Cyclosporiasis
Cyclosporiasis
Disease History, Characteristics, and Transmission
Introduction
Cyclosporiasis, (sigh-clo-spore-EYE-uh-sis) also called Cyclospora, is an infection caused by the pathogenic protozoan Cyclospora cayetanensis. The protozoan is a coccidium (causing disease in the gut) parasite that infects the gastrointestinal (GI) tract. It is spread when humans drink water or eat food that is contaminated with infected feces. The Cyclospora needs days or even a week after being passed in a bowel movement to become infectious.
Imported produce, especially raspberries, is most frequently associated with outbreaks of Cyclospora infection. Cyclospora often infect humans and other animals such as moles, myriapods (small, long arthropods such as centipedes), rodents, and vipers (poisonous snakes). Although still unproven, transmission between humans, and between animals and humans is unlikely. The primary source of the parasite is unknown. The infection sometimes causes diarrhea in travelers visiting foreign countries.
Disease History, Characteristics, and Transmission
According to the Division of Parasitic Diseases within the Centers for Disease Control and Prevention (CDC), the first human case of Cyclospora infection was documented in 1979, although it had been recognized as early as 1977. During the mid–1980s, cases frequently were reported. According to the Epidemiology and Disease Control Program (EDCP), large outbreaks were reported in the 1990s and 2000s within the United States and Canada. The first U.S. case occurred in Chicago, Illinois, inside a medical dormitory whose water source became infected. A U.S. epidemic occurred between 1996 and 1997 when basil, lettuce, and raspberries became contaminated. A Canadian epidemic occurred in 1999 when berries became contaminated. In 2004, a Pennsylvania outbreak happened with basil and snow peas. After the AIDS (acquired immunodeficiency syndrome) epidemic bloomed, reported occurrences of Cyclosporiasis became more frequent.
The Cyclospora cayetanensis parasite is a one-celled organism and requires specialized microscopic inspection for identification, often from multiple stool samples. Transmission occurs when an oocyst (a fertilized sex cell) of C. cayetanensis is located within contaminated water that is ingested. It enters the small intestine (bowel) and travels to the mucous membrane (the moist lining inside body passages). The oocyst incubates for approximately one week (with a range from one to 14 days). After incubation is complete, the victim begins to experience symptoms of watery bloating, diarrhea, frequent and sometimes large bowel movements, low-grade fever, muscle aches, and stomach cramps. Other diarrhea-caused symptoms include fatigue, appetite and weight loss, and increased gas. However, some people show no symptoms. If not treated, the illness lasts from several days to about one month, sometimes longer. Relapses of the illness often occur.
All humans are susceptible to the infection world-wide. However, people in developing countries are most susceptible. Death rarely occurs, however, death can result in infected people with immunosuppressed systems, such as persons with AIDS. Cyclospora affect both sexes, and all ages and races equally, though children in developing countries are especially susceptible, as they are often the primary water carriers for their families.
Scope and Distribution
It is possible for the infection to occur anywhere in the world, although it is often found in underdeveloped or developing countries. It is frequently found (endemic) in Haiti, Nepal, and Peru. It has also been reported from people traveling within India, Indonesia, Mexico, Morocco, Pakistan, Puerto Rico, and Southeastern Asia. When it occurs in the United States, it happens mostly in the warmer months of late spring and summer.
WORDS TO KNOW
COCCIDIUM: Any single-celled animal (protozoan) belonging to the sub-class Coccidia. Some coccidia species can infest the digestive tract, causing coccidiosis.
ENDEMIC: Present in a particular area or among a particular group of people.
FOOD PRESERVATION: The term food preservation refers to any one of a number of techniques used to prevent food from spoiling. It includes methods such as canning, pickling, drying and freeze-drying, irradiation, pasteurization, smoking, and the addition of chemical additives. Food preservation has become an increasingly important component of the food industry as fewer people eat foods produced on their own lands, and as consumers expect to be able to purchase and consume foods that are out of season.
OOCYST: An oocyst is a spore phase of certain infectious organisms that can survive for a long time outside the organism and so continue to cause infection and resist treatment.
PROTOZOA: Single-celled animal-like microscopic organisms that live by taking in food rather than making it by photosynthesis and must live in the presence of water. (Singular: protozoan.) Protozoa are a diverse group of single-celled organisms, with more than 50,000 different types represented. The vast majority are microscopic, many measuring less than 5 one-thousandth of an inch (0.005 millimeters), but some, such as the freshwater Spirostomun, may reach 0.17 inches (3 millimeters) in length, large enough to enable it to be seen with the naked eye.
Treatment and Prevention
The diagnosis is oftentimes difficult because oocysts in feces and water are difficult to identify. Stool specimens are used; frequently, several specimens are taken over numerous days. The EDCP suggests that physicians specifically request a Cyclospora test in order to assure accurate laboratory results. The polymerase chain reaction-based DNA (deoxyribonucleic acid) test and acid-fast staining test are often used.
Treatment involves antibiotics, often in combinations such as trimethoprim and sulfamethoxazole. Traditional anti-protozoan drugs are usually not effective enough to stop the protozoan. People with compromised immune systems and severe diarrhea require additional supportive treatment.
To prevent its transmission through food, all fruits and vegetables should be washed before consuming. Handwashing before handling or eating food removes most of the parasites. Drinking water suspected to be contaminated, especially from rivers, streams, springs, and other untreated waters, should be avoided in order to prevent cyclosporiasis. Handwashing after using the toilet and changing diapers also prevents transmission of Cyclospora.
Impacts and Issues
Cyclosporiasis infection is part of a wider problem: emerging widespread foodborne outbreaks on a countrywide and international scale. Foodborne illnesses such as cyclosporiasis continue to increase in numbers and severity as the world rapidly moves toward a global food market. A contaminated food in one part of the world can now lead to an outbreak halfway across the globe in a matter of days.
According to the CDC, better recognition and management of outbreaks of foodborne infections such as those caused by Cyclospora are needed. Specifically, this would include: better coordination and action by federal, state, and local agencies; more comprehensive laboratory diagnostic training; structured development of epidemiologic studies; coordination between affected governments and the media; and early and effective involvement of companies involved in the growing, processing, exporting, importing, transporting, and wholesale and retail sales of foods.
Irradiation, the use of ionizing radiation for food pasteurization, is suggested as a way to reduce bacterial and parasitic causes of foodborne diseases. The CDC and World Health Organization and other international groups promote irradiation as a safe and effective method to reduce the risk of infection in globally distributed foods—but the use of ionizing radiation is opposed by some food advocacy groups and research continues.
See AlsoFood-borne Disease and Food Safety; Microorganisms; Travel and Infectious Disease.
BIBLIOGRAPHY
Books
Arguin, Paul M., Phyllis E. Kozarsky, and Ava W. Navin, eds. Health Information for International Travel, 2005–2006. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, 2005.
U.S. Food and Drug Administration Center for Food Safety and Applied Nutrition. Bad Bug Book: Foodborne Pathogenic Microorganisms and Natural Toxins Handbook. McLean, VA: International Medical Publishing, Inc., 2004.
Web Sites
Centers for Disease Control and Prevention. “Cyclospora Infection or Cyclosporiasis (sigh–clo–spore–EYE–uh–sis).” <http://www.cdc.gov/ncidod/dpd/parasites/cyclospora/factsht_cyclospora.htm> (accessed March 8, 2007).
Epidemiology and Disease Control Program (EDCP). “Cyclosporiasis Fact Sheet.” <http://edcp.org/factsheets/cyclospor.html> (accessed March 8, 2007).
Cyclosporiasis
Cyclosporiasis
Definition
Cyclosporiasis refers to infection by the sporeforming protozoan known as Cyclospora. Protozoa are a group of parasites that infect the human intestine. Parasites are organisms that live in another body, called the host, and get food and liquids from that host. This parasite is a member of the group of protozoa known as coccidia, to which Cryptosporidia also belongs. This group of parasites infects the human intestine, and causes chronic recurrent infections in those with altered immunity or AIDS. Even in people with normal immune function, Cyclopsora can cause prolonged bouts of diarrhea and other gastrointestinal symptoms.
Description
Until recently, Cyclospora was considered to be a form of algae. The parasite causes a common form of waterborne infectious diarrhea throughout the world. Just how the parasite gets into water sources is not yet clear. It is known that ingestion of small cysts in contaminated water leads to disease.
Causes and symptoms
Symptoms begin after an incubation period of about a day or so following ingestion of cysts. A brief period of flu-like illness characterized by weakness and low-grade fever is followed by watery diarrhea, nausea, loss of appetite, and muscle aches. In some patients, symptoms may wax and wane for weeks, and there are those in whom nausea and burping may predominate. It is also believed that infection can occur without any symptoms at all.
In patients with abnormal immunity (immunocompromised patients), such as those with AIDS and cancer, prolonged diarrhea and severe weight loss often become a major problem. The bile ducts are also susceptible to infection in AIDS patients.
Diagnosis
The disease should be suspected in anyone with a history of prolonged or recurrent diarrhea. The parasite is identified either by staining stool specimens or by applying certain fluorescent ultraviolet techniques to find the characteristic cysts. Biopsy of an infected organ such as the intestine through an endoscope is another way to make the diagnosis.
Treatment
The first aim of treatment as with any severe diarrheal illness is to avoid dehydration and malnutrition. Oral Rehydration Solution (ORS) or intravenous fluids are sometimes needed. Medications used to treat diarrhea by decreasing intestinal motility, such as loperamide or diphenoxylate are also useful, but should only be used with the advice of a physician.
The use of the medication, trimethoprim-sulfamethoxazole (Bactrim) for one week can be successful in treating intestinal infections and prevents relapse in those with a normal immune system. The same medicine can be prescribed to treat infections of both the intestine or bile ducts in immunocompromised individuals, but maintenance or continuous treatment is often needed.
Prognosis
The outlook is quite good for individuals in whom a diagnosis is made. Even without treatment, symptoms usually do not last much more than a month except in cases with altered immunity. Fortunately, treatment is usually successful even in those patients.
Prevention
Aside from a waterborne source as the origin of infection, little else is known about how the parasite is transmitted. Therefore, little can be done regarding prevention, except to maintain proper hand washing techniques and hygiene.
KEY TERMS
Anti-motility medications— Medications such as loperamide (sold as Imodium), dephenoxylate (sold as Lomotil), or medications containing codeine or narcotics that decrease the ability of the intestine to contract. This can worsen the condition of a patient with dysentery or colitis.
Cyst— A protective sac that includes either fluid or the cell of an organism. The cyst enables many organisms to survive in the environment for long periods of time without need for food or water.
Immunocompromised— A change or alteration of the immune system that normally serves to fight off infections other illnesses. This can involve changes in antibodies that the body produces (hygogammaglo-bulinemia), or a defect in the cells that partake in the immune response. Diseases such as AIDS and cancer exhibit changes in the body's natural immunity.
Oral Rehydration Solution (ORS)— A liquid preparation developed by the World Health Organization that can decrease fluid loss in persons with diarrhea. Originally developed to be prepared with materials available in the home, commercial preparations have recently come into use.
Parasite— An organism that lives on or in another and takes nourishment (food and fluids) from that organism.
Protozoa— Group of extremely small single cell (unicellular) or acellular organisms that are found in moist soil or water. They tend to exist as parasites, living off other life forms.
Spore— A resistant form of certain species of bacteria, protozoa, and other organisms.
Resources
ORGANIZATIONS
Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. (800) 311-3435, (404) 639-3311. 〈http://www.cdc.gov〉.
OTHER
"Cyclospora." Centers for Disease Control. 〈http://www.cdc.gov/ncidod/diseases/cyclospo/cyclohp.htm〉.