eMedicine Specialties > Infectious Diseases > Parasitic Infections

Cryptosporidiosis

A Clinton White Jr, MD, The Paul R Stalnaker, MD, Distinguished Professor of Internal Medicine, Director, Infectious Disease Division, Department of Internal Medicine, University of Texas Medical Branch

Updated: Jun 23, 2008

Introduction

Background

Human cryptosporidiosis is caused by infection with the Apicomplexa protozoans of the genus Cryptosporidium. Human illness was formerly thought to be caused by a single species, but recent molecular studies have demonstrated that several different species cause human cryptosporidiosis.^1,2,3,4,5 Among the more common species are Cryptosporidium hominis, for which humans are the only natural host, and Cryptosporidium parvum, which infects bovines as well as humans.

Cryptosporidiosis mainly affects children. It causes a self-limited diarrheal illness in healthy individuals. Cryptosporidiosis is also recognized as a cause of persistent diarrhea in children and severe prolonged diarrhea in persons with AIDS. The source of most endemic cryptosporidiosis cases is human-to-human fecal-oral transmission, but infection may also result from animal-to-person transmission and waterborne transmission. Major outbreaks resulting from waterborne transmission have been recorded.

Pathophysiology

Cryptosporidium oocysts are highly infectious, requiring only 10¹ -10³ oocysts to cause human disease (50% infectious dose, 10²). The oocysts are infectious immediately, and the life cycle of the parasite produces forms that invade the intestine. The location of the parasite in the intestine is intracellular but extracytoplasmic, which may contribute to the marked resistance of Cryptosporidium species to treatment. Large numbers of oocysts are excreted and are resistant to harsh conditions, including chlorine at levels usually applied in water treatment.

The mechanism by which Cryptosporidium causes diarrhea includes a combination of increased intestinal permeability, chloride secretion, and malabsorption, which are all thought to be caused by the host response to infection. In immunocompetent persons, the infection is usually limited to the small intestines. In persons with AIDS or certain congenital immunodeficiencies, the biliary tract may be involved.

Frequency

United States

The frequency of cryptosporidiosis has not been well-defined. About 30% of the adult population of the United States is seropositive. The number of cases diagnosed has increased with improved diagnostic testing, with over 8,000 cases reported in 2005. Still, most laboratories do not routinely test for this organism, and many laboratories use insensitive tests when testing for Cryptosporidium. ¹ Recent studies have documented cryptosporidiosis in about 4% of stools sent for parasitologic examination.⁶ Prior to the availability of highly active antiretroviral therapy, approximately 10-15% of patients with AIDS developed cryptosporidiosis over their lifetime. Like other opportunistic infections, the prevalence of cryptosporidiosis in AIDS patients has dropped dramatically.

International

In developing countries, most people are infected as children. For example, studies in Brazil documented 90% of children in slums were infected before age 5 years. Serologic and stool studies have documented high rates of infection in Latin America, Africa, the Middle East, and South Asia. Overall, about 13% of stool studies submitted for parasitologic studies in developing countries reveal Cryptosporidium oocysts. In persons with AIDS, the rate of cryptosporidiosis is higher in developing countries, ranging from 12-48% of those with diarrhea.^1,2,3

Mortality/Morbidity

Cryptosporidiosis is an important cause of persistent diarrhea in developing countries. Children with persistent diarrhea develop worsening malnutrition, which may result in cognitive and fitness problems that persist for years. Chronic cryptosporidiosis may be complicated by biliary tract disease, malabsorption, and death in individuals with AIDS and malnourished children.

Age

The peak incidence of cryptosporidiosis is in children younger than 5 years. Infection is rare in immunocompetent adults in developing countries but can occur in persons with AIDS.

Clinical

History

After an incubation period of 5-10 days (range 2-28 d), an infected individual develops watery diarrhea, which may be associated with abdominal cramps and a low-grade fever. Parasitologically diagnosed cases typically last for about 5-10 days and may persist for 2-4 weeks. Individuals with AIDS and very low CD4 cell counts may develop a profuse, choleralike diarrhea, which can be complicated by volume depletion and malabsorption. Biliary tract involvement is seen in persons with AIDS who have very low CD4 cell counts and is common in children with X-linked immunodeficiency with hyper–immunoglobulin M (IgM). Biliary involvement may include acalculous cholecystitis, sclerosing cholangitis, papillary stenosis, or pancreatitis. All are associated with right upper quadrant pain, nausea, and vomiting.

Physical

Physical findings are nonspecific. Temperature higher than 39°C is not characteristic of cryptosporidiosis and warrants investigation for other infections. Patient may have signs of volume depletion or wasting from malabsorption.

Differential Diagnoses

Other Problems to Be Considered

Cyclospora cayetanensis infection

Workup

Laboratory Studies

• Stool microscopy: Modified acid-fast staining of stool shows red-stained round oocysts against a blue-green background (see Image 1). White and red blood cells should not be seen in the stool. Antigen-detection assays are more sensitive and include immunofluorescent assays, enzyme-linked immunosorbent assay (ELISA), and immunochromatographic tests. Polymerase chain reaction (PCR) assays, when available, are more sensitive than other tests.
• Stool culture: Perform a stool culture to rule out the presence of other bacterial pathogens.
• Urea and electrolytes: These tests are used to assess electrolyte replacement requirements and the presence of prerenal uremia.
• Liver function tests: Elevated alkaline phosphatase and glutamyl transpeptidase without hyperbilirubinemia are typical signs of biliary infection.
• Lymphocyte subset analysis: CD4⁺ lymphocyte counts predict the duration of disease in patients infected with HIV. When the counts are greater than 150 cells/μL, the diarrhea is likely to resolve spontaneously, but diarrhea may be chronic with lower counts. Counts are typically less than 50 cells/μL in patients with either biliary involvement or choleralike syndromes.

Imaging Studies

• Abdominal ultrasonography: Dilated or irregular intrahepatic and extrahepatic bile ducts, along with a thickened gallbladder, indicate biliary involvement.
• Endoscopic retrograde cholangiopancreatography (ERCP): ERCP is often needed to diagnose sclerosing cholangitis or papillary stenosis.

Procedures

• ERCP: Identification of Cryptosporidium oocysts in bile or intracellular forms on biopsy confirms the diagnosis of biliary cryptosporidiosis. Papillary stenosis may be present and responds symptomatically to endoscopic sphincterotomy, often with stent placement.

Histologic Findings

Histological examination of the small intestine is not required to confirm the diagnosis of cryptosporidiosis. The small intestine shows the parasite projecting from the brush border of the mucosal surface. Parasites may also be identified in bile or biliary tract biopsies.

Treatment

Medical Care

• Nitazoxanide significantly shortens the duration of diarrhea and can decrease the risk of mortality in malnourished children.⁷ Trials have also demonstrated efficacy in adults.^8,9,1,2
• Initial studies with antiparasitic drugs in patients with AIDS and cryptosporidiosis were disappointing. Nitazoxanide, paromomycin, and azithromycin are partially active. Combination antiretroviral therapy that includes an HIV protease inhibitor is associated with dramatic improvement in many cases.^1,2 Improvement is likely to result from immune reconstitution but may in part reflect the antiparasitic activity of the protease inhibitors. Nucleoside antiretroviral drugs are malabsorbed in chronic cryptosporidiosis. For that reason, it is probably wise to use partially active antiparasitic drugs (eg, nitazoxanide or paromomycin combined with azithromycin) prior to initiating antiretroviral therapy.
• Symptomatic therapy includes replacement of fluids, nutrition, and treatment with antimotility agents. Loperamide or diphenoxylate-atropine may help in some cases. More potent opiates, including anhydrous morphine (Paregoric), may work in some cases that fail to respond to milder agents. Patients should avoid dietary lactose.

Surgical Care

Patients with acalculous cholecystitis should generally be treated with cholecystectomy.

Consultations

• Infectious disease specialist - For consideration of antiparasitic and antiretroviral therapy
• Gastroenterologist - For ERCP and sphincterotomy; endoscopy sometimes required for diagnosis
• General surgeon - For suspected acalculous cholecystitis

Diet

Attention to nutritional aspects of patient care is crucial because malnutrition can cause death. Lactose intolerance is common in cryptosporidiosis, and lactose-containing foods should be avoided. Enteral nutrition is usually sufficient; studies have not supported the use of parenteral nutrition.¹⁰

Medication

Recent studies of healthy hosts and malnourished children have demonstrated the importance of nitazoxanide treatment.^7,1,11 Since the advent of highly active antiretroviral therapy (HAART), cryptosporidiosis is much less common in persons with AIDS. Stabilize patients who are not on HAART and who present with cryptosporidiosis by using the treatments described below, and then commence antiretroviral therapy. Antiparasitic drugs aim to treat diarrhea by a direct anticryptosporidial effect, but maintenance treatment is often required. Antimotility agents are administered to relieve symptoms and to increase exposure to the antiparasitic and antiretroviral agents. Somatostatin analogues are partially beneficial for reducing secretory diarrhea in some refractory cases.

Antiparasitic drugs

Nitazoxanide, paromomycin, and azithromycin have activity against Cryptosporidium.

Paromomycin (Humatin)

An oral nonabsorbed aminoglycoside that is partially active in cryptosporidiosis. Amebicidal and antibacterial aminoglycoside obtained from a strain of Streptomyces rimosus that is active in intestinal amebiasis. Recommended for treatment of Diphyllobothrium latum, Taenia saginata, Taenia solium, Dipylidium caninum, and Hymenolepis nana.

Dosing

Adult

25-35 mg/kg/d PO given in 2-4 daily doses for 28 d, then 500 mg PO bid maintenance

Pediatric

Administer as in adults

Interactions

Nephrotoxic potential may increase with concurrent administration of other aminoglycosides, penicillins, cephalosporins, amphotericin B, and loop diuretics

Contraindications

Documented hypersensitivity; intestinal obstruction; renal insufficiency

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

GI intolerance is most common adverse effect; with gut lesions (eg, cryptosporidiosis) systemic absorption may produce renal toxicity and ototoxicity; due to narrow therapeutic index and toxic hazards associated with extended administration, long-term therapy should be undertaken with caution; caution in renal failure, hypocalcemia, myasthenia gravis, and conditions that depress neuromuscular transmission; adjust dose in renal impairment

Azithromycin (Zithromax)

Macrolide antibiotic. In clinical study, the combination with paromomycin gave good symptom control.

Dosing

Adult

600 mg PO qd for 28 d

Pediatric

Not established

Interactions

May increase toxicity of theophylline, warfarin, and digoxin; effects are reduced with coadministration of aluminum and/or magnesium antacids; nephrotoxicity and neurotoxicity may occur when coadministered with cyclosporine

Contraindications

Documented hypersensitivity; hepatic impairment; do not administer with pimozide

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Diarrhea common; site reactions can occur with IV route; bacterial or fungal overgrowth may result with prolonged antibiotic use; may increase hepatic enzymes and cholestatic jaundice; caution in impaired hepatic function and prolonged QT intervals

Nitazoxanide (Alinia)

Inhibits growth of C parvum sporozoites and oocysts and Giardia lamblia trophozoites. Elicits antiprotozoal activity by interfering with pyruvate-ferredoxin oxidoreductase (PFOR) enzyme-dependent electron transfer reaction, which is essential to anaerobic energy metabolism. Available as a 20 mg/mL PO susp.

Dosing

Adult

500 mg PO bid for 3 d in healthy hosts; dose may be safely increased to 1 g PO bid in AIDS patients and the duration may be prolonged

Pediatric

<1 year: Not established
1-4 years: 100 mg (5 mL) PO q12h for 3 d with food
4-12 years: 200 mg (10 mL) PO q12h for 3 d with food
>12 years: Administer as in adults

Interactions

Tizoxanide (nitazoxanide metabolite) is >99.9% bound to plasma protein and may displace other highly plasma protein–bound drugs, resulting in increased toxicity

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

May cause abdominal pain, diarrhea, vomiting, or headache; administer with food; caution when coadministered with other highly plasma protein–bound drugs with narrow therapeutic indices

Antidiarrheal agents

These agents are used to decrease the frequency of diarrheal stools and possibly the duration of episodes.

Loperamide hydrochloride (Imodium)

Has antimotility effect on GI tract via cholinergic and opiate receptors. First choice as antidiarrheal agent. More potent effect than diphenoxylate hydrochloride or codeine. Acts on intestinal muscles to inhibit peristalsis and slow intestinal motility. Prolongs movement of electrolytes and fluid through bowel, increases viscosity, and decreases loss of fluids and electrolytes.

Dosing

Adult

4 mg PO, then 2 mg PO after each loose stool; not to exceed 16 mg/d

Pediatric

<12 years: Not recommended
>12 years: Administer as in adults

Interactions

Phenothiazines, tricyclic antidepressants, and CNS depressants may increase toxicity

Contraindications

Documented hypersensitivity; diarrhea resulting from infections; pseudomembranous colitis

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Constipation in overdosage; discontinue use if no clinical improvement in 48 h; because primarily metabolized in liver, monitor for CNS toxicity in patients with hepatic insufficiency; do not use if high fever or blood in stool coincides with diarrhea

Diphenoxylate and atropine (Lomotil)

Pethidine analogue that reduces intestinal motility but not as effective as loperamide hydrochloride.
Drug combination that consists of diphenoxylate, which is a constipating meperidine congener, and atropine to discourage abuse; inhibits excessive GI propulsion and motility.

Dosing

Adult

15-20 mg/d PO divided tid/qid
Maintenance dose: 5-15 PO mg/d

Pediatric

<12 years: Not recommended
>12 years: Administer as in adults

Interactions

May delay metabolism of drugs in liver; CNS depressants, MAOIs, and antimuscarinic agents may increase the toxicity of this drug combination

Contraindications

Documented hypersensitivity; narrow-angle glaucoma or hepatic insufficiency; not for use in colitis resulting from invasive bacterial infection

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Opiate toxicity present in overdosage; in young children, dehydration may influence variability of response and predispose patient to delayed diphenoxylate intoxication; caution in ulcerative colitis; decrease in intestinal motility be detrimental to patients with diarrhea resulting from Shigella and Salmonella species and toxigenic strains of Escherichia coli

Anhydrous morphine (Paregoric)

More potent opiates can decrease motility more than is achieved by loperamide or diphenoxylate and atropine.

Dosing

Adult

2 mg/5 mL take 5-10 mL PO qid as needed for diarrhea; dose may be titrated upward as needed to produce firm stools

Pediatric

0.25-0.5 mL/kg PO qid prn diarrhea

Interactions

None reported

Contraindications

Marked inflammatory diarrhea associated with passing blood or pus

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Overdose may be associated with constipation and respiratory depression

Somatostatin analogues

These agents inhibit secretion of hormones involved in vasodilation.

Octreotide (Sandostatin)

Synthetic octapeptide analogue of somatostatin. Inhibits secretion of multiple endocrine hormones. Acts primarily on somatostatin receptor subtypes II and V. Inhibits GH secretion and has multitude of other endocrine and nonendocrine effects, including inhibition of glucagon, VIP, and GI peptides. Efficacy has not been proven.

Dosing

Adult

100 mcg SC tid, then increase to 500 mcg SC tid for 8 wk

Pediatric

Not established

Interactions

May reduce effects of cyclosporine; patients on insulin, oral hypoglycemics, beta-blockers, and calcium channel blockers may need dosage adjustments

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Adverse effects primarily related to altered GI motility and include nausea, abdominal pain, diarrhea, and increased incidence of gallstones and biliary sludge; because of alteration in counterregulatory hormones (eg, insulin, glucagon, GH), hypoglycemia or hyperglycemia may occur; bradycardia, cardiac conduction abnormalities, and arrhythmias have been reported; because of inhibition of TSH secretion, hypothyroidism may also occur; caution in patients with renal impairment; cholelithiasis may occur

Follow-up

Inpatient & Outpatient Medications

• In patients with AIDS, cryptosporidiosis usually cannot be eradicated prior to restoration of the CD4 cell count in response to HAART. During early immune reconstitution, patients should generally continue antiparasitic therapy (such as nitazoxanide or paromomycin) and antimotility agents, as needed.

Deterrence/Prevention

• Drinking water should be purified by filtration. This can be accomplished using 1-μm water filters when drinking tap water. Patients with AIDS should drink only filtered water.
• Boil or filter water in countries with a high risk of transmission.
• Avoid newborn animals (eg, calves, lambs), including domestic animals. New pets for patients with AIDS should be older than 6 months and should not have diarrhea.
• Health care worker, childcare workers, and health-compromised patients should avoid fecal-oral spread by wearing gloves and washing their hands after contact with human feces. Spread can occur after activities such as changing diapers.

Complications

• Sclerosing cholangitis, acalculous cholecystis, papillary stenosis, and pancreatitis may develop with biliary involvement.
• Patients with AIDS may develop respiratory tract infections.
• Rare cases of pancreatitis have been recorded in immunocompetent patients.

Prognosis

• Prolonged diarrhea (ie, >1 mo) and biliary disease indicate a poor prognosis in persons with AIDS.

Patient Education

• Encourage immunocompromised patients to consider using 1-μm water filters when drinking tap water.
• Instruct patients to boil or filter water in countries with a high risk of transmission.
• Instruct immunocompromised patients to avoid newborn animals (eg, calves, lambs), including domestic animals, and people with diarrhea. New pets for patients with AIDS should be older than 6 months and should not have diarrhea.
• Instruct patients with AIDS, daycare workers, and health care workers to avoid fecal-oral spread by wearing gloves and washing their hands after contact with human feces. Spread can occur after activities such as changing diapers.

Miscellaneous

Medicolegal Pitfalls

• Prolonged diarrhea caused by cryptosporidiosis may warrant HIV testing. Provide appropriate counseling before and after administration of the HIV test.
• Outbreaks of cryptosporidiosis should be detected by vigilant observation for increased case numbers at primary and public health care levels.

Multimedia

Media file 1: Modified acid-fast stain of stool shows red oocysts of Cryptosporidium parvum against the blue background of coliforms and debris.

References

1. White AC Jr. Cryptosporidiosis (Cryptosporidium hominis, Cryptosporidium parvum, other species). In: Mandell GL, Bennett JE, Dolin R, ed. Principles and Practice of Infectious Diseases. 6^th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2005:3215-3228.

2. Bushen OY, Lima AA, Guerrant RL. Cryptosporidiosis. In: Guerrant RL, Walker DH, Weller PF, eds. Tropical Infectious Diseases. Philadelphia, PA: Elsevier-Churchill Livingstone Principle, Pathogens, and Practice.; 2006:1003-1014.

3. Kosek M, Alcantara C, Lima AA, Guerrant RL. Cryptosporidiosis: an update. Lancet Infect Dis. Nov 2001;1(4):262-9. [Medline].

4. Ramirez NE, Ward LA, Sreevatsan S. A review of the biology and epidemiology of cryptosporidiosis in humans and animals. Microbes Infect. Jul 2004;6(8):773-85. [Medline].

5. Thompson RC, Olson ME, Zhu G, Enomoto S, Abrahamsen MS, Hijjawi NS. Cryptosporidium and cryptosporidiosis. Adv Parasitol. 2005;59:77-158. [Medline].

6. Amin OM. Seasonal prevalence of intestinal parasites in the United States during 2000. Am J Trop Med Hyg. Jun 2002;66(6):799-803. [Medline].

7. Amadi B, Mwiya M, Musuku J, Watuka A, Sianongo S, Ayoub A, et al. Effect of nitazoxanide on morbidity and mortality in Zambian children with cryptosporidiosis: a randomised controlled trial. Lancet. Nov 2 2002;360(9343):1375-80. [Medline].

8. Rossignol JF, Kabil SM, el-Gohary Y, Younis AM. Effect of nitazoxanide in diarrhea and enteritis caused by Cryptosporidium species. Clin Gastroenterol Hepatol. Mar 2006;4(3):320-4. [Medline].

9. Rossignol JF, Ayoub A, Ayers MS. Treatment of diarrhea caused by Cryptosporidium parvum: a prospective randomized, double-blind, placebo-controlled study of Nitazoxanide. J Infect Dis. Jul 1 2001;184(1):103-6. [Medline].

10. Kotler DP, Fogleman L, Tierney AR. Comparison of total parenteral nutrition and an oral, semielemental diet on body composition, physical function, and nutrition-related costs in patients with malabsorption due to acquired immunodeficiency syndrome. JPEN J Parenter Enteral Nutr. May-Jun 1998;22(3):120-6. [Medline].

11. Smith HV, Corcoran GD. New drugs and treatment for cryptosporidiosis. Curr Opin Infect Dis. Dec 2004;17(6):557-64. [Medline].

12. Blackburn BG, Mazurek JM, Hlavsa M, Park J, Tillapaw M, Parrish M. Cryptosporidiosis associated with ozonated apple cider. Emerg Infect Dis. Apr 2006;12(4):684-6. [Medline].

13. Buch K, Nguyen S, Divino CM, Weber K, Morotti RA. Cryptosporidiosis presenting as acute appendicitis: a case report. Am Surg. Jun 2005;71(6):537-8. [Medline].

14. Cunha BA. Antibiotic Essentials. 5^th ed. Royal Oak, Mich: Physicians Press; 2006.

15. Insulander M, Lebbad M, Stenström TA, Svenungsson B. An outbreak of cryptosporidiosis associated with exposure to swimming pool water. Scand J Infect Dis. 2005;37(5):354-60. [Medline].

16. Mac Kenzie WR, Hoxie NJ, Proctor ME, Gradus MS, Blair KA, Peterson DE, et al. A massive outbreak in Milwaukee of cryptosporidium infection transmitted through the public water supply. N Engl J Med. Jul 21 1994;331(3):161-7. [Medline].

17. Mahdi NK, Ali NH. Cryptosporidiosis and other intestinal parasitic infections in patients with chronic diarrhea. Saudi Med J. Sep 2004;25(9):1204-7. [Medline].

18. Roy SL, DeLong SM, Stenzel SA, Shiferaw B, Roberts JM, Khalakdina A. Risk factors for sporadic cryptosporidiosis among immunocompetent persons in the United States from 1999 to 2001. J Clin Microbiol. Jul 2004;42(7):2944-51. [Medline].

19. Yoder JS, Beach MJ. Cryptosporidiosis surveillance--United States, 2003-2005. MMWR Surveill Summ. Sep 7 2007;56(7):1-10. [Medline].

Keywords

cryptosporidiosis, biliary cryptosporidiosis, calf scours, slim disease, Cryptosporidium parvum, C parvum, Cryptosporidium hominis, C hominis, cryptosporidia, Apicomplexa protozoan, diarrhea, abdominal cramps, low-grade fever, acalculous cholecystitis, sclerosing cholangitis, papillary stenosis, pancreatitis

Contributor Information and Disclosures

Author

A Clinton White Jr, MD, The Paul R Stalnaker, MD, Distinguished Professor of Internal Medicine, Director, Infectious Disease Division, Department of Internal Medicine, University of Texas Medical Branch
A Clinton White Jr, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Federation for Medical Research, American Society of Tropical Medicine and Hygiene, Christian Medical & Dental Society, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Medical Editor

Jeffrey D Band, MD, Clinical Professor of Medicine, Wayne State University School of Medicine; Director, Division of Infectious Diseases and International Medicine, William Beaumont Hospital Corporation
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Joseph F John Jr, MD, FACP, FIDSA, FSHEA, Clinical Professor of Medicine, Molecular Genetics and Microbiology, Medical University of South Carolina; Associate Chief of Staff for Education, Ralph H Johnson Veterans Affairs Medical Center
Disclosure: BioMerieux Honoraria Review panel membership; Cubist Honoraria Review panel membership; Pfizer Honoraria Speaking and teaching; Merck Stock dividends stock holdings

CME Editor

Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital
Eleftherios Mylonakis, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Society for Microbiology, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Chief Editor

Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital
Burke A Cunha, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

The authors and editors of eMedicine gratefully acknowledge the contributions of previous coauthor Damon Eisen, MD, to the development and writing of this article.

© 1994- by Medscape.
All Rights Reserved
(http://www.medscape.com/public/copyright)