Introduction:
Cystoisosporiasis is an infection that affects the intestine. The parasite may be transmitted through contaminated food or water. The most common symptom is diarrhea. Cases of cystoisosporiasis are seen throughout the world. However, the infection occurs more commonly in subtropical and tropical regions. This coccidian parasite is widely distributed in the cosmopolitan world and is frequently found in India, Africa, South East Asia, Central America, and South America. This infection is generally associated with autoimmune deficiency syndrome (AIDS) in the United States. Cystoisosporiasis is the primary autoimmune deficiency syndrome (AIDS) in around 2 to 3 % of patients from South Africa. In South America, 10 %of patients with chronic diarrhea with autoimmune deficiency syndrome (AIDS) have cystoisosporiasis. In Haiti, with autoimmune deficiency syndrome patients (AIDS), 7 to 20 % with chronic diarrhea have cystoisosporiasis.
Human immunodeficiency virus (HIV) infected patients and other immunocompromised patients are at a higher risk for chronic infection. Preventive measures should be adopted to avoid the infection.
What Is the Causative Agent of Cystoisosporiasis?
It is caused by the microscopic parasite Cystoisospora belli which was earlier known as Isospora belli (a protozoan parasite). It is an opportunistic infection (which occurs in immunocompromised individuals). The infection majorly affects the small intestine and grows in the cell cytoplasm of the epithelial cells.
What Is the Lifecycle Of Cystoisosporiasis?
The oocysts of Cystoisosporiasis belli are shed in the feces of infected individuals and sporulate outside the host to become infective. However, the life cycle of Cystoisospora belli is completed in human beings. The maturation process is completed in around two days but occurs more quickly under certain conditions. The parasite, after ingestion, reaches the enterocytes in the small intestine. Immature oocysts are finally produced and later shed in the stool.
How Is Cystoisosporiasis Transmitted?
Cystoisosporiasis is usually transmitted indirectly through food or water contaminated with infected feces. The immature parasites are transmitted from the shed feces of an infected person. To mature, the parasite requires around two days in the environment to infect another person. However, sometimes the parasite may multiply within a day. Oral or anal contact with an infected person leads to the spread of the disease.
What Are the Symptoms of Cystoisosporiasis?
The most common clinical feature is non-bloody, watery diarrhea, and the following symptoms occur:
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Abdominal pain.
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Cramping.
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Anorexia (an eating disorder characterized by fear of weight gain leading to low body weight and food restriction).
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Nausea.
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Vomiting.
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Low-grade fever.
In immunocompromised patients, diarrhea can be prolonged, causing severe dehydration and hypokalemia (low potassium level in blood) due to electrolyte imbalance. In addition, malabsorption and weight loss are also present. In certain cases, cholangiopathy (damage to bile ducts caused by insufficient blood flow) and reactive arthritis (joint pain caused by an infection in another part of the body) are also reported.
How Is Cystoisosporiasis Diagnosed?
The parasites that cause cystoisosporiasis are tiny organisms that cannot be observed under a microscope. To diagnose the infection, stool or fecal samples are examined under a microscope. Usually, the infection is diagnosed by identifying the oocysts of Cystoisospora belli (23 to 36 micrometers by 12 to 17 micrometers) in fecal samples. These oocysts may be shed at a low level and intermittently, even in patients with severe diarrhea. Multiple samples may be required to find the parasite and reach the exact diagnosis.
Other sensitive methods, like modified acid-fast techniques and ultraviolet fluorescence microscopy, can be used on which these oocysts stain bright red and show autofluorescence, respectively. Infection can also be diagnosed by identifying these oocysts in duodenal mucus or in the intestinal biopsy.
In postmortem examinations of human immunodeficiency virus HIV-infected patients, extraintestinal infection, like the lymph nodes, biliary tract, spleen, and liver, has also been reported.
How Can Cystoisosporiasis Be Prevented?
The infection can be prevented by
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Avoid food and water that may be contaminated with stool.
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Maintaining good personal hygiene also helps to prevent infection.
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Hands should be washed with soap and warm water after using the washrooms, changing diapers, and handling food items.
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Children should understand the importance of washing their hands properly before eating.
In some cases, chemoprophylaxis with Trimethoprim-Sulfamethoxazole has lowered the incidence of this infection. In a randomized, placebo-controlled trial, daily Trimethoprim-Sulfamethoxazole was protective against cystoisosporiasis in patients with early stages of human immunodeficiency virus (HIV) infection. In another study, it was reported the incidence of this infection decreased after the massive introduction of antiretroviral therapy (ART), except in patients with CD4 counts of less than 50 cells per cubic millimeter.
Research has revealed that the prevalence of cystoisosporiasis was lower in patients with versus without a history of pneumocystis pneumonia (indirect evidence of a protective effect from the use of Trimethoprim-Sulfamethoxazole for pneumocystis pneumonia).
How Is Cystoisosporiasis Infection Treated?
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Generally, antibiotics are prescribed for the treatment of cystoisosporiasis.The treatment usually involves trimethoprim-sulfamethoxazole (also known as Bactrim, Septra, or Cotrim). Alternative antibiotics are prescribed to patients with sulfa allergy or when there is a failure in the treatment.
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Plenty of fluids should be administered to patients with diarrhea. Taking proper rest is also advised.
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Clinically the infection is managed by the administration of electrolytes to dehydrated patients and nutritional supplements to malnourished patients.
Conclusion:
The exact incidence of this infection in human beings is still unknown. The cases of Cystoisospora belli infection have been documented as the cause of diarrheal illness in daycare centers and mental institutions. It has been regarded as traveler’s diarrhea in endemic areas.
Cystoisosporiasis belli infection is distinctly rare among immunocompetent individuals. In the United States, cystoisosporiasis is commonly associated with 0.2 to 3 % of autoimmune disorder syndrome (AIDS) patients.
However, the rate has decreased since the use of Trimethoprim-Sulfamethoxazole Pneumocystis pneumonia. The cases of cystoisosporiasis have been documented in patients with leukemia, lymphoma, and recipients of kidney and liver transplants.
In developing countries, approximately 8 to 40 % of patients with autoimmune deficiency syndrome (AIDS) are infected with this infection.
Cystoisosporiasis affects individuals of all ages but can cause a more severe infection in infants and young children, with an increased risk of dehydration. There is no gender predilection for this infection has been recorded.
