Zoonotic concern: Salmonellosis in Reptiles

Introduction

The physical and psychological benefits of pet ownership have been well established (8), however pet ownership is not without risks such as the potential for transmission of zoonotic disease. Reptiles can carry a number of bacterial, fungal, protozoal, and parasitic pathogens including Salmonella spp. (Fig 1). Approximately 6% of human Salmonella spp. infections are acquired from reptiles (10).

Figure 1. Reptiles can carry a number of pathogens including Salmonella spp. Shown here, Dr. Paul Gibbons with tortoise. Click on image to enlarge.

Reptiles are asymptomatic carriers of Salmonella spp.

In some reptile species, it is estimated that 83.6% to 93.7% of the population harbors Salmonella spp. as part of normal intestinal flora (7,14). In rare instances, Salmonella spp. can be associated with clinical disease in reptiles, however most individuals show no clinical signs. Salmonella spp. is shed continuously or intermittently in the feces in these reptiles, and the incidence of shedding may increase with stress. Water can serve as an amplification site for the growth of Salmonella bacteria (7,9).

How is Salmonella transmitted to humans?

Salmonella may be spread through direct or indirect contact with the reptile or its droppings (7,10,14). In fact, “Simply having a reptile in the household increases the risk of infection” (11).

The sale or distribution of small turtles, those with shell lengths less than 10 cm (4 inch), has been prohibited in the United States since 1975 (14). The 4-inch rule was developed so that it would be difficult for infants and young children to treat turtles like toys or place them in their mouths (14). The federal ban in the United States reduced the number of turtle-associated human Salmonella infections during subsequent years, especially among children (14). Although numerous sporadic turtle-associated infections were reported in humans after the ban went into effect, significant outbreaks were not reported until relatively recently. Since 2006, multistate outbreaks of turtle-associated Salmonella infections have been documented in the United States (1,9,4-6). It is unclear why this is so. This may reflect improved surveillance, or perhaps turtle ownership is again increasing in the United States.

Who is most at risk?

Both animal care workers and reptile owners are at risk for contracting reptile-associated salmonellosis (2). The relatively weak immune system of children combined with the difficulty of enforcing good hygiene practices in youngsters can make reptile ownership a significant risk in households with young children (4-6,9,12). In one survey, 45% of reptile-associated salmonellosis cases were in children aged 5 years or less (12). Other immunosuppressed individuals at risk include the elderly, patients on chemotherapy, and individuals positive for the human immunodeficiency virus (HIV).

What are the signs of salmonellosis in human patients?

Salmonellosis usually causes a self-limiting gastroenteritis (13). Clinical signs in humans typically include diarrhea, fever, abdominal pain, and nausea. Unfortunately severe, invasive infections may be particularly common in immunocompromised individuals such as infants and children under 5 years. These infections can lead to meningitis, brain abscesses, myocarditis, sepsis, and death (13).

How can reptile-associated salmonellosis be prevented?

Veterinary health care professionals must educate owners about the zoonotic potential of Salmonella spp., particularly when children live in the household. In a survey of patients involved in two reptile-associated salmonellosis outbreaks, less than 30% reported knowing that reptiles commonly shed Salmonella spp. (9).

Additional preventive measures include (1-3,14):

• Wash hands thoroughly with soap and water after handling reptiles or anything in the reptile area. Do not touch your face, other people, or any surface until hands have been washed.
• Reptiles should not be recommended as pets for children under five years of age, adults over 65 years of age, or individuals with weakened immune systems.
• Do not acquire turtles with a shell length measuring less than 10 cm (4 in) in size.
• Educate owners about high-risk behaviors, such as kissing reptiles, allowing reptiles access to food preparation areas, or cleaning reptile habitats in kitchen or bathroom sinks.
• Careful and appropriate animal sanitation procedures are required. A utility sink should be used to clean reptile caging and never the kitchen sink.

Download LafeberVet’s client education handout: Responsible Reptile & Amphibian Ownership: Know the Facts on Salmonellosis. Visit the Association of Reptile and Amphibian Veterinarians and the Centers for Disease Control and Prevention for additional resources, including:

• Compendium of Measures to Prevent Disease Associated with Animals in Public Settings, 2013External
• The Trouble with Tiny Turtles 

References