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Cryptosporidium

Cryptosporidium is a very common intestinal infection of dogs and puppies although most don’t need treatment. Lots of dogs infected with “Crypto” shed the parasite in their stools without showing any symptoms. When symptoms do arise, occasional or ongoing abnormal stools (watery diarrhea) are most common.[2] For dogs with these or other signs of digestive upset, include microbe screening by PCR (ClueJay Dog Stool Test Level 3) as a reliable way to search for Cryptosporidium and other disease-causing microbes found in dog intestines.

Most dogs and puppies show no signs of Cryptosporidium infection and remain healthy, while others break with watery diarrhea that can lead to dehydration.

Companion Animal Parasite Council (CAPC)

All About Cryptosporidium

What Is Cryptosporidium?

Cryptosporidium is a common intestinal parasite that can infect a wide variety of animals, including (but not limited to) dogs, cats, and even humans.[2,4]  Most of the time the type of Crypto infection is very specific to the type of animal. Dogs get infected with Cryptosporidium canis, while cats get C. felis and humans get C. parvum and C.hominis.[2,3]

Like Giardia and coccidia (Cystoisospora spp.), Cryptosporidium are protozoa and not “worms”. They are not susceptible to “deworming” medications used for roundworms, hookworms, tapeworms, or whipworms. With the naked eye you won’t ever see Crypto (or other coccidia) in your dog’s stool. This is because all stages of their life are microscopic.

Dogs become infected with Cryptosporidium coccidia by accidently swallowing their infective spores (oocysts) from the environment.[1,2,4]  Crypto oocysts are very resilient to disinfectants and can survive for many months indoors within a kennel, shelter, or household, or outdoors for the same amount of time if the temperature and humidity are right.[2]

Fortunately, most dogs infected with Cryptosporidium appear as normal, healthy dogs. Their immune systems can keep Crypto activity in check, so the intestinal damage is mild and easily repaired. These dogs probably don’t have or only rarely have abnormal stools (diarrhea).

When dogs do get sick from Crypto, the symptoms can range from mild to serious and mimic signs of other intestinal diseases. Clinical signs from Crypto are the result of this parasite damaging the hair-like lining (microvillous) of the small intestines. This leads to watery (secretory) diarrhea that can be severe enough to cause dehydration.[1,2,4] The diarrhea can be occasional or ongoing, and might turn bloody.

Searching for Crypto in stool samples is best done with microbe testing by PCR (ClueJay Dog Stool Test Level 3).

How Common Is Cryptosporidium?

Cryptosporidium is considered a common, contagious parasite in dogs and other animals.[2] Most of the time the type of Crypto infection is very specific to the type of animal. Dogs get infected with Cryptosporidium canis, while cats get C. felis and humans get C. parvum and C.hominis.[2,3] Fortunately, most dogs infected do not show symptoms of illness.

While Crypto is common, finding it under the microscope isn’t. On occasion Crypto oocysts are suspected on a fecal O&P (ova (egg) and parasite) stool test. However, it cannot be reliably diagnosed this way because it looks like some other coccidia. Most of the time, a microbe PCR test (ClueJay Dog Stool Test Level 3) is needed to detect the presence of this parasite in dog stool.

What Does Cryptosporidium Look Like?

Cryptosporidium are a type of protozoa called coccidia. All life stages of Crypto are too small to be seen by the naked eye. Some life stages can only be seen by biopsy of the intestine and microscopy, so it’s best to search for the oocysts (spores) of Crypto in stool samples.

The oocysts (sporozoites) are the egg-like form of Crypto in the stool which can occasionally be seen during a fecal O&P (ova (egg) and parasite) test used to look for parasitic worms (roundworms, hookworms, tapeworms, and whipworms) and some other types of coccidia (Cystoisospora spp.) under the microscope. Even if suspected though, it is nearly indistinguishable from some other types of coccidia so this is not a good way to screen for Crypto.[2] Searching for Crypto in stool samples is best done with microbe testing by PCR (ClueJay Dog Stool Test Level 3).

What Symptoms Are Caused By Cryptosporidium?

Most dogs infected with Cryptosporidium appear as normal, healthy dogs. Their immune systems can keep Crypto activity in check, so the intestinal damage is mild and easily repaired. These dogs probably don’t have or only rarely have abnormal stools (diarrhea).

However, if their health situation changes then these dogs can become sick from Cryptosporidium (called Cryptosporidiosis). Dogs and puppies that are immune-suppressed, fighting off other infections (e.g., canine distemper virus), and/or in stressful conditions (like being transported/relocated or overcrowded) may become unable to keep the Crypto in check.[2,4

When dogs do get sick from Crypto, the symptoms can range from mild to serious and mimic signs of other intestinal diseases. Clinical signs from Crypto are the result of this parasite damaging the hair-like lining (microvillous) of the small intestines. This leads to watery (secretory) diarrhea that can be severe enough to cause dehydration.[1,2,4] The diarrhea can be occasional or ongoing, and might turn bloody.

If your dog is acting sick, please contact a veterinarian right away.

How Do Dogs Get Cryptosporidium?

Dogs become infected with Cryptosporidium coccidia by accidently swallowing their infective spores (oocysts) from the environment.[1,2,4]  Crypto oocysts are very resilient to disinfectants and can survive for many months indoors within a kennel, shelter, or household, or outdoors for the same amount of time if the temperature and humidity are right.[2]

Crypto contaminate the indoor or outdoor environment from the stool of an infected dog. These coccidia can then re-infect the same dog or infect new dogs when the infective oocysts are swallowed. This can occur from licking the floor or toys, by eating soil, grass, or plants, or drinking water that had been contaminated with Crypto.

Dogs that are immune-suppressed or fighting off other infections (e.g., canine distemper virus) are at higher risk for more severe, prolonged, or even life-threatening Crypto infections.[2] Puppies are also at higher illness risk from Crypto because their immune systems are less mature. Dogs and puppies in stressful conditions (like being transported/relocated or overcrowded) may be at more risk of Crypto symptoms (watery diarrhea and dehydration) if infected.

What Is The Cryptosporidium Life Cycle?

Cryptosporidium spp. coccidia start their life as immature spores (called unsporulated oocysts) which are shed within the stool of a dog within a week of first infection.[2] A spore is a reproductive cell that is quite resilient and can survive for months (indoors or outdoors) unless subjected to freezing or very high temperatures (scalding water or steam) and desiccation (drying). Kennels, shelters, day cares, and home environments can stay contaminated with Crypto for long periods of time.

The oocysts are immediately infectious when passed in the stool.[2] This means that the four microscopic, motile sporozoites within each oocyst don’t need to develop further in the environment like some other parasites. After getting swallowed, these sporozoites get ‘hatched’ from the oocyst in the dog’s intestines. They then invade the hair-like (microvillous) lining of the small intestines to reproduce (as gamonts) and release the next generation of immature oocysts.[1] Once in the environment, they may get swallowed to re-infect the same dog or infect a new dog.

It’s the activity of Crypto in the hair-like lining of the small intestines which can damage cells and disturb normal food and fluid absorption, leading to symptoms of digestive upset. While many dogs with Crypto don’t show any signs of illness, enough damage to the lining can lead to occasional or ongoing episodes of watery (fluid-loss) diarrhea.[2,4]

Can People Or Other Pets Get Cryptosporidium?

Most of the time the type of Crypto infection is very specific to the type of animal. Dogs get infected with Cryptosporidium canis, while cats get C. felis and humans get C. parvum and C.hominis.[2,3] Dogs and cats with healthy immune systems are unlikely to get Crypto from each other or from people. Humans with healthy immune systems are also unlikely to get Crypto from a dog (or cat).

However, C. canis (dogs) and C. felis (cats) have been shown to infect people with weakened immune systems (e.g., diabetes, chronic illness, HIV positive, during chemotherapy, etc.) and potentially be quite dangerous in such situations.[2,3] Crypto symptoms in people include watery diarrhea, stomach cramps or pain, dehydration, nausea, vomiting, fever, and weight loss.[3] Humans are much more likely to get Cryptosporidiosis through soil, food (unwashed fruits and vegetables), water (municipal or recreational water contaminated with sewage), or surfaces contaminated with human stool than from a pet’s stool.[2,3,4]

If your dog (or cat) had carried or does carry Crypto and you or a family member that interacts with the pet becomes sick with intestinal problems, then be sure to tell the human healthcare professionals. While the chance of transmission to humans from a dog or cat is extremely low, it isn’t zero and people with immune suppression are at much greater risk.[2,3]

How Is Cryptosporidium Prevented & Treated?

Dogs become infected with Cryptosporidium coccidia by accidently swallowing their infective spores (oocysts) from the environment.[1,2,4] Crypto contaminate the indoor or outdoor environment from the stool of an infected dog. These coccidia can then re-infect the same dog or infect new dogs when the infective oocysts are swallowed from licking the floor or toys, by eating soil, grass, or plants, or drinking water that had been contaminated with Crypto.

Preventing Cryptosporidium is first and foremost about hygiene. Cryptosporidium ‘eggs’ (oocysts) are infective immediately once passed in the dog’s stool, so daily removal of stool is the best way to prevent exposure. This includes thoroughly cleaning indoor areas where dog stool has been present.[1] Crypto oocysts are very resilient to disinfectants and can survive for many months indoors within a kennel, shelter, or household, or outdoors if the temperature and humidity are right.[2] Steam and pressure washing may help to dislodge stool particles from kennel and cage surfaces. Painting and sealing kennel floors will help prevent stool from adhering to these surfaces while cleaning.

Humans are much more likely to get Cryptosporidiosis through soil, food (unwashed fruits and vegetables), water (municipal or recreational water contaminated with sewage), or surfaces contaminated with human stool than from a pet’s stool.[2,3,4] For people, prevention is best achieved by washing hands with soap and water after exposure, washing fruits and vegetables, and not drinking from contaminated sources. Additional information on human prevention can be found with the Centers for Disease Control (CDC).[5] People that are immune-suppressed, or have any concern about the risk of Crypto should consult with their healthcare professionals.

Dogs that are immune-suppressed or fighting off other infections (e.g., canine distemper virus) are at higher risk for more severe, prolonged, or even life-threatening Crypto infections.[2] Puppies are at risk from Crypto because their immune systems are less mature. Dogs and puppies in stressful conditions (like being transported/relocated or housed in groups) may be at more risk of developing Crypto symptoms (watery diarrhea and dehydration) if infected.

Healthy dogs with strong immune systems can usually suppress the Cryptosporidium infection on their own and not get sick. However, the risk of infection to other dogs that live in the same household or community needs to be considered. Stool testing (ClueJay Dog Stool Test Level 3) can help detect which dogs are carrying and shedding Crypto. For dogs and puppies that have symptoms (watery diarrhea), antibiotics are the preferred treatment but none are consistently effective against Crypto.[2] Sometimes anti-parasitic drugs are tried if antibiotics aren’t working.[1,2] All such treatments require a veterinarian’s prescription.

Where Are Cryptosporidium Medications Purchased?

ClueJay does not dispense or prescribe medications, and there are no FDA-approved medications in the U.S. for Cryptosporidium treatment.[2,4] Antibiotics like azithromycin, tylosin, and paromomycin are sometimes used off-label.[2] Nitazoxanide is an anti-protozoal that has been used but efficacy is questionable. All of these drugs require a veterinarian’s prescription in the U.S., and none are consistently effective against Crypto.

While it is always best to consult with a veterinarian prior to administering any medication, even an OTC version, it is especially true for off-label treatment of Cryptosporidium. Always read the medication administration directions carefully and be on the lookout for potential side effects (like vomiting) when any medication is administered.

When/How is Dog Stool Tested For Cryptosporidium?

Simply put, include a PCR test for Cryptosporidium whenever a dog has frequent or ongoing diarrhea (especially if watery), increased urgency to pass stool, or other digestive problems. Need details? Read on.

Many dogs infected with Cryptosporidium do not get clinical symptoms. Their immune systems keep Crypto in check and they remain healthy. When dogs do get sick from Crypto, the symptoms (watery diarrhea) can look like those of worms (hookworms), bacteria (Salmonella), viruses (canine parvovirus), different protozoa (Giardia), and many other causes. Figuring out the underlying reason(s) for the symptoms is best done through testing.

ClueJay Dog Stool Test Level 3 includes a Cryptosporidium by Polymerase Chain Reaction (PCR) assay along with PCR tests for other disease-causing protozoa, bacteria, and viruses found in dog intestines. These tests are designed to find the DNA of hard to find microbe pathogens.

Veterinarians recommend stool (fecal) testing puppies 2 to 4 times during their first year of life, and 1 to 2 times each year in adult dogs (every 6 to 12 months). Veterinarians often call this stool health test a “Fecal O&P”, with the O&P meaning “ova (eggs) and parasites”. It includes special preparations of the stool sample and analysis using a microscope to look for roundworms, hookworms, tapeworms, whipworms, and some types of coccidia. While Crypto is common, they are only rarely seen using this method. Even if suspected though, they are nearly indistinguishable from some other types of coccidia so this is not a good way to screen for Crypto.[2] ClueJay Dog Stool Test Level 1, 2, and 3 include a stool O&P, but the O&P is unlikely to identify Crypto. However, they will get reported if suspected. Searching for Crypto in stool samples is best done with microbe testing by PCR (ClueJay Dog Stool Test Level 3).

With ClueJay’s simple and intuitive testing solution from home, you can directly access this same professional reference lab testing for Crypto that veterinary professionals use every day.

My Dog Tested Positive for Cryptosporidium?

ClueJay Dog Stool Test Level 3 includes PCR assay tests for disease-causing bacteria, viruses, and protozoa found in dog intestines. One of those protozoa is Cryptosporidium. A positive test means Cryptosporidium DNA was detected in the stool. Most veterinarians then assume the cat is infected with Cryptosporidium (called Cryptosporidiosis) and actively shedding Crypto in the stool.

However, your dog may not need treatment unless there are symptoms of illness. Healthy dogs with strong immune systems may clear or suppress a Crypto infection on their own and some veterinarians don’t treat for this reason. Alternatively, your dog may have clinical signs (such as diarrhea) and a positive Crypto result but have another cause or combination cause of the illness (such as canine distemper virus).[2]  A test result is not the same as a veterinarian’s diagnosis, so it’s always best to consult with a veterinarian about your dog’s test results to determine the safest and most effective treatment and prevention plan, and when to do follow-up stool tests.

It’s important to know that some dogs will continue to test positive for Cryptosporidium even after treatment. This is most likely because the dog remains in an environment where re-infection keeps occurring, but not always. Other considerations for treatment failure are poor immune response and drug resistance.

ClueJay Dog Stool Test Levels 1, 2, and 3 include a reference lab stool O&P (fecal ova and parasites) which screens for roundworms, hookworms, tapeworms, whipworms, and some types of coccidia. While Crypto may rarely be found in this type of stool preparation, this is not a reliable method because it is nearly indistinguishable from some other coccidia. Therefore, microbe testing by PCR is used to reliably test for the presence of Crypto. If this parasite was reported in this way, it’s best to consider this a “tentative finding of Cryptosporidium” or “finding suspicious of Cryptosporidium”. When this happens (Crypto suspected from stool O&P), it’s best to double-check with a Cryptosporidium PCR test through your veterinarian or using ClueJay Dog Stool Test Level 3. Summary: the stool O&P is a great test to find worms and some types of coccidia, but not Cryptosporidium.

My Dog Tested Negative for Cryptosporidium?

ClueJay Dog Stool Test Level 3 includes PCR assay tests for disease-causing bacteria, viruses, and protozoa found in dog intestines. One of those protozoa is a type of coccidia called Cryptosporidium. A negative test means Crypto DNA was not detected in the stool. This is good news because no one wants their dog or puppy shedding Crypto, putting other dogs at risk of infection.

Depending on their lifestyle, dogs can remain at risk of Crypto exposure so a negative test result today doesn’t mean it couldn’t be positive later. Since dogs may shed Cryptosporidium intermittently, it’s possible to test a stool sample from an infected dog without any of this parasite’s DNA. This is called a “false negative” when the test result is negative but the dog is infected. 

If Crypto infection was suspected and you have other dogs in the household, consider testing them as well since Cryptosporidium in one dog can often lead to Crypto in others. Dogs negative on Crypto by PCR but still with Cryptosporidium-like symptoms such as watery stools, likely have a different explanation for the symptoms. Please consult with a veterinarian if this is the situation with your dog.

Sources

  1. PetMD, Intestinal Parasite (Cryptosporidium) in Dog
  2. Companion Animal Parasite Council, Cryptosporidium
  3. Centers for Disease Control and Prevention, Parasites – Cryptosporidium
  4. Pet Health Network, Cryptosporidium in Dogs, Cats, and People

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