Coccidia are microscopic protozoa that infect the intestinal tracts of animals. The resulting infection, Coccidiosis, is one of the most common intestinal parasites affecting domestic animals, especially in high-density environments. These parasites reproduce within the cells lining the small intestine. Their eggs, called oocysts, are shed into the environment through the host’s feces. Coccidia is frequently encountered in young animals, such as puppies, whose developing immune systems may not be robust enough to suppress the infection.
Understanding Species Specificity and Human Risk
The primary question for many pet owners is whether they can contract Coccidiosis from their infected dog, and the answer is generally no. The Coccidia species that commonly infect dogs belong to the genus Cystoisospora, and these parasites are highly species-specific. This means the variety that infects a dog is typically unable to complete its life cycle and cause disease in a healthy human.
The canine Coccidia is not considered a significant public health risk because of this biological barrier. The parasite is adapted to a specific host, and the human intestinal tract does not provide the necessary environment for the dog-specific oocysts to mature and multiply. Good hygiene, such as promptly cleaning up pet waste and frequent handwashing, is recommended to minimize exposure to any pathogens found in feces.
While the primary canine Coccidia is not transmissible to people, other types of coccidian parasites have zoonotic potential. For example, Cryptosporidium can infect both dogs and humans, although the species that infect dogs are often different from those that cause human illness.
Symptoms and Diagnosis in Dogs
In dogs, Coccidiosis symptoms are most often observed in puppies under six months old, as their intestines are more susceptible to damage from the multiplying parasites. Many healthy adult dogs can harbor the parasite and shed oocysts without showing signs of illness. When symptoms appear, they result from the parasite destroying the cells that line the intestinal tract.
The most common sign of Coccidiosis is watery diarrhea, which may contain excessive mucus or streaks of blood. Persistent diarrhea, particularly in small or young dogs, can lead to dehydration and lethargy. Owners may also notice vomiting, weight loss, and a general lack of appetite as the infection progresses.
Diagnosis
Diagnosing Coccidiosis requires a veterinarian to perform a fecal flotation test on a fresh stool sample. This procedure involves mixing the feces with a solution that causes the microscopic oocysts to float to the surface for identification under a microscope. Because dogs can shed oocysts intermittently, a single negative test result does not always rule out the parasite, and repeat testing may be necessary if clinical signs persist.
Environmental Management and Treatment
The treatment for Coccidiosis in dogs typically involves prescription anti-coccidial medications, which are often sulfa-type antibiotics such as sulfadimethoxine. These drugs work by interrupting the parasite’s life cycle within the dog’s intestinal cells, which helps to reduce oocyst shedding and allows the intestinal lining to heal. The course of treatment usually lasts for a specified period and may be followed by a re-test to confirm the infection has cleared.
Environmental sanitation is equally important because the oocysts shed in the feces can survive in the environment for months and are resistant to many common disinfectants. The most effective step is the prompt removal of all feces from the yard or kennel, ideally within hours, before the oocysts have time to mature into their infective stage. Once oocysts become sporulated, they are much harder to eliminate.
To clean contaminated indoor areas, veterinarians often recommend using steam cleaning or a diluted bleach solution of one cup of bleach mixed with a gallon of water. The infective oocysts are highly resistant to cold, but they can be destroyed by high temperatures, making steam a useful tool for surfaces. Preventing access to standing water and ensuring a dry environment can also help to break the parasite’s life cycle and reduce the risk of reinfection.