The genus Entamoeba contains many species, six of which (Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba polecki, Entamoeba coli, and Entamoeba hartmanni) reside in the human intestinal lumen. Entamoeba histolytica is the causative agent of amebiasis and is considered a leading parasitic cause of death worldwide in humans. Although recent studies highlight the recovery of E. dispar and E. moshkovskii from patients with gastrointestinal symptoms, there is still no convincing evidence of a causal link between the presence of these two species and the symptoms of the host. New approaches to the identification of E. histolytica are based on detection of E. histolytica-specific antigen and DNA in stool and other clinical samples. Several molecular diagnostic tests, including conventional and real-time PCR, have been developed for the detection and differentiation of E. histolytica, E. dispar, and E. moshkovskii in clinical samples. The purpose of this review is to discuss different methods that exist for the identification of E. histolytica, E. dispar, and E. moshkovskii which are available to the clinical diagnostic laboratory. To address the need for a specific diagnostic test for amebiasis, a substantial amount of work has been carried out over the last decade in different parts of the world. The molecular diagnostic tests are increasingly being used for both clinical and research purposes. In order to minimize undue treatment of individuals infected with other species of Entamoeba such as E. dispar and E. moshkovskii, efforts have been made for specific diagnosis of E. histolytica infection and not to treat based simply on the microscopic examination of Entamoeba species in the stool. The incorporation of many new technologies into the diagnostic laboratory will lead to a better understanding of the public health problem and measures to control the disease.

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Laboratory Diagnostic Techniques for Entamoeba Species

s of the annual meeting of the American Society of Tropical Medicine and Hygiene, San Juan, Puerto Rico, 18-22 October1998. North- brook, IL: 1998. 56. Gilman R, Islam M, Paschi S, Goleburn J, Ahmad F Comparison of con- ventional and immunofluorescent techniques for the detection of Entamoeba histolytica in rectal biopsies. Gastroenterology 1980;78:435-9. 57. Rails PW. Focal inflammatory disease of the liver. Radiol Clin North Am 1998; 36:377-89. 58. Kimura K, Stoopen M, Reeder MM, Moncada R. Amebiasis: modern diagnostic imaging with pathological and clinical correlation. Semin Roent- genol 1997; 32:250-75. 59. Huston CD, Petri WA Jr. Amebiasis. In: Rakel RE, ed. Conn's current therapy. New York: W.B. Saunders (in press). 60. Rajak CL, Gupta S, Jain S, Chawla Y, Gulati M, Suri S. Percutaneous treatment of liver abscesses: needle aspiration versus catheter drainage. AJR Am J Roentgenol 1998; 170:1035-9. 61. Tandon A, Jain AK, Dixit VK, Agarwal AK, Gupta JP. Needle aspiration in large amoebic liver abscess. Trop Gastroenterol 1997; 18:19-21. 62. Petri WA Jr, Ravdin JI. Protection of gerbils from amebic liver abscess by immunization with the galactose-specific adherence lectin of Entamoeba histolytica. Infect Immun 1991;59:97-101. 63. Zhang T, Stanley SL Jr. Protection of gerbils from amebic liver abscess by This content downloaded from 157.55.39.23 on Sun, 26 Mar 2017 18:12:48 UTC All use subject to http://about.jstor.org/terms CID 1999;29 (November) Amebiasis1125 immunization with a recombinant protein derived from the 170-kilodalton surface adhesin of Entamoeba histolytica. Infect Immun 1994; 62:2605-8. 64. Zhang T, Cieslak PR, Foster L, Kuntz-Jenkins C, Stanley SL Jr. Antibodies to the serine rich Entamoeba histolytica protein (SREHP) prevent amoebic liver abscess in severe combined immunodeficient (SCID) mice. Parasite Immunol 1994; 16:225-30. 65. Soong CJG, Kain KC, Abd-Alla M, Jackson TFHG, Ravdin JI. A recombinant cysteine-rich section of the Entamoeba histolytica galactose inhib- itable lectin is efficacious as a subunit vaccine in the Gerbil model of amebic liver abscess. J Infect Dis 1995; 171:645-51. 66. Mann BJ, Burkholder BV, Lockhart LA. Protection in a gerbil model of amebiasis by oral immunization with Salmonella expressing the galactose N-acetyl D-galactosamine inhibitable lectin of Entamoeba histolytica. Vac- cine 1997; 15:659-63. 67. Huston CD, Petri WA Jr. The host-pathogen interaction in amebiasis: Is a vaccine feasible? Eur J Clin Microbiol Infect Dis 1998; 17:601-14. 68. Salata RA, Pearson RP, Murphy CF, Ravdin JI. Interaction of human leu- kocytes with Entamoeba histolytica: killing of virulent amebae by the activated macrophage. J Clin Invest 1985; 76:491-9. 69. Denis M, Chadee K. Human neutrophils activated by interferon-gamma and tumor necrosis factor-alpha kill Entamoeba histolytica trophozoites in vitro. J Leukoc Biol 1989;46:270-4. This content downloaded from 157.55.39.23 on Sun, 26 Mar 2017 18:12:48 UTC All use subject to http://about.jstor.org/terms

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Diagnosis and management of amebiasis.

During the approximately 20 years that percutaneous abscess drainage (PAD) has been an extant procedure and as the millennium begins, PAD has become, by consensus, the treatment of choice for abscesses Indications for PAD continue to expand, and currently almost all abscesses are considered amenable On occasion, PAD is an adjunctive procedure that provides a beneficial temporizing effect for the surgeon who eventually must operate for a coexisting problem such as a bowel leak Simple unilocular abscesses are cured almost uniformly by PAD; more complicated abscesses, such as those with enteric fistulas (eg, diverticular abscess) or pancreatic abscesses, have cure rates ranging from 65% to 90% Various catheters and insertion techniques have proven effective Ultrasonography, computed tomography, and fluoroscopy are the staple modalities that guide PAD PAD is the prototype interventional radiology procedure, providing detection of the abscess by imaging, needling for diagnosis, and catheterization for therapy

Percutaneous Abscess Drainage: Update

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Molecular epidemiology of amebiasis.

Numerous investigations have revealed a bias toward males in the susceptibility to and severity of a variety of infectious diseases, especially parasitic diseases. Although different external factors may influence the exposure to infection sources among males and females, one recurrent phenomenon indicative of a hormonal influence is the simultaneous increase in disease occurrence and hormonal activity during the aging process. Substantial evidence to support the influence of hormones on disease requires rigorously controlled human population studies, as well as the same sex dimorphism being observed under controlled laboratory conditions. To date, only very few studies conducted have fulfilled these criteria. Herein, we introduce tropical infectious diseases, including amebiasis, malaria, leishmaniasis, toxoplasmosis, schistosomiasis, and paracoccidioidomycosis, in which hormones are suspected to play a role in disease processes. We summarize the most recent findings from epidemiologic studies in humans and from hormone replacement studies in animal models, as well as data regarding the influence of hormones on immune responses underlying the pathology of the diseases.

Sex Bias in the Outcome of Human Tropical Infectious Diseases: Influence of Steroid Hormones

The increase in immigration to the United States is associated with diseases, such as amebiasis, that are endemic to developing countries. We retrospectively reviewed 49 public-hospital patients with hepatic amebiasis occurring between 1985 and 1995. Most patients were immigrants (47) from Latin America (43), male (43), and young (mean age, 39.8 years). Symptoms noted by more than half were abdominal pain and fever. Ultrasonography showed single lesions in 70% and right-sided involvement in 85%. Serologies against Entamoeba histolytica were noted in 86%. After treatment, the median interval from admission to defervescence was 2 days, to normalization of white cell count 3 days, and to resolution of abdominal pain 4 days. Morbidity (one case of pericarditis) and mortality (one death in a cirrhotic man) were low. Hepatic amebiasis continues to be diagnosed in the United States, primarily among Hispanic and Asian immigrants. When appropriately considered, current diagnostic and therapeutic modalities result in rapid improvement and excellent outcome.

Bollam P

Papers

Hepatic amebiasis among patients in a public teaching hospital