What is Cryptosporidium?
Cryptosporidium is believed to be a secondary, rather than primary pathogen, as it can lead to severe infections in immunocompromised birds, and has often appeared along with other diseases.
The primary route of transmission involves sporulated oocysts, rather than eggs, that are shed by the infected bird into the environment with its feces. These sporulated oocysts are developed eggs that are infective. Once these sporulated oocysts are eaten or inhaled by a healthy bird, sporozoites are released from the oocysts to attach to gastrointestinal or respiratory tissues, where they multiply and reproduce. Oocysts develop, which then sporulate inside the host bird. Some of these sporulated oocysts infect surrounding tissues in the host, while others are shed in the feces.
Protozoan parasites in the Cryptosporidiidae family cause this potentially chronic or life-threatening disease in many species of animals, including birds. These parasites can invade wild birds, gamebirds, poultry, and pet birds, such as parrots, cockatiels, finches, parakeets, budgerigars, and cockatoos. Signs of an infection reflect the invaded systems, and can include respiratory and digestive complaints.
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Symptoms of Cryptosporidium in Birds
While some infected birds will be asymptomatic, others can show signs that relate to the digestive or respiratory systems, depending on where the parasites choose to live. These signs can last several weeks, and can include:
- Weight loss
- Ruffled feathers
- Breathing difficulties
- Clicking, rattling, or bubbling lung sounds
- Open-mouthed breathing
- Discharge from the eyes or nostrils
- Swollen sinuses
- Airsacculitis, or inflammation of the air sacs
- Tail bobbing
- Low exercise tolerance
There are two recognized clinical forms of cryptosporidium.
Cryptosporidium live in the respiratory tract, including the nasopharynx, larynx, sinuses, trachea, air sacs, and conjunctiva. This results in symptoms relating to breathing, the sinuses, and the eyes.
Cryptosporidium live in the digestive tract, including the salivary glands, small intestine, cecum, colon, and bursa. This results in symptoms involving digestive malfunction, and subsequent malnourishment.
Causes of Cryptosporidium in Birds
The cause of this infection is the invasion of the cryptosporidium parasite into a healthy bird. Transmission is solely through ingestion or inhalation of sporulated oocysts and not transmitted by the eggs. Transmission can occur through:
- Contaminated feces
- Contaminated water or feed
- Exposure to infected soils, litters, or dust
- Exposure to contaminated human handlers, clothes, and equipment
Infected birds that show no symptoms can still shed sporulated oocysts into the environment.
Diagnosis of Cryptosporidium in Birds
Diagnosis of a cryptosporidium infection can be difficult, as the oocysts are very small and difficult to see. A history of symptoms in your bird, and any others in the population, can help your veterinarian to narrow down a cause. Fecal samples provide the best starting point, and can reveal these sporulated oocysts. Tissue scrapings from the trachea, sinuses, intestines, or other various digestive organs can be microscopically examined for signs of the parasite. Other tests can include a PCR, Sheather’s sugar flotation test, and the use of immunofluorescent stains. If no parasites were found in fecal samples, it may suggest that the infection is confined to the respiratory system.
Treatment of Cryptosporidium in Birds
There are no known anticoccidial or antimicrobial drugs that have shown success in eliminating the cryptosporidium parasite. However, a cryptosporidial infection can resolve on its own without any treatment. If treatment is given, it will attempt to treat any concurrent problems that could cause immunosuppression in your bird, as well as to reduce parasite numbers and prevent reinfection or further spread of the parasite.
Treatment can include administration of various antibiotics, which could include paromomycin or azithromycin, for several weeks. Supportive therapy may help to reduce fatalities, although many birds die or are euthanized after treatment.
It is important to clean your bird’s environment to prevent a reinfection in your recovering bird, and to prevent the spread of this parasite to healthy birds. Cryptosporidium are very resistant to chemical disinfectants, but steam cleaning has been shown to reduce infection, as sporulated oocysts become inactive when exposed to temperatures over 65°C. Practicing good hygiene and sanitation routinely, and incinerating all infected birds, should reduce the potential for transmission.
Recovery of Cryptosporidium in Birds
Recovery for Cryptosporidium can vary. Many birds will die or be euthanized even after treatment, while others can spontaneously recover on their own. Your bird many need several weeks of drug and other supportive therapies. Cleaning the environment is key to both your bird’s recovery and to stop the spread of this parasite. Prevention also lies in good sanitation and hygiene routines that can break the cycle of cryptosporidium before it infects your bird.