José M. Saugar

Effects of HIV aspartyl-proteinase inhibitors on Leishmania sp.

In this work, we have found an antiproliferative effect on Leishmania sp. promastigotes and axenic amastigotes by the human immunodeficiency virus (HIV) aspartyl-proteinase inhibitors, Ac-Leu-Val-Phenylalaninal, Saquinavir mesylate and Nelfinavir, the latter two being used as part of antiretroviral therapy. This effect appears to be the result of cell division blockage. In addition, these drugs induced in culture a decrease in the percentage of co-infected HIV/Leishmania monocytes and amastigotes of Leishmania per macrophage. The finding of a dose-dependent inhibition of Leishmania promastigotes aspartyl-proteinase activity by these drugs allows us to propose this activity as the drug parasite target. A direct action of these HIV aspartyl-proteinase inhibitors on the parasite, would be correlated with the effect that highly active antiretroviral therapy have had in the decrease of HIV/Leishmania coinfection, opening an interesting perspective for new drugs research development based on this novel parasite proteinase family.

Application of real-time PCR for the detection of Strongyloides spp. in clinical samples in a reference center in Spain

Strongyloidiasis is one of the major intestinal helminthic infections in humans with a worldwide distribution, affecting especially tropical and subtropical regions. This disease can occur without any symptoms or as a potentially fatal hyperinfection or disseminated infection. Definitive diagnosis of Strongyloides stercoralis infection relies mainly on demonstration of larvae in stool, but at present there is no gold standard for this diagnosis. Our main objective was to evaluate a real-time PCR targeting the 18S rRNA gene of Strongyloides spp. and to compare it with routine parasitological methods. DNA from Strongyloides venezuelensis was used to optimize PCR protocols obtaining an analytical sensitivity of 0.1 pg of parasite DNA per sample. Sensitivity and specificity of real-time PCR on fecal samples from 231 patients screened for suspected strongyloidiasis attending two hospitals in Madrid were 93.8% and 86.5%, respectively. No significant differences were found when comparing Ct-values of positive PCR between parasitological positive and negative samples. This study showed that real-time PCR is an effective tool for diagnosing strongyloidiasis and could be applied in association with parasitological methods in epidemiological studies in endemic areas. It would be also important to assess its performance in immunocompromised populations who are at risk of fatal disease.

Usefulness of Strongyloides stercoralis serology in the management of patients with eosinophilia.

Strongyloides stercoralis infection is being increasingly diagnosed out of endemic areas. The aim of this study is to evaluate the usefulness of S. stercoralis serology for the management of probable strongyloidiasis in patients presenting with eosinophilia. Overall, 147 patients were included, 89 (60.5%) patients had a positive S. stercoralis serology. Strongyloides stercoralis larvae were detected only in 15 (10.2%) patients. Twenty-eight patients had human immunodeficiency virus infection. Eighty patients received ivermectin 200 mcg/Kg/day for 2 days, and follow-up 6 months after treatment could be performed in 32 patients: 26 (81.3%) patients reached the response to treatment criteria (negative serology 6 months after treatment or when by enzyme-linked immunosorbent assay the optical density ratio of post-treatment to pre-treatment decreased to 0.6), and 11 (34.4%) patients fulfilled the cure criteria (negative serology 6 months after treatment). Strongyloides stercoralis serology is a useful diagnostic tool both in the diagnosis of probable strongyloidiasis and follow-up after treatment.

Effects of the disruption of the HSP70-II gene on the growth, morphology, and virulence of Leishmania infantum promastigotes

The 70-kDa heat shock protein (HSP70) is highly conserved among both prokaryotes and eukaryotes and plays essential roles in diverse cellular functions not only under stress but also under normal conditions. In the protozoan Leishmania infantum, the causative agent of visceral leishmaniasis, HSP70 is encoded by two HSP70 genes. Here, we describe the phenotypic alterations of HSP70-II-deficient (Deltahsp70-II) promastigotes. The absence of HSP70-II caused a major alteration in growth as the promastigotes reached stationary phase. In addition, aberrant forms were frequently observed in Deltahsp70-II mutant cultures. An accumulation of cells in the G2/M phase in cultures of the Deltahsp70-II mutant was determined by flow cytometry. Furthermore, Deltahsp70-II promastigotes showed a limited capacity of multiplication within macrophages, even though attachment to and uptake by macrophages did not differ significantly from the wild-type. Moreover, Deltahsp70-II was highly attenuated in BALB/c mouse experimental infections. In mutants re-expressing HSP70-II, the growth rate was restored, the normal morphology was recovered, and interactions with macrophages increased. However, promastigotes re-expressing HSP70-II did not recover their virulence. Overall, these data highlight the essential role played by HSP70-II expression in Leishmania virulence, pointing to this gene as a promising target for therapeutic interventions.

Prevalence and Genetic Diversity of Giardia duodenalis and Cryptosporidium spp. among School Children in a Rural Area of the Amhara Region, North-West Ethiopia.

Backgroud Giardia duodenalis and Cryptosporidium spp. are enteric protozoan causing gastrointestinal illness in humans and animals. Giardiasis and cryptosporidiosis are not formally considered as neglected tropical diseases, but belong to the group of poverty-related infectious diseases that impair the development and socio-economic potential of infected individuals in developing countries. Methods We report here the prevalence and genetic diversity of G. duodenalis and Cryptosporidium spp. in children attending rural primary schools in the Bahir Dar district of the Amhara Region, Ethiopia. Stool samples were collected from 393 children and analysed by molecular methods. G. duodenalis was detected by real-time PCR, and the assemblages and sub-assemblages were determined by multilocus sequence-based genotyping of the glutamate dehydrogenase and β-giardin genes of the parasite. Detection and identification of Cryptosporidium species was carried out by sequencing of a partial fragment of the small-subunit ribosomal RNA gene. Principal Findings The PCR-based prevalences of G. duodenalis and Cryptosporidium spp. were 55.0% (216/393) and 4.6% (18/393), respectively. A total of 78 G. duodenalis isolates were successfully characterized, revealing the presence of sub-assemblages AII (10.3%), BIII (28.2%), and BIV (32.0%). Discordant typing results AII/AIII and BIII/BIV were identified in 7.7% and 15.4% of the isolates, respectively. An additional five (6.4%) isolates were assigned to assemblage B. No mixed infections of assemblages A+B were found. Extensive genetic variation at the nucleotide level was observed within assemblage B (but no within assemblage A), resulting in the identification of a large number of sub-types. Cryptosporidium diversity was demonstrated by the occurrence of C. hominis, C. parvum, and C. viatorum in the population under study. Conclusions Our data suggest an epidemiological scenario with an elevated transmission intensity of a wide range of G. duodenalis genetic variants. Importantly, the elevated degree of genetic diversity observed within assemblage B is consistent with the occurrence of intra-assemblage recombination in G. duodenalis.

Detection and molecular characterization of Giardia duodenalis in children attending day care centers in Majadahonda, Madrid, Central Spain.

AbstractInfections by the protozoan enteroparasites Giardia duodenalis and Cryptosporidium spp are a major cause of morbidity in children attending day care facilities in developed countries. In this cross-sectional study, we aimed to estimate the occurrence and genotype frequencies of these pathogens in children attending day care centers in Majadahonda, Central Spain. To do so, single stool samples were obtained from 90 children and tested for the presence of G duodenalis and Cryptosporidium spp by conventional microscopy and immunochromatography. Positive results by these techniques were subsequently confirmed by immunofluorescence microscopy. G duodenalis-positive samples were subjected to molecular characterization studies by multilocus sequence-based genotyping of the glutamate dehydrogenase and &bgr;-giardin genes of the parasite. G duodenalis assemblages were confirmed by restriction fragment length polymorphism analyses and sequencing. A socioepidemiological questionnaire was used to identify variables potentially associated with giardiasis/cryptosporidiosis in the population of children under investigation. Overall, G duodenalis and Cryptosporidium spp were detected in 15.5% and 3.3% of stool samples, respectively. Giardiasis and cryptosporidiosis were found in 3/3 and 2/3 day care centers, respectively, affecting mainly infants aged 13 to 24 months. A total of 8 G duodenalis isolates were confirmed as subassemblage BIV, all of them belonging to asymptomatic children. Attempts to genotype Cryptosporidium isolates failed. None of the variables considered could be associated with higher risk of infection with giardiasis or cryptosporidiosis. These results clearly indicate that asymptomatic infections with G duodenalis and Cryptosporidium spp are frequent in <3-year-old children in Central Spain.

Evaluation of five commercial methods for the extraction and purification of DNA from human faecal samples for downstream molecular detection of the enteric protozoan parasites Cryptosporidium spp., Giardia duodenalis, and Entamoeba spp.

High quality, pure DNA is required for ensuring reliable and reproducible results in molecular diagnosis applications. A number of in-house and commercial methods are available for the extraction and purification of genomic DNA from faecal material, each one offering a specific combination of performance, cost-effectiveness, and easiness of use that should be conveniently evaluated in function of the pathogen of interest. In this comparative study the marketed kits QIAamp DNA stool mini (Qiagen), SpeedTools DNA extraction (Biotools), DNAExtract-VK (Vacunek), PowerFecal DNA isolation (MoBio), and Wizard magnetic DNA purification system (Promega Corporation) were assessed for their efficacy in obtaining DNA of the most relevant enteric protozoan parasites associated to gastrointestinal disease globally. A panel of 113 stool specimens of clinically confirmed patients with cryptosporidiosis (n=29), giardiasis (n=47) and amoebiasis by Entamoeba histolytica (n=3) or E. dispar (n=10) and apparently healthy subjects (n=24) were used for this purpose. Stool samples were aliquoted in five sub-samples and individually processed by each extraction method evaluated. Purified DNA samples were subsequently tested in PCR-based assays routinely used in our laboratory. The five compared methods yielded amplifiable amounts of DNA of the pathogens tested, although performance differences were observed among them depending on the parasite and the infection burden. Methods combining chemical, enzymatic and/or mechanical lysis procedures at temperatures of at least 56°C were proven more efficient for the release of DNA from Cryptosporidium oocysts.

Strong-LAMP: A LAMP Assay for Strongyloides spp. Detection in Stool and Urine Samples. Towards the Diagnosis of Human Strongyloidiasis Starting from a Rodent Model

Background Strongyloides stercoralis, the chief causative agent of human strongyloidiasis, is a nematode globally distributed but mainly endemic in tropical and subtropical regions. Chronic infection is often clinically asymptomatic but it can result in severe hyperinfection syndrome or disseminated strongyloidiasis in immunocompromised patients. There is a great diversity of techniques used in diagnosing the disease, but definitive diagnosis is accomplished by parasitological examination of stool samples for morphological identification of parasite. Until now, no molecular method has been tested in urine samples as an alternative to stool samples for diagnosing strongyloidiasis. This study aimed to evaluate the use of a new molecular LAMP assay in a well-established Wistar rat experimental infection model using both stool and, for the first time, urine samples. The LAMP assay was also clinically evaluated in patients´ stool samples. Methodology/Principal Findings Stool and urine samples were obtained daily during a 28-day period from rats infected subcutaneously with different infective third-stage larvae doses of S. venezuelensis. The dynamics of parasite infection was determined by daily counting the number of eggs per gram of feces from day 1 to 28 post-infection. A set of primers for LAMP assay based on a DNA partial sequence in the 18S rRNA gene from S. venezuelensis was designed. The set up LAMP assay (namely, Strong-LAMP) allowed the sensitive detection of S. venezuelensis DNA in both stool and urine samples obtained from each infection group of rats and was also effective in S. stercoralis DNA amplification in patients´ stool samples with previously confirmed strongyloidiasis by parasitological and real-time PCR tests. Conclusions/Significance Our Strong-LAMP assay is an useful molecular tool in research of a strongyloidiasis experimental infection model in both stool and urine samples. After further validation, the Strong-LAMP could also be potentially applied for effective diagnosis of strongyloidiasis in a clinical setting.

High prevalence of Strongyloides stercoralis in school-aged children in a rural highland of north-western Ethiopia: the role of intensive diagnostic work-up

BackgroundSoil-transmitted helminthiases (hookworms, Ascaris lumbricoides and Trichuris trichiura) are extremely prevalent in school-aged children living in poor sanitary conditions. Recent epidemiological data suggest that Strongyloides stercoralis is highly unreported. However, accurate data are essential for conducting interventions aimed at introducing control and elimination programmes.MethodsWe conducted a cross-sectional survey of 396 randomly selected school-aged children in Amhara region in rural area in north-western Ethiopia, to assess the prevalence of S. stercoralis and other intestinal helminths. We examined stools using three techniques: conventional stool concentration; and two S. stercoralis-specific methods, i.e. the Baermann technique and polymerase chain reaction. The diagnostic accuracy of these three methods was then compared.ResultsThere was an overall prevalence of helminths of 77.5%, with distribution differing according to school setting. Soil-transmitted helminths were recorded in 69.2%. Prevalence of S. stercoralis and hookworm infection was 20.7 and 54.5%, respectively, and co-infection was detected in 16.3% of cases. Schistosoma mansoni had a prevalence of 15.7%. Prevalence of S. stercoralis was shown 3.5% by the conventional method, 12.1% by the Baermann method, and 13.4% by PCR, which thus proved to be the most sensitive.ConclusionsOur results suggest that S. stercoralis could be overlooked and neglected in Ethiopia, if studies of soil-transmitted helminths rely on conventional diagnostic techniques alone. A combination of molecular and stool microscopy techniques yields a significantly higher prevalence. In view of the fact that current control policies for triggering drug administration are based on parasite prevalence levels, a comprehensive diagnostic approach should instead be applied to ensure comprehensive control of helminth infections.

Real-Time Polymerase Chain Reaction in Stool Detects Transmission of Strongyloides stercoralis from an Infected Donor to Solid Organ Transplant Recipients

Solid organ transplant recipients can acquire Strongyloides stercoralis from an infected donor. The diagnosis of S. stercoralis in immunocompromised individuals may be challenging due to a lower sensitivity of available parasitological and serological methods, compared with immunocompetent individuals. Recently, a real-time polymerase chain reaction (RT-PCR) in stool has been developed for S. stercoralis diagnosis. We report two cases of S. stercoralis infection transmitted by a donor to two solid organ transplant recipients, who were diagnosed with RT-PCR in stool. This test could play an important role inS. stercoralis diagnosis in immunosuppressed patients, facilitating rapid treatment initiation and reducing the risk of severe strongyloidiasis. Adherence to current recommendations of screening among donors and recipients from endemic areas is also urgently needed.