Progress in the research on diagnosis and vaccines in amebiasis

Abstract

Entameba histolytica causes amebiasis, which includes both intestinal and extraintestinal amebiasis. E. histolytica causes 34 million to 50 million symptomatic cases of amebiasis worldwide every year, causing 40 thousand to 100 thousand deaths annually. E. histolytica, the pathogenic species of amebae is indistinguishable in its cyst and trophozoite stages from those of E. moshkovskii, a free-living ameba, and E. dispar, a non-invasive ameba, by microscopy, except in cases of invasive disease, where E. histolytica trophozoite may contain ingested red blood cells, but such a finding is rarely seen. This leads to a confusing scenario for the definite identification and differentiation of E. histolytica from E. moshkovskii and E. dispar by conventional microscopy, in the diagnosis of intestinal amebiasis. The advent of molecular methods such as multiplex PCR and real time PCR have facilitated a better and accurate diagnosis of E. histolytica, E. moshkovskii, and E. dispar in stool, urine, saliva, and other specimens. Multiplex PCR for the diagnosis of amebic liver abscess, using urine and saliva as clinical specimens, has been used, and the results have been encouraging. Real-time PCR is a new and a very attractive methodology for laboratory diagnosis of amebiasis, because of its characteristics that eliminate post-PCR analysis, leading to a shorter turnaround time. Microarray-based approaches represent an attractive diagnostic tool for the detection and identification of amebae in clinical and epidemiological investigations. Development of vaccines against amebiasis is still in its infancy. However, in recent years, progress has been made in the identification of possible vaccine candidates, the route of application, and the understanding of the immune response, which is required for protection against amebiasis. Thus, it is just a matter of time, and hopefully, amebiasis vaccine for human trials will be available in the next few years.

Differentiation of Entamoeba histolytica from Entamoeba dispar by nested multiplex polymerase chain reaction

“…Even the commercial ELISA-based method for specific identification and detection of E. histolytica in fecal specimens [23] has shown poor sensitivity and specificity in many studies because of cross-contaminations with other parasites [24,25] . In the last decade, molecular-based diagnostic tests have gained importance in the diagnosis of many infectious diseases including amoebiasis to overcome the problems of conventional methods with the advantages of increased sensitivity, specificity, and simplicity [26,27] . Several PCR assays designed to differentiate E. histolytica from E. dispar have been described [15,28,29] .…”

Distribution of individual members of the mosquito Anopheles maculipennis complex in Germany identified by newly developed real‐time PCR assays

“…However, qPCR is considerable faster and minimizes the risk of laboratory contamination (Fotedar et al. , ; Parija, ), which is especially a problem when large sample collections have to be analysed as is the case in large‐scaled mosquito monitoring programmes. The newly developed assays reported here allow differentiation of all four An.…”

“…gel electrophoresis, were already available (Danabalan et al, 2013;Kronefeld et al, 2014). However, qPCR is considerable faster and minimizes the risk of laboratory contamination (Fotedar et al, 2007;Parija, 2011), which is especially a problem when large sample collections have to be analysed as is the case in large-scaled mosquito Fig. 4.…”

Laboratory methods of identification of Entamoeba histolytica and its differentiation from look-alike Entamoeba spp.

“…Studies in animal models like gerbils, and severe combined immunodeficiency mice reveal SREHP and Gal/Gal NAc lectin as potential and promising vaccine candidates for prevention of invasive amebic diseases. [ 23 ] These antigen targets are yet to be studied for their diagnostic role in amebiasis.…”