infection of birds with influenza type A viruses whose natural hosts include many species of wild waterfowl and domestic water and land birds (Influenza in Animals, 2018). Depending on the pathogenicity and virulence of the virus, waterfowl, such as ducks, geese, shorebirds, and swans, do not always show signs of avian influenza virus (AIV) infection, but poultry flocks can experience a range of illness, from decreased egg production to extremely high death rates. Avian influenza viruses are classified as low pathogenic or highly pathogenic based on the ability of the virus to cause disease in chickens in the laboratory and/or on certain genetic markers of pathogenicity. During 2014–2015 more than 50 million chickens and turkeys died or were destroyed in the most devastating outbreak of infections with highly pathogenic avian influenza A (HPAI) viruses in domestic poultry in the United States to date.

AIV transmission from birds to people can occur through direct contact with infected birds, indirect contact with virus-contaminated surfaces, or through inhalation of virus in the air in droplets or dust (Avian Influenza A Virus Infections in Humans, 2022; “How Infected Backyard Poultry Could Spread Bird Flu,” n.d.). In cases of human infection, the spread from one sick person to another is very rare and not sustained. To date, there have been no reports of human illnesses caused by AIV in the United States associated with infected birds (Avian Influenza A Virus Infections in Humans, 2022). One reported AIV infection in the United States was from exposure to AIV-infected cats (Influenza in Cats, 2018; Lee et al, 2017). Cases of illness and death in people in Africa, Asia, and Europe have occurred from several AIV subtypes (mainly H5, H7, and H9), and with rare, isolated reports of limited, non-sustained human-to-human transmission (Liu et al, 2013). Most initial cases of human infection occur after unprotected contact with sick birds (including in live animal market settings) or virus-contaminated surfaces. Because of the possibility that avian influenza viruses could change (primarily by reassortment or mutation) and gain the ability to spread easily between people, monitoring wild birds and domestic poultry for outbreaks and monitoring for human infections and person-to-person spread is extremely important. People who have contact with known or possibly infected birds should take precautions to protect against infection and monitor their health for possible symptoms (Avian Influenza A Virus Infections in Humans, 2022).

IV. Avian paramyxovirus (the cause of Virulent Newcastle Disease)

Newcastle disease is a viral disease of birds that can cause a range of illness in birds, from no symptoms to mild illness or up to 100% mortality, depending on the viral strain. Newcastle disease viruses rarely infect people; when they do, they can cause mild to severe conjunctivitis or mild influenza-like symptoms. Reported human cases have occurred only after exposure to particularly high concentrations of virus (Virulent Newcastle Disease (vND), 2021). Virulent Newcastle disease (vND) refers to the most severe form of the disease in poultry, which is only caused by certain viral strains. Although many birds can become infected, wild cormorants and domestic poultry are particularly susceptible. Large outbreaks of vND occur periodically in commercial poultry, and previous outbreaks in the western United States have resulted in large losses of birds. This outbreak is primarily associated with backyard exhibition chickens raised or smuggled illegally for fighting. Hundreds of premises have been affected, including homes with backyard flocks in other states, due to movement of exposed and infected birds (Virulent Newcastle Disease (vND), 2021).

I. Salmonella

Live and frozen feeder animals have been associated with multiple outbreaks of Salmonella infection in the United States. Rodents used as feeder animals were most commonly associated with these outbreaks (“Notes from the Field: Infections with Salmonella,” 2012; “Salmonella Typhimurium Infections,” 2014). In addition to feeder rodents, feeder animals like chicks and other poultry pose a risk of Salmonella infection to those caring for NTPs. Freezing does not kill Salmonella, and the bacteria have been shown to survive freezing for over 19 months (Cartwright et al, 2016). For more detailed information on Salmonella infections see the Rodents and other small mammals and Backyard poultry sections.

In a 2010 outbreak of Salmonella infections, illnesses were associated with exposure to pet reptiles and frozen feeder rodents used as feed for pet reptiles (Cartwright et al, 2016; “Salmonella Typhimurium Infections,” 2014) This multistate outbreak was linked to an international outbreak of Salmonella in the United Kingdom in 2009, in which feeder mice imported from the United States were found to be the source of human illness.

II. Lymphocytic choriomeningitis virus (LCMV)

Live feeder rodents have been associated with human cases of infection with LCMV in the United States, mainly among employees at feeder rodent breeding facilities (Knust et al, 2014). The principal transmission route of LCMV to people is through contact with the urine, feces, saliva, or blood of the natural reservoir species, the house mouse (M. musculus) (Knust et al, 2014). For more detailed information on LCMV infections associated with small mammals see Rodents and other small mammals.

Exposure to wild mice was believed to the source of LCMV introduction into a breeding colony that led to a 2012 multistate outbreak linked to a rodent breeding facility, resulting in 4 confirmed cases of aseptic meningitis in employees (Knust et al, 2014). This outbreak illustrates potential occupational health risks related to feeder rodents and the need to educate purchasers and handlers throughout the supply chain. Investigators found that nearly one-third of rodent facility employees tested positive for LCMV antibodies. At each of the two facilities where testing was performed for frozen feeder mice, 21% and 33% of the mice had antibodies to LCMV. To stop transmission of the virus, the facility quarantined shipments, depopulated all live mice, and disposed of frozen mice (Knust et al, 2014).

III. Streptobacillus moniliformis (the cause of rat-bite fever)

Rat-bite fever is a rare bacterial disease caused by Streptobacillus moniliformis that is primarily associated with exposure to colonized rats. Other rodents that can carry the bacteria are mice, guinea pigs, gerbils, and squirrels (“Infection in Animals, Rat-Bite Fever,” 2019). Rat-bite fever is not commonly associated with feeder animals, but it is important to note that there is a risk for rat-bite fever when working with live feeder rodents. Colonized rats usually appear healthy, so symptoms consistent with rat-bite fever that occur in people breeding, distributing, selling, or using rats as feeder rodents should be evaluated and treated properly (Hardin, 2013).

Increased education and awareness of rat-bite fever risks are needed among feeder rodent producers, people caring for rodents, and healthcare providers.

For more detailed information on rat bite fever infections associated with small mammals see Rodents and other small mammals.

Audiences for messaging

Awareness and education efforts should be tailored to anyone who owns or may come in to contact with NTPs or their environments. People might come in contact with NTPs at home or away from home in places such as pet stores, agricultural feed stores, fairs, petting zoos or farms, schools, daycares, camps, long-term care facilities, educational shows, flea markets, animal swap meets, work, and more. Messaging about the risk for more severe illness from NTPs should be tailored to parents/caretakers of children younger than 5 years old and other people at higher risk of illness including adults 65 and older, people with weakened immune systems due to illness or certain medications, and pregnant people.

All relevant partners should work together to communicate to the public and NTP owners, including those who are fostering or adopting NTPs, the following information:

Veterinarians

Physicians and allied healthcare providers

Government agencies representing public health and animal health officials

Provide resources and community outreach to inform and educate constituents on relevant local, state, and federal laws related to NTP ownership, zoonotic disease risks associated with NTPs, and evidence-based zoonotic disease prevention methods.

Industry leadership (breeders, distributors/importers, retailers)

Other relevant One Health partners (industry groups, associations, and affiliated organizations)

General messaging

Include the following types of public awareness messaging:

Information for current and potential NTP owners should be incorporated into existing communication and education methods. These might include client or patient intake forms, investigative interviews, and other educational outreach. It is especially important that people at higher risk for serious illness from zoonotic diseases and their caregivers are aware of the risks and receive information about preventing zoonotic disease transmission from NTPs.

Educational information should be prominent and delivered in multiple formats, such as signage in a retail location, verbal education delivered during a sale, placards under animal displays, and printed materials for animal owners to take home. Educational information should also be made widely available electronically, such as on websites and social media platforms.

Sample messaging

Antimicrobial stewardship recommendations for veterinarians

Good husbandry and preventive care can improve a pet's health and reduce the need for antimicrobial treatment. Antimicrobials should only be used in NTPs and other animals when prescribed by a veterinarian under a valid veterinary-client-patient relationship (Veterinarian-Client-Patient Relationship (VCPR) FAQ, n.d.) and consistent with stewardship principles as defined by the American Veterinary Medical Association (AVMA). Judicious use of antimicrobials, use of laboratory testing to determine disease etiology, and culture and susceptibility testing to aid in appropriate antimicrobial selection are critical when antimicrobial therapy is warranted (Judicious Therapeutic use of Antimicrobials, n.d.). Antimicrobials should not be used as a substitute for disease prevention measures such as good animal husbandry and sanitation. Several resources exist to help veterinarians practice antimicrobial stewardship (Table 1. Antimicrobial Stewardship Resources) (Handbook of Antibiotic Stewardship in Companion Animal Veterinary Settings, 2022).

It is critical that veterinarians communicate with non-traditional pet owners about appropriate antimicrobial use when discussing diagnostic and treatment plans for their pets, including the importance of culture and sensitivity to ensure the effectiveness of the antimicrobial. Veterinarians should emphasize to owners their role in preserving the effectiveness of all antimicrobials by not requesting antimicrobials when they are not needed, following instructions when antimicrobials are prescribed, and never using a medication in an animal unless prescribed for that animal (“Antibiotic use is Changing,” n.d., Antimicrobial Stewardship Definition and Core Principles, n.d.).

While they have been considered non-traditional pet species for the purpose of this Compendium, backyard poultry are food-producing animals and as such the animals themselves and their products (e.g., eggs) are subject to oversight by USDA and FDA. Treatment of backyard poultry with medically important antimicrobials given in feed falls under the FDA Veterinary Feed Directive rule and must be under the supervision of a veterinarian with a valid veterinary-client-patient relationship (“FACT SHEET: Veterinary Feed Directive Final Rule,” 2022; “FDA Releases Draft Guidance,” 2021).

Antimicrobial stewardship recommendations for industry

A critical component of antimicrobial stewardship for all sectors of industry is ensuring adherence to best practices for prevention and management of disease to ensure animals are healthy, thereby reducing the need for antimicrobials.

Antimicrobial use and Salmonella

Reptiles, amphibians, backyard poultry, and small mammals can carry Salmonella bacteria in their intestinal tract and shed it in their feces, even if they appear healthy. Thus, there are circumstances where fecal culture of NTPs may be necessary and recommended (e.g., during an outbreak investigation when there is concern about human transmission). Testing or using culture of fecal specimens or of environmental specimens may also be warranted to characterize circulating strains or to develop vaccines. But because Salmonella bacteria are shed intermittently in feces, culture will not detect Salmonella infection in all animals.

Healthy animals should not be treated with antimicrobial agents with the intent of eliminating Salmonella from the intestinal tract because this can lead to a carrier state in the animal, disrupt the animals' gut flora, and increase the risk of antimicrobial resistance. In cases of known infection, it may be difficult to determine if an animal has cleared an infection after antimicrobial therapy because of the potential for intermittent shedding and false negative test results. Veterinarians should discourage antimicrobial treatment of healthy animals for Salmonella if animal owners request it, and they should provide education on health effects of inappropriate use of antimicrobials (including disruption of the microbiome/gut flora), and antimicrobial resistance and its potential effects on human and animal health. Safe handling tips to share with animal owners are available in Appendix H. Selected Educational Resources.

Occupational health plan

Employers can protect employees by establishing an occupational health plan for all employees who will be working with or around NTP species. The plan should include written and verbal instructions for implementation and documented refresher training on a regular basis. Specific plans depend on the NTP species. In general, an occupational health plan should include the following:

Employees are more likely to stay home and not infect co-workers, clients, or the animals if they receive paid sick leave. If employees or volunteers have questions about their health or immune status, they should talk with their healthcare provider.

Education and training for employees

Employers should provide routine education and training for all employees who will be working with or around animals on basic principles of disease prevention. This should include education at the time of hiring and refresher training on a regular basis (e.g., annually), before a change in job duties, or if new procedures are implemented. Training should include information on animal husbandry, handling, feeding, zoonotic disease risks, handwashing, personal protective equipment use, and other biosecurity protocols. Employers can find resources on inclusive communication principles to employ in training materials here.

Biosecurity and personal protective equipment (PPE) in the workplace

Biosecurity refers to measures taken to prevent transmission of pathogens, including bacteria, viruses, fungi, and parasites, to people and animals. Biosecurity measures may be structural, such as physical barriers, or they may be operational, such as procedures, practices (e.g., use of PPE), and policies that aim to prevent disease (Defend the Flock- Biosecurity 101, n.d.). All employees should follow basic biosecurity practices, including handwashing (Appendix E. Handwashing). Facilities should have a written biosecurity protocol in conjunction with or in addition to the employee health plan.

PPE is equipment worn to prevent exposure to hazards that cause workplace injuries and illnesses that may result from direct or indirect animal contact (Personal Protective Equipment—Overview, n.d.). All PPE should be safely designed, constructed, and maintained in a clean and reliable fashion, and fit properly. For PPE to be most effective it should be worn correctly. If PPE is to be used in a workplace, a PPE program should be implemented that addresses the hazards present; selection, maintenance, and use of PPE; employee training; and program monitoring. Employers are required to provide or pay for most types of PPE (1910.132—General requirements, n.d.).

Required use of respiratory protection

If hazards in the workplace indicate the need for respiratory protection, the Occupational Safety and Health Administration (OSHA) requires the employer to establish and maintain a written respiratory protection program (1910.134—Respiratory Protection, n.d.).

The main elements of the respiratory protection program include

Voluntary use of respiratory protection

The employer should provide a copy of Appendix D of the OSHA Respiratory Protection Standard to employees who wear respirators voluntarily (when it is not required by the employer) and encourage employees who voluntarily wear respirators to follow all aspects of proper respirator use including being clean shaven when using a tight-fitting respirator to ensure a good seal.

In addition, the employer must establish and implement those elements of a written respiratory protection program necessary to ensure that any employee using a respirator voluntarily is medically able to use that respirator, and that the respirator is cleaned, stored, and maintained so that its use does not present a health hazard to the user.

Employee vaccination policies and record keeping

Employers should maintain up-to-date emergency contact information and staff records including vaccinations in accordance with ACIP recommendations and rabies virus antibody titers when indicated (e.g., for those employees working with or around animals that can carry rabies). Employee health information should be collected on a voluntary basis and confidentially maintained. Employees should inform their supervisors of changes in health status, such as pregnancy, that may affect work assignments. New employees should receive training regarding the importance of informing their healthcare provider that their work duties involve contact with animals.

Employees should follow ACIP recommendations and any state or local regulations regarding employee vaccination for rabies, influenza virus, tetanus, SARS-CoV-2, and any other relevant vaccine preventable pathogens that may be encountered in the workplace. NASPHV's Compendium of Veterinary Standard Precautions for Zoonotic Disease Prevention in Veterinary Personnel provides more information on employee vaccination in veterinary settings.

Record keeping

Breeders, distributors, and retailers should establish and maintain a record system for traceability of animals during movement from breeder to distributor and retailer for all animals.

At a minimum, records should include the following:

Poultry retailers should inquire with the hatchery about the source of origin of the birds for recordkeeping/traceability (drop shipping).

For feeder animals, records might include lot numbers for packages of feeder animals to assist in minimizing the scope of recall or euthanasia in the case of an outbreak.

Animal health and husbandry

Picking the right pet

Together, veterinarians, physicians, and allied healthcare professionals such as nurses can help animal owners select appropriate non-traditional pets, educate them about zoonotic disease risks and prevention measures, and provide advice on who is at higher risk of illness. For species-specific information, please see Appendix F. Guidelines for animals in schools, childcare settings, and long-term care and assisted living facilities, and the General recommendations for all partners, awareness and education, sample messaging for NTP owners and the public section. The sample messaging for NTP owners and the general public has information that can be easily shared with current or potential NTP owners to help them determine the pet that is right for them.

Physicians and other human healthcare professionals can educate patients and their families on the zoonotic disease risks associated with keeping reptiles, amphibians, backyard poultry, and small mammals as pets. They play an important role in advising patients who may have specific health concerns that would make them more vulnerable to a zoonotic disease. Veterinarians can also provide information on zoonotic disease risks as well as animal-specific information such as animal behavior and temperament, husbandry, welfare needs, required veterinary care, and overall pet suitability. Veterinarians serve as a valuable resource for physicians and other healthcare professionals to refer to for advice on counseling patients. Veterinarians can also inform NTP owners that they should tell their healthcare providers about what pets they have at home and any animals they come in to contact with outside the home. Many veterinarians offer a pre-purchase visit for clients who would like to discuss appropriate pets or to examine an animal before it is purchased. However, many times a pet owner will bring an animal to the clinic for an exam after it is purchased, this first visit is also an important opportunity to educate pet owners. Pet industry partners, including retailers, also have resources for pet owners on choosing the appropriate NTP.

To reduce the possibility of illness or injury from NTPs, healthcare professionals should remind parents about matching the size and temperament of a pet to the age and behavior of children, providing close supervision of young children, and educating children about appropriate human-animal interactions (Pickering et al, 2008). People thinking about having children should take pet selection and the pet's lifespan into consideration when thinking about adopting NTPs. These reminders are especially important for patient populations at highest risk of infection or serious consequences of infection, including children younger than 5 years old, adults 65 and older, and people with weakened immune systems, including patients undergoing chemotherapy, organ transplant patients, or pregnant people.

Considerations for suspected cases of zoonotic diseases

As a part of both regular check-ups and in the case of a suspected infectious disease, human healthcare providers should collect a thorough history of animal ownership and animal contact, including in public settings such as exhibits, petting farms or zoos, classrooms, and fairs. Obtaining animal ownership and contact history can lead to specific testing, an accurate diagnosis, and specific treatment recommendations (Day, 2016; Hodgson et al, 2017). It is important to include animal species when taking the history of animal contact (e.g., did you come in contact with rodents, backyard poultry, fish or their habitat etc.?) because in some instances people do not consider these animals as pets, but asking about the species will remind them they should be included (D. Crum, personal communication, Maryland Department of Health).

Upon suspicion or confirmation of a zoonotic disease in a pet, veterinarians should recommend follow up by the pet's owner with a healthcare provider, especially in cases of reported symptoms or illness in owners that may be related to contact with the animal. In these cases, veterinarians should provide information and recommendations on steps that the pet owners can take to reduce the risk of disease transmission from the pet to themselves and anyone else encountering the animal. This includes the information provided above in the General Recommendations section.

Role during outbreak investigations, and reportable or notifiable diseases

In the case of a known or suspected zoonotic disease outbreak, it is important for both human and animal healthcare providers to cooperate with authorities conducting the investigation. Healthcare providers and veterinarians should be familiar with appropriate points of contact for zoonotic diseases at their state or local public health departments. These points of contact can assist with testing and treatment recommendations.

Physicians, veterinarians, and other healthcare professionals should be aware of the conditions and diseases they are required to report to local or state public health authorities as well as when to report conditions that may not be specified on the list but should still be reported (e.g., outbreaks of an unknown illness). They should report suspected cases of human or animal illness to the appropriate authority as soon as possible in compliance with local or state laws. Some reporting requirements are statewide, while others are determined by the local health jurisdiction.

Role during outbreak investigations, and reportable or notifiable diseases

During an outbreak or case associated with NTP species, these groups may help facilitate communication and contact tracing of animal movement between those in the pet industry such as breeders, distributors, and retailers with the appropriate government agency. They can help to determine the source and extent of the outbreak, implement prevention practices, and increase awareness among potentially affected consumers as well as others in the supply chain. Effective communication between these groups and government agencies helps to improve both animal and human health and reduce economic impacts of zoonotic disease outbreaks. Access to these networks and building positive relationships can help government agencies during and after an outbreak investigation because many times they include hard-to-reach populations.

Role in prevention messaging

Industry groups, associations, and other affiliated organizations can use their knowledge and expertise to collaborate with government agencies to help inform and distribute prevention messaging. Industry groups can develop best practice guidelines for animal species based on current science and public health issues. They should disseminate these messages throughout industry and association networks to reach as many partners as possible with consistent and effective recommendations.

Education and outreach

Public health agencies, agriculture health agencies, and environmental health agencies should collaborate to develop and disseminate infection prevention messaging, to develop data collection and surveillance programs, and to collaborate during outbreak investigations and response efforts. In the event of a suspected or confirmed outbreak associated with animal contact from an NTP species agencies can notify industry groups or associations to allow them to respond and work with agencies to stop the spread of disease. These industry groups have access to networks of breeders, distributors, and retailers, and access to these networks may be able to help inform the outbreak investigation as well as disseminate information to all involved in the industry and supply chain.

Government agencies should include zoonotic disease prevention education and outreach as part of regular agency duties. These outreach and education efforts can be enhanced by partnering with groups such as community leaders, animal or human healthcare providers, animal or human health professional associations, industry associations or groups, academic institutions including health professions' education programs (e.g., for veterinarians, physicians, physicians' assistants, nurses, and allied health professions), and others. These groups can help to reach a wider range of partner populations, provide subject matter expertise, and provide input on the feasibility of recommendations to help ensure individuals will follow them. Agencies should conduct surveillance activities for human infections associated with contact with NTP species to help evaluate and improve these recommendations.

Oversight of regulations or recommendations

Government agencies play a critical role in preventing, detecting, and responding to zoonotic disease outbreaks, including by enforcing regulations, recommendations, or advisories with the goal of preventing and controlling infectious disease threats. Government agencies should encourage or require oversight by the appropriate authority (e.g., local public health or animal health agencies, industry groups, or associations) to ensure compliance with recommendations at various public settings at which NTP species are present, such as backyard poultry retailers, pet stores, petting zoos and farms, schools, daycares, educational animal shows, and others. Agencies should consult The Compendium of Measures to Prevent Disease Associated with Animals in Public Settings, 2017 for further recommendations for disease prevention for animal exhibitors and venue operators. All appropriate venues should be encouraged or required to ensure compliance with recommendations to reduce the risk to human health from zoonotic diseases transmitted by NTP species.

Outbreak response

During an outbreak response, involved sectors should take the following steps as appropriate: