People can become infected with Cystoisospora by consuming food or water contaminated with the parasite.
Cystoisosporiasis symptoms are more severe and prolonged in people with a weakened immune system Overview of Immunodeficiency Disorders Immunodeficiency disorders involve malfunction of the immune system, resulting in infections that develop and recur more frequently, are more severe, and last longer than usual. Immunodeficiency... read more , such as people with AIDS Human Immunodeficiency Virus (HIV) Infection Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys certain white blood cells and is treated with antiretroviral medications. If untreated, it can cause... read more
.Symptoms vary but include watery diarrhea, abdominal cramping, fever, and weight loss.
Doctors usually diagnose the infection by identifying Cystoisospora in a sample of stool.
Cystoisosporiasis can be treated with trimethoprim/sulfamethoxazole (TMP/SMX).
(See also Overview of Parasitic Infections Overview of Parasitic Infections A parasite is an organism that lives on or inside another organism (the host) and benefits (for example, by getting nutrients) from the host at the host's expense. Although this definition actually... read more .)
Cystoisosporiasis is most common in tropical and subtropical climates. When encountered in the United States, it is usually in immigrants or travelers with exposure in endemic areas.
Symptoms of Cystoisosporiasis
The primary symptom of cystoisosporiasis is sudden, nonbloody, watery diarrhea. Other symptoms include fever, abdominal cramps, nausea, fatigue, and weight loss. Symptoms in people with a normal immune system usually last weeks, then subside.
In people with a weakened immune system Overview of Immunodeficiency Disorders Immunodeficiency disorders involve malfunction of the immune system, resulting in infections that develop and recur more frequently, are more severe, and last longer than usual. Immunodeficiency... read more , including people with AIDS More severe symptoms Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys certain white blood cells and is treated with antiretroviral medications. If untreated, it can cause... read more , cystoisosporiasis may cause severe diarrhea that may persist for a long time.
Diagnosis of Cystoisosporiasis
Stool tests
To diagnose cystoisosporiasis, a stool sample is examined under a microscope for Cystoisospora eggs. Specialized techniques can be used to increase the chances of identifying the eggs.
When stool analysis does not identify a cause for persistent diarrhea, doctors may use a flexible viewing tube (endoscope Endoscopy Endoscopy is an examination of internal structures using a flexible viewing tube (endoscope). In addition to examinations, doctors can use endoscopy to do biopsies and give treatment. Endoscopes... read more ) to examine the upper part of digestive tract. Doctors may use this procedure to obtain a sample of tissue to be examined and analyzed (biopsied). Cystoisospora, if present, can be seen in a biopsy sample from the intestine.
Prevention of Cystoisosporiasis
When traveling to tropical and subtropical areas where the infection is common, people should avoid eating uncooked foods, including salads and vegetables, and should avoid consuming potentially contaminated water and ice. Hand washing with soap and water is important. Drinking water that has been boiled is safe. Filtering water through a 0.1 or 0.4 micron filter can remove cysts of Cystoisospora and other parasites, as well as bacteria that cause diseases.
Treatment of Cystoisosporiasis
Trimethoprim/sulfamethoxazole (TMP/SMX)
Infected people who have symptoms can be treated with trimethoprim/sulfamethoxazole (TMP/SMX) taken by mouth.
In people with AIDS More severe symptoms Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys certain white blood cells and is treated with antiretroviral medications. If untreated, it can cause... read more , it is very important to treat HIV infection Antiretroviral Treatment of Human Immunodeficiency Virus (HIV) Infection Antiretroviral medications used to treat human immunodeficiency virus (HIV) infection aim to do the following: Reduce the amount of HIV RNA (viral load) in the blood to an undetectable amount... read more as effectively as possible with antiretroviral drugs. Such treatment can strengthen the weakened immune system, which usually helps control the diarrhea and other symptoms. People with AIDS may need a higher dose of TMP/SMX and a longer course of treatment. Sometimes long-term TMP/SMX maintenance therapy is needed in people with HIV/AIDS.
For cystoisosporiasis, people who are allergic to (or intolerant of) TMP/SMX can be treated with pyrimethamine. Leucovorin is given concurrently to prevent anemia and low white blood count, which are side effects of pyrimethamine.
Ciprofloxacin has been used to treat cystoisosporiasis, but it is less effective than TMP/SMX.
