Abstract. Follow-up stool examinations were carried out on two groups of the subjects who were screened negative (group 1) or positive (group 2) for Strongyloides stercoralis by the agar plate culture. This technique could detect S. stercoralis larvae in 87.5-96.4% of the subjects in group 2 and 0-5.9% of the subjects in group 1 on various days of the eight-week and four-week follow-up periods, respectively. The detection rate on each day of examination was not statistically different from that on the first day in both groups. Quantitative measurement of S. stercoralis larvae excreted in the feces of the subjects in group 2 by the standard direct smear method of Beaver and others revealed slight to marked fluctuations of the larval output in individual subjects. From the results of both stool examination methods, it could be implied that 52% of S. stercoralis-infected individuals had low-level infection.Strongyloides stercoralis is an intestinal nematode of humans with a rather unique biology in that it has a free-living phase outside the host. Human infections due to S. stercoralis are distributed primarily throughout tropical and subtropical regions of the world. 1 Reports of S. stercoralis infections in non-endemic countries were from the ex-prisoners of the World War II 2,3 or the Southeast Asian immigrants. 4 The clinical spectrum of strongyloidiasis varies from asymptomatic infection, to mild symptomatic abdominal and skin diseases, to fatal disseminated infection in immunosuppressed patients. 5 The reported prevalences of S. stercoralis infection are difficult to ascertain and may have been underestimated because most infections are with low larval densities in the feces.1 They are also difficult to compare because of the difference in the coprologic methods used to detect the larvae. Earlier methods for the diagnosis of S. stercoralis infection such as the simple direct smear and formalin-ether concentration are often unreliable because of their relatively low sensitivity. In recent years, the agar plate culture technique has been introduced and found to give consistently higher sensitivity (78-100%) than simple direct smear (0-52% sensitivity) and formalin-ether concentration method (13-55% sensitivity). 6-10 Several immunologic methods have also been used in the diagnosis of strongyloidiasis. Currently, the most widely used method has been the ELISA using crude antigen extracts of filariform larvae as antigens. Most reports on the ELISA for strongyloidiasis have shown consistently high sensitivity, but the specificity has varied widely due to different criteria used for the selection of uninfected individuals. [11][12][13][14][15][16] Recently, Western blot analysis has been applied to the immunodiagnosis of strongyloidiasis. Preliminary data have indicated that immunodominant proteins (apparent molecular weights of 41, 31, and 28 kD) of S. stercoralis filariform larvae are recognized by strongyloidiasis sera with high sensitivity and specificity. [17][18][19] It is generally known that the detection o...

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Several investigators have successfully applied the polymerase chain reaction to the amplification of DNA from Trichinella spiralis muscle-stage larvae. We show herein that specific DNA can be amplified from T. spiralis migratory larvae in the blood of experimentally infected mice. The polymerase chain reaction detected the presence of migratory larvae in mouse blood from day 5 to day 14 of infection. The technique may be applied to human trichinosis, but its diagnostic value will depend on the severity and stage of the infection.

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Exoerythrocytic stages of Plasmodium berghei cultured in HepG2-A16 hepatoma cells and those of P. falciparum in human hepatocytes transplanted under the kidney capsule of CB-17/ICr scid/scid mice were used to evaluate expression of heat-shock-related stress proteins. Although undetectable in the sporozoites, the expression of proteins similar in sequence of a heat-shock protein of 70 kDa and a glucose-regulated protein of 78 kDa was markedly induced in the hepatic stages of malaria parasites. Expression of these proteins in the exoerythrocytic stages of the malaria parasite warrants a systematic evaluation of their potential role in eliciting cellular immune responses directed against infected hepatocytes.

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SUMMARYThe survey was carried out to investigate the presence of potentially pathogenic free-living amoebae (FLA) during flood in Chiang Mai, Thailand in 2011. From different crisis flood areas, seven water samples were collected and tested for the presence of amoebae using culture and molecular methods. By monoxenic culture, FLA were detected from all samples at 37 °C incubation. The FLA growing at 37 °C were morphologically identified as Acanthamoeba spp., Naegleria spp. and some unidentified amoebae. Only three samples (42.8%), defined as thermotolerant FLA, continued to grow at 42 °C. By molecular methods, two non-thermotolerant FlA were shown to have 99% identity to Acanthamoeba sp. and 98% identity to Hartmannella vermiformis while the two thermotolerant FLA were identified as Echinamoeba exundans (100% identity) and Hartmannella sp. (99% identity). This first report of the occurrence of FLA in water during the flood disaster will provide information to the public to be aware of potentially pathogenic FLA.

The advanced third-stage larvae (aL3) of Gnathostoma spinigerum contain a 24 kDa glycoprotein with diagnostic potential. Immunoscreening with the monoclonal antibody to the 24-kDa protein (mAb GN6/ 24) has identified a cDNA clone with an insert of 932 base pairs (bp). The insert contains a full-length gene of 732 bp encoding a protein that is 33-39% similar to matrix metalloproteinases (MMPs) of Caenorhabditis elegans and several lower and higher vertebrates. The MMP-like protein of G. spinigerum possesses the catalytic domain, but lacks the propeptide and hemopexin-like domains found in other MMPs. A signal peptide of 23 amino acids at its amino terminus indicates that it is a secretory protein, which is confirmed by Western blot analysis showing the presence of the 24 kDa protein in the excretory-secretory products of aL3.