Zoonotic concern: Salmonellosis in Reptiles

Introduction

The physical and psychological benefits of pet ownership have been well established (Friedman 2009), 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 (Mermin 2004).

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

Who: The immunocompromised are most at risk for reptile-associated salmonellosis.

Both veterinary staff and owners are at risk for contracting reptile-associated salmonellosis, however children are at greatest risk because of their relatively weak immune system. In one survey, 45% of reptile-associated salmonellosis cases were in children aged 5 years or less. Other immunosuppressed individuals at risk include the elderly, patients on chemotherapy, and the HIV-positive.

What: Clinical disease can range from gastroenteritis to fatal meningitis.

Salmonellosis usually causes a self-limiting gastroenteritis. 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.

Why: Most 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. 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 then serve as an amplification site for Salmonella bacteria (Harris 2010).

How: Salmonella may be spread through contact with the reptile or its droppings.

Transmission of disease may be direct or indirect, in fact “Simply having a reptile in the household increases the risk of infection” (Mermin 2004).

The sale or distribution of small turtles, those with shell lengths less than 4 inch (10 cm), has been prohibited in the United States since 1975. 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. The federal ban in the United States reduced the number of turtle-associated human Salmonella infections during subsequent years, especially among children. Although numerous sporadic turtle-associated infections have been reported in humans since the ban went into effect, significant outbreaks have not been reported until recently. Since 2006, three multi-state outbreaks of turtle-associated Salmonella infections have been documented in the United States. It is unclear why this is so. This may reflect improved surveillance, or perhaps turtle ownership is again increasing in the United States.

Client education

Prevention of disease is crucial. In a survey of patients involved in two reptile-associated salmonellosis outbreaks, less than 30% reported knowing that reptiles commonly shed Salmonella spp. (Harris 2010). Veterinary health care professionals must educate owners about the zoonotic potential of Salmonella spp., particularly when children live in the household. 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.

Download LafeberVet’s client handout: Salmonellosis in Reptiles and go to the Association of Reptile and Amphibian Veterinarians, or the Centers for Disease Control and Prevention for additional resources.

References