Coccidia
Coccidia are protozoal parasites of the gastrointestinal tract. Infection is most commonly caused by Cystoisospora spp. (formerly known as Isospora spp.). These microscopic parasites spread easily and can cause severe diarrhea and dehydration in some animals. Coccidiosis is most often seen in puppies and kittens younger than 6 months, though it can affect dogs and cats of any age in crowded shelters because of the parasite’s ability to survive in the environment and resist some disinfectants. The risk of shelter spread can be reduced by empirical deworming for coccidia in puppies and kittens upon intake, implementing strict cleaning and sanitation measures and reducing stress and overcrowding in the shelter.
What You Should Know
Coccidia infection in adult dogs or cats with a healthy immune system may be asymptomatic and self-limiting. Clinical signs are most often seen in animals with co-infections, high stress levels or weakened immune systems. This makes puppies and kittens younger than 6 months old the most likely to have clinical signs of coccidia. Clinical signs of coccidia include:
- Diarrhea or vomiting
- Mucus or blood in stool
- Dehydration
- Lethargy
- Decreased appetite or anorexia
- Poor growth in young animals
Coccidia oocysts (eggs) are shed in the infected animal’s feces. The oocysts sporulate (a maturation process that makes them infectious) after spending anywhere from 6 hours to 3 days in the environment, with this process occurring more rapidly in humid conditions. Once they have sporulated, these oocysts become very hardy against disinfectants and can survive up to a year in the environment.
Coccidia is most commonly transmitted by ingestion of sporulated oocysts, either through direct contact with contaminated feces or through contact with a contaminated environment. While less of a concern in a shelter setting, transmission can also occur through ingestion of infected transport hosts, such as rodents and small vertebrates.
Zoonotic Potential
The various Cystoisospora spp. are species-specific and not zoonotic (not infectious to humans).
In many shelter environments, empirical deworming for coccidiosis is commonly initiated based on a combination of age and consistent clinical signs. This routine approach can be incorporated into a shelter’s standard operating procedures as appropriate.
Definitive diagnosis can be made through fecal parasite testing, where Cystoisospora spp. oocysts are identified on fecal flotation. It is important to differentiate the type of coccidia oocysts seen on fecal flotations, as dogs and cats may ingest coccidia of other species, which is clinically insignificant (e.g., finding the rabbit- or livestock-specific Eimeria coccidia in dog feces after the dog ingests rabbit feces). Dog and cat coccidia are characterized by having 2 sporozoites (internal structures of the oocyst) while coccidia of other species have 4 sporozoites. False negatives can also occur due to intermittent shedding of the parasite.
Other advanced diagnostic tools include a Cystoisospora antigen test and fecal PCR tests. The Cystoisospora antigen test detects coccidia proteins, while the Cystoisospora PCR tests detect DNA, making them sensitive diagnostic tests that can detect early or nonclinical infections. Both tests are often included in larger panels (looking for multiple organisms), which can be beneficial in evaluating co-infections; however, these tests can be costly and result in delayed diagnosis as they cannot be performed in a shelter.
Individual Animal Care
Cats and dogs with coccidiosis generally have a good prognosis. Although Cystoisospora can be self-limiting in animals with low stress and healthy immune systems, treatment for any clinical coccidia-positive animal is recommended while in a shelter environment. Individual animal care commonly includes heat support, fluid therapy to correct dehydration, nutritional support and hygiene maintenance to prevent fecal scalding and secondary skin infections. Broad-spectrum deworming is recommended to treat any potential co-infections that are exacerbating clinical signs.
Ponazuril and toltrazuril are antiprotozoal medications commonly used for off-label treatment of coccidiosis. Ponazuril is the treatment of choice in a shelter setting, as the 3-5 day treatment course makes this drug more efficient to administer and cost-effective. To properly dose, shelters must dilute brand-name ponazuril (i.e., Marquis paste) or purchase compounded ponazuril. Be sure to review your local compounding laws for storage of compounded ponazuril in your shelter. Sulfadimethoxine (Albon) is the only drug labeled to treat coccidia in the United States; however, it requires dosing for 1-3 weeks which can be logistically and financially difficult in a shelter. Reinfection can occur, so patients who have completed treatment should be thoroughly bathed and their environments disinfected appropriately.
Population Considerations
Puppies and kittens younger than 6 months old have a higher risk of Cystoisospora spp. infections. Empiric treatment of these puppies and kittens and nursing animals on intake will reduce coccidia spread within the shelter and help to protect this vulnerable population. Any adult animals with high levels of stress or who live in overcrowded environments are also at risk.
Disease Outbreak Management
Since this parasite requires time in the environment to become infective, outbreak management should focus on reducing environmental contamination and contact with susceptible animals. The following environmental management is necessary to reduce spread:
- Remove fecal material immediately from kennels and during walks.
- Ensure appropriate 2-step sanitation process is practiced.
- Use PPE and proper hand hygiene when handling infected animals. Clean coccidia-positive animal housing after the more susceptible and healthy animals.
- Avoid taking coccidia-positive animals to environments that are difficult to sanitize (such as grass, soil or dirt). Avoid play groups, play yards, and group-housing.
- Reduce the number of susceptible animals in the shelter by sending puppies and kittens to foster care.
The best way to prevent coccidia in a shelter is to reduce opportunities for the oocysts to sporulate and contaminate the environment. To accomplish this, implement an empirical coccidia treatment for all kittens and puppies younger than 6 months old and nursing animals on intake, as described in this example Kitten Intake Protocol. This is beneficial for individual patient health and also reduces the load of coccidia entering the facility.
Since it can take only hours for coccidia oocysts to sporulate and become infective, remove fecal matter from the environment immediately. Thoroughly clean all residual fecal matter by mechanically scrubbing with a detergent. Having sealed kennel floors for dogs or stainless-steel condos for cats will allow for easier removal and cleaning of organic debris. Consider disposable litterboxes for any cats or kittens with diarrhea. While heavily soiled bedding may be discarded, ensure all other laundry is washed using detergent and hot water, and without overloading the machine.
Sporulated oocysts are hardy in the environment and resistant to common disinfectants, making the prompt removal and mechanical scrubbing of residual fecal material incredibly important in management. While there are no published studies, facilities have used accelerated hydrogen peroxide products (e.g., Rescue) at 1:16 dilution to successfully manage protozoal outbreaks in facilities. Steam cleaning can also be used to destroy the oocysts but may be challenging in a shelter environment. As coccidia thrives in moist environments, ensure that laundry and housing areas are completely dried after cleaning.
Any shared environment (such as a yard or walking hallway) is considered high-risk for coccidia spread. Shared spaces should be mechanically scrubbed and sanitized regularly. Outdoor areas and play yards with dirt or grass present challenges for appropriate sanitation. If coccidia presents a consistent problem in your shelter, consider modifying these areas to allow better sanitation (e.g., replace dirt play yards with artificial turf).
Stress plays a role in host susceptibility to Cystoisospora spp., especially in adult dogs and cats. Approach stress reduction holistically and practice active population management and minimize individual animal stress to combat the risk to adult cats and dogs.
Sending puppies and kittens to foster homes when possible is the best way to prevent infection in these high-risk populations. Since Cystoisospora spp. are host-specific, there is potential for cats to infect other cats, or dogs to infect other dogs. If infected animals are clinically stable, foster and/or adoption can be considered during treatment. Ensure proper counselling on this infection so that any potential foster or adopter understands the risk of coccidia spread to resident animals.
