Santiago Mas-Coma
Universitat de València, Parasitology, Faculty Member
- Acad. Prof. Dr. Dr. Honoris Causa Santiago Mas-Coma is Parasitology Chairman and Director of the Human Parasitic Dise... moreAcad. Prof. Dr. Dr. Honoris Causa Santiago Mas-Coma is Parasitology Chairman and Director of the Human Parasitic Disease Unit of the Parasitology Department, University of Valencia, Spain, and Director of the "Collaborating Centre of the World Health Organization on Fascioliasis and Its Snail Vectors" (WHO CC SPA-37, WHO/OMS Headquarters Geneva, Switzerland) and of the "FAO-United Nations Reference Centre for Parasitology" (FAO Headquarters Rome, Italy). He is currently the President of the International Federation for Tropical Medicine (IFTM 2012-2020), former President of the European Federation of Parasitologists (EFP 2004-2012), and former President of the Spanish Society of Parasitology (SEP 2000-2004). He is also an Expert Member of WHO in Human Parasitology (Headquarters Geneva) and was a member of the WHO-STAG Committee (WHO/OMS, Headquarters Geneva, 2009-2014). S. Mas-Coma is a parasitologist mainly working on Helminthology but also protozoan diseases and vectors (molluscs and arthropods) of vector-borne parasitoses. A specialist in Parasitology and Microbiology, during his career he has been mainly dedicated to Neglected Tropical Diseases (NTDs) in developing countries throughout the world. His international scientific relationships and research collaborations cover almost all countries of Europe, the Americas, Africa and Asia. From the 80s, his research activities have focused on fluke diseases, among which mainly human fascioliasis, intestinal parasitic diseases, American trypanosomiasis or Chagas disease, and recently also working on malaria and leishmaniasis vectors. His articles (400 research papers, among which books and reviews) have been published in numerous scientific journals of Parasitology, Tropical Medicine, Public Health and Molecular Biology and his numerous contributions (more than 800 papers/conferences) presented in international and national events, congresses and centres. He is a member and/or honorary member of numerous societies, adviser of many international and national agencies, and of journals and international research projects, member of editorial boards, and evaluation committees of different countries, institutions and centres. He has been honoured with many international and national prizes and awards.edit
Research Interests: Biology, Chile, Medicine, Biological Sciences, Phylogeny, and 15 moreMitochondrial DNA, Animals, Fauna, Fasciola hepatica, Cluster Analysis, South America, Introduced species, Geographic distribution, Health Problems, Acanthaceae, DNA sequence, Mitochondrial Proteins, Molecular Sequence Data, Medical and Health Sciences, and remote sensing data
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The complete 18S rRNA gene sequences of the following six European hard-tick species were obtained by direct PCR cycle sequencing and silver-staining methods: Rhipicephalus pusillus, Boophilus annulatus, Dermacentor marginatus, Hyalomma... more
The complete 18S rRNA gene sequences of the following six European hard-tick species were obtained by direct PCR cycle sequencing and silver-staining methods: Rhipicephalus pusillus, Boophilus annulatus, Dermacentor marginatus, Hyalomma lusitanicum, Haemaphysalis punctata, and Ixodes ricinus. Differences observed in the sequence alignment of these six species together with the 18S rRNA gene sequences of 13 other hard-tick species demonstrate that this gene is a good marker for supraspecific differentiation as well as genus grouping among hard ticks. Phylogenetic analyses strongly support that Hyalomma species share a common ancestor with Rhipicephalinae and, consequently, Hyalomminae should no longer be considered an independent subfamily. However, no definitive conclusion could be reached to support or oppose the separation of the subfamilies Haemaphysalinae and Amblyomminae.
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Fasciola hepatica and F. gigantica are liver flukes causing fascioliasis, a worldwide zoonotic, complex disease. Human infection/reinfection occurs in endemic areas where preventive chemotherapy is applied, because of fasciolid... more
Fasciola hepatica and F. gigantica are liver flukes causing fascioliasis, a worldwide zoonotic, complex disease. Human infection/reinfection occurs in endemic areas where preventive chemotherapy is applied, because of fasciolid transmission ensured by livestock and lymnaeid snail vectors. A One Health control action is the best complement to decrease infection risk. The multidisciplinary framework needs to focus on freshwater transmission foci and their environment, lymnaeids, mammal reservoirs, and inhabitant infection, ethnography and housing. Local epidemiological and transmission knowledge furnished by previous field and experimental research offers the baseline for control design. A One Health intervention should be adapted to the endemic area characteristics. Long-term control sustainability may be achieved by prioritizing measures according to impact depending on available funds. Fascioliasis: complexity, and impact on communities Fascioliasis is a zoonotic disease caused by two species of liver fluke, Fasciola hepatica and F. gigantica, both originated by speciation derived from F. nyanzae specific to hippopotamuses, after a host capture (see Glossary) phenomenon to sylvatic ruminants. Whereas F. gigantica kept the same freshwater lymnaeid snail species of the Radix group as the vector in southeastern Africa, F. hepatica jumped from the warm-preferring-lowland bigger Radix to cooler-habitatpreferring smaller Galba/Fossaria lymnaeids in Near-Eastern Asia [1]. Animal domestication in the Fertile Crescent allowed F. hepatica and F. gigantica to later expand with domesticated ruminants, equines, and camelids throughout the Old World during the Neolithic, and subsequently colonize the Americas and Oceania with livestock transported with ships in the last 500-year period. Their low host specificity enables them to also infect omnivores such as humans and pigs. In that way, fascioliasis became the only human trematodiasis of worldwide distribution [2].
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A 58-year-old man who was very fond of eating raw fish and had not left Zaragoza Province in Spain in the last 20 years excreted a short chain of gravid proglottids. Treatment with 50 mg/kg of paromomycin sulfate was divided into three... more
A 58-year-old man who was very fond of eating raw fish and had not left Zaragoza Province in Spain in the last 20 years excreted a short chain of gravid proglottids. Treatment with 50 mg/kg of paromomycin sulfate was divided into three doses, all given within the same day, followed by administration of a laxative at night. On days 1 and 2 post-treatment, several chains of degenerated proglottids were evacuated. Only eggs were expelled on days 3 and 4. A long complete strobila including the scolex, and immature, mature, and gravid segments was spontaneously discharged on day 25 after treatment. It was identified as Diplogonoporus balaenopterae, and was the first confirmed case of diplogonoporiasis outside the Far East (all previous cases were reported from Japan, except for one recent case reported from Korea). The origin of this case, outside of its normal geographic location, may be associated with the importation of fish into Spain. The viability of the infective larval stage is evidence of its resistance to export/import conditions. Treatment with paromomycin sulfate did not result in the whole worm being discharged but several short strobilar chains showed drug-induced degeneration.
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A pseudogene, paralogous to rDNA 5.8S and ITS-2, is described in Meccus dimidiata dimidiata, M. d. capitata, M. d. maculippenis, M. d. hegneri, M. sp. aff. dimidiata, M. p. phyllosoma, M. p. longipennis, M. p. pallidipennis, M. p.... more
A pseudogene, paralogous to rDNA 5.8S and ITS-2, is described in Meccus dimidiata dimidiata, M. d. capitata, M. d. maculippenis, M. d. hegneri, M. sp. aff. dimidiata, M. p. phyllosoma, M. p. longipennis, M. p. pallidipennis, M. p. picturata, M. p. mazzottii, Triatoma mexicana, Triatoma nitida and Triatoma sanguisuga, covering North America, Central America and northern South America. Such a nuclear rDNA pseudogene is very rare. In the 5.8S gene, criteria for pseudogene identification included length variability, lower GC content, mutations regarding the functional uniform sequence, and relatively high base substitutions in evolutionary conserved sites. At ITS-2 level, criteria were the shorter sequence and large proportion of insertions and deletions (indels). Pseudogenic 5.8S and ITS-2 secondary structures were different from the functional foldings, different one another, showing less negative values for minimum free energy (mfe) and centroid predictions, and lower fit between mfe, partition function, and centroid structures. A complete characterization indicated a processed pseudogenic unit of the ghost type, escaping from rDNA concerted evolution and with functionality subject to constraints instead of evolving free by neutral drift. Despite a high indel number, low mutation number and an evolutionary rate similar to the functional ITS-2, that pseudogene distinguishes different taxa and furnishes coherent phylogenetic topologies with resolution similar to the functional ITS-2. The discovery of a pseudogene in many phylogenetically related species is unique in animals and allowed for an estimation of its palaeobiogeographical origin based on molecular clock data, inheritance pathways, evolutionary rate and pattern, and geographical spread. Additional to the technical risk to be considered henceforth, this relict pseudogene, designated as "ps(5.8S+ITS-2)", proves to be a valuable marker for specimen classification, phylogenetic analyses, and systematic/taxonomic studies. It opens a new research field, Chagas disease epidemiology and control included, given its potential relationships with triatomine fitness, behaviour and adaptability.
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ABSTRACT From several gnathostome species the complete internal transcribed spacer ITS-2 ribosomal DNA (rDNA) repeat sequence and a fragment of the 5.8S rDNA were obtained by direct polymerase chain reaction cycle-sequencing and... more
ABSTRACT From several gnathostome species the complete internal transcribed spacer ITS-2 ribosomal DNA (rDNA) repeat sequence and a fragment of the 5.8S rDNA were obtained by direct polymerase chain reaction cycle-sequencing and silver-staining methods. The size of the complete ITS-1 sequence in agarose gel electrophoresis was also obtained. The ITS-2 enabled the differentiation of Gnathostoma spinigerum from Thailand and Gnathostoma binucleatum from Mexico and Ecuador and confirmed the validity of the latter. Gnathostoma turgidum, Gnathostoma sp. I (=Gnathostoma procyonis sensu Almeyda-Artigas et al., 1994), and Gnathostoma sp. II (=G. turgidum sensu Foster, 1939 pro parte), all from Mexico, proved to be independent species, but Gnathostoma sp. III, also from Mexico, could not be differentiated from G. turgidum. In Mexico and Ecuador, gnathostomes involved in human infection and that had been classified as G. spinigerum belong to G. binucleatum. The 5.8S rDNA sequences of the 6 Gnathostoma species studied were identical. The results of the ITS-1 agreed with those results of ITS-2.
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Fascioliasis is of well-known veterinary importance and an increasing human health problem, with reported cases in the five continents. The causative agents, Fasciola hepatica and Fasciola gigantica, present geographical distributions,... more
Fascioliasis is of well-known veterinary importance and an increasing human health problem, with reported cases in the five continents. The causative agents, Fasciola hepatica and Fasciola gigantica, present geographical distributions, which overlap in many regions of Africa and Asia, and in which the differentiation of both species is usually difficult because of the many variations in their morphological characteristics. Moreover, in humans, liver fluke classification cannot be achieved by clinical, pathological, coprological or immunological methods. The differential diagnosis between F. hepatica and F. gigantica infection is very important because of their different transmission and epidemiological characteristics. A simple and rapid PCR-restriction fragment length polymorphism (RFLP) assay, using the common restriction enzymes Ava II and Dra II, is described to distinguish between both fasciolid species. It is based on a 618-bp-long sequence of the 28S rRNA gene recently obtained from liver fluke populations of South America, Europe and Africa. This sequence showed a few nucleotide differences between both fasciolids and no intraspecific variations within each species. This assay provides unambiguous results and may be useful for both individual subject diagnosis and epidemiological surveys of humans and animals in endemic regions of sympatry.
Research Interests: Biology, Medicine, Liver, Animals, Polymerase Chain Reaction, and 15 moreFasciola hepatica, Differential Diagnosis, Cattle, Human health, Intraspecific Variation, Geographic distribution, Base Sequence, Ribosomal DNA, Fasciola, Nucleotides, Biochemistry and cell biology, Liver Fluke, restriction enzyme, Fascioliasis, and Fasciola gigantica
Seven hundred and twenty five female culicid mosquitoes were captured in an area of Western Spain where Dirofilaria immitis is endemic. PCR was applied for the detection of larval D. immitis DNA in mosquitoes. The ITS-2 rDNA region of the... more
Seven hundred and twenty five female culicid mosquitoes were captured in an area of Western Spain where Dirofilaria immitis is endemic. PCR was applied for the detection of larval D. immitis DNA in mosquitoes. The ITS-2 rDNA region of the mosquito DNA was also amplified and sequenced to characterize the haplotype of infected individuals. Two Cx. pipiens showed positive reaction to D. immitis DNA, both specimens belonging to the haplotype H1. It is the first time that a culicid mosquito species is incriminated in the transmission of D. immitis and that its haplotype identified in Spain. The anthropophilic behaviour of this species, and its capture with human bait as attractant, led the authors to speculate that Cx. pipiens could be implicated in the transmission of human dirofilariosis in this endemic area.
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Research Interests: Microbiology, Medical Microbiology, Biology, Medicine, Phylogeny, and 15 moreHumans, Animals, Deoxyribonucleic Acid, South America, Chagas disease, ribosomal RNA, Public health systems and services research, Control Strategy, Ribosomal DNA, Genetic Markers, SSU rRNA, DNA marker, Insect Vectors, ribonucleic acid, and Internal transcribed spacer
ABSTRACT Although, in the endemic areas throughout the world, human fascioliasis presents varying patterns in its epidemiology, the species of lymnaeid snail that act as intermediate hosts and vectors are always crucial in the... more
ABSTRACT Although, in the endemic areas throughout the world, human fascioliasis presents varying patterns in its epidemiology, the species of lymnaeid snail that act as intermediate hosts and vectors are always crucial in the transmission of the causative parasites. Species in the Galba/Fossaria group of snails, such as Lymnaea cubensis, L. viatrix var. A ventricosa, L. viatrix var. B elongata and Galba truncatula, appear to be frequently involved in the transmission of Fasciola hepatica in Central and South America, although specific classification within this morphologically and anatomically confusing group is often very difficult. To explore the potential use of molecular analyses in the identification of vector snails, regions of the ribosomal DNA - the small subunit (18S) gene and internal transcribed spacers (ITS-2 and ITS-1) - and of the mitochondrial DNA - the cytochrome c oxidase subunit I (COI) - of wild-caught lymnaeid snails of L. cubensis, L. viatrix var. A ventricosa, L. viatrix var. B elongata and G. truncatula have been sequenced. The samples of the Latin American species included specimens from the respective type localities. The genetic distances observed and the results of phylogenetic analyses demonstrate that two different species exist within L. viatrix. Lymnaea neotropica n. sp. (=L. viatrix var. B elongata) is here proposed for specimens from Lima, Peru, and is differentiated from L. viatrix (=L. viatrix var. A ventricosa), L. cubensis and G. truncatula. The data collected on the 18S ribosomal-RNA gene indicate that the snails investigated may cover more than one supraspecific taxon. The ITS-2, ITS-1 and COI nucleotide sequences are clearly useful markers for the differentiation of these morpho-anatomically similar lymnaeid species. The numerous microsatellite repeats found within ITS-2 are potential tools for differentiation at population level.
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Research Interests: Mathematics, Biology, Medicine, Biological Sciences, Animals, and 15 moreBacteria, Anemia, Iron, Feces, Biological markers, Haematological Parameters, Microbial Viability, Bacterial Infection, Gastrointestinal bleeding, Fasciolosis, Cell Size, Bile, Fascioliasis, High risk, and Medical and Health Sciences
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Research Interests: Global Health, Human Development, Biology, Ecology, Environmental Change, and 15 moreGlobal change, Intestinal Parasites, Humans, Animals, Fasciola hepatica, Endemic Diseases, For, High Altitude, Food Chain, Fasciola, Helminthiasis, Food Parasitology, Fascioliasis, Environmental factor, and Fasciola gigantica
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Research Interests: Medical Microbiology, Biology, Medicine, Dna Sequencing, South Africa, and 15 moreMitochondrial DNA, Sequence alignment, Mutation, Gastropoda, Female, Animals, Shrews, Male, Public health systems and services research, Base Sequence, Shrew, Intermediate Host, Molecular Sequence Data, Epizootiology, and Life Cycle Stages
Research Interests: Genetics, Geography, Biology, Applied Research, Ecology, and 15 moreInternational Cooperation, Dominican Republic, Haplotypes, Animals, Cryptic Species, Disease Control, Experimental Infection, Egg Laying, Geographic distribution, Genotype, Lymnaea, Biological markers, Conservation of Natural Resources, Fasciolosis, and disease transmission
Fascioliasis causes high economic losses in livestock and underlies public health problems in rural areas, mainly of low-income countries. The increasing animal infection rates in Bangladesh were assessed, by focusing on host species,... more
Fascioliasis causes high economic losses in livestock and underlies public health problems in rural areas, mainly of low-income countries. The increasing animal infection rates in Bangladesh were assessed, by focusing on host species, different parts of the country, and rDNA sequences. Fasciolid flukes were collected from buffaloes, cattle, goats and sheep from many localities to assess prevalences and intensities of infection. The nuclear rDNA internal transcribed spacer (ITS) region including ITS-1 and ITS-2 spacers was analyzed by direct sequencing and cloning, given the detection of intermediate phenotypic forms in Bangladesh. The 35.4% prevalence in goats and 55.5% in buffaloes are the highest recorded in these animals in Bangladesh. In cattle (29.3%) and sheep (26.8%) prevalences are also high for these species. These prevalences are very high when compared to lowlands at similar latitudes in neighboring India. The high prevalences and intensities appear in western Bangladesh where cross-border importation of animals from India occur. The combined haplotype CH3A of Fasciola gigantica widely found in all livestock species throughout Bangladesh fits its historical connections with the western Grand Trunk Road and the eastern Tea-Horse Road. The “pure” F. hepatica sequences only in clones from specimens showing heterozygotic positions indicate recent hybridization events with local “pure” F. gigantica, since concerted evolution did not yet have sufficient time to homogenize the rDNA operon. The detection of up to six different sequences coexisting in the cloned specimens evidences crossbreeding between hybrid parents, indicating repeated, superimposed and rapidly evolving hybridization events. The high proportion of hybrids highlights an increasing animal infection trend and human infection risk, and the need for control measures, mainly concerning goats in household farming management. ITS-1 and ITS-2 markers prove to be useful for detecting recent hybrid fasciolids. The introduction of a Fasciola species with imported livestock into a highly prevalent area of the other Fasciola species may lead to a high nucleotide variation in the species-differing positions in the extremely conserved fasciolid spacers. Results suggest that, in ancient times, frequent crossbreeding inside the same Fasciola species gave rise to the very peculiar characteristics of the present-day nuclear genome of both fasciolids.
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Palaeoparasitology investigates parasitological infections in animals and humans of past distance by examining biological remains. Palaeofaeces (or coprolites) are biological remains that provide valuable information on the disease, diet,... more
Palaeoparasitology investigates parasitological infections in animals and humans of past distance by examining biological remains. Palaeofaeces (or coprolites) are biological remains that provide valuable information on the disease, diet, and population movements in ancient times. Today, advances in detecting ancient DNA have cast light on dark corners that microscopy could never reach. The archaeological site of the Chehrabad salt mine of Achaemenid (550–330 BC) and Sassanid (third–seventh century AD) provides remains of various biotic and abiotic samples, including animal coprolites, for multidisciplinary studies. In the present work, we investigated coprolites for helminth eggs and larvae by microscopy and traced their biological agents’ DNA by Next Generation Sequencing. Our results revealed various helminths, includingTaenia asiatica, the species introduced in the 1990s. Implementing advanced modern molecular techniques like NGS gives a paramount view of pathogenic agents in sp...
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Schistosome eggs play a key role in schistosomiasis diagnosis and research. The aim of this work is to morphogenetically study the eggs of Schistosoma haematobium found in sub-Saharan migrants present in Spain, analyzing their... more
Schistosome eggs play a key role in schistosomiasis diagnosis and research. The aim of this work is to morphogenetically study the eggs of Schistosoma haematobium found in sub-Saharan migrants present in Spain, analyzing their morphometric variation in relation to the geographical origin of the parasite (Mali, Mauritania and Senegal). Only eggs considered “pure” S. haematobium by genetic characterization (rDNA ITS-2 and mtDNA cox1) have been used. A total of 162 eggs obtained from 20 migrants from Mali, Mauritania and Senegal were included in the study. Analyses were made by the Computer Image Analysis System (CIAS). Following a previously standardized methodology, seventeen measurements were carried out on each egg. The morphometric analysis of the three morphotypes detected (round, elongated and spindle) and the biometric variations in relation to the country of origin of the parasite on the egg phenotype were carried out by canonical variate analysis. Mahalanobis distances, when ...
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BackgroundThe trematodeFasciola hepaticais the most widespread causative agent of fasciolosis, a parasitic disease that mainly affects humans and ruminants worldwide. DuringF. hepaticainfection, newly excysted juveniles (FhNEJ) emerge in... more
BackgroundThe trematodeFasciola hepaticais the most widespread causative agent of fasciolosis, a parasitic disease that mainly affects humans and ruminants worldwide. DuringF. hepaticainfection, newly excysted juveniles (FhNEJ) emerge in the duodenum of the mammalian host and migrate towards the definitive location of the parasite, the intra-hepatic biliary ducts. Understanding howF. hepaticatraverses the intestinal wall and migrates towards the liver is pivotal for the development of more successful strategies against fasciolosis. The central enzyme of the mammalian fibrinolytic system is plasmin, a serine protease whose functions are exploited by a number of parasite species owing to its broad spectrum of substrates, including components of tissue extracellular matrices. The aim of the present work is to understand whether FhNEJ co-opt the functions of their host fibrinolytic system as a mechanism to facilitate trans-intestinal migration.Methodology/Principal FindingsAn FhNEJ tegu...
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Calodium hepaticum is a zoonotic nematode with a worldwide distribution. Although the host range of C. hepaticum includes a wide spectrum of mammals (including humans), this parasite is predominantly associated with the families Muridae... more
Calodium hepaticum is a zoonotic nematode with a worldwide distribution. Although the host range of C. hepaticum includes a wide spectrum of mammals (including humans), this parasite is predominantly associated with the families Muridae and Cricetidae. Several Sigmodontinae species from Argentina were found to be infected by C. hepaticum, with a high prevalence in Akodon azarae. The present study focuses on C. hepaticum eggs from natural infection of three species of sigmodontine rodents from Argentina. Eggs were genetically characterized (intergenic 18S rRNA region). The objectives of this work are: (i) to propose a new analytical methodology; and (ii) to morphologically characterize C. hepaticum eggs, from three Sigmodontinae species (A. azarae, Calomys callidus and Oligoryzomys flavescens). Analyses were made by the Computer Image Analysis System based on the new standardized measurements and geometric morphometric tools. The resulting factor maps clearly illustrate global size d...
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Systemic analysis is proposed in this manuscript as a tool to analyze the life-cycle and transmission of F. hepatica and F. gigantica. To be precise, chaos analysis of a temporary series of F. hepatica eggs shedding in murid (Wistar rats)... more
Systemic analysis is proposed in this manuscript as a tool to analyze the life-cycle and transmission of F. hepatica and F. gigantica. To be precise, chaos analysis of a temporary series of F. hepatica eggs shedding in murid (Wistar rats) faeces is used by means of Chaos Data Analyzer software with the aim to analyze the possible existence of attractors, sensibility to initial conditions and chaos.
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Fascioliasis is an important human and animal disease caused by Fasciola hepatica and Fasciola gigantica. In Iran, the distribution of these two species overlaps in most areas, including the northern human endemic province of Gilan where... more
Fascioliasis is an important human and animal disease caused by Fasciola hepatica and Fasciola gigantica. In Iran, the distribution of these two species overlaps in most areas, including the northern human endemic province of Gilan where both fasciolids are simultaneously found in individual cattle and buffaloes. A phenotypic study of fasciolid adult flukes from naturally infected bovines from Gilan was carried out by means of an exhaustive morphometric analysis using traditional microscopic measurements and an allometric model. The Iranian fasciolids were compared to F. hepatica and F. gigantica standard populations, i.e. from geographical areas where both species do not co-exist (Bolivia and Burkina Faso, respectively). Although morphometric values somewhat overlapped, there were clear differences in allometric growth. The allometric function was adjusted to 25 pairs of variables. Results obtained revealed that Iranian F. hepatica-like specimens are larger than the F. hepatica standard and Iranian F. gigantica-like specimens are longer and narrower than the F. gigantica standard, but with smaller body area. Measurements which permit a specific differentiation in allopatric populations (distance between ventral sucker and posterior end of the body; ratio between body length and body width) overlap in the specimens from Gilan, thus proving the presence of intermediate forms. When compared to the standard populations, the different Iranian fasciolid morphs show greater differences in F. gigantica-like specimens than in F. hepatica-like specimens. This study shows that simple, traditional microscopic measurements may be sufficient for the morphometric characterisation of fasciolids, even in areas where intermediate forms are present.
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Fascioliasis pathogenesis depends on fluke burden. In human hyperendemic zones, individual infection intensities reach very high levels and the majority of infected subjects should be in the advanced chronic phase. The rat model offers a... more
Fascioliasis pathogenesis depends on fluke burden. In human hyperendemic zones, individual infection intensities reach very high levels and the majority of infected subjects should be in the advanced chronic phase. The rat model offers a useful approach for pathological research in the advanced chronic period. The influence of infection intensity per rat on fluke development, pre-patent period and egg shedding (eggs/g faeces/worm) was analysed in 3 groups (I: 1–3 worms/rat; II: 4–6; III: 7–9). Ontogenetic trajectories of fluke body measures followed a logistic model. Results showed that when the burden increases, the maximum values of fluke measures decrease. The crowding effect is manifest when fluke measures approximate their maximums in the advanced chronic stage. The pre-patent period and egg production decrease when the burden increases. This means that measurements of eggs per gramme of faeces tend to underestimate the fluke burden. The present study demonstrates how to quanti...
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Research Interests: Biology, Egypt, Dogs, Female, Animals, and 15 moreCluster Analysis, Gene, Canine, Giardiasis, Cattle, Density gradient, Genotype, Adult, Feces, Genotyping, Base Sequence, Giardia, DNA sequence, Direct sequence, and Giardia lamblia
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A population genetic study using starch gel electrophoresis was performed on populations of several species of lymnaeid snails acting as intermediate hosts for Fasciola hepatica (Trematoda, Plathyhelminth). Lymnaea viatrix was collected... more
A population genetic study using starch gel electrophoresis was performed on populations of several species of lymnaeid snails acting as intermediate hosts for Fasciola hepatica (Trematoda, Plathyhelminth). Lymnaea viatrix was collected in 16 sites from the Bolivian Northern Altiplano. L. cubensis were obtained in one site from Venezuela, one site from Guadeloupe, three sites from Cuba and one site from the Dominican Republic. L. truncatula were collected in one site from France, one from Portugal and one from Morocco. Multilocus enzyme electrophoresis (MEE) were determined for 282 snails at 18 loci. A complete monomorphism was encountered at each geographic site. However, among these 18 loci, 13 are polymorphic and low and high levels of genetic divergence were observed between samples. Two genotypic groups can be differentiated by their multilocus genotypes. The western genotypic group associates together samples from Venezuela, Guadeloupe, Cuba and Dominican Republic (L. cubensis) while samples from France, Portugal and Morocco (L. truncatula) belong to the eastern genotypic group. Surprisingly, the Northern Bolivian Altiplano populations (L. viatrix) do not present any genetic divergence with the Portuguese sample. Therefore, the Bolivian snails belong entirely to the eastern genetic group. Within each group slight genetic divergences were observed. These results strongly support the European origin of the lymnaeid snails from the Northern Bolivian Altiplano.
Research Interests: Genetics, Biology, Bolivia, Medicine, France, and 15 moreCuba, Dominican Republic, Biological Sciences, Humans, Biological Diversity, Genetic Structure, Guadeloupe, Animals, Fasciola hepatica, Genetic Divergence, Lymnaea, Gel electrophoresis, Genetic Variability, Fascioliasis, and Medical and Health Sciences
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Fascioliasis is a snail-borne zoonotic disease with impact on the development of human subjects and communities. It is caused by two liver-infecting fasciolid trematode species, the globally-distributed Fasciola hepatica and the... more
Fascioliasis is a snail-borne zoonotic disease with impact on the development of human subjects and communities. It is caused by two liver-infecting fasciolid trematode species, the globally-distributed Fasciola hepatica and the Africa/Asia-restricted but more pathogenic, larger F. gigantica. Fasciola gigantica is the cause of endemicity in livestock throughout the warm lowlands from Pakistan to southeastern Asia since old times. Human fascioliasis is emerging in this region at present, with an increase of patient reports. Complete sequences of rDNA ITS-1 and
ITS-2 spacers and mtDNA nad1 and cox1 genes were obtained from fasciolid eggs found in the endoscopic bile aspirate from a patient of Arunachal Pradesh, northeastern India. Egg measurements, pronounced ITS heterozygosity, and pure F. gigantica mtDNA haplotypes demonstrate an infection by a recent F. gigantica-like hybrid. Sequence identities and similarities with the same DNA markers found in livestock from Bangladesh prove the human-infecting fasciolid to present identical ITSs and nad1 haplotypes and only one silent transversion in cox1 when compared to a widely-spread combined haplotype in animals. In northeastern India and Bangladesh, human fascioliasis emergence appears linked to increasing livestock prevalences due to: ruminant importation from other countries because of the increasing demand of rapidly growing human populations; numerous livestock movements, including transborder corridors, due to the uncontrolled small-scale household farming practices; and man-made introduction of F. hepatica with imported livestock into an area originally endemic for F. gigantica leading to frequent hybridization. Sequences, phylogenetic trees, and networks indicate that the origins of intermediate/hybrid fasciolids and factors underlying human infection risk differ in eastern and western South Asia. The emergence scenario in southern China and Vietnam resembles the aforementioned of northeastern India and Bangladesh, whereas in Pakistan it is linked to increasing monsoon rainfall within climate change combined with an impact of an extensive irrigation system. ..................
ITS-2 spacers and mtDNA nad1 and cox1 genes were obtained from fasciolid eggs found in the endoscopic bile aspirate from a patient of Arunachal Pradesh, northeastern India. Egg measurements, pronounced ITS heterozygosity, and pure F. gigantica mtDNA haplotypes demonstrate an infection by a recent F. gigantica-like hybrid. Sequence identities and similarities with the same DNA markers found in livestock from Bangladesh prove the human-infecting fasciolid to present identical ITSs and nad1 haplotypes and only one silent transversion in cox1 when compared to a widely-spread combined haplotype in animals. In northeastern India and Bangladesh, human fascioliasis emergence appears linked to increasing livestock prevalences due to: ruminant importation from other countries because of the increasing demand of rapidly growing human populations; numerous livestock movements, including transborder corridors, due to the uncontrolled small-scale household farming practices; and man-made introduction of F. hepatica with imported livestock into an area originally endemic for F. gigantica leading to frequent hybridization. Sequences, phylogenetic trees, and networks indicate that the origins of intermediate/hybrid fasciolids and factors underlying human infection risk differ in eastern and western South Asia. The emergence scenario in southern China and Vietnam resembles the aforementioned of northeastern India and Bangladesh, whereas in Pakistan it is linked to increasing monsoon rainfall within climate change combined with an impact of an extensive irrigation system. ..................
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Current knowledge of animal and zoonotic helminthiases in which effects of climate change have been detected is reviewed. Climate variables are able to affect the prevalence, intensity and geographical distribution of helminths, directly... more
Current knowledge of animal and zoonotic helminthiases in which effects of climate change have been detected is reviewed. Climate variables are able to affect the prevalence, intensity and geographical distribution of helminths, directly influencing free-living larval stages and indirectly influencing mainly invertebrate, but also vertebrate, hosts. The impact of climate change appears to be more pronounced in trematodes, and is mainly shown by increased cercarial production and emergence associated with global warming. Fascioliasis, schistosomiasis (S. japonicum) and cercarial dermatitis caused by avian schistosomes have been the focus of study. Alveolar echinococcosis is currently the only cestode disease that climate change has been found to influence. Nematodiases, including heterakiasis, different trichostrongyliases and protostrongyliases, ancylostomiases and dirofilariases, are the helminth diseases most intensively analysed with regard to climate change. It may be concluded that helminth diseases should be listed among the infectious diseases with which special care should be taken because of climate change in the future, especially in temperate and colder northern latitudes and in areas of high altitude.