2 SummaryNaegleria fowleri is a protist pathogen that can cause lethal brain infection. Despite decades of research, the mortality rate related with primary amoebic meningoencephalitis owing to N. fowleri remains more than 90%. The amoebae pass through the nose to enter the central nervous system killing the host within days, making it one of the deadliest opportunistic parasites. Accordingly, we present an up to date review of the biology and pathogenesis of N.fowleri and discuss needs for future research against this fatal infection.

Balamuthia disease in the United States is characterized by a highly fatal encephalitis that affects patients of all ages. Hispanics were disproportionately affected. The southwest region of the U.S. reported the most cases. Clinician awareness of Balamuthia as a cause of encephalitis might lead to earlier diagnosis and initiation of treatment, resulting in better outcomes.

We developed a real-time-PCR assay utilizing a molecular-beacon probe for the detection of Entamoeba histolytica and compared its sensitivity to stool antigen detection and traditional PCR. A total of 205 stool and liver abscess pus specimens from patients and controls were used for this purpose, 101 (49%) of which were positive by the TechLab E. histolytica-specific antigen detection test, while the other 104 (51%) stool and liver abscess pus specimens were negative by the antigen detection test. DNA was extracted from the stool and liver abscess pus specimens by the QIAGEN method and the small-subunit rRNA gene of E. histolytica and then amplified by traditional and real-time PCR. Out of these 205 stool and liver abscess pus specimens, 124 were positive by the real-time-PCR assay and 90 were positive by the traditional-PCR test. Compared to the real-time-PCR assay, the antigen detection test was 79% sensitive and 96% specific. When the traditional-PCR test results were compared to the real-time-PCR assay, the sensitivity of traditional PCR was 72% and the specificity was 99%. In conclusion, all three methods for the detection of E. histolytica were highly specific, with real-time PCR being the most sensitive.The World Health Organization has recommended that Entamoeba histolytica "should be specifically identified and if present should be treated" (27). Classic microscopic examination of the parasite E. histolytica in stool cannot differentiate it from the nonpathogenic but identically appearing parasites Entamoeba dispar and Entamoeba moshkovskii. While E. histolytica trophozoites are more likely than E. dispar and E. moshkovskii to contain ingested erythrocytes, most often E. histolytica trophozoites in patient stools lack ingested red cells (7, 10, 11). Not only is microscopy unable to differentiate E. histolytica from E. dispar or E. moshkovskii, it is at best only 10 to 60% sensitive and confounded with false-positive results due to misidentification of macrophages and nonpathogenic species of Entamoeba (12,13,18,23). Culture along with isoenzyme (zymodeme) analysis enables differentiation of E. histolytica from E. dispar or E. moshkovskii and was considered the gold standard for diagnosing amebic infection in the last 2 decades. However, amebic cultures and isoenzyme analysis require a week to complete and are negative with many microscopy-positive stool samples, in some cases due to delay in sample processing or due to the institution of antiamebic therapy prior to stool collection (13,14,23).New approaches to the detection of E. histolytica are based on the detection of an E. histolytica-specific antigen and DNA. Several groups have reported the detection of amebic antigen in stool samples, serum, liver abscess pus samples, and saliva using enzyme-linked immunosorbent assay methods (1,2,4,5,9,12,13,14,15,16,19,20,21,22,23). The TechLab (Blacksburg, Virginia) Entamoeba histolytica II kit is the only Food and Drug Administration-approved test that is specific and sensitive for the detection of E. histoly...