Invasive amebiasis: Challenges in diagnosis in a non-endemic country (Kuwait)

Invasive zymodemes of the enteric protozoan Entamoeba histolytica infect th e large intestine and cause extra-intestinal lesions such as amebic liver a bscess (ALA). The clinical manifestations of ALA are protean, particularly in patients presenting in a non-endemic, desert country such as Kuwait, and diagnosis becomes problematic. In this study, we present cases of ALA to i llustrate the clinical and diagnostic challenges. For serodiagnosis of ALA, we compared the sensitivity and specificity of the indirect hemagglutinati on assay (IHA) with the ImmunoTab assay and an enzyme-linked immunosorbent assay (ELISA) for this geographic region. We tested sera of 110 patients wi th ALA, 1,224 patients suspected of having invasive amebic infection, and 5 0 Europeans with no travel history to an amebic-endemic area. The IHA was s imple, rapid, easy to perform, and reliable (sensitivity = 99%, specificity > 95%). The performance of the IHA in detecting ALA in suspected cases was significantly better than that of the ELISA and the ImmunoTab test. Compar ed with the IHA, both the ELISA and ImmunoTab assay detected relatively hig her numbers of false-positive cases (4.7% and 3.6%, respectively). With the availability of ultrasound and computed tomography scans, the serology cor relates excellently with the clinical presentation. In chronic cases where fibrosis may be present around the abscess, the IIIA has limitations, as in the follow-up of treated patients. Pitfalls in diagnosis are highlighted b y discussing the differential diagnosis of ALA from bacterial hepatic absce sses and infected hydatid cysts. Most importantly, the IHA in such cases wa s invariably at a titer that is considered not significant.