Interactions between West Nile Virus and the Microbiota of Culex pipiens Vectors: A Literature Review.

The flavivirus West Nile virus (WNV) naturally circulates between mosquitoes and birds, potentially affecting humans and horses. Different species of mosquitoes play a role as vectors of WNV, with those of the Culex pipiens complex being particularly crucial for its circulation. Different biotic and abiotic factors determine the capacity of mosquitoes for pathogen transmission, with the mosquito gut microbiota being recognized as an important one. Here, we review the published studies on the interactions between the microbiota of the Culex pipiens complex and WNV infections in mosquitoes. Most articles published so far studied the interactions between bacteria of the genus Wolbachia and WNV infections, obtaining variable results regarding the directionality of this relationship. In contrast, only a few studies investigate the role of the whole microbiome or other bacterial taxa in WNV infections. These studies suggest that bacteria of the genera Serratia and Enterobacter may enhance WNV development. Thus, due to the relevance of WNV in human and animal health and the important role of mosquitoes of the Cx. pipiens complex in its transmission, more research is needed to unravel the role of mosquito microbiota and those factors affecting this microbiota on pathogen epidemiology. In this respect, we finally propose future lines of research lines on this topic.

Surveillance of avian malaria and related haemoparasites in common terns (Sterna hirundo) on the Atlantic coast of South America.

Haemosporidia (Apicomplexa, Haemosporida) are protozoa that infect vertebrate blood cells and are transmitted by vectors. Among vertebrates, birds possess the greatest diversity of haemosporidia, historically placed in 3 genera: Haemoproteus, Leucocytozoon and Plasmodium, the causative agent of avian malaria. In South America, existing data on haemosporidia are spatially and temporally dispersed, so increased surveillance is needed to improve the determination and diagnosis of these parasites. During the non-breeding season in 2020 and 2021, 60 common terns (Sterna hirundo) were captured and bled as part of ongoing research on the population health of migratory birds on the Argentinian Atlantic coast. Blood samples and blood smears were obtained. Fifty-eight samples were screened for Plasmodium, Haemoproteus and Leucocytozoon, as well as for Babesia parasites by nested polymerase chain reaction and by microscopic examination of smears. Two positive samples for Plasmodium were found. The cytochrome b lineages detected in the present study are found for the first time, and are close to Plasmodium lineages found in other bird orders. The low prevalence (3.6%) of haemoparasites found in this research was similar to those reported for previous studies on seabirds, including Charadriiformes. Our findings provide new information about the distribution and prevalence of haemosporidian parasites from charadriiforms in the southernmost part of South America, which remains understudied.

Tungiasis in a southern tamandua (Tamandua tetradactyla) from Formosa province, Argentina.

Tunga penetrans causes tungiasis, a parasitic disease of humans and domestic animals. In this work we report the presence of tungiasis in the southern tamandua (Tamandua tetradactyla) from Formosa, Argentina. An individual of southern tamandua was found dead on the roadside and it presented lesions consisted with neosomes located on its four limbs. We identified neosomes as T. penetrans. Records of T. penetrans in wild mammals acquire relevance because monitoring wildlife could help prevent possible outbreaks of tungiasis and other zoonosis.

Update of Dicrocoeliidae (Digenea) parasitizing rodents from the Americas with a description of a new Platynosomoides species from Argentina.

Digeneans are common parasites of small mammals. Dicrocoeliidae is a family with a cosmopolitan distribution, with 18 genera previously recorded from mammals in the Americas, six of them parasitizing rodents in Argentina. In this study, an updated compilation is provided of Dicrocoeliidae from rodents in the Americas. Also, a new Platynosomoides species is described parasitizing the cricetid rodent Akodon montensis of the Atlantic Forest in Argentina. Digital repositories were used to search for Dicrocoeliidae from rodents in the Americas. Rodents were collected in four localities of the Atlantic Forest, Argentina. Digeneans were removed from the rodent's bile duct, and conventional studies were used for the morphological description. A total of 15 Dicrocoeliidae species were found parasitizing 18 rodent species from eight countries in the Americas. The new species of Platynosomoides from Akodon montensis differs from the other two species of genus by the size of body, testes, ovary, cecum length and position and length of the vitelline bands. Dicrocoeliidae show growing diversity, and the compilation of species in a rodent host base allows a clearer comparison and identification of new taxa in the future.

Nutritional status, intestinal parasitic infections, and socio-environmental conditions in Mbyá-guaraní children: The current situation in communities in central Misiones, Argentina.

OBJECTIVES: Our previous research in Mbyá-guaraní communities of central Misiones showed high levels of growth stunting and intestinal parasites in children, as well as associations between these variables and deficient sanitary conditions. New studies were necessary to update the present health status of the previously studied Mbyá populations after around two decades. Therefore, we evaluated the current nutritional status, intestinal parasites, and socio-environmental conditions among Mbyá-guaraní children from these communities. METHODS: Body weight and height of 102 individuals (aged 2-14) were measured and nutritional status was estimated according to the World Health Organization criteria. Serial fecal samples and anal swabs were analyzed from 75 children (aged 1-14). Socio-environmental data were obtained from questionnaires. RESULTS: The prevalence of undernutrition was 31.4% and excess of weight was 10.8%. The prevalence of stunting and of overweight reached 30.4% and 8.8%, respectively. About 85% of the children were infected with at least one of the 14 species identified, and around 44% had multiple parasite infections. The most prevalent species were Enterobius vermicularis and hookworms. Among undernourished children, 88.2% were parasitized by at least one of the potentially pathogenic species detected. Most of the families lived in overcrowded conditions in precarious houses, defecated in latrines, and consumed well water. A higher risk of parasitosis was associated with the source of drinking water. CONCLUSIONS: Although the prevalence of undernutrition and intestinal parasites decreased compared with our previous studies, we still observed the coexistence of stunting, excess weight, and parasitic infections, in a context of socio-environmental vulnerability.

Percepción social sobre roedores urbanos y riesgo sanitario en barrios del Gran La Plata, Provincia de Buenos Aires, Argentina / Social perception on urban rodents and sanitary risk in neighborhoods from Gran La Plata, Province of Buenos Aires, Argentina

NTRODUCCIÓN: Los roedores sinantrópicos, representados por el ratón doméstico (Mus musculus), la rata parda (Rattus norvegicus) y la rata negra (Rattus rattus), representan un riesgo importante para la salud. En Sudamérica, la fragmentación socioeconómica se refleja en marcadas diferencias entre centros urbanos y áreas periféricas, y se asocia a un registro heterogéneo. El objetivo fue relevar datos por encuestas a los habitantes de dos barrios del Gran La Plata con características contrastantes para explorar, describir y evaluar la percepción en relación con la presencia de roedores en domicilio, peridomicilio y barrio como vehículos de transmisión de enfermedades. MÉTODOS: A partir de un diseño descriptivo exploratorio, se confeccionaron y realizaron encuestas siguiendo la técnica de muestreo estratificado. Se consideraron las variables género y grupo, de tal manera que la muestra tuviese la misma distribución. La información se transfirió a una base de datos y se analizó a través de IBM SPSS Statistics V25. RESULTADOS: Existe una preocupación común respecto al rol de los roedores urbanos como reservorios y fuentes de infección de patologías zoonóticas. En el barrio más vulnerable, la presencia de roedores fue más frecuente que en el centro de la ciudad. DISCUSIÓN: Este estudio provee un abordaje diferente en relación con roedores y patologías asociadas, considerando la percepción social y revelando su importancia para los programas de manejo y control.

Digenean parasites of Sigmodontinae rodents from Argentina: a list of species, new host, and geographical records.

INTRODUCTION: Among Argentinean rodents, only one species of Muridae and seven of Cricetidae were reported as digenean hosts. Despite the available data, the taxonomic diversity of the Digenea from rodents has been little explored. An update on digeneans of Sigmodontinae rodents (Cricetidae-Muroidea) in Cuenca del Plata is provided. New host and geographical data are recorded and taxonomic and ecological data are summarized. METHODS: Rodents were collected from 11 localities in the region Cuenca del Plata, Argentina. Moreover, other unidentified specimens from four localities, deposited in the Colección de Helmintología del Museo de La Plata, were studied. Prevalence, mean intensity, and mean abundance are provided. RESULTS: Eight species of digeneans belonging to four families were identified. Twelve new geographical records for five provinces of Argentina are presented. In addition, six new host-parasite associations are reported. The information is presented in a taxonomic list for each digenean species: site of infection, host records, locality records, and comments. CONCLUSIONS: It becomes interesting to explore the diets and habits of each rodent species to understand the dispersal and transmission ability of each group of digeneans. This survey constitutes an update on digeneans of Sigmodontinae rodents in Cuenca del Plata, Argentina.

A new species of Stilestrongylus (Nematoda, Heligmonellidae) from the Atlantic Forest of Misiones, Argentina, parasitic in Euryoryzomys russatus (Cricetidae, Sigmodontinae).

A new species of Heligmonellidae (Trichostrongylina, Heligmosomoidea), Stilestrongylus kaaguyporai n. sp. is described from the small intestine of Euryoryzomys russatus (Rodentia, Cricetidae, Sigmodontinae) from the Argentine Atlantic Forest, in the Misiones province. The new species was found at Campo Anexo Manuel Belgrano, Reserva de Vida Silvestre Urugua-í and Parque Provincial Urugua-í, with a prevalence of 73% in 15 hosts examined. Stilestrongylus includes 24 Neotropical species, all parasitic in rodents, mostly Sigmodontinae. Stilestrongylus kaaguyporai n. sp. can be differentiated from its congeners by the following characters: caudal bursa dissymmetrical with right lobe larger and pattern of type1-4 in both lobes, rays 6 not forming a lateral trident with rays 4 and 5, rays 8 with dissymmetrical pathway, genital cone hypertrophied with a conspicuous hood-like projection and females with a marked dorso-ventral torsion of the posterior end. This report is the second record of a Stilestrongylus species in E. russatus, increasing to nine the number of parasitic species known from this host.

Description of the helminth communities of sympatric rodents (Muroidea: Cricetidae) from the Atlantic Forest in northeastern Argentina.

Taxonomic and ecological aspects of the helminths found in the assemblage of sigmodontine rodents (Cricetidae-Muroidea) of the Atlantic Forest in Argentina are studied in this paper. The following species Akodon montensis, Brucepattersonius sp. and Thaptomys nigrita (Tribe Akodontini), as well as, Euryoryzomys russatus, Nectomys squamipes, Oligoryzomys nigripes, and Sooretamys angouya (Tribe Oryzomyini) are analyzed. A complete taxonomic list with a total of 25 species of helminths, including Digenea (Dicrocoeliidae), Cestoda (Hymenolepididae) and Nematoda (Trichuridae, Capillariidae, Cooperidae, Helligmonellidae, Oxyuridae, and Onchocercidae) is provided. Twenty new host and locality records for Misiones, Argentina, are reported and the results of the ecological descriptors of component communities are given. The highest value of richness was observed for A. montensis (S=8) and E. russatus (S=7). The diversity index (H´) reached values between 1.03 and 1.39 in all rodents, with the exception of N. squamipes that reached 0.75. The equitability indeces with highest value were observed for T. nigrita and E. russatus. The Berger-Parker index of dominance was similar for all host species. The highest prevalence, mean abundance and mean intensity values corresponded to Nippostrongylinae, followed by Syphacinii. This survey constitutes the report with the most diverse parasitic assemblage of rodents described for the Atlantic Forest ecoregion and for Argentina.

A new species of Syphacia (Seuratoxyuris) (Nematoda: Oxyuridae) from Sooretamys angouya Fischer, 1814 (Rodentia: Cricetidae) in Argentina.

Syphacia (Seuratoxyuris) hugoti n. sp. (Nematoda: Oxyuridae) is described from the cecum of Sooretamys angouya (Cricetidae: Sigmodontinae: Oryzomyini) captured in Formosa Province, Argentina. The diagnosis of the subgenus is emended, and the new species is separated from eight congeners by the distribution of submedian papillae and amphids, shape of the cephalic plate, presence of deirids, absence of cervical and lateral alae, length of the spicule, structure of the accessory hook of the gubernaculum and distance of excretory pore and vulva from the anterior extremity. The analysis suggests that S. (Se.) oryzomyos should be removed from Seuratoxyuris and redesignated as S. (Syphacia) oryzomyos n. comb. To date, of the species of Syphacia found in South and North American, 7 parasitize Oryzomyini rodents, of which two are distributed in Argentina. The present study constitutes the first record of the subgenus Seuratoxyuris from Argentina and the third record of a Syphacia species from rodents of the tribe Oryzomyini.

Redescription of Ingliseria cirrohamata (Linstow, 1888) (Nematoda: Acuariidae), including new hosts and geographical records.

Inglisera cirrohamata (Linstow, 1888) (Nematoda: Acuariidae) is redescribed based on specimens collected from the type host, Phalacrocorax verrucosus (Aves: Phalacrocoracidae), and the type locality, Kerguelen Island, in the southern Indian Ocean. Three new hosts and 2 new localities were recorded, i.e., Phalacrocorax [atriceps] albiventer and P. brasilianus from Puerto Madryn, Argentina and P. magellanicus from Puerto Williams, Chile. The structure of the cephalic ornamentations was observed and fully described. The presence of 6 pairs of postcloacal papillae is confirmed, a description of the tip of left spicule is given, and the presence of post-deirids is reported for the first time. This constitutes the first record of this nematode in South America and provides the first study of the genus by scanning electron microscopy.