In the Dawn of an Early Invasion: No Genetic Diversity of Angiostrongylus cantonensis in Ecuador?

The nematode Angiostrongylus cantonensis has been reported worldwide. However, some basic questions remain unanswered about A. cantonensis in Ecuador: (1) Was the invasion of A. cantonensis in Ecuador unique, or did it occur in different waves? (2) Was this invasion as recent as historical records suggest? (3) Did this invasion come from other regions of South America or elsewhere? To address these issues, we assessed the genetic diversity of MT-CO1 gene sequences from isolates obtained in 11 of Ecuador's 24 provinces. Our Bayesian inference phylogenetic tree recovered A. cantonensis as a well-supported monophyletic group. All 11 sequences from Ecuador were identical and identified as AC17a. The haplotype AC17a, found in Ecuador and the USA, formed a cluster with AC17b (USA), AC13 (Thailand), and AC12a-b (Cambodia). Notably, all the samples obtained in Ecuadorian provinces' different geographic and climatic regions had no genetic difference. Despite the lack of genetic information on A. cantonensis in Latin America, except in Brazil, our finding differs from previous studies by its absence of gene diversity in Ecuador. We concluded that the invasion of A. cantonensis in Ecuador may have occurred: (1) as a one-time event, (2) recently, and (3) from Asia via the USA. Further research should include samples from countries neighboring Ecuador to delve deeper into this.

Pathological effects of ECHINOSTOMA PARAENSEI infection associated with pyogenic abscesses caused by PSEUDOMONAS AERUGINOSA in swiss mice / Efectos patológicos de la infección por ECHINOSTOMA PARAENSEI asociada a abscesos piógenos causados ​​por PSEUDOMONAS AERUGINOSA en ratones suizos / Efeitos patológicos da infecção por ECHINOSTOMA PARAENSEI associada a abscessos piogênicos causados ​​por PSEUDOMONAS AERUGINOSA em camundongos suíços

The trematode Echinostoma paraensei is an intestinal parasite transmitted by ingestion of the infectious stage of metacercariae. For scientific purposes, its life cycle has been maintained in the laboratory, allowing analysis using various biological approaches. Different parasite isolates have revealed atypical patterns of migration and establishment in ectopic sites in Swiss-Webster mice. During the investigation of the biological life cycle of an E. paraensei isolate from the silvatic rodent Nectomys squamipes collected in the municipality of Rio Bonito (State of Rio de Janeiro), a bacterial coinfection with Pseudomonas aeruginosa was observed, which produced anatomopathological alterations, mainly in the liver, bile ducts, pancreas, and small intestine. The main macroscopic signs were the whitish suppurative pyogenic punctual lesions. The histological sections stained by hematoxylin-eosin showed an intense inflammatory reaction formed by mononuclear cells and macrophages surrounding the bile ducts, although the hepatic parenchyma still presented its normal aspect. Thus, pyogenic abscesses can be associated with E. paraensei infection depending on the strain and aggravating pathogenesis in the definitive host.

El trematodo Echinostoma paraensei es un parásito intestinal transmitido por ingestión de la etapa infecciosa de las metacercarias. Para fines científicos, su ciclo de vida se ha mantenido en el laboratorio, lo que permite el análisis mediante diversos enfoques biológicos. Diferentes aislamientos de parásitos han revelado patrones atípicos de migración y establecimiento en sitios ectópicos en ratones Swiss-Webster. Durante la investigación del ciclo biológico de un aislado de E. paraensei del roedor silvático Nectomys squamipes colectado en el municipio de Rio Bonito (Estado de Rio de Janeiro), se observó una coinfección bacteriana con Pseudomonas aeruginosa, que produjo alteraciones anatomopatológicas, principalmente en el hígado, los conductos biliares, el páncreas y el intestino delgado. Los principales signos macroscópicos fueron las lesiones puntuales piógenas blanquecinas supurativas. Los cortes histológicos teñidos con hematoxilina-eosina mostraron una intensa reacción inflamatoria formada por células mononucleares y macrófagos que rodeaban las vías biliares, aunque el parénquima hepático aún presentaba su aspecto normal. Por tanto, los abscesos piógenos pueden asociarse con la infección por E. paraensei dependiendo de la cepa y agravando la patogenia en el hospedador definitivo.

O trematódeo Echinostoma paraensei é um parasita intestinal transmitido pela ingestão da fase infecciosa das metacercárias. Para fins científicos, seu ciclo de vida foi mantido em laboratório, permitindo análises por meio de diversas abordagens biológicas. Diferentes isolados de parasitas revelaram padrões atípicos de migração e estabelecimento em sítios ectópicos em camundongos Swiss-Webster. Durante a investigação do ciclo de vida biológico de um isolado de E. paraensei do roedor silvático Nectomys squamipes coletado no município de Rio Bonito (Estado do Rio de Janeiro), foi observada uma coinfecção bacteriana por Pseudomonas aeruginosa, que produziu alterações anatomopatológicas, principalmente no fígado, dutos biliares, pâncreas e intestino delgado. Os principais sinais macroscópicos foram as lesões pontuais piogênicas supurativas esbranquiçadas. Os cortes histológicos corados pela hematoxilina-eosina mostraram intensa reação inflamatória formada por células mononucleares e macrófagos circundando as vias biliares, embora o parênquima hepático ainda apresentasse seu aspecto normal. Assim, abscessos piogênicos podem estar associados à infecção por E. paraensei dependendo da cepa e agravando a patogênese no hospedeiro definitivo.

Helminth metacommunity structure of wild rodents in a preserved area of the Atlantic Forest, Southeast Brazil / Estrutura da metacomunidade de helmintos de roedores silvestres em uma área preservada da Floresta Atlântica, sudeste do Brasil

Abstract The helminth fauna and metacommunity structure of eight sympatric sigmodontine rodents were investigated at the Serra dos Órgãos National Park, an Atlantic Forest reserve located in the State of Rio de Janeiro, southeast Brazil. Rodents of the species Abrawayaomys ruschii, Akodon montensis, Blarinomys breviceps , Delomys dorsalis, Oligoryzomys flavescens, Oligoryzomys nigripes, Oxymycterus quaestor and Thaptomys nigrita were found infected with helminths. Akodon montensis presented the highest total helminth species richness, with six different species of helminths. The nematode Stilestrongylus lanfrediae was the most abundant and prevalent helminth species observed. The host-parasite network analysis showed little interactions among host species. Akodon montensis seems to act as a keystone-species in the rodent community. This species shared the nematodes Stilestrongylus aculeata with A. ruschii and Protospirura numidica criceticola with T. nigrita, and the cestode Rodentolepis akodontis with D. dorsalis. The congeners host species O. flavescens and O. nigripes shared the nematodes Guerrerostrongylus zetta and S. lanfrediae. The rodents B. breviceps and O. quaestor did not share any helminths with other hosts. The helminth metacommunity showed a random pattern on both infracommunity and component community levels, indicating different responses by each helminth species to the environmental gradient.

Resumo Foram investigadas a helmintofauna e suas estruturas da metacomunidade em oito roedores sigmodontíneos simpátricos ao longo do Parque Nacional da Serra dos Órgãos, uma reserva de Mata Atlântica no estado do Rio de Janeiro, Brasil. Roedores das espécies Abrawayaomys ruschii, Akodon montensis, Blarinomys breviceps, Delomys dorsalis, Oligoryzomys flavescens, Oligoryzomys nigripes, Oxymycterus quaestor e Thaptomys nigrita foram infectados por helmintos. Akodon montensis apresentou a maior riqueza total de espécies de helmintos, com seis espécies. O nematoide Stilestrongylus lanfrediae foi a espécie de helminto com maior abundância e prevalência. A análise de rede parasito-hospedeiro mostrou poucas interações entre as espécies hospedeiras e A. montensis atuou como uma espécie-chave na comunidade de roedores. Esta espécie compartilhou os nematoides Stilestrongylus aculeata com A. ruschii e Protospirura numidica criceticola com T. nigrita, e o cestoide Rodentolepis akodontis com D. dorsalis. As espécies congêneres O. flavescens e O. nigripes compartilharam os nematoides Guerrerostrongylus zetta e S. lanfrediae. Os roedores B. breviceps e O. quaestor não compartilharam helmintos com outros hospedeiros. A metacomunidade de helmintos mostrou um padrão aleatório em ambos os níveis, comunidade componente e infracomunidade, indicando diferentes respostas de cada espécie de helminto ao gradiente ambiental.

Helminth metacommunity structure of wild rodents in a preserved area of the Atlantic Forest, Southeast Brazil.

The helminth fauna and metacommunity structure of eight sympatric sigmodontine rodents were investigated at the Serra dos Órgãos National Park, an Atlantic Forest reserve located in the State of Rio de Janeiro, southeast Brazil. Rodents of the species Abrawayaomys ruschii, Akodon montensis, Blarinomys breviceps , Delomys dorsalis, Oligoryzomys flavescens, Oligoryzomys nigripes, Oxymycterus quaestor and Thaptomys nigrita were found infected with helminths. Akodon montensis presented the highest total helminth species richness, with six different species of helminths. The nematode Stilestrongylus lanfrediae was the most abundant and prevalent helminth species observed. The host-parasite network analysis showed little interactions among host species. Akodon montensis seems to act as a keystone-species in the rodent community. This species shared the nematodes Stilestrongylus aculeata with A. ruschii and Protospirura numidica criceticola with T. nigrita, and the cestode Rodentolepis akodontis with D. dorsalis. The congeners host species O. flavescens and O. nigripes shared the nematodes Guerrerostrongylus zetta and S. lanfrediae. The rodents B. breviceps and O. quaestor did not share any helminths with other hosts. The helminth metacommunity showed a random pattern on both infracommunity and component community levels, indicating different responses by each helminth species to the environmental gradient.

New records of three species of nematodes in Cerdocyon thous from the Brazilian Pantanal wetlands.

We report the occurrence of nematodes collected from the gut of roadkilled crab-eating foxes (two adult males and one juvenile female), Cerdocyon thous (Linnaeus, 1766), found on the BR 262 highway in Mato Grosso do Sul state, Brazil in 2011. Three helminth species were identified: Ancylostoma buckleyi, Pterygodermatites (Multipectines) pluripectinata, and Ascaridia galli. These nematodes are reported for the first time to infect C. thous from the Brazilian Pantanal wetlands, thereby expanding their geographical distribution.

New records of three species of nematodes in Cerdocyon thous from the Brazilian Pantanal wetlands / Novos registros de três espécies de nematoides em Cerdocyon thous do Pantanal brasileiro

We report the occurrence of nematodes collected from the gut of roadkilled crab-eating foxes (two adult males and one juvenile female), Cerdocyon thous (Linnaeus, 1766), found on the BR 262 highway in Mato Grosso do Sul state, Brazil in 2011. Three helminth species were identified: Ancylostoma buckleyi, Pterygodermatites (Multipectines) pluripectinata, and Ascaridia galli. These nematodes are reported for the first time to infect C. thous from the Brazilian Pantanal wetlands, thereby expanding their geographical distribution.

Este estudo relata a ocorrência de nematoides coletados no sistema digestório de cachorros-do-mato Cerdocyon thous (Linnaeus, 1766) encontrados atropelados na rodovia BR 262, no Estado do Mato Grosso do Sul, Brasil, em 2011. Três espécies foram identificadas: Ancylostoma buckleyi, Pterygodermatites (Multipectines) pluripectinata e Ascaridia galli. A ocorrência destes nematoides foi registrada pela primeira vez em C. thous no bioma Pantanal, ampliando a distribuição geográfica destes helmintos parasitos em C. thous.

Hematological and histopathological changes in Rattus norvegicus (Wistar) experimentally infected by Angiostrongylus cantonensis (Chen, 1935).

Eosinophilic meningitis caused by Angiostrongylus cantonensis is a zoonosis endemic to Southeast Asia and the Pacific islands. It is considered an emerging disease because it has been expanding both geographically and in terms of the range of hosts. In South America, the first cases were reported in Brazil and were attributed to eating infected snails. In this study, 70 adult females of Rattus norvegicus (Wistar) were used to evaluate hematology, blood gases, cardiac markers and lung histopathology changes caused by this parasite. Of them, 60 were individually infected by orogastric gavage with 100 L(3) larvae and 10 uninfected animals formed the control group. The results obtained demonstrate that infection caused by A. cantonensis in R. norvegicus promotes significant hematological changes induced in the vertebrate host, manifested mainly in the form of regenerative anemia, thrombocytopenia and eosinophilia. Additionally, histopathological changes in the lung parenchyma demonstrated in rodents reveal the occurrence of areas of necrosis and extensive fibrosis, being directly related to the development of cellular hypoxia and enzyme cardiac changes. This study can contribute to a better understanding of the relationship between A. cantonensis and R. norvegicus.

Metabolic and histopathological profile of Rattus norvegicus (Wistar) experimentally infected by Angiostrongylus cantonensis (Chen, 1935).

Eosinophilic meningitis is a disease characterized by increased eosinophils in the cerebrospinal fluid (CSF), which is the most commonly caused by invasion of the central nervous system by helminths, as occurs in Angiostrongylus cantonensis infections. The rodent Rattus norvegicus is the definitive natural host and humans act as accidental hosts and can become infected by eating raw or undercooked snails or food contaminated with infective L3 larvae. Recently in Brazil there have been four cases of eosinophilic meningitis due to ingestion of infected Achatina fulica. To evaluate biochemical and histopathological changes caused by this parasite, R. norvegicus were experimentally infected with 100 L3 larvae of A. cantonensis. After the anesthetic procedure, serum from the rodents was collected from the inferior vena cava for evaluation of the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALKP), gamma-glutamyl transferase (GGT), total protein and its fractions. During the necropsy, the liver was collected and weighed. Then a 1-g fragment was extracted from the major lobe to quantify the hepatic glycogen and fragment remainder was taken from the same lobe and fixed in Milloning's formalin for histopathological examination. Additionally, helminths were collected from the brain and lungs of the rodents. The activities of AST, ALT, ALKP and GGT in the serum and hepatic glycogen increased in response to infection, while the levels of globulin and total protein increased only in the eighth week of infection and there was a reduction in the levels of serum glucose. Albumin and bilirubin concentrations remained stable during the experiment. Infection with A. cantonensis caused metabolic and histopathological changes in the rodents. This study can contribute to a better understanding of the relationship between A. cantonensis and R. norvegicus.

Angiostrongylus cantonensis and rat lungworm disease in Brazil.

The metastrongyloid nematode genus Angiostrongylus includes 18 species, two of which are relevant from a medical standpoint, Angiostrongylus costaricensis and Angiostrongylus cantonensis. The first was described from Costa Rica in 1971 and causes abdominal angiostrongyliasis in the Americas, including in Brazil. Angiostrongylus cantonensis, first described in 1935 from Canton, China, is the causative agent of eosinophilic meningitis. The natural definitive hosts are rodents, and molluscs are the intermediate hosts. Paratenic or carrier hosts include crabs, freshwater shrimp, amphibians, flatworms, and fish. Humans become infected accidentally by ingestion of intermediate or paratenic hosts and the parasite does not complete the life cycle as it does in rats. Worms in the brain cause eosinophilic meningitis. This zoonosis, widespread in Southeast Asia and the Pacific islands, has now been reported from other regions. In the Americas there are records from the United States, Cuba, Jamaica, Brazil, Ecuador, and Haiti. In Brazil seven human cases have been reported since 2007 from the southeastern and northeastern regions. Epidemiological studies found infected specimens of Rattus norvegicus and Rattus rattus as well as many species of molluscs, including the giant African land snail, Achatina fulica, from various regions of Brazil. The spread of angiostrongyliasis is currently a matter of concern in Brazil.