Richard Thomas

Mr. Richard Thomas

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Research Focus & Metrics

Academic Career Length

29Years (1998-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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11 November 2022 in Transboundary and Emerging Diseases
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Journal Article
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ASAdriana Santodomingo
Adriana Santodomingo
SRSofía Robbiano
Sofía Robbiano
RTRichard Thomas
Richard Thomas
CPCatalina Parragué‐Migone
Catalina Parragué‐Migone
JCJavier Cabello‐Stom
Javier Cabello‐Stom
SMSebastián Muñoz-Leal
Sebastián Muñoz-Leal

1 February 2022 in Parasitology Research
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Journal Article
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ASAdriana Santodomingo
Adriana Santodomingo
RTRichard Thomas
Richard Thomas
JQJulian F. Quintero-Galvis
Julian F. Quintero-Galvis
DBDIANA MARITZA ECHEVERRY BERRIO
DIANA MARITZA ECHEVERRY BERRIO
MFMaría Carolina Silva-De la Fuente
María Carolina Silva-De la Fuente
SMSebastián Muñoz-Leal
Sebastián Muñoz-Leal

9 March 2022 in Pathogens
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POPablo Oyarzún-Ruiz
Pablo Oyarzún-Ruiz
RTRichard Thomas
Richard Thomas
ASAdriana Santodomingo
Adriana Santodomingo
GCGonzalo A. Collado
Gonzalo A. Collado
PMPamela Muñoz
Pamela Muñoz
LSLucila Moreno Salas
Lucila Moreno Salas
Avian schistosomes are blood flukes parasitizing aquatic birds and snails, which are responsible for a zoonotic disease known as cercarial dermatitis, a hypersensitive reaction associated to the cutaneous penetration of furcocercariae. Despite its worldwide distribution, its knowledge is fragmentary in the Neotropics, with most of data coming from Argentina and Brazil. In Chile, there are only two mentions of these parasites from birds, and one human outbreak was associated to the genus “Trichobilharzia”. However, the identity of such parasites is pending. The aim of this study was to identify the furcocercariae of avian schistosomes from Southern Chile using an integrative approach. Thus, a total of 2283 freshwater snails from different families were collected from three different regions. All snails were stimulated for the shedding of furcocercariae, but only Chilina dombeyana (Chilinidae) from the Biobío region was found to be parasitized. The morphology and phylogenetic analyses of 28S and COI genes stated two lineages, different from Trichobilharzia, shared with Argentina. This study provides new information on Neotropical schistosomes, highlighting the need for major research on these neglected trematodes, which are considered to be emerging/re-emerging parasites in other parts of the globe as consequence of anthropogenic disturbances and climatic change. Highlights: 1. Two different lineages (Lineage I and II) were described and molecularly characterized (28S and COI genes); 2. Cercaria chilinae I y II are proposed as a synonymous of Lineage II. Thus, a total of four different lineages of avian schistosomes are related to Chilina spp.; 3. Chilina spp. represents an important intermediate host for avian schistosomes in South America, constituting a reservoir de schistosomes with zoonotic potential; 4. Coinfection between the two different lineages was found, a finding previously not reported for avian schistosomes; 5. Expansion in the geographic distribution of Nasusbilharzia melancorhypha from its original record in Argentina, with Chilina dombeyana as an additional intermediate host.

1 January 2021 in Revista Brasileira de Parasitologia Veterinária
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DBDIANA MARITZA ECHEVERRY BERRIO
DIANA MARITZA ECHEVERRY BERRIO
ASAdriana Santodomingo
Adriana Santodomingo
RTRichard Thomas
Richard Thomas
JGJorge González-Ugás
Jorge González-Ugás
POPablo Oyarzún-Ruiz
Pablo Oyarzún-Ruiz
Carlos Landaeta-AquevequeCarlos Landaeta-Aqueveque
Carlos Landaeta-Aqueveque
Trichinellosis is a zoonosis caused by nematodes of the Trichinella genus, of which 10 species have been described. Species identification when larvae is found is only possible using molecular tools. Meat from pigs and game animals not subjected to veterinary inspection are the main sources of human infections. The hunting of native carnivores is prohibited in Chile due to conservation issues and the fact that those animals favor pest control. The illegal hunting of a cougar (Puma concolor) occurred in September 2020. Herein, the molecular identification of Trichinella larvae, by analyzing nuclear (expansion segment V) and mitochondrial (cytochrome C oxidase subunit I) sequences are described. Both the amplification of the expansion segment V region and the phylogenetic analysis of a segment of a fragment of the cytochrome c-oxidase subunit I sequence confirmed that the larvae belonged to T. spiralis. The case described herein represents the first evidence of illegal hunting of a protected mammal infected with Trichinella in Chile, highlighting the ‘One Health’ perspective to face this disease in the rural-sylvatic interphase.

24 June 2023 in Animals
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POPablo Oyarzún-Ruiz
Pablo Oyarzún-Ruiz
RTRichard Thomas
Richard Thomas
ASAdriana Santodomingo
Adriana Santodomingo
JUJuan Esteban Uribe
Juan Esteban Uribe
MCMarlon Mauricio Ardila Chávez
Marlon Mauricio Ardila Chávez
AHAnaLía Henríquez
AnaLía Henríquez
In Chile, studies of parasites from the family Sarcocystidae (Apicomplexa) have mostly been related to domestic animals. We aimed to assess the presence of Sarcocystidae taxa in cricetid rodents from Central and Southern Chile. We studied 207 rodents, encompassing six species, from 13 localities. We isolated DNA from tissue samples, amplified the Sarcocystidae 18S rRNA gene with polymerase chain reaction, and performed phylogenetic analyses using maximum likelihood and Bayesian inferences. In addition, we examined blood smears and performed histological studies in organs from Sarcocystidae DNA-positive animals. Three specimens were DNA-positive and three genotypes were retrieved and named: Sarcocystis sp. P61, related to Sarcocystis strixi, was detected in two Abrothrix olivacea. Toxoplasmatinae gen. sp. P99 was retrieved from those same two specimens, and was related to Toxoplasma and other genera, although it branched independently. Besnoitia sp. R34 was detected in one Abrothrix hirta, and was clustered with congeneric species associated with rodents. No protozoa were found during microscopic studies; thus, it was not possible to confirm parasitic interactions rather than accidental encounters. However, the close relatedness of the retrieved genotypes to parasites of rodents supports the hypothesis of host–parasite associations. All three genotypes are suggested as potential new taxa, including a putative new genus.

3 February 1998 in Copeia
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Journal Article
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RTRichard Thomas
Richard Thomas
SHS. Blair Hedges
S. Blair Hedges