Diagnosis, Diagnostics, Immunodiagnosis & Immunodiagnostics:



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 January 2003

5925.      Garcia LS, Shimizu RY, Bernard CN. Detection of Giardia lamblia, Entamoeba histolytica/Entamoeba dispar, and Cryptosporidium parvum antigens in human fecal specimens using the triage parasite panel enzyme immunoassay. J Clin Microbiol  2000 Sep;38(9):3337-40


The Triage parasite panel (BIOSITE Diagnostics, San Diego, Calif.) is a new qualitative enzyme immunoassay (EIA) panel for the detection of Giardia lamblia, Entamoeba histolytica/E. dispar, and Cryptosporidium parvum in fresh or fresh, frozen, unfixed human fecal specimens. By using specific antibodies, antigens specific for these organisms are captured and immobilized on a membrane. Panel performance was evaluated with known positive and negative stool specimens (a total of 444 specimens) that were tested by the standard ova and parasite (O&P) examination as the "gold standard," including staining with both trichrome and modified acid-fast stains. Specimens with discrepant results between the reference and Triage methods were retested by a different method, either EIA or immunofluorescence. A number of samples with discrepant results with the Triage device were confirmed to be true positives. After resolution of discrepant results, the number of positive specimens and the sensitivity and specificity results were as follows: for G. lamblia, 170, 95.9%, and 97.4%, respectively; for E. histolytica/E. dispar, 99, 96.0%, and 99.1%, respectively; and for C. parvum, 60, 98.3%, and 99.7%, respectively. There was no cross-reactivity with other parasites found in stool specimens, including eight different protozoa (128 challenges) and three different helminths (83 challenges). The ability to perform the complete O&P examination should remain an option for those patients with negative parasite panel results but who are still symptomatic.

5926.      Misra A, Agrahari D, Gupta R. Cullen's sign in amoebic liver abscess. Postgrad Med J  2002 Jul;78(921):427-8


A 45 year old woman presented with pain in her right upper abdomen and fever. Ultrasound of her abdomen showed a large liver abscess with subhepatic collection. She had Cullen's sign. The liver abscess was managed by percutaneous catheter drainage.

5927.      Schunk M, Jelinek T, Wetzel K, Nothdurft HD. Detection of Giardia lamblia and Entamoeba histolytica in stool samples by two enzyme immunoassays. Eur J Clin Microbiol Infect Dis  2001 Jun;20(6):389-91.

Two commercially produced enzyme immunoassays (EIAs) to detect antigens of

- Giardia lamblia and Entamoeba histolytica in stool specimens were evaluated. A total of 276 stool specimens were collected from patients who presented with various medical complaints in the outpatient clinic of the Department of Infectious Diseases and Tropical Medicine, University of Munich. Every specimen was examined by conventional microscopy and tested by both EIA kits. When microscopy was used as the reference standard, the EIA kit detecting Giardia lamblia showed a sensitivity of 100% and a specificity of 99.6%. The EIA kit detecting Entamoeba histolytica had a sensitivity of 81.8% and a specificity of 99.2%. Both tests showed no cross-reactivity with other intestinal protozoa. Antigen detection by EIA has the potential to become a valuable tool capable of making stool diagnostics more effective, although it should not be considered as a replacement for microscopic examination, since other potential pathogens could otherwise escape detection.

5928.      Sharp SE, Suarez CA, Duran Y, Poppiti RJ. Evaluation of the Triage Micro Parasite Panel for detection of Giardia lamblia, Entamoeba histolytica/Entamoeba dispar, and Cryptosporidium parvum in patient stool specimens. J Clin Microbiol  2001 Jan;39(1):332-4


A study comparing the Triage Micro Parasite Panel (Biosite Diagnostics, Inc., San Diego, Calif.) to conventional O&P examination (O&P) was performed using patient fecal specimens. Five hundred twenty-three stool samples were compared. Nineteen specimens were found to be positive by Triage, and 29 were found to be positive by O&P. Seven specimens were positive for Giardia lamblia, four were positive for Entamoeba histolytica/E. dispar, and three were positive for Cryptosporidium parvum as determined by both methods. There was one false positive by Triage (C. parvum) and four false negatives by O&P (two G. lamblia, one E. histolytica/E. dispar, and one C. parvum). The Triage test accurately detected all 18 specimens that contained one of the three organisms that it was designed to detect. The Triage test is a rapid, easy-to-use enzyme immunoassay for the detection of G. lamblia, E. histolytica/E. dispar, and C. parvum in fresh or fresh-frozen fecal specimens. These data suggest that the Triage test can be used as a screen for the immediate testing of stool specimens for these three pathogenic parasites. If Triage test results are negative, O&P can be performed if parasitic infections other than G. lamblia, E. histolytica/E. dispar, or C. parvum are suspected.



5929.      Haque R, Duggal P, Ali IM, Hossain MB, Mondal D, Sack RB, Farr BM, Beaty TH, Petri WA Jr. Innate and acquired resistance to amebiasis in bangladeshi children. J Infect Dis  2002 Aug 15;186(4):547-52.


Entamoeba histolytica infection and colitis occurred in 55% and 4%, respectively, of a cohort of Bangladeshi preschool children observed for 2 years. DNA typing demonstrated that infecting E. histolytica isolates were genetically diverse. Innate resistance to infection in children was linked to the absence of serum anti-trophozoite IgG. Most children who lacked serum anti-trophozoite IgG failed to develop it in response to a new infection. The serum anti-trophozoite IgG response clustered in families, which is consistent with genetic inheritance. Acquired resistance to infection was linked to intestinal IgA against the carbohydrate-recognition domain of the E. histolytica galactose N-acetyl-d-galactosamine lectin. This was associated with an 86% reduction in new infection over 1 year. Amebiasis is a common and potentially serious infection in children from Dhaka, and both innate and acquired immune responses limit infection.


5930.      Khan NA, Jarroll EL, Paget TA. Molecular and physiological differentiation between pathogenic and nonpathogenic Acanthamoeba. Curr Microbiol  2002 Sep;45(3):197-202


In this study, 14 isolates of Acanthamoeba from both clinical and environmental sources belonging to seven different species were assayed for tolerance of high osmotic pressure, temperature tolerance, extracellular proteases, and cytopathic effects (CPE) on immortalized rabbit corneal epithelial cells. On the basis of the results, amoeba isolates were divided into pathogenic and nonpathogenic groups. Ribosomal DNA sequencing was performed on these isolates. Phylogenetic relationships revealed that all the pathogenic strains tested clustered together as one group, while nonpathogenic strains clustered into other groups. Sequence comparisons with previously published sequences determined that among the six new pathogenic isolates used in this study, five belong to T4 genotype and one to T11. This is the first report of a T11 genotype being found in Acanthamoeba keratitis.

5931.      Rivera MA, Padhya TA. Acanthamoeba: a rare primary cause of rhinosinusitis. Laryngoscope  2002 Jul;112(7 Pt 1):1201-3


Parasitic infections, especially Acanthamoeba, are rarely implicated as a specific cause of rhinosinusitis. It is a fatal disease found in the immunocompromised population, in particular in patients infected with the human immunodeficiency virus (HIV). Less than 10 cases of Acanthamebic rhinosinusitis have been reported in the literature, and only 1 has survived. This case report presents an Acanthamebic infection misdiagnosed as a squamous cell carcinoma of the nasal septum on a presumptive healthy, immunocompetent 35-year-old woman. She was later diagnosed with AIDS (AIDS) along with disseminated Acanthamoebiasis and became the second reported case surviving this deadly illness. This case report also discusses the difficulty in diagnosing this rare parasite, the pathogenesis, and the multidisciplinary treatment required to control and manage this uniformly fatal disease.

5932.      Schuster FL. Cultivation of pathogenic and opportunistic free-living amebas. Clin Microbiol Rev  2002 Jul;15(3):342-54.


Free-living amebas are widely distributed in soil and water, particularly

 - members of the genera Acanthamoeba and NAEGLERIA: Since the early 1960s, they have been recognized as opportunistic human pathogens, capable of causing infections of the central nervous system (CNS) in both immunocompetent and immunocompromised hosts. Naegleria is the causal agent of a fulminant CNS condition, primary amebic meningoencephalitis; Acanthamoeba is responsible for a more chronic and insidious infection of the CNS termed granulomatous amebic encephalitis, as well as amebic keratitis. Balamuthia sp. has been recognized in the past decade as another ameba implicated in CNS infections. Cultivation of these organisms in vitro provides the basis for a better understanding of the biology of these amebas, as well as an important means of isolating and identifying them from clinical samples. Naegleria and Acanthamoeba can be cultured axenically in cell-free media or on tissue culture cells as feeder layers and in cultures with bacteria as a food source. Balamuthia, which has yet to be isolated from the environment, will not grow on bacteria. Instead, it requires tissue culture cells as feeder layers or an enriched cell-free medium. The recent identification of another ameba, Sappinia diploidea, suggests that other free-living forms may also be involved as causal agents of human infections.



5933.      Kumar R, Lloyd D. Recent advances in the treatment of Acanthamoeba keratitis. Clin Infect Dis  2002 Aug 15;35(4):434-41


Infection of the eye caused by Acanthamoeba species constitutes a burgeoning and unsolved problem. Of individuals with Acanthamoeba keratitis, 85% wear contact lenses; abrasion of the cornea is implicated. Corneal infection often can be prevented by good lens care and hygiene. Severe Acanthamoeba keratitis often can be very difficult to treat; surgery can be less than successful and may lead to further problems. The encysted stage in the life cycle of Acanthamoeba species appears to cause the most problems; many biocides are ineffective in killing the highly resistant cysts. Combination therapy--that is, use of 2 or 3 biocides, sometimes with antibacterial antibiotics--appears to work best. Recurrence is common if treatment is stopped prematurely. Immunologic methods are being investigated as a form of prevention, and oral immunization of animals recently has been successful in the prevention of Acanthamoeba keratitis by inducing immunity before infection occurs. Immunization thus may eventually become the best approach for reduction of the incidence of amebic infection in humans.

5934.  Steinberg JP, Galindo RL, Kraus ES, Ghanem KG. Disseminated acanthamebiasis in a renal transplant recipient with osteomyelitis and cutaneous lesions: case report and literature review. Clin Infect Dis  2002 Sep 1;35(5):e43-9


Disseminated acanthamebiasis is a rare disease that occurs predominantly in patients with human immunodeficiency virus (HIV) infection or acquired immunodeficiency syndrome but also in immunosuppressed transplant recipients. Few reports have focused on non-HIV-infected patients, in whom the disease is more likely to go unsuspected and undiagnosed before death. We describe a renal transplant recipient with Acanthamoeba infection and review the literature. The patient presented with osteomyelitis and widespread cutaneous lesions. No causative organism was identified before death, despite multiple biopsies with detailed histological analysis and culture. Disseminated Acanthamoeba infection was diagnosed after death, when cysts were observed in histological examination of sections of skin from autopsy, and trophozoites were found in retrospectively reviewed skin biopsy and surgical bone specimens. In any immunosuppressed patient, skin and/or bone lesions that fail to show improvement with broad-spectrum antibiotic therapy should raise the suspicion for disseminated acanthamebiasis. Early recognition and treatment may improve clinical outcomes.

5935.      Wiwanitkit V, Suwansaksri N, Suwansaksri J. Causative agents of liver abscess in those with liver cirrhosis: a 10-year case review of hospitalized patients in Thailand. Ann Trop Med Parasitol  2002 Jul;96(5):513-6


Although patients with cirrhosis of the liver show relative immunosuppression and therefore have increased susceptibility to most infections, they rarely develop liver abscesses. In a retrospective case review, the pathogens causing the liver abscesses observed, between January 1992 and December 2001 at the King Chulalongkorn Memorial Hospital, Bangkok, Thailand, in 44 hospitalized patients diagnosed as cases of liver cirrhosis were investigated. The most common clinical symptoms and signs of the abscesses--abdominal pain (80%), fever and chills (73%), and abdominal tenderness (73%)--were similar to those seen in non-cirrhotic patients with abscesses. The frequency of liver abscess among the cirrhotic patients was low (0.46%). Most (71%) of the abscesses were in the right lobe and most (71%) of those with abscesses only had a single abscess. Surprisingly, many of the abscesses (36%) were apparently caused by amoebae. Bacterial pathogens were identified in eight patients (18%) by blood culture and 15 (34%) patients by pus culture. Seven (16%) of the blood cultures and 13 (30%) of the pus contained Gram-negative aerobes, indicating that such pathogens, particularly Klebsiella pneumoniae (in six pus and six blood cultures) and Escherichia coli (in three pus cultures and one blood), were the most common causes of the bacterial abscesses. Pus culture appeared more successful than blood culture for bacterial abscesses, and amoebic abscesses could always be identified by direct microscopical examination of pus samples. Aspiration of liver abscesses, to obtain pus samples for culture and microscopy, is therefore recommended.


April 2003

6545.   Mahajan R C, Vohra V, Sehgal R, Ganguly N K. Immunodiagnosis  of amoebiasis. Proc natn Acad Sci India –Sect b 2000 ,70(3-4),189-96. (isa 017220, Vol 38 No17 ,1 Sept 2002)

6546.   McCarthy JS, Peacock D, Trown KP, Bade P, Petri Jr WA, Currie BJ. Endemic invasive amoebiasis in northern Australia. Med J Aust  2002 Nov 18;177(10):570 No abstract.


6547. Zhang Z, Duchene M, Stanley SL Jr. A monoclonal antibody to the amebic  lipophosphoglycan-proteophosphoglycan antigens can prevent disease in human intestinal xenografts infected with Entamoeba histolytica. Infect Immun  2002 Oct;70(10):5873-6. Entamoeba histolytica trophozoites are covered by lipophosphoglycan-peptidoglycan molecules which may be key virulence factors. We found that pretreatment of severe combined immunodeficient mice bearing human intestinal xenografts with a monoclonal antibody to the amebic lipophosphoglycan-peptidoglycan molecules can prevent or significantly reduce the human intestinal inflammation and tissue damage that are normally seen with E. histolytica colonic infection.


 July 2003


7057.      McGarr PL, Madiba TE, Thomson SR, Corr P. Amoebic liver abscess--results of a conservative management policy. S Afr Med J  2003 Feb;93(2):132-6

OBJECTIVE: To evaluate the safety and efficacy of conservative management of amoebic liver abscesses. DESIGN: A prospective study carried out over a 1-year period. SETTING: Inpatients and outpatients in a tertiary referral institution. SUBJECTS: Amoebic liver abscess was diagnosed on clinical, ultrasonographic, and serological features. All patients were treated with metronidazole. The indication for ultrasound-guided aspiration of the abscess was failure to improve clinically within 48-72 hours. MAIN OUTCOME MEASURES: Clinical improvement, clinical deterioration and failure of clinical improvement (persistent pain). RESULTS: In total 178 patients (male-to-female ratio 5:1) with 203 abscesses were treated during this period. Of these, 23 patients required percutaneous aspiration and 150 patients were managed without intervention and clinically resolved spontaneously. Abscesses requiring aspiration tended to be larger than those managed without aspiration (10.7 cm v. 8.2 cm) (p = 0.003). There were no complications following aspiration. Mean hospital stay was longer (12.3 days) for patients who underwent aspiration compared with those who did not (6.7 days) (p = 0.031). Only 5 patients presented with ruptured abscesses, 1 cutaneously and 4 intraperitoneally, with the only death in this latter category. CONCLUSION: Conservative medical management of amoebic liver abscess is safe. Percutaneous ultrasound-guided aspiration is indicated only in patients who fail to improve clinically after 48-72 hours rather than on rigid criteria.

7058.      Schwarzwald H, Shah P, Hicks J, Levy M, Wagner ML, Kline MW. Disseminated Acanthamoeba infection in a human immunodeficiency virus-infected infant. Pediatr Infect Dis J  2003 Feb;22(2):197-9

Infection with Acanthamoeba is difficult to diagnose and treat. We present the first case of disseminated Acanthamoeba infection in an HIV-infected infant. The infant survived 2 years with treatment with several agents having anti-Acanthamoeba activity in vitro.

7059.      Stanley SL Jr. Amoebiasis. Lancet  2003 Mar 22;361(9362):1025-34.

Amoebiasis is the second leading cause of death from parasitic disease worldwide. The causative protozoan parasite, Entamoeba histolytica, is a potent pathogen. Secreting proteinases that dissolve host tissues, killing host cells on contact, and engulfing red blood cells, E histolytica trophozoites invade the intestinal mucosa, causing amoebic colitis. In some cases amoebas breach the mucosal barrier and travel through the portal circulation to the liver, where they cause abscesses consisting of a few E histolytica trophozoites surrounding dead and dying hepatocytes and liquefied cellular debris. Amoebic liver abscesses grow inexorably and, at one time, were almost always fatal, but now even large abscesses can be cured by one dose of antibiotic. Evidence that what we thought was a single species based on morphology is, in fact, two genetically distinct species--now termed Entamoeba histolytica (the pathogen) and Entamoeba dispar (a commensal)--has turned conventional wisdom about the epidemiology and diagnosis of amoebiasis upside down. New models of disease have linked E histolytica induction of intestinal inflammation and hepatocyte programmed cell death to the pathogenesis of amoebic colitis and amoebic liver abscess.



7060.      Kumar CS, Anand Kumar H, Sunita V, Kapur I. Prevalence of anemia and worm infestation in school going girls at Gulbargha, Karnataka. Indian Pediatr  2003 Jan;40(1):70-2  No abstract available.


October 2003 


7793.      Ali IK, Hossain MB, Roy S, Ayeh-Kumi PF, Petri WA Jr, Haque R, Clark CG. Entamoeba moshkovskii infections in children, Bangladesh. Emerg Infect Dis. 2003 May;9(5):580-4.


Entamoeba moshkovskii cysts are morphologically indistinguishable from those of the disease-causing species E. histolytica and the nonpathogenic E. dispar. Although sporadic cases of human infection with E. moshkovskii have been reported, the organism is considered primarily a free-living amoeba. No simple molecular detection tool is available for diagnosing E. moshkovskii infections. We used polymerase chain reaction (PCR) to detect E. moshkovskii directly in stool. We tested 109 stool specimens from preschool children in Bangladesh by PCR; 17 were positive for E. histolytica (15.6%) and 39 were positive for E. dispar (35.8%). In addition, we found that 23 (21.1%) were positive for E. moshkovskii infection, and 17 (73.9%) of these also carried E. histolytica or E. dispar. The high association of E. moshkovskii with E. histolytica and E. dispar may have obscured its identification in previous studies. The high prevalence found in this study suggests that humans may be a true host for this amoeba.

7794.      Haque R, Huston CD, Hughes M, Houpt E, Petri WA Jr. Amebiasis. N Engl J Med. 2003 Apr 17;348(16):1565-73.  No abstract

7795.      Haseeb AN, el-Shazly AM, Arafa MA, Morsy AT. Evaluation of excretory/secretory Fasciola (Fhes) antigen in diagnosis of human fascioliasis. J Egypt Soc Parasitol. 2003 Apr;33(1):123-38.


No doubt, human fascioliasis is an increasing worldwide zoonotic liver fluke. Clinically, human fascioliasis has to be differentially diagnosed from many hepatic diseases as acute & chronic hepatitis, schistosomiasis mansoni, visceral toxocariasis, visceral leishmaniasis, hepatic amoebiasis, biliary tract diseases and others. The parasitological diagnosis based on the demonstration of the eggs in stool, duodenal contents or bile is usually unsatisfactory due to false passage of eggs, ectopic fascioliasis, and failure of immature worm to maturation. So, ELISA-Fhes antigen (Fasciola hepatica excretory/secretory) and IHAT were evaluated in the immunodiagnosis of parasitologically proven cases of human fascioliasis compared with proven cases of human schistosomiasis mansoni and parasite-free individuals. ELISA-Fhes gave 100% sensitivity and 100% specificity. On the other hand, IHAT was less sensitive and less specific.

7796.      Hoda SA, Ali A. Images in pathology. Food for thought! Vegetable cells in histopathological sections. Int J Surg Pathol. 2003 Apr;11(2):120. No abstract.


7797.      Marciano-Cabral F, Cabral G. Acanthamoeba spp. as agents of disease in humans. Clin Microbiol Rev. 2003 Apr;16(2):273-307.


Acanthamoeba spp. are free-living amebae that inhabit a variety of air, soil, and water environments. However, these amebae can also act as opportunistic as well as nonopportunistic pathogens. They are the causative agents of granulomatous amebic encephalitis and amebic keratitis and have been associated with cutaneous lesions and sinusitis. Immuno compromised individuals, including AIDS patients, are particularly susceptible to infections with Acanthamoeba. The immune defense mechanisms that operate against Acanthamoeba have not been well characterized, but it has been proposed that both innate and acquired immunity play a role. The ameba's life cycle includes an active feeding trophozoite stage and a dormant cyst stage. Trophozoites feed on bacteria, yeast, and algae. However, both trophozoites and cysts can retain viable bacteria and may serve as reservoirs for bacteria with human pathogenic potential. Diagnosis of infection includes direct microscopy of wet mounts of cerebrospinal fluid or stained smears of cerebrospinal fluid sediment, light or electron microscopy of tissues, in vitro cultivation of Acanthamoeba, and histological assessment of frozen or paraffin-embedded sections of brain or cutaneous lesion biopsy material. Immunocytochemistry, chemifluorescent dye staining, PCR, and analysis of DNA sequence variation also have been employed for laboratory diagnosis. Treatment of Acanthamoeba infections has met with mixed results. However, chlorhexidine gluconate, alone or in combination with propamidene isethionate, is effective in some patients. Furthermore, effective treatment is complicated since patients may present with underlying disease and Acanthamoeba infection may not be recognized. Since an increase in the number of cases of Acanthamoeba infections has occurred worldwide, these protozoa have become increasingly important as agents of human disease.

7798.      Zardawi IM, Kattampallil JS, Rode JW. Amoebic appendicitis. Med J Aust. 2003 May 19;178(10):523-4. No abstract  


7799.      Ooi BS, Seow-Choen F. Endoscopic view of rectal amebiasis mimicking a carcinoma. Tech Coloproctol. 2003 Apr;7(1):51-3. 


We report the case of a 45-year-old man with rectal amebiasis, presenting with rectal bleeding and chronic diarrhea, confirmed on rectal biopsy. The endoscopic view was highly suggestive of a carcinoma and caused confusion about its etiology. The striking difference in the endoscopic view before and after medical therapy of the tumor-like lesion was remarkable. This case illustrates the importance of an accurate histologic diagnosis before definitive treatment and highlights the mimicry of rectal carcinoma by rectal amebiasis on endoscopy.



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