Cryptosporidiosis

Objectives:  Upon successful completion of this course, the student will have an understanding of the causes, diagnoses , treatments and preventions of Cryptosporidiosis.

What is Cryptosporidium?

Cryptosporidiosis (krip-toe-spo-rid-e-o-sis), is a diarrheal disease caused by a microscopic parasite, Cryptosporidium parvum. It can live in the intestine of humans and animals and is passed in the stool of an infected person or animal. Both the disease and the parasite are also known as "Crypto." The parasite is protected by an outer shell that allows it to survive outside the body for long periods of time and makes it very resistant to chlorine disinfection. During the past two decades, Crypto has become recognized as one of the most common causes of waterborne disease (drinking and recreational) in humans in the United States. The parasite is found in every region of the United States and throughout the world.

What are the symptoms of Crypto?

Symptoms include diarrhea, loose or watery stool, stomach cramps, upset stomach, and a slight fever. Some people have no symptoms.

How long after infection do symptoms appear?

Symptoms generally begin 2-10 days after being infected.

How long will symptoms last?

In persons with average immune systems, symptoms usually last about 2 weeks; the symptoms may go in cycles in which you may seem to get better for a few days, then feel worse, before the illness ends. 

How is Crypto spread?

Crypto lives in the intestine of infected humans or animals. Millions of Crypto can be released in a bowel movement from an infected human or animal. You can become infected after accidentally swallowing the parasite. Crypto may be found in soil, food, water, or surfaces that have been contaminated with the feces from infected humans or animals. Crypto is not spread by contact with blood. Crypto can be spread:

• By putting something in your mouth or accidentally swallowing something that has come in contact with the stool of a person or animal infected with Crypto. 
• By swallowing recreational water contaminated with Crypto. Recreational water is water in swimming pools, hot tubs, jacuzzis, fountains, lakes, rivers, springs, ponds, or streams that can be contaminated with sewage or feces from humans or animals. Note: Crypto is chlorine resistant and can live for days in pools.
• By eating uncooked food contaminated with Crypto. Thoroughly wash with uncontaminated water all vegetables and fruits you plan to eat raw. See below for information on making water safe.
• By accidentally swallowing Crypto picked up from surfaces (such as toys, bathroom fixtures, changing tables, diaper pails) contaminated with stool from an infected person. 
  

I have been diagnosed with Crypto. Should I worry about spreading infection to others? 

Yes, Crypto can be very contagious. Follow these guidelines to avoid spreading Crypto to others.

• Wash your hands with soap and water after using the toilet, changing diapers, and before eating or preparing food.
• Avoid swimming in recreational water (pools, hot tubs, lakes or rivers, the ocean, etc.) if you have Crypto and for at least 2 weeks after diarrhea stops. You can pass Crypto in your stool and contaminate water for several weeks after your symptoms have ended. This has resulted in many outbreaks of Crypto among recreational water users. Note: you are not protected in a chlorinated pool because Crypto is chlorine resistant and can live for days in pools.
• Avoid fecal exposure during sex.

Am I at risk for severe disease?

Although Crypto can infect all people, some groups are more likely to develop more serious illness. Young children and pregnant women may be more susceptible to the dehydration resulting from diarrhea and should drink plenty of fluids while ill. 

If you have a severely weakened immune system, you are at risk for more serious disease. Your symptoms may be more severe and could lead to serious or life-threatening illness. Examples of persons with weakened immune systems include those with HIV/AIDS; cancer and transplant patients who are taking certain immunosuppressive drugs; and those with inherited diseases that affect the immune system. 

What is the treatment for Crypto?

There is no effective treatment. Most people with a healthy immune system will recover on their own. If you have diarrhea, drink plenty of fluids to prevent dehydration. Rapid loss of fluids because of diarrhea can be life-threatening in babies; parents should consult their health care provider about fluid replacement therapy options for babies. Antidiarrheal medicine may help slow down diarrhea.

People who are in poor health or who have a weakened immune system are at higher risk for more severe and more prolonged illness. For persons with AIDS, anti-retroviral therapy that improves immune status will also decrease or eliminate symptoms of Crypto. However, Crypto is usually not cured and may come back if the immune status worsens. 

How can I prevent Crypto?

1. Wash hands thoroughly with soap and water
   a. Wash hands after using the toilet and before handling or eating food (especially for persons with diarrhea).
   b. Wash hands after every diaper change, especially if you work with diaper-aged children, even if you are wearing gloves.
2. Protect others by not swimming if experiencing diarrhea (essential for children in diapers).

Avoid water that might be contaminated.

1. Avoid swallowing recreational water. 

   Recreational water is defined as swimming pools, waterparks, spas, decorative or interactive fountains, rivers, lakes, and the ocean.

   This summer, swimming pools will be filled with millions of people having fun and staying cool. But did you know that germs can contaminate swimming water? In the past we weren't as concerned but today there are new germs that can contaminate water and cause illness. This summer, learning new information about recreational water illnesses (RWIs), which are spread by swimming in contaminated recreational waters such as swimming pools, water parks, lakes, and the ocean, can protect you from getting sick.

   RWIs are caused by germs like "Crypto" (KRIP-toe), short for Cryptosporidium, Giardia (gee-ARE-dee-uh), E. coli 0157:H7, and Shigella (Shi-GE-luh) and are spread by accidentally swallowing water that has been contaminated with fecal matter. How does a pool get contaminated? You share the water with everyone in the pool. If someone with diarrhea contaminates the water, swallowing the water can make you sick.

   The great news is that germs causing RWIs are killed by chlorine. However, chlorine doesn't work right away. It takes time to kill germs and some germs like Cryptare chlorine resistant and can live in pools for days. This is why even the best-maintained pools can spread illness. Therefore, healthy swimming behaviors are needed to protect you and your kids from RWIs and will help stop germs from getting in the pool in the first place.
   

2. Avoid drinking untreated water from shallow wells, lakes, rivers, springs, ponds, and streams.
3. Avoid drinking untreated water during community-wide outbreaks of disease caused by contaminated drinking water. In the United States, nationally distributed brands of bottled or canned carbonated soft drinks are safe to drink. Commercially packaged noncarbonated soft drinks and fruit juices that do not require refrigeration until after they are opened (for example, those that can be stored unrefrigerated on grocery shelves) also are safe. 
4. Avoid using ice or drinking untreated water when traveling in countries where the water supply might be unsafe. 
5. If you are unable to avoid drinking or using water that might be contaminated, then treat the water yourself by:
   Heating the water to a rolling boil for at least 1 minute.
   
   OR
   
   Using a filter that has an absolute pore size of at least 1  micron or one that has been NSF-rated for "cyst removal."

Do not rely on chemical disinfection of Crypto because it is highly resistant to inactivation by chlorine or iodine.

Avoid food that might be contaminated.

1. Wash and/or peel all raw vegetables and fruits before eating.
2. Use uncontaminated water to wash all food that is to be eaten raw.
3. Avoid eating uncooked foods when traveling in countries with minimal water treatment and sanitation systems.

Avoid fecal exposure during sex.

This fact sheet is for information only and is not meant to be used for self-diagnosis or as a substitute for consultation with a health care provider. If you have any questions about the disease described above or think that you may have a parasitic infection, consult a health care provider.

	Clinical Features: Infection with Cryptosporidium parvum results in a wide range of manifestations, from asymptomatic infections to severe, life-threatening illness.  Watery diarrhea is the most frequent symptom, and can be accompanied by dehydration, weight loss, abdominal pain, fever, nausea and vomiting.  In immunocompetent persons, symptoms are usually short lived (1 to 2 weeks); they can be chronic and more severe in immunocompromised patients, especially those with CD4 counts <200/µl.  While the small intestine is the site most commonly affected, symptomatic Cryptosporidium infections have also been found in other organs including other digestive tract organs, the lungs, and possibly conjunctiva. Laboratory Diagnosis: Acid-fast staining methods, with or without stool concentration, are most frequently used in clinical laboratories.  For greatest sensitivity and specificity, immunofluorescence microscopy is the method of choice (followed closely by enzyme immunoassays).  Molecular methods are mainly a research tool. Microscopy 1) Wet mounts: Wet mount examination (with iodine) is used mainly for screening, and is especially useful with specimens containing moderate to high numbers of oocysts.  However, it should be combined with a more sensitive confirmatory stain or assay.  Fresh or concentrated fecal specimens can be examined, using either conventional bright light, phase contrast or differential interference contrast (or Nomarsky) microscopy.   A A: Oocysts of Cryptosporidium parvum, in wet mount, seen with differential interference contrast (DIC) microscopy.  The oocysts are rounded, 4.2 to 5.4 µm in diameter.  Sporozoites are visible inside the oocysts, indicating that sporulation has occurred.  (In comparison, oocysts of Cyclospora cayetanensis, another important coccidian parasite of humans, are twice larger and upon excretion are not sporulated, i.e., do not contain sporocysts.) 2) Stained smears: Traditional parasitology stains (e.g., Giemsa) are of limited value.  They do not differentiate between oocysts and similarly-sized fecal yeasts (the main differential diagnosis of Cryptosporidium in microscopy) and other debris.  Kinyoun's modified acid-fast staining technique is a simple and effective method: the oocysts stain bright red against a background of blue-green fecal debris and yeasts.  The acid-fast staining technique has been modified and improved, including: hot and cold modified acid-fast stains; incorporation of dimethyl sulfoxide (DMSO); and incorporation of the detergent tergitol into the modified cold Kinyoun acid-fast method. B B: Oocysts of Cryptosporidium parvum stained by the acid-fast method.  Against a blue-green background, the oocysts stand out in a bright red stain.  Sporozoites are visible inside the two oocysts to the right. C C: Oocysts of Cryptosporidium parvum stained by the acid-fast method.  This image shows that the staining can be variable.  In particular, infections that are resolving can be accompanied by increasing numbers of non acid-fast oocysts “ghosts”. 3) Immunofluorescence microscopy for detection of oocysts: This method offers increased sensitivity and specificity compared to staining techniques.  It has found widespread application in research and clinical laboratories as well as for monitoring oocyst presence in environmental samples.  The assays generally work well with fresh or preserved stools (formalin, potassium dichromate), but some fixatives can cause problems (e.g. MIF).  Several commercial IFA products are presently available, including MeriFluor™ Cryptosporidium/Giardia (Meridian Diagnostics Inc., Cincinnati, OH, 45244, USA); Detect IF Cryptosporidium (Shield Diagnostics, Ltd., Dundee DD1 1 SW, Scotland, UK); and Crypto IF Kit (TechLab, Blacksburg, VA, 24060, USA).  These assays exhibit broad reactivity with C. parvum and other Cryptosporidium species, so they should be applicable to human and veterinary specimens. D D: Oocysts of C. parvum (upper left) and cysts of Giardia intestinalis (lower right) labeled with immunofluorescent antibodies. 4) Several additional methods for microscopic detection of oocysts include: alternate bright-field stains (e.g., hot safranin-methylene blue stain, modified Kohn’s stain, modified Koster stain, aniline-carbol-methyl violet and tartrazine) negative stains fluorescent stains (including auramine O, auramine-rhodamine, auramine-carbol-fuchsin, acridine orange, mepacrine, and 4’,6-diamidino-2-phenylindole (DAPI) and propidium iodide staining) These exhibit potentially higher sensitivities but, like all non-specific chemical staining methods, yield false positives and may leave some oocysts unstained; these methods may be useful for screening samples, but identification should be confirmed with more specific assays (IFA, EIA). E E: Oocysts of Cryptosporidium parvum stained with the fluorescent stain auramine-rhodamine.   Enzyme immunoassays At least four commercial EIA tests (see Table below) have been introduced for the detection of cryptosporidial antigens in stool samples.  These kits are reportedly superior to conventional microscopic examination (especially acid-fast staining) and show good correlation with the monoclonal antibody-based immunofluorescence assays.  Kit sensitivities and specificities ranged from 66.3% to 100% and 93% to 100%, respectively (see Table). Commercially available diagnostic kits for detection of Cryptosporidium spp. (primarily in clinical specimens; partial list) Kit Name (Clinical specimens) Manufacturer/ distributor Type of test1 Sensitivity2 Specificity2 Comparison test Reference ProSpecT/ Cryptosporidium Alexon, Inc. EIA-plate 97 98 96 94 (97) 98 98 99.5 99 (98) acid-fast stain, IIF3 acid-fast stain M-DIF4 M-DIF4, acid-fast, Color Vue 1 2 3 4 IDEIA Cryptosporidium Dako Corp. EIA-plate 100 (93.1) 100 (98.7) auramine stain, N-DIF5 5 MeriFluor™ Cryptosporidium/Giardia Meridian Diagnostics, Inc. DFA, IgG 100 96 (100) 100 100 (100) acid-fast stain acid-fast, ProSpecT, Color Vue 6 4 Color Vue Cryptosporidium Seradyn, Inc. EIA-plate 93 76 94 (92) 93 100 100 (100) IIF3 M-DIF4 M-DIF4, acid-fast, ProSpecT 7 3 4 Cryptosporidium Antigen Detection Microwell ELISA LMD Laboratories EIA-plate 66.3 93 99.8 99 acid-fast, auramine IIF3 8 9 1EIA = enzyme immunoassay; DFA = direct immunofluorescence assay, IIF = indirect immunofluorescence assay, NA = not available 2Percent specificity or specificity compared to conventional methods, numbers in parentheses indicate values reported by the manufacturer 3IIF = indirect immunofluorescence (MeriFluor Cryptosporidium/Giardia assay) 4M-DIF = direct immunofluorescence (MeriFluor Cryptosporidium/Giardia assay) 5N-DIF = direct immunofluorescence (DetectIF Cryptosporidium, Shield Diagnostics, Ltd.) References: Molecular diagnosis   A A: Agarose gel (2%) analysis of a PCR diagnostic test for detection of Cryptosporidium parvum DNA.  PCR was performed using primers CPBDIAGF and CPBDIAGR1. Lane S: Molecular base pair standard (100-bp ladder).  Black arrows show the size of standard bands. Lane 1: C. parvum positive fecal specimen.  The red arrow shows the diagnostic band for C. parvum zoonotic genotype (size: 435 bp).
	Diagnostic findings: Antibody detection: There are currently no commercially available serologic assays for the detection of Cryptosporidium-specific antibodies.  However, immunoblots for detecting the 17 and 27 kDa sporozoite antigens associated with recent infection may be useful for epidemiologic investigations. Acid-fast staining methods, with or without stool concentration, are most frequently used in clinical laboratories.  For greatest sensitivity and specificity, immunofluorescence microscopy is the method of choice (followed closely by enzyme immunoassays). Safety Oocysts in stool specimens (fresh or in storage media) remain infective for extended periods.  Thus stool specimens should be preserved in 10% buffered formalin or sodium acetate-acetic acid-formalin (SAF) to render oocysts non-viable.  (Contact time with formalin necessary to kill oocysts is not clear; we suggest at least 18 to 24 hours).  In addition, the usual safety measures for handling potentially infectious material should be adopted. Specimen processing Stool specimens may be submitted fresh, preserved in 10% buffered formalin (see above, “Safety”), or suspended in a storage medium composed of aqueous potassium dichromate (2.5% w/v, final concentration).  The use of mercuric chloride-containing preservatives (e.g.,  polyvinyl alcohol, PVA) is not recommended due to incompatibilities with some methodologies and the environmental hazards posed by the disposal of mercury-containing compounds.  Oocyst numbers can be quite variable, even in liquid stools.  Multiple stool samples should be tested before a negative diagnostic interpretation is reported.  To maximize recovery of oocysts, stool samples should be concentrated prior to microscopic examination.  Formalin-ethyl acetate sedimentation is the recommended stool concentration method for clinical laboratories.  Two potential shortcomings of oocyst concentration techniques are: Sedimentation methods are generally performed using low speed centrifugation.  Given their small size and mass, cryptosporidial oocysts may become trapped in the ether or ethyl acetate plug and fail to sediment properly.  Increased centrifugation speed or time (500 x g, 10 min.) may be warranted when attempting to recover cryptosporidial oocysts. Resolution of cryptosporidial infections is accompanied by increasing numbers of non-acid-fast, oocyst “ghosts”.  Such oocysts may not float or sediment as expected, giving rise to false negative results. Treatment: There is no established specific therapy for human cryptosporidiosis.  Rapid loss of fluids because of diarrhea can be managed by fluid replacement and electrolyte balance.  Infection in healthy, immunocompetent persons is self-limited, but infection in immunocompromised persons and those in poor health are at higher risk for more severe illness.  For persons with AIDS, anti-retroviral therapy, which improves immune status, will also decrease or eliminate.  Paromomycin* is approved for treatment.  * This drug is approved by the FDA, but considered investigational for this purpose

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9. Rosenblatt, J. E. and Sloan, L. M., Evaluation of an enzyme-linked immunosorbent assay for detection of Cryptosporidium spp. in stool specimens, J. Clin. Microbiol. 1993; 31:1468.

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