Amoebiasis laboratory tests

Jump to: navigation, search

Amoebiasis Microchapters

Home

Patient Information

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Amoebiasis from other Diseases

Epidemiology and Demographics

Risk Factors

Natural History, Complications and Prognosis

Diagnosis

History and Symptoms

Physical Examination

Laboratory Findings

Imaging

Treatment

Medical Therapy

Surgery

Prevention

Cost-Effectiveness of Therapy

Future or Investigational Therapies

Case Studies

Case #1

Amoebiasis laboratory tests On the Web

Most recent articles

cited articles

Review articles

CME Programs

Powerpoint slides

Images

American Roentgen Ray Society Images of Amoebiasis laboratory tests

All Images
X-rays
Echo & Ultrasound
CT Images
MRI

Ongoing Trials at Clinical Trials.gov

US National Guidelines Clearinghouse

NICE Guidance

FDA on Amoebiasis laboratory tests

CDC onAmoebiasis laboratory tests

Amoebiasis laboratory tests in the news

Blogs on Amoebiasis laboratory tests

to Hospitals Treating Amoebiasis

Risk calculators and risk factors for Amoebiasis laboratory tests

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Jesus Rosario Hernandez, M.D. [2]

Overview

Laboratory Findings

Asymptomatic human infections are usually diagnosed by finding cysts shed with the stool. Various flotation or sedimentation procedures have been developed to recover the cysts from fecal matter and stains help to visualize the isolated cysts for microscopic examination. Since cysts are not shed constantly, a minimum of 3 stools should be examined. In symptomatic infections, the motile form (the trophozoite) can often be seen in fresh feces. Serological tests exist and most individuals (whether with symptoms or not) will test positive for the presence of antibodies. The levels of antibody are much higher in individuals with liver abscesses. Serology only becomes positive about two weeks after infection. More recent developments include a kit that detects the presence of ameba proteins in the feces and another that detects ameba DNA in feces. These tests are not in widespread use due to their expense.

Microscopy is still by far the most widespread method of diagnosis around the world. However it is not as sensitive or accurate in diagnosis as the other tests available. It is important to distinguish the E. histolytica cyst from the cysts of nonpathogenic intestinal protozoa such as Entamoeba coli by its appearance. E. histolytica cysts have a maximum of four nuclei, while the commensal Entamoeba coli has up to 8 nuclei. Additionally, in E. histolytica, the endosome is centrally located in the nucleus, while it is off-center in Entamoeba coli. Finally, chromatoidal bodies in E. histolytica are rounded, while they are jagged in Entamoeba coli. However, other species, Entamoeba dispar and E. moshkovskii, are also a commensal and cannot be distinguished from E. histolytica under the microscope. As E. dispar is much more common than E. histolytica in most parts of the world this means that there is a lot of incorrect diagnosis of E. histolytica infection taking place. The WHO recommends that infections diagnosed by microscopy alone should not be treated if they are asymptomatic and there is no other reason to suspect that the infection is actually E. histolytica.

Food Analysis

E. histolytica cysts may be recovered from contaminated food by methods similar to those used for recovering Giardia lamblia cysts from feces. Filtration is probably the most practical method for recovery from drinking water and liquid foods.E. histolytica cysts must be distinguished from cysts of other parasitic (but nonpathogenic) protozoa and from cysts of free-living protozoa as discussed above. Recovery procedures are not very accurate; cysts are easily lost or damaged beyond recognition, which leads to many falsely negative results in recovery tests. (See the FDA Bacteriological Analytical Manual.)

Gallery

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 "Public Health Image Library (PHIL)".




Linked-in.jpg