Genova Dx: The increase in worldwide travel, coupled with increasing immigration into the United States, contributes to the spread and incidence of parasitic infections. In addition, parasitic infections are commonly transmitted through fecally contaminated food, water, or other materials within this country. Genova Diagnostics' Comprehensive Parasitology Profile uses the most technologically advanced procedures to accurately identify a wide range of protozoal parasites, including amoebae, flagellates, ciliates, coccidia and microsporidia. Specimens are carefully analyzed by highly trained technicians using computer-enhanced video microscopy, new staining procedures, and advanced immunoassay techniques. These accurate detection methods allow for increased detection rates, increasing the awareness of the important relationship between parasitic infection and a broad spectrum of illnesses and diseases. Frequently Asked Questions What's bugging you? Parasites affect millions of Americans--even those who never leave the country. They can cause symptoms from intestinal disorders to problems throughout the body. Why should I be concerned about parasites? Parasites are much more common in the United States and other developed countries than you may realize. They also cause many diarrheal diseases, which can lead to serious illness and even death. An intestinal parasite can weaken your body's natural immune system, making you more susceptible to other illnesses. The frequency of world travel and increased immigration to the United States has resulted in the significant spread of parasitic infection. What are intestinal parasites? Intestinal parasites are organisms that live within the intestinal tract, growing and feeding off your body. They range from visible worms (like tapeworms and pinworms) to microscopic organisms such as Giardia lamblia. How do you get parasites? Parasites are found in raw and undercooked food and treated and untreated water; are transmitted by insects and household pets; and are passed from person to person through unsanitary habits and poor hygiene. Parasites travel in different ways. For example, the microorganism Giardia, which causes persistent diarrhea, fever, cramps and other symptoms, is contained in feces. It gets into public water supplies when animal or human sewage contaminates the water source. It can also be transmitted from person to person through careless diaper changing and poor hygiene in day care centers. Another parasite, Cryptosporidium, infests public water systems and can cause widespread outbreaks of severe diarrhea and cramps. It has been found in water supplies throughout the United States, and the disease it causes can prove fatal for people with weakened immune systems. Other parasites are found in raw, rare or undercooked meats and fish, while others are in contaminated soil. Many immigrants to the United States unknowingly carry parasites that can produce symptoms in Americans, transmitting the organisms into food through unsanitary practices in restaurant kitchens. What are the symptoms of a parasite infection? Almost any persistent digestive disorder could result from a parasite. The most common symptoms are diarrhea and abdominal pain. Other symptoms include nausea, vomiting, gas and bloating, foul-smelling stools, anorexia or weight loss, gastritis, fever and chills, headache, constipation, blood or mucus in stools, and fatigue. Other health problems can result from disturbed digestive processes or toxins produced by the parasite, such as aches and pains in the joints and muscles, anemia, allergies, chronic fatigue, immune dysfunction, sleep disturbances and depression. Ongoing irritation from a parasitic infection can alter the lining of your intestine, creating the "leaky gut" syndrome which permits toxic compounds to permeate into the body through the intestine. A variety of disorders, including food allergy and inflammatory bowel disease, can result from altered intestinal permeability. How can I tell if I have parasites? Many symptoms of a parasitic infection are similar to other illnesses, making it particularly important to test for parasites for proper diagnosis and treatment. A comprehensive parasite test, using a stool sample analyzed by a laboratory specializing in parasite testing, is the most effective way to diagnose this type of infection. How do you treat parasites? Eliminating the parasitic infection is the key to relieving the symptoms of infection, or the parasites will continue to grow and reproduce. Health care professionals use a variety of treatments to eliminate parasites, including antiparasitic drugs, diet changes and adding "friendly" bacteria to your gastrointestinal tract. How do I get a parasitology test? Talk to your health care professional about your symptoms and ask if a Comprehensive Parasitology test from Genova Diagnostics would be useful to you. How do I prevent parasites? Wash your hands before eating, after cleaning up and after playing with pets. Order your food cooked to medium or well-done when eating out. Don't eat in places that appear unsanitary. Don't drink unfiltered or untreated water, no matter how pure it looks. Drink bottled or boiled water when traveling in undeveloped countries. Insist on antiseptic cleaning practices at day care centers. Ask yourself: A parasitic infection can happen to almost anyone, not just world travelers. Complete this checklist to determine if your health problems could be caused by parasites. Do you have diarrhea frequently? Do you have abdominal cramps or pains? Do you have intestinal gas frequently? Do you suffer from bloating? Have you lost weight without trying? Are you anorexic now or have you ever been? After meals, do you often have heartburn or find it necessary to belch frequently? Are you often constipated? Do you often feel nauseous? Do you suffer from chronic fatigue? Have you noticed blood or mucus in your stools? Have you traveled outside the U.S. in the past year? If you answered yes to two or more questions, an intestinal parasite may be causing your symptoms, but treating the symptoms alone won't eliminate the parasitic infection. Share this information with your health care professional to see if a parasite detection test would be helpful. With every new out-break of food- and waterborne parasite infection, more people are coming to realize the enormous impact of parasites and diarrheal diseases on human health. Diarrheal diseases (bacterial as well as parasitic) constitute the greatest worldwide cause of morbidity and mortality.1 Numerous studies show parasitic infection up to 99% in undeveloped countries.2 In the United States, diarrheal diseases caused by intestinal infections are the third leading cause of morbidity and mortality. Most Americans have grown up with modern sanitation, and it is often assumed parasitic infections are encountered only in impoverished foreign countries.3 According to Neva, "The United States citizen can acquire amebiasis, giardiasis, pinworms, and strongyloides, for example, without so much as a passport application."4 The increase in worldwide travel, coupled with increasing immigration into the United States and a rise in imported foods, contributes to the spread and incidence of parasitic infections. In a study of outpatients at the Gastroenterology Clinic in Elmhurst, N.Y., a 74% incidence of parasites was found.5 A total of 20% of this population harbored pathogens. One survey of public health laboratories reported that 15.6% of specimens examined contained a parasite.6 At Genova Diagnostics, almost 30% of specimens examined are positive for a parasite. The prevalence of parasitic infections in the United States is difficult to quantify. Most figures are underestimates that can be traced to inadequate parasitologic training of physicians and laboratory technicians.3 As detection methods become more accurate and sophisticated, physicians are recognizing the increased incidence of parasitic infection and its relationship to a broad spectrum of diseases. What are parasites? The two major classifications, predator and scavenger, are differentiated by their nutritional relationships.7 Further modification leads to symbiosis and commensalism. Parasitism is where the host is injured through the activities of the parasite during an intimate and protracted relationship between the two. Some organisms have a changing interaction with their host-sometimes as a parasite and sometimes commensal. Clinical significance In general, a parasite interferes with the host's vital processes through secretions, excretions, or other products.7 These products include proteolytic enzymes that erode the intestinal wall, enterocytotoxins (from E. histolytica), and serotonin-like products.8 Parasitic infections can trigger autoimmune reactivity. The parasite might cause tissue destruction, thus releasing high amounts of self antigens which stimulate the autoreactivity.9 The most common symptoms of intestinal parasitic infections are abdominal pain and moderate or severe diarrhea, but there is a wide range of both acute and chronic effects. Giardiasis is an interesting model for the systemic effects of gastrointestinal parasites. Giardia lamblia, although capable of causing acute illness (diarrhea), can hide in the GI tract for years with few symptoms.10 Among the common systemic complaints of this disease are fatigue and anorexia. It is reasonable to suspect that many long-term effects are due to phenomena occurring at or within the mucosal membranes. Zinneman reported that giardiasis is associated with reduced secretory IgA, a primary mucosal defense mechanism against foreign infections.11 Moreover, Giardia lamblia is known to be a cause of malabsorption, suggesting a decreased mucosal permeability. Giardiasis is also associated with asthma, urticaria, arthritis, and uveitis, suggesting increased mucosal permeability. 12 It could be hypothesized that giardiasis results in altered permeability-increased permeability to some types of molecules and decreased permeability to other types. Decreased secretory IgA levels, either as a cause or as a consequence of this phenomenon, would result in increased susceptibility to secondary infections and systemic symptoms. Symptoms of parasitic infection The most common symptom of parasite infection is diarrhea, with abdominal pain as the second most common symptom.10,13 Other symptoms include flatulence, foul-smelling stools, cramps, distention, anorexia, nausea, weight loss, belching, heartburn, headache, constipation, vomiting, fever, chills, bloody stools, mucus in stools, and fatigue.10 (see sidebar). Although specific symptoms are associated with certain organisms (e.g. fever with malaria), most symptoms can be present with almost any parasite. In addition, there is an increasing number of parasite cases with systemic complaints not traditionally thought to be caused by parasites. Endolimax nana has been associated with urticaria, and Blastocystis hominis with infective arthritis.14 Symptoms of parasitic infection Abdominal pain and cramps Anorexia Autoimmune disease Chronic fatigue Constipation Depressed sIgA Distention Fever Food allergy Gastritis Inflammatory bowel disease Altered intestinal permeability Irregular bowel movements Irritable bowel syndrome Low back pain Pruritus ani Rash and itching of skin Urticaria Weight loss Arthritis Bloody stools Colitis Crohn's disease Diarrhea Dysentery Flatulence Foul-smelling stools Headaches Leukopenia Malabsorption Rectal bleeding Vomiting Substantial literature associates parasites with allergy, but it isn't known whether parasites enhance the probability of getting allergies or whether being allergic predisposes one to parasitic infection.15 Two reports associate Trichuris infection with diminished mental development in children and recovery of mental function after treatment.16,17 Leo Galland, M.D., has reported intestinal protozoans as an unsuspected cause of chronic illness and fatigue among his patients.18,19 Potentially pathogenic protozoa were detected in 27% of a group of urban patients with irritable bowel syndrome.20 Organisms included B. hominis, D. fragilis, G. lamblia, E. histolytica and Entamoeba coli. Cryptosporidium, a supposed weak pathogen most frequently causing a self-limited diarrhea in adults, is a major cause of diarrheal disease in the pediatric population.21 Cryptosporidiosis has been associated with reactive arthritis and acute pancreatitis.22,23 Cryptosporidium has rapidly become the most frequently cited cause of outbreaks of parasite-related gastroenteritis in drinking and recreational waters (fresh and treated), highlighting the inability of many water systems to protect people from this organism. In the most widely publicized outbreak of cryptosporidiosis (1993 in Milwaukee), over 400,000 people were infected and more than 100 died.24,25 Pathogenicity Among the many organisms classified as parasites, only some are referred to as "pathogens." In fact, the classification of organisms as pathogens continues to fluctuate. Few people realize that only a few decades ago Giardia lamblia, the leading cause of intestinal parasitic infections in the United States, was not considered a pathogen.26 Even more recently, Cryptosporidium, a well-known pathogen in animals, was identified as a human pathogen. Today, a controversy continues about the status of Blastocystis hominis. Next to yeast, B. hominis is the most frequently observed organism in fecal samples. Part of the problem in classifying parasites is defining "pathogen" and "commensal." Many individuals harbor pathogens such as Giardia lamblia or Entamoeba histolytica but don't have discernible gastrointestinal symptoms. And conversely, the apparent pathological effects of supposed commensals such as Entamoeba coli or Endolimax nana have been reported.27-30 One hypothesis to explain variable pathogenicity is that distinct pathogenic and nonpathogenic strains of organisms appear morphologically identical. 31 Another hypothesis postulates pathogenic and non-pathogenic states of an organism and proposes mechanisms whereby modulators related to the microenvironment or the host could switch the parasite from one state to the other.31 The true nature of pathogenicity, however, may rest in both hypotheses. Pathogenicity and symptom severity may vary depending on the parasite itself, the host (especially its immune status), and the microecological environment where the parasite lives. Factors relevant to the parasite include production of toxins, cytolytic ability, and adherence.32 Factors related to the host include immune competence, secretory IgA levels, T and B lymphocyte levels, gut motility and permeability. Affecting both the parasite and the host are the stool transit time and microenvironment (pH, fat and fiber content, the health and number of bacterial organisms making up the normal flora, and the ability of normal flora to compete for nutrients with potential pathogens).33 Common protozoal parasites Information on parasites is available in several excellent texts.26,34 The protozoa that parasitize the intestinal lumen belong to five groups: amoebae, flagellates, ciliates, coccidia, and microsporidia. Most are transmitted through fecally contaminated food, water or other materials. Contaminated water supplies are a particular problem because many cysts are not killed by usual levels of chlorination - especially the common pathogens Giardia, which is relatively chlorine-resistant, and Cryptosporidium, which is >50-fold more resistant to chlorine than Giardia. Few water supplies are equipped with the sophisticated and expensive filtration systems necessary to effectively control these organisms.24 Blastocystis hominis Blastocystis hominis is the most prevalent parasite but often isn't detected due to poor laboratory techniques.35 At Genova Diagnostics, Blastocystis is found in more than 20% of clinical specimens.36 The weight of evidence supports treating it as a potential pathogen.37 Together with other weak pathogens, it is associated with many chronic conditions, including irritable bowel, chronic fatigue, and arthritic/rheumatoid complaints. Three forms have been identified, and the vacuolated form is most commonly seen in fecal specimens. Blastocystis has been found to produce gastrointestinal cramps, vomiting, sleeplessness, nausea, weight loss, lassitude, dizziness, flatus, anorexia, and pruritus. B. hominis is often found in patients with classic symptoms of irritable bowel syndrome.38 Treatment with metronidazole has been found to eradicate the organism. Blastocystis hominis may be highly variable in its pathogenicity. The organism is present in a number of healthy individuals, and an asymptomatic carrier state has been postulated.39 In many patients with gastrointestinal illness, this organism is the only identifiable parasite, and these patients improve when Blastocystis is eradicated.37 We find its presence highly correlates with gastrointestinal symptoms; and, along with others, suggest it may be a pathogen in symptomatic patients.14,40 Dientamoeba fragilis Dientamoeba fragilis, a pathogenic flagellate and one of the most frequent parasitic infections, often goes undetected due to poor laboratory technique.41-43 Symptoms include diarrhea and abdominal discomfort. It resides in the colon, has a cosmopolitan distribution, is found as a trophozoite, and has no cyst stage. Transmission is by direct ingestion of the trophozoite and can be found within the eggs of some helminths, especially pinworms. Amoeba Amoeba including Endolimax nana, Entamoeba histolytica, E. coli, and E. hartmanni are cosmopolitan in distribution. E. histolytica is linked to acute diarrhea, GI distress, and hepatic disease (by means of blood draining the intestine and returning to the liver). While other amoeba, such as E. nana, E. hartmani, and E. coli, may be only occasionally patho-genic,44 their identification is important to differentiate them from other amoeba, which are pathogenic.45 There are two forms of amoeba-the motile trophozoite and the cyst-and trans-mission is by ingestion of the cyst stage. The cyst, the infective form of the organism, resists environmental changes and may spread from person to person or indirectly via food or water. Symptoms occur primarily with tissue invasion and include intermittent diarrhea and constipation, flatulence, and cramping. Intestinal infection symptoms include mild diarrhea, food intolerance, fatigue, and dysentery. Giardia lamblia Giardia lamblia, a flagellate with cosmopolitan geographic distribution, is found in duodenal contents and bile. In the duodenum it can be demonstrated in the mucosal crypts where it attaches itself to the mucosal cells, causing gastroenteritis. When swept into the fecal stream, the trophozoite encysts. Consequently, most fecal specimens contain the encysted parasite rather than the flagellated trophozoite form, which is usually found only in severe diarrhea. In the cyst (resistant) form, they spread the disease from host to host by fecal/oral routes, either directly (as between children in day-care centers or between sexual partners) or by food and water.46 Waterborne epidemics involve mountain streams, well water, and even some chlorinated community water systems. (See the preceding section for more detailed signs and symptoms.) Iodamoeba butschlii Iodamoeba butschlii is an amoeba with a low pathogenicity associated with chronic complaints. It has a cosmopolitan distribution and is located in the lumen of the colon and cecum. Transmission is by ingestion of the cyst stage. Fungal conidia Fungal conidia are yeast. They are very small (2 to 4 microns), have considerable structure (typically with pointed ends and an interior vacuole), and are difficult to culture. The few studies on this organism cite its ability to ferment complex polysaccharides to produce alcohol. In a recent review of Genova Diagnostics' parasitology results, we found fungal conidia in 5.4% of the samples.47 They were more prevalent in women and frequently found in the absence of other parasites. Almost all the patients suffered from gastrointestinal complaints, but diarrhea (38%), gas (33%), and bloating (33%) were most common. At this time we know little about fungal conidia pathogenicity. Our advice is to put fungal conidia in the same category as Blastocystis hominis or yeast overgrowth and treat (or not treat) with the same criteria. Intestinal helminths Intestinal worms are a leading cause of morbidity and mortality and usually diagnosed by detection of eggs or larvae in fecal specimens. Some of the more common helminths are Nematodes, including Enterobius vermicularis, Ascaris lumbricoides, Trichuris trichiura, Necator americanus, and Strongyloides stercoralis. Detection of parasites The diagnosis of most parasitic infections depends on the laboratory. 46 For intestinal parasites, morphological demonstration of diagnostic stages is the principal means of diagnosis. The emerging area of immunodiag-nostic techniques is of growing importance. Detection rates are a function of: Specimen collection and handling Number, kind and type of specimens examined Concentration procedures Staining procedures Macroscopic and microscopic examination techniques Quality of microscopes Use of advanced immunoassay methods Quality of training, frequency of practice and dedication of laboratory personnel. Many studies show that detection rates dramatically increase with the sophistication of detection procedures, such as adding concentration, flotation, appropriate preservatives, specialized permanent stains and other methods.48-50 Various studies show that when increasing from a single specimen to three specimens, detection can increase as much as 30%, depending upon species.49-51 In addition to using formed stools as a specimen, purged samples (induced by oral purgative) provide valuable specimens.52 Recent reports show that a rectal mucosal swab specimen aids in detection of certain parasites. Computer-enhanced video microscopy also aids in identification and provides the physician with a picture of organisms found. Several immunoassay techniques are now available, increasing detection of intestinal organisms from 40 - 60 % to >90% for some species.53 When to suspect parasitic infections Office diagnosis of parasitic infections requires physicians to check for such symptoms as diarrhea, unexplained fever, cough, itching or rash of the skin, abdominal pain, and bloody stools. Certain people are at particular risk for infection, including those who recently trav-eled outside the United States and individuals who are immune compromised.44,54,55 In addition to diarrhea, the most common symptom, other symptom complexes may suggest parasitic infection. For example, amoebic colitis can mimic Crohn's disease of the colon and ulcerative colitis.56 Fulminant amoebic colitis may be present with rectal bleeding and colonic ulcerations and can be difficult to differentiate from inflammatory bowel disease.57 Inflammatory bowel disease patients can also be carriers of amoebae. Because steroids can provoke amoebic activity and cause a fulminating colitis, it is necessary to determine if amoebae exist. Recent reports suggest that intestinal infections with Giardia lamblia and Blastocystis hominis cause symptoms identical to those observed in patients with inflammatory bowel disease.58 Treatment led to resolution of symptoms in approximately 90% of the study population. As more data becomes available, stool examination for parasites may become an integral part of the evaluation of patients with inflammatory bowel disease or other undiagnosed gastrointestinal complaints. Nutrition and parasites Antiparasitic drugs, while effective, are powerful pharmacologic agents to be taken with careful consideration.59 Therefore, nutritional and other approaches to parasite infestation are worth noting. Leitch et al. reported that dietary fiber reduces the rate of intestinal infection by Giardia lamblia.60 The authors speculate that fiber induces mucus secretion and reduces the attachment of trophozoites. It may also affect the growth of bacterial flora, pH, and the competition for nutritional resources among organisms. Measures that build and restore the gastrointestinal immune system are worth-while interventions. Modification of bowel flora, bowel environment, and digestive enzymes can produce effects synergistically in eradicating parasites. Natural alternatives Mirelman reported that allicin, the active principle of garlic extract, is an inhibitor of growth for Entamoeba histolytica.61 Other studies suggest its effectiveness with other parasites as well. Other reports claim that berberine, the active ingredient of goldenseal (Hydrastis), oregon grape root (mahonia aquifolium), and Barberry (Berberis vulgaris) are effective against Entamoeba histolytica and compare favorably to Quinacrine HCl in the treatment of giardiasis.62,63 Quassia appears to be another useful anti-helminthic, which anecdotally has been used successfully for Ascaris lumbricoides, amoebic dysentery and giardiasis. An advantage of Quassia is its low toxicity.64,65 References 1 Thorne GM. Diagnosis of infectious diarrheal diseases. Infect Dis Clin North Am 1988;2(3):747-51. 2 Gonçalves JF, Tanabe M, Medeiros F, Gonçalves FJ, Aca I, daMotta SRB, Tateno S, Takeuchi T. Parasitological and serological studies on amoebiasis and other intestinal parasitic infections in the rural sector around Recife, Northeast Brazil. Rev Inst Med Trop Sao Paulo 1990;32(6):428-35. 3 Dalton HP, Nottebart HC, eds. Interpretive Medical Microbiology. New York: Churchill Livingston, 1986:501. 4 Neva FA. Parasitic diseases of the GI tract in the United States. Disease-a-month: DM [serial]. Chicago : Year Book Publishers, June 1972: 3-44. 5 Wajsman R, Lee M. Prevalence of B. hominis and other parasites in an immigrant population. Presentation at American College of Gastroenterology, 56th Annual Meeting, 1991; October 13-15. 6 Johnston TS. Diagnosis and treatement of five parasites: Enterobius vermicularis, Giardia lamblia, Trichuris trichiura, Ascaris lumbricoides, Entamoeba histolytica. Drug Intell Clin Pharm 1981;15(2):103-10. 7 Markell EK, John DT, Krotoski WA. Markell and Voge's Medical Parasitology. 8th ed. Philadelphia: Saunders, 1999:6-9. 8 Guerrant R, Petri WA, Weikel CS. Parasitic causes of dis-ease. In: Lebenthal E, Duffy M, editors. Textbook of Secretory Diarrhea. New York: Raven Press, 1990;273-80. 9 Abu-Shakra M, Shoenfeld Y. Parasitic infection and autoimmunity. Autoimmunity 1991;9(4):337-44. 10 Wolfe MS. Giardiasis. Clin Microbiol Review 1992;5(1):93-100. 11 Zinneman HH, Kaplan AP. The association of giardiasis with reduced intestinal secretory immunoglobulin A. Dig Dis 1972;17(9):793-7. 12 Gillon J. Giardiasis: review of epidemiology, pathogenetic mechanisms and host responses. Qtr J Med 1984; NS LIII(209):29-39. 13 Jones JE. Signs and symptoms of parasitic diseases. Primary Care 1991;18(1):1-12. 14 Lee MG, Rawlins SC, Didier M, DeCeulaer K. Infective arthritis due to Blastocystic hominis. Ann Rheum Dis 1990;49(3):192-3. 15 Moqbel R, Pritchard DI. Parasites and allergy: evidence for a 'cause and effect' relationship. Clin Exp Allergy 1990;20:611-8. 16 Callender JE, Grantham-McGregor S, Walker S, Cooper ES. Trichuris infection and mental development in children [letter]. Lancet 1992; 339(8786):181. 17 Nokes C, Bundy DAP. Trichuris trichiura infection and men-tal development in children. Lancet 1992;339(8791):500. 18 Galland L, Lee M, Bueno H, Heimowitz C. Giardia lamblia infection as a cause of chronic fatigue. J Nut Med 1990;1:27-31. 19 Galland L. Intestinal protozoan infection is a common unsuspected cause of chronic illness. J Adv Med 1989;2(4):539-52. 20 Galland L. Intestinal protozoan and Irritable Bowel Syndrome. Presentation at American Academy of Family Practice; 1992, October. San Diego, CA. 21 Public Health Laboratory Service Study Group. Cryptosporidiosis in England and Wales: prevalence and clinical and epidemiological features. BMJ 1990;300(March 24):774-7. 22 Hay EM, Winfield J, McKendrick MW. Reactive arthritis associated with cryptosporidium enteritis. BMJ 1987;295(July):249. 23 Hawkins SP, Thomas RP, Teasdale C. Acute pancreatitis: a new finding in cryptosporidium enteritis. BMJJ 1987;294(Feb 21):483. 24 Barwick RS, Levy DA, Craun GF, Beach MJ, Calderon RL. Surveillance for waterborne-disease outbreaks - United States, 1997-1998. MMWR 2000;49(SS-4):1-21. 25 Gostin LO, Lazzarini SZ, Neslund VS, Osterhold MT. Water quality laws and waterborne disease: Cryptosporidium and other emerging pathogens. Am J Public Health 2000;90:847-53. 26 Sun T. Color Atlas and Textbook of Diagnostic Parasitology. New York: Igaku-Shoin Medical Publishers, 1988. 27 Wahlgren M. Entamoeba coli as cause of diarrhoea? [let-ter]. Lancet 1991;337(8742):675. 28 Corcoran GD, O'Connell, Gilleece, Mulvihil TE. Entamoeba coli as cause of diarrhoea? [comment] Lancet 1991;338(8761):254. 29 Veraldi S, Schianchi-Veraldi R, Gasparini G. Urticaria probably caused by Endolimax nana [letter]. Int J Derm 1991;30:376. 30 Rolston KVI, Hoy J, Mansell PWA. Diarrhea caused by "nonpathogenic amoebae" in patients with AIDS [letter]. N Engl J Med 1986;(July 17):192. 31 Ravdin JI. Amebiasis now. Am J Trop Med Hyg 1989;41(3 Suppl):40-8. 32 Ravdin JI. Entamoeba histolytica: pathogenic mechanisms, human immune response, and vaccine development. Clin Res 1990;38(2):215-25. 33 Lee MJ. Relationship between stool pH and butyrate lev-els [letter]. Nutr Cancer 1991;75-6. 34 Ash LR, Orihel TC. Atlas of Human Parasitology. 2nd ed. Chicago: American Society of Clinical Pathologists Press, 1980. 35 Lee MJ. Pathogenicity of Blastocytis hominis [letter]. J Clin Microbiology 1991(Sept):2089. 36 Fleming C, Frye C, Lee MJ. Morphology and freuency of occurrence of Blastocystis hominis. Poster presentation at ASCP/CAP Spring Meeting 1991; March 2-7, Nashville, Tenn. 37 Zierdt CH. Blastocystis hominis - past and future. Clin Microbiol Rev 1991;4(1):61-79. 38 Johanson JF et al. Am College Gastroenterol, 57th Ann Mtg, Oct 1992; Miami Beach, FL. 39 Doyle PW, Helgason MM, Mathias RG, Proctor EM. Epidemiology and pathogenicity of Blastocystis hominis. J Clin Microbiol 1990; 28(1):116-21. 40 Babb RR, Wagener S. Blastocystis hominis - a potential intestinal pathogen. West J Med 1989;151(5):518-9. 41 Grendon JH, Digiacomo RF, Frost FJ. Dientamoeba fragilis detection methods and prevalence: a survey of state pub-lic health laboratories. Public Health Rep May-June 1991;106(3):322-5. 42 Yang J, Scholten T. Dietamoeba fragilis: a review with notes on its epidemiology, pathogenicity, mode of transmission, and diagnosis. Am J Trop Med Hyg 1977; 26(1):16-22. 43 Kean BH, Malloch CL. The neglected ameba: Dientamoeba fragilis. Am J Dig Dis 1966;II(9):735-46. 44 Owen RL. Parasitic diseases. In: Sleisenger M, Fordtran JS, editors. Gastrointestinal Disease: Pathophysiology, Diagnosis, Management. 2 vol. 5th ed. Philadelphia: Saunders, 1993: 1:1190-1207. 45 Garcia LS, Bruckner DA. Diagnostic Medical Parasitology. 3rd ed. Washington, D.C.: ASM Press, 1997: 6-33. 46 Garcia LS, Shimizu RY, Palmer JC. Algorithms for detec-tion and identification of parasites. In: Murray PR, Baron EJ, Pfaller MA, Tenover FC, Yolken RH, editors. Manual of Clinical Microbiology. 7th Ed. Washington, DC: American Society for Microbiology, 1999:1335-44. 47 Lee M, Sherlin L, Cupp B. Identification and characteriza-tion of the yeast Kloeckera in human stool samples. Presentation at ASM 92nd General Meeting; 1992, May 26-30; New Orleans, LA. 48 Gardner BB, Del Junco DJ, Fenn J, Hengesbaugh JH. Comparison of direct wet mount and trichrome staining techniques for detecting Entamoeba species trophozoites in stools. J Clin Micro 1980;12(5):656-8. 49 Sawitz WG, Faust EC. The probability of detecting intesti-nal protozoa by successive stool examinations. Am J Trop Med 1942; 22:131-6. 50 Hiatt RA, Markell EK, NG E. How many stool examina-tions are necessary to detect pathogenic intestinal proto-zoa? Am J Trop Med Hyg 1995;53(1):36-39. 51 Ash LR, Orlhel TC. Parasites: a guide to laboratory proce-dures and identification. Chicago: ASCP Press, 1987: 4-5. 52 Dowell LB. Stool examinations: a procedure to increase their worth. Off J AMT 1961 (Jan-Feb):23-5 53 Jelinek T, Peyerl G, Loscher T, Northdurft HD. Evaluation of an antigen-capture enzyme immunoassay for detection of Entamoeba histolytica in stool samples. Eur J Clin Microbiol Infect Dis 1996;15(9):752-59. 54 Smith PD, Quinn TC, Strober W, Janoff EN, Masur H. Gastrointestinal infections in AIDS. Ann Intern Med 1992;116(1):63-77. 55 Kotler DP, Francisco A, Clayton F, Scholes JV, Orenstein JM. Small intestinal injury and parasitic diseases in AIDS. Ann Intern Med 1990; 113(6):444-9. 56 Korelitz BI. When should we look for amebae in patients with inflammatory bowel disease? J Clin Gastroent 1989;11(4):373-5. 57 Radvin JL. Entamoeba histolytica: from adherence to enteropathy. J Infect Dis 1989;159:420-9. 58 O'Gorman MA,Orenstein SR, Proujansky R, Wadowsky R, Putnam PE, Kocoshis SA. Prevalence and characteris-tics of Blastocystis hominis infection in children [abstract number 213]. Am J Gastroenterol 1989;84:1192. 59 The Medical Letter. Drugs for parasitic infections. December 1993;35(911):111. 60 Leitch GJ, Visvesvara GS, Wahlquist SP, Harmon CT. Dietary fiber and giardiasis: dietary fiber reduces rate of intestinal infection by Giardia lamblia in the gerbil. Am J Trop Med Hyg 1989;41(5):512-20. 61 Mirelman D, Monheit D, Varon S. Inhibition of growth of Entamoeba histolytica by allicin, the active principle of garlic extract (Allium sativum) [letter]. J Infec Dis 1987;156(1):243-4. 62 Subbaiah TV, Amin AH. Effect of berberine sulphate on Entamoeba histolytica. Nature 1967; 215:527-8. 63 Gupte S. Use of berberine in treatment of giardiasis [clini-cal memorandum]. Am J Dis Child 1975;129:866. 64 Kirby GC, O'Neill MJ, Phillipson D, Warhurst DC. In vitro studies on the mode of action of quassinoids with activity against chloroquine-resistant Plasmodium falciparum. Biochem Pharmacol 1989;38(24):4367-74. 65 Phillipson JD, Wright CW. Medicinal plants in tropical medicine: 1. medicine plants against protozoal diseases. Trans Royal Society Trop Med Hyg 1991;85:18-21. gsp$198.95 Add-on EIA procedure(Giardia or Crypto) (Stool) gseia$45.95