Overview
Isosporiasis (also called cystoisosporiasis or intestinal coccidiosis) is an infection of the small intestine caused by a tiny parasite called Cystoisospora belli (previously known as Isospora belli). This parasite enters the body through contaminated food or water and infects the cells lining the small intestine, causing damage that leads to digestive problems. The infection is spread through a fecal-oral route, meaning the parasite's eggs (called oocysts) pass out of an infected person in their stool and can contaminate water or food that others then consume. The most common symptoms include watery, non-bloody diarrhea, stomach cramps, nausea, vomiting, weight loss, and fatigue. In people with healthy immune systems, the illness is usually self-limiting and goes away on its own within a few weeks. However, in people with weakened immune systems — such as those living with HIV/AIDS, organ transplant recipients, or people on immune-suppressing medications — the infection can become severe, long-lasting, and even life-threatening. Treatment with the antibiotic trimethoprim-sulfamethoxazole (TMP-SMX, also known as co-trimoxazole) is highly effective and is the standard of care. People with HIV/AIDS may need long-term preventive doses to stop the infection from coming back. With proper treatment, most people recover fully. Early diagnosis and access to medication are the most important factors in a good outcome.
Also known as:
Key symptoms:
Watery diarrhea (often frequent and large volume)Stomach cramps and painNausea and vomitingUnintended weight lossFatigue and low energyFever (usually mild)Loss of appetiteBloating and gasDehydrationMalabsorption (body not absorbing nutrients properly)In severe cases, diarrhea lasting weeks or months
Sporadic
Usually appears on its own, not inherited from a parent
Variable
Can begin at different ages, from infancy through adulthood
Treatments
3 availableUrea 39.5% With 2% Salicylic Acid
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Dermacure
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Urea Cream 40 Percent
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Clinical Trials
View all trials with filters →No actively recruiting trials found for Isosporiasis at this time.
New trials open frequently. Follow this disease to get notified.
Specialists
View all specialists →No specialists are currently listed for Isosporiasis.
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Isosporiasis.
Community
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
Rare disease caregiving can be isolating. Connect with counseling and peer support.
Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.How long will I need to take antibiotics, and what happens if I miss a dose?,Am I at risk of the infection coming back, and do I need long-term preventive medication?,Are there any foods or drinks I should avoid while I am sick or recovering?,What signs should I watch for that would mean I need to go to the emergency room?,If I am allergic to sulfa drugs, what alternative treatments are available for me?,How can I prevent getting this infection again in the future?,Should my close contacts or family members be tested or treated?
Common questions about Isosporiasis
What is Isosporiasis?
Isosporiasis (also called cystoisosporiasis or intestinal coccidiosis) is an infection of the small intestine caused by a tiny parasite called Cystoisospora belli (previously known as Isospora belli). This parasite enters the body through contaminated food or water and infects the cells lining the small intestine, causing damage that leads to digestive problems. The infection is spread through a fecal-oral route, meaning the parasite's eggs (called oocysts) pass out of an infected person in their stool and can contaminate water or food that others then consume. The most common symptoms includ
How is Isosporiasis inherited?
Isosporiasis follows a sporadic inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.