Amebiasis is a protozoan disease caused by Entamoeba histolytica and a potential health threat in areas where sanitation and hygiene are inappropriate. Highly sensitive PCR methods for detection of E. histolytica in clinical and environmental samples are extremely useful to control amebiasis and to promote public health. The present study compared several primer sets for small subunit (SSU) rDNA and histone genes of E. histolytica cysts. A 246 bp of the SSU rDNA gene of pure cysts contained in phosphate-buffered saline (PBS) and in stool samples was successfully amplified by nested PCR, using the 1,147-246 bp primer set, of the primary PCR products which were pre-amplified using the 1,147 bp primer as the template. The detection limit of the nested PCR using the 1,147-246 primer set was 10 cysts in both groups (PBS and stool samples). The PCR to detect histone gene showed negative results. We propose that the nested PCR technique to detect SSU rDNA can be used as a highly sensitive genetic method to detect E. histolytica cysts in stool samples.
DNA Primers/genetics ; DNA, Protozoan/genetics ; DNA, Ribosomal/genetics ; Entamoeba histolytica/genetics/*isolation & purification ; Entamoebiasis/*diagnosis ; Histones/genetics ; Humans ; Molecular Diagnostic Techniques/*methods ; Parasitology/*methods ; Polymerase Chain Reaction/*methods ; Protozoan Proteins/genetics ; Sensitivity and Specificity

This study investigated the effect of breast-feeding in protection against protozoan infection in infants with persistent diarrhea. Infants were classified into 2 groups; 161 breast-fed infants and the same number of non-breast-fed infants. Microscopic examinations of stool were done for detection of parasites and measuring the intensity of infection. Moreover, serum levels of IgE and TNF-alpha were measured by ELISA. Cryptosporidium spp., Entamoeba histolytica/Entamoeba dispar, Giardia lamblia, and Blastocystis sp. were demonstrated in infants with persistent diarrhea. The percentage of protozoan infections was significantly lower in breast-fed infants than that in the non-breast-fed infants. The levels of IgE and TNF-alpha were significantly lower in the breast-fed group than in the non-breast-fed group. There were significant positive associations between the serum levels of IgE and TNF-alpha and the intensity of parasite infection in the breast-fed group. It is suggested that breast-feeding has an attenuating effect on the rate and intensity of parasite infection.
Antigens, Protozoan/analysis/*immunology ; Diarrhea, Infantile/*diagnosis/parasitology ; Entamoeba ; Entamoeba histolytica/*isolation & purification ; Entamoebiasis/*diagnosis/parasitology ; Enzyme-Linked Immunosorbent Assay ; Feces/parasitology ; Female ; Giardia lamblia ; Giardiasis/*diagnosis/parasitology ; Humans ; Infant ; Intestines/parasitology ; Protozoan Infections/*diagnosis/parasitology ; Tumor Necrosis Factor-alpha/metabolism