Mercury levels in blood, urine and hair in a nation-wide sample of Spanish adults

Mercury (Hg) is among the top 10 environmental chemicals of major public health concern (WHO). The Minamata Convention on Mercury (United Nations Environment Program, 2017), commits signing countries to control anthropogenic mercury emissions and reduce human exposure. Human biomonitoring (HBM) programs, are the most straight-forward approaches to get information on the actual exposure levels in the population and assess over time. We report here the results of a HBM study in a nationwide cross-section of Spanish adults (18-65y) as baseline values obtained before the Minamata Convention entered into force. Subsequent follow-ups will show if the Convention has been successful. The study includes 1880 blood samples, 1704 urine samples and 577 hair samples from all Spanish regions collected and analysed under a strictly quality controlled and quality assured protocol. The EU-DEMOCOPHES project demonstrated that fish and seafood are the major sources of mercury exposure and that the Spanish as well as the Portuguese populations have higher levels than other European countries. The data from the present study confirms this pattern at national level and that inhabitants in coastal regions have higher values than from inland regions. The geometric mean (GM) for blood is 6.35 μg Hg/l, in urine is 1.11 μg Hg/l and for hair is 1.91 μg Hg/g. In an international comparison these values are not exceptional. Spanish concentrations fall into the group of Easter Mediterranean populations. Although information on gender, age, occupational sector, geographical area, sampling period and frequency of fish consumption is reported in the tables, the purpose of this paper has not been to analyse the determinants of exposure in detail but to provide baseline data for future assessments and for regional authorities.

Genetic analysis of Cryptosporidium from 2414 humans with diarrhoea in England between 1985 and 2000

The characterization of Cryptosporidium using DNA extracted from whole faecal samples collected from 2414 humans with diarrhoea in England between 1985 and 2000 where cryptosporidial oocysts were detected using conventional methods is described. Characterization was achieved by PCR/RFLP and DNA sequencing of fragments of the Cryptosporidium oocyst wall protein and the 18S rDNA genes. Cryptosporidium parvum was detected in 56.1 % of cases, Cryptosporidium hominis in 41.7 % and a mixture of C. parvum and C. hominis in 0.9 %. In the remainder of cases, Cryptosporidium meleagridis (0.9 %), Cryptosporidium felis (0.2 %), Cryptosporidium andersoni (0.1 %), Cryptosporidium canis (0.04 %), Cryptosporidium suis (0.04 %) and the Cryptosporidium cervine type (0.04 %) were detected.

Sensitive PCR-restriction fragment length polymorphism assay for detection and genotyping of Giardia duodenalis in human feces

An assay that uses heminested PCR-restriction fragment length polymorphism analysis for the detection and genotyping of Giardia duodenalis on the basis of polymorphism in the triose phosphate isomerase (tpi) gene was developed. This assay was evaluated with DNA extracted from purified parasite material, bacterial cultures, whole human feces containing G. duodenalis and other parasites, and their corresponding immunofluorescence-stained fecal smears on glass microscope slides. The assay was specific and discriminated between G. duodenalis assemblages A and B. RFLP analysis further distinguished two groups (designated groups I and II) within assemblage A. Among 35 DNA samples extracted from whole feces from patients with confirmed sporadic giardiasis, the tpi gene was amplified from 33 (94%). Of these, nine (27%) samples contained assemblage A group II, 21 (64%) contained assemblage B, and 3 (9%) contained a mixture of assemblage A group II and assemblage B. The tpi gene of G. duodenalis assemblage B was amplified from 21 of 24 (88%) DNA samples extracted from whole feces from patients with confirmed cases of infection in a nursery outbreak. No amplification was detected from the remaining three DNA samples. Overall, analysis of DNA extracted from material recovered from stained microscope slides identified identical G. duodenalis genotypes in 35 (65%) of the 54 samples for which a genotype was established with DNA from whole feces. The heminested PCR method developed is sensitive, simple, and rapid to perform and is applicable for the analysis of other intestinal pathogens.

Cryptosporidium meleagridis from humans: molecular analysis and description of affected patients

OBJECTIVES

To genetically characterize an unusual genotype of Cryptosporidium from the stools of humans with diarrhoea and to identify risk factors in the affected patients.

METHODS

DNA was extracted from human faeces where Cryptosporidium oocysts were detected by light microscopy. Cryptosporidial gene fragments from six different loci were analysed by PCR alone, PCR/RFLP and by DNA sequencing. Oocysts were characterized by light and immunofluorescence microscopy and epidemiological data was collected from the affected patients.

RESULTS

Analysis of the Cryptosporidium oocyst wall protein (COWP) gene amplified from > 2000 human faecal samples identified 19 patients all of which produced an unusual RFLP profile. Subsequent DNA sequence analysis of this and an additional four genetic loci (including 18S rRNA sequences) confirmed these as a homogeneous group which was genetically distinct from Cryptosporidium parvum. The isolates were identified as Cryptosporidium meleagridis since the gene sequences were identical to those from this species recovered from birds. Conventional microscopy showed oocysts indistinguishable from C. parvum and reacted strongly with two different commercially available anti-oocyst monoclonal antibodies. None of the patients showed risk factors unusual for cryptosporidiosis; however, ten of the cases occurred during the summer/autumn, six had a history of foreign travel, four were co-infected with Giardia, two were HIV positive, and six were without identifiable immunocompromising factors.

CONCLUSIONS

This study further confirms that C. meleagridis, in addition to C. parvum, is involved in human disease. The study also highlights the lack of basic information on the host range of this genus of parasites, the complexity of the transmission routes involved in human cryptosporidiosis, and the value of molecular techniques in identify hitherto unrecognised differences in Cryptosporidium from human faeces.

Unusual cryptosporidium species recovered from human faeces: first description of Cryptosporidium felis and Cryptosporidium 'dog type' from patients in England

DNA was extracted from faecal samples collected from 1680 patients in which Cryptosporidium oocysts were recognised by light microscopy. DNA from faeces from five of these patients failed to amplify by PCR three gene fragments--the Cryptosporidium oocyst wall protein (COWP) gene, the thrombospondin-related adhesive protein of Cryptosporidium-1 (TRAP-C1) gene and the thrombospondin-related adhesive protein of Cryptosporidium-2 (TRAP-C2) gene--with primers designed from C. parvum sequences. However, DNA from these five patients did amplify cryptosporidial 18S rDNA gene fragments and a heat-shock protein (HSP70) gene fragment was also amplified from four of them. The purpose of this study was to characterise further the Cryptosporidium associated with infection in these patients. DNA sequence analysis of 18S rDNA genes showed that four of these patients were infected by C. felis, and the remaining one by an as yet un-named Cryptosporidium species designated the 'dog type' (C. dt). Infection by C. felis was further confirmed in all four patients by DNA sequence analysis of the HSP70 gene. Oocysts present in all five samples reacted strongly with two anti-cryptosporidial oocyst monoclonal antibodies, except for the C. dt, which was tested with only one of the antibodies. Two of the patients infected by C. felis had underlying illness; one 8-year-old male had an undefined severe inherited underlying condition, and the second patient, a 32-year-old male, was HIV positive. Two of the remaining three patients (two females aged 1 and 2 years, respectively) were apparently immunocompetent (one infected with C. felis and one with the C. dt). No information was obtained for the fifth patient. The patient infected by C. dt had a recent history of travel to Africa. This is the first report of infection with these two Cryptosporidium species in immunocompetent patients, and in any patient in the UK.

Extraction and genotyping of Cryptosporidium parvum DNA from fecal smears on glass slides stained conventionally for direct microscope examination

A method was developed for extracting cryptosporidial DNA from stained fecal smears on glass microscope slides. The correct genotype of Cryptosporidium parvum was amplified by PCR from 89 (85%) of 105 smears following conventional staining but not from negative controls. This technique may have applications for analysis of other infectious agents.

Nested polymerase chain reaction for amplification of the Cryptosporidium oocyst wall protein gene

We developed a sensitive nested polymerase chain reaction procedure for the Cryptosporidium oocyst wall protein (COWP) gene. Amplification and genotyping were successful in 95.2% of 1,680 fecal samples, 77.6% by the unnested and 17.6% by the nested COWP procedure. The COWP gene was amplified from 2,128 fecal samples: 71 from livestock animals and 2,057 from humans. This series included 706 cases from seven drinking water-associated outbreaks and 51 cases from five swimming pool-associated outbreaks, as well as 1,300 sporadic cases.

Molecular epidemiological analysis of Cryptosporidium spp. in the United Kingdom: results of genotyping Cryptosporidium spp. in 1,705 fecal samples from humans and 105 fecal samples from livestock animals

Cryptosporidium present in 1,705 fecal samples from humans and 105 from livestock animals were analyzed by PCR-restriction fragment length polymorphism of the Cryptosporidium oocyst wall protein. Overall, genotype 1 (human exclusive type) was detected in 37.8% of the samples from humans, genotype 2 (broad host range) was detected in 61.5%, a third genotype designated genotype 3 (Cryptosporidium meleagridis) was detected in 0.3%, and both genotypes 1 and 2 were recovered from 0.4%. All samples from livestock yielded genotype 2. Among 469 patients infected during eight drinking water-related outbreaks, five outbreaks were predominantly due to genotype 1, and three were due to genotype 2. Fifty-four samples were collected from patients involved with five swimming pool-associated outbreaks: two outbreaks were due to genotype 1, one was due to genotype 2, and the remaining two involved both genotypes 1 and 2. Among 26 family outbreaks and 1 children's nursery outbreak (2 to 3 members per group), the same genotype was recovered from the different members of each outbreak: 13 were due to genotype 1, and 14 were due to genotype 2. In eighteen patients reporting contact with animals and/or farms, genotype 1 was recovered from one patient and genotype 2 was recovered from the remaining 17. Among the sporadic cases, there were distinct geographical and temporal variations in the distribution of the genotypes. The spring peak in cases was due to genotype 2. Genotype 1 was significantly more common in patients infected during the late-summer-autumn peak and in those with a history of foreign travel.

The identification and characterisation of an unusual genotype of Cryptosporidium from human faeces as Cryptosporidium meleagridis

An unusual genotype of Cryptosporidium was identified in the faeces of six human patients by PCR/RFLP analysis of the Cryptosporidium oocyst wall protein (COWP) gene. Conventional microscopy showed oocysts indistinguishable in size from those of Cryptosporidium parvum, which reacted with two different commercially available anti-oocyst monoclonal antibodies. The isolates were further characterised by PCR/RFLP analysis of the thrombospondin-related adhesive protein of Cryptosporidium-1 (TRAP-C1) genes as well as by DNA sequencing of the COWP and the TRAP-C1 gene fragments and of two regions of the 18S rRNA gene. Sequence analysis of the COWP, TRAP-C1, and 18S rRNA gene fragments confirmed that this genotype is genetically distinct from C. parvum. 18S rRNA gene sequences were found to be identical to those published for Cryptosporidium meleagridis.

Structure of the human oxytocinase/insulin-regulated aminopeptidase gene and localization to chromosome 5q21

The human oxytocinase/insulin-regulated aminopeptidase (OTase/IRAP) is a 1024 amino acid type II integral membrane protein that is expressed mainly in fat, muscle and placenta tissues. It has been thought to be involved mainly in the control of onset of labour but recently rat OTase/IRAP was shown to participate in the regulation of glucose transporter isoform 4 vesicle trafficking in adipocytes as well. To approach an understanding of OTase/IRAP gene regulation the organization of the human gene was determined. Accordingly, three overlapping genomic clones were isolated and characterized. The human OTase/IRAP gene (OTASE) was found to span approximately 75 kb containing 18 exons and 17 introns. The gluzincin aminopeptidase motif: GAMEN-(31 amino acids)-HELAH-(18 amino acids)-E associated with Zn2+-binding, substrate binding and catalysis is encoded by exons 6 and 7. A major and a minor transcriptional initiation site in OTASE were identified by primer extension 514 bp and 551 bp, respectively, upstream of the translation start codon. Chloroamphenicol acetyltransferase-reporter assays revealed a functional CpG-rich promoter/enhancer region located between nucleotide -621 and the major transcriptional initiation site. Human OTASE was assigned to chromosome 5 by hybridization to genomic DNA from characterized somatic cell hybrids. Finally, the OTASE and the human aminopeptidase A gene were subchromosomally localized to 5q21 and 4q25, respectively, by in situ hybridization.

Genetic characterization of Cryptosporidium strains from 218 patients with diarrhea diagnosed as having sporadic cryptosporidiosis

Samples of whole feces in which Cryptosporidium oocysts were recognized by hospital laboratories were collected from 218 patients with diarrhea. All samples were reexamined by light microscopy, and oocysts were detected in 211 samples. A simple and rapid procedure for the extraction of DNA from whole feces was developed, and this was used to amplify fragments of the Cryptosporidium outer wall protein (COWP), the thrombospondin-related adhesive protein C1 (TRAP-C1), and the 18S rRNA genes by PCR. For seven samples oocysts were not detected by microscopy and DNA failed to be amplified by the three PCR procedures. Among the 211 samples "positive" by microscopy, the sensitivities of PCRs for the 18S rRNA, COWP, and TRAP-C1 gene fragments were 97, 91, and 66%, respectively. The sensitivities of all three PCR procedures increased with increasing numbers of oocysts as observed by microscopy. Two genotypes of the COWP and TRAP-C1 genes can be detected by PCR-restriction fragment length polymorphism analysis. With this series of samples, the same genotypes of the COWP and TRAP-C1 genes always segregated together. A combined genotyping data set was produced for isolates from 194 samples: 74 (38%) were genotype 1 and 120 (62%) were genotype 2. Genotype 2 was detected in a significantly greater proportion of the samples with small numbers of oocysts, and genotype 1 was detected in a significantly greater proportion of the samples with larger numbers of oocysts. There were no significant differences in the distribution of the genotypes by patient sex and age. The distribution of the genotypes was significantly different both in patients with a history of foreign travel and in those from different regions in England.

The identification of Cryptosporidium species and Cryptosporidium parvum directly from whole faeces by analysis of a multiplex PCR of the 18S rRNA gene and by PCR/RFLP of the Cryptosporidium outer wall protein (COWP) gene

A multiplex polymerase chain reaction (PCR) procedure to amplify 18S rRNA gene fragments has been developed. Amplified DNA fragments of the expected size were obtained which were specific for Cryptosporidium parvum and Cryptosporidium wrairi (422 bp), Cryptosporidium baileyi (11106 bp) and Cryptosporidium muris (1346 bp). Criptosporidium parvum and C. wrairi can be distinguished using a PCR/restriction fragment length polymorphism (RFLP) analysis of the Cryptosporidium outer wall protein (COWP) gene, and these two techniques were applied to DNA extracted from whole faeces using a simple and rapid procedure. Cryptosporidium parvum DNA was detected in the faeces of 72 humans and 24 calves where cryptosporidial oocysts were demonstrated using conventional light microscopy. The specific DNA fragments were not amplified using extracts of material containing other lower eukaryotic parasites.

Molecular characterisation of Cryptosporidium parvum from two large suspected waterborne outbreaks. Outbreak Control Team South and West Devon 1995, Incident Management Team and Further Epidemiological and Microbiological Studies Subgroup North Thames 1997

Polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) analysis of the Cryptosporidium parvum outer wall protein (COWP) gene was applied to specimens collected from 95 patients with cryptosporidiosis associated with two suspected waterborne outbreaks, 46 sporadic human cases and 62 infected livestock from other areas, and 12 patients infected with other gastrointestinal parasites. Ninety-six per cent of C. parvum isolates from patients linked to the two suspected waterborne outbreaks were of genotype 1; all the isolates from livestock were of genotype 2. Isolates from 59% of the sporadic human infections were of genotype 1 and 35% were of genotype 2. Specimens from two patients yielded both genotypes. Specimens from patients infected with other parasites yielded no amplicons.