Amebiasis

The causative agent of amebiasis is Entamoeba hystolitica, exists in three forms: tissue( forma magna), luminal( forma minuta) and cystic( forma cystica).The disease is met everywhere. In many regions, healthy carriers account for 14-20% of the total population. The diagnosis of intestinal amebiasis is established based on the detection of the pathogen in feces or tissues( examine the biopsy) using special dyes. In the feces of Ag Entamoeba hystolitica( adhesin) can be detected by ELISA.The diagnostic sensitivity of ELISA for the detection of Entamoeba hystolitica adhesin in feces is 96.9-100%, specificity is 94.7-100%.In some cases, the diagnosis of extraintestinal amebiasis is difficult, since the test systems for detection of Entamoeba hystolitica can give false-positive results. Often they are caused by the presence of other intestinal pathogens( Ascaris lumbricoides, Blastocystis hominis, Clostridium difficile, Cryptosporidium, Entamoeba coli, Salmonella typhimurium, Shigella zonnei, etc.). To resolve such cases, the level of specific antigen in the blood serum is examined.

ANTIBODIES TO ENTAMOEBA HYSTOLITICA IN BLOOD SERUM

AT to Entamoeba hystolitica in serum is normally absent.

The most sensitive of serological methods is RPHA( sensitivity and specificity at a titer of more than 1: 128 - about 95%), RIF and ELISA( reveals Ig IgM and IgG, more sensitive and specific).AT to Entamoeba hystolitica in serum using RPGA is detected in almost all patients with amebic liver abscess( AST and ALT are increased 2-6 times, alkaline phosphatase 2-3 times) and in most individuals with acute amebic dysentery. Diagnosis is considered to increase the titre of AT at the study of paired sera after 10-14 days not less than 4 times or at a single study of the titer above 1: 128.AT usually does not reveal in asymptomatic cysts( only in 9% of cases), which indicates that the synthesis of AT requires the introduction of an agent in the tissue, and in patients with immunosuppression. Elevated titre of AT can persist for several months or years after complete recovery.

Specific AT in RIF with amoebic arteries is revealed in 98-100% of cases of clinically expressed amebic liver abscess, RIF gives a positive result in 75-80% of patients with invasive amoebiasis of the intestine, especially with fulminant colitis, amoeboma and peritonitis. When interpreting the results of the RIF, it should be taken into account that the titer AT 1: 320 and higher indicates, as a rule, a clinically pronounced, often extra-intestinal form of amoebiasis. In the titer of 1: 80-1: 160 AT are detected in patients with amebaass at the time of examination or recovered in the recent past, as well as in the case of sluggish, erased forms of intestinal amebiasis. The titer AT 1:40 may be detected in persons with symptoms of intestinal amebiasis, with a corresponding epidemic history and unresolved status of the patient. In this case, the study of paired sera is effective. Under the

, the titre of AT after treatment is evidence in favor of the amoebic etiology of the process. False positive result in the titer of 1:40 can be registered in patients with systemic and oncological diseases. Low titer AT( 1: 20-1: 40) is often found among asymptomatic carriers of the pathogen amoebiasis. A consistent steady decline in the patients who have recovered the titer of AT is below 1:20 - the indicator of the effectiveness of treatment, the rise of titres and the appearance of clinical symptoms should be regarded as a relapse of the disease.

ATM IgM to Entamoeba hystolitica in serum using ELISA is detected in almost all patients with amebic liver abscess( more than 90%) and in the majority of individuals with acute amebic dysentery( in 84% of cases).They disappear within 6 weeks after effective treatment. IgG Ig is detected approximately at the same frequency as IgM, they indicate the current( with increasing AT titer) or previously transmitted( if the AT content does not change) infection. In the presence of symptoms of diarrhea, serological tests are usually positive in more than 90% of patients, in their absence - less than 50%.

The determination of AT to Entamoeba hystolitica is used for the diagnosis of amoebiasis infection( amebic dysentery), monitoring the dynamics of the disease and the consequences of infection.