Melissa Kaplan's
Herp Care Collection
Last updated December 18, 2009

Salmonella and Other Zoonoses: The Basics

©2002 Melissa Kaplan

If you have an iguana, chances are someone you know has already grilled you or freaked you out because they think you are going to get sick or die because your iguana has Salmonella. There is indeed a risk of contracting or causing others to contract a Salmonella infection from your iguana if you are not aware of the potential for infection and fail to take adequate means to avoid infection and transmission.

What the person who informed you about iguana salmonellosis probably doesn't know is that he or she is just as likely to get sick from other reptiles, other pets, and foodborne organisms and chemicals.

Potentially harmful organisms and chemicals are all around us - and in us. Iguanas have been making headlines in the past decade because they were the top-selling reptile in the US (and increasingly in other countries) and were sold by people who were clueless about zoonoses to people who were equally clueless. When the Pet Industry Joint Advisory Council (PIJAC) was recommending iguanas as great holiday gifts because they are so easy to care for, with no mention of any health concerns, well, it was only a matter of time before iguana-associated salmonellosis became a well publicized public health issue. Back in the 1960s through the early 1970s, headlines and health concerns were centered around the equally cheap, widely sold--and wildly ill-treated--aquatic turtles who were riddled with Salmonella.

The reality is that all reptiles can--and a significant number do--carry one or more serotypes of Salmonella and many other organisms that can cause illness in humans and other animals. By the same token, all mammals and birds can be host to a wide range of bacterial and viral organisms that can cause illness in healthy humans as well as those individuals who are at high risk for infections. Amphibians and fish can also be vectors for some zoonotic organisms.

Reptile-Associated Zoonoses
There are several other zoonotic organisms that can be transmitted from reptiles to their keepers (and their keepers' families) that can cause the same types of symptoms as a Salmonella infection:

Pet- and Wildlife-Associated Zoonoses
Reptiles aren't the only animals that pose a potential health risk to humans. The following zoonotic organisms are just some of the diseases and organisms that can be transmitted from animals (or their parasites) to humans. The links are to the CDC's information on these diseases. Please keep in mind that the CDC data often reflects underreporting due to misdiagnosis and/or questionable reporting criteria of parasitic and infectious zoonotic diseases.

*The prion causing bovine spongiform encephalopathy (mad cow disease) and ovine spongiform encephalopathy (scrapie) is also responsible for atypical Creutzfeldt-Jakob disease (CJD). Prion diseases have been recorded in the U.S., as they are found in cattle, elk, mink, mule deer, and squirrel. CJD in Kentucky humans has been linked to their consumption of squirrel brains.

Other Foodborne Diseases
We tend to think of Salmonella as being the leading foodborne disease. In fact, it is only one of over 250 potentially deadly organisms and chemicals found in our food supply in frequencies that surprise most people.

Foodborne infections are estimated to cause 76 million illnesses, 325,000 hospitalizations, and 5,200 deaths in the United States each year. Known pathogens account for an estimated 14 million illnesses, 60,000 hospitalizations, and 1,800 deaths annually. Foodborne Infections, CDC, 2001

Foodborne organisms include:

Gastroenteritis can also be caused by viruses, including:

Gastroenteritis and other symptoms can also be caused by various marine toxins. Seafood and fish that contain these organisms may look, smell and taste just fine. The most common diseases caused by marine toxins in the U.S. are, in order of frequency, scombrotoxic fish poisoning, ciguatera poisoning, paralytic shellfish poisoning, neurotoxic shellfish poisoning, and amnesic shellfish poisoning. The ones that cause can cause gastritis-type symptoms are:

Ciguatera poisoning (ciguatera)
From contaminated tropical reef fish. Ciguatoxins are produced by microscopic dinoflagellates consumed by small fish. The toxins bioaccumulate as larger fish eat the smaller fish, reaching the highest concentrations in large predatory tropical reef fish, including barracuda, grouper, sea bass, snapper, mullet, and other popular sport fish catches that live in oceans reefs around Hawaii, Guam and other South Pacific islands, the Virgin Islands, and Puerto Rico. Ciguatoxin usually causes symptoms within a few minutes to 30 hours after eating contaminated fish. Common nonspecific symptoms include nausea, vomiting, diarrhea, cramps, excessive sweating, headache, and muscle aches. The sensation of burning or "pins-and-needles," weakness, itching, and dizziness can occur. Patients may experience reversal of temperature sensation in their mouth (hot surfaces feeling cold and cold, hot), unusual taste sensations, nightmares, or hallucinations. Ciguatera poisoning is rarely fatal. Symptoms usually clear in 1 to 4 weeks.

Neurotoxic shellfish poisoning
Caused by another type of dinoflagellate, the toxins accumulate in oysters, clams, and mussels from the Gulf of Mexico and the Atlantic coast of the southern states. Symptoms begin 1 to 3 hours after eating the contaminated shellfish and include numbness, tingling in the mouth, arms and legs, incoordination, and gastrointestinal upset. As in ciguatera poisoning, some patients report temperature reversal. Death is rare. Recovery normally occurs in 2 to 3 days.

Amnesic shellfish poisoning
Rare. Caused by a toxin made by Nitzchia pungens, a microscopic diatom consumed by shellfish such as mussels and causes disease when the contaminated shellfish are eaten. Patients first experience gastrointestinal distress within 24 hours after eating the contaminated shellfish. Other reported symptoms have included dizziness, headache, disorientation, and permanent short-term memory loss. In severe poisoning, seizures, focal weakness or paralysis, and death may occur.

Symptoms of Salmonella and Other Enteric Organisms
The following description is from the CDC's article on Salmonella enteritidis:

"A person infected with the Salmonella enteritidis bacterium usually has fever, abdominal cramps, and diarrhea beginning 12 to 72 hours after consuming a contaminated food or beverage. The illness usually lasts 4 to 7 days, and most persons recover without antibiotic treatment. However, the diarrhea can be severe, and the person may be ill enough to require hospitalization.

"The elderly, infants, and those with impaired immune systems may have a more severe illness. In these patients, the infection may spread from the intestines to the blood stream, and then to other body sites and can cause death unless the person is treated promptly with antibiotics."

How sick an infected person will get depends on several things, including the serotype of Salmonella, the number of organisms ingested, and how well the person's body (immune system, gut function, state of health overall, etc.) is equipped to handle the infection. Some individuals are considered to be at high risk just due to their age or health status.

If one has a reptile and becomes ill as described above, it may be reptile-related salmonellosis, or it may be salmonellosis from another source (meat, poultry, eggs, produce, or foods prepared with these ingredients), or another foodborne organism or zoonotic organism from another type of pet.

Knowing that there is a potential for zoonotic illness, and taking proper precautions to prevent such transmission, will greatly reduce the risk of getting sick or causing illness in others.

Sources include:
CDC Diseases: Health A-Z, Bacterial, Diseases & Conditions, Mold, Mosquito, Parasitic, Tick
CDC Foodborne Illnesses
CDC Salmonella Infection
Los Angeles County Veterinary Public Health
Potential Zoonotic Diseases in Exotic Pets
Zoonoses of House Pets Other Than Dogs, Cats and Birds

See also Emerging Human Infectious Diseases: Anthroponoses, Zoonoses, and Sapronoses