A new species of Trichuris Roederer, 1761 (Nematoda: Trichuridae) from <i>Heteromys gaumeri</i> Allen & Chapman (Rodentia: Heteromyidae) in Yucatan, Mexico

In Mexico, four species of Trichuris Roederer, 1761 have been recorded in wild rodents belonging to the family Heteromyidae. In the present paper, we describe a new species based on specimens collected from Heteromys gaumeri Allen & Chapman (Heteromyidae: Heteromyinae) in the tropical forests of the Yucatan Peninsula, Mexico. Trichuris silviae n. sp. can be differentiated from the congeners described in North and South American rodents by morphological and morphometric features, such as the possession of a wide spicular tube, a thicker proximal cloacal tube, a shorter distal cloacal tube and a cylindrical spicular sheath. This is the first description of a Trichuris spp. from heteromyid rodents in Mexico and the fourth in North America. Despite the broad distribution of Heteromys spp., few cases of Trichuris infection have been reported. Further studies are necessary to verify if the new species is present in other heteromyid rodents in order to increase our knowledge about its geographical and host distribution.Centro de Estudios Parasitológicos y de Vectore

Prevalence of Human Intestinal Entamoeba spp. in the Americas: A Systematic Review and Meta-Analysis, 1990–2022

Among the seven species of Entamoeba known to infect humans, E. histolytica is widely recognized as a pathogen. It is reported that Entamoeba infections are common in the developing world, but rare in developed countries. The best way to diagnose these protozoan parasites is to detect antigens or DNA in the stool. This study aimed to review the prevalence, distribution, and diagnosis methods of Entamoeba spp. infecting humans in the Americas between 1990 and 2022. A systematic review and meta-analysis were performed, including 227 studies on Entamoeba infections from 30 out of 35 American countries. The pooled prevalence of each species of Entamoeba was calculated using the random-effects model. The assignment of Entamoeba species was mainly performed by microscopy. The most widely distributed and prevalent species was E. coli (21.0%). Of the studies, 49% could not differentiate the species of the Entamoeba complex. The pathogenic species E. histolytica was distributed among 22 out of 30 American countries studied, with a pooled prevalence of 9%. Molecular data on Entamoeba species are still scarce. This is the first study that reviewed and summarized data on the prevalence of this protozoan genera among American countries.Fil: Servian, Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Helman, María Elisa. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Departamento de Epizootiología y Salud Pública. Laboratorio de Inmunoparasitología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Iglesias, María del Rosario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Panti May, Jesús Alonso. Universidad Autonoma de Yucatan (uady);Fil: Zonta, Maria Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Navone, Graciela Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; Argentin

Estudio histopatológico de tejido cardiaco de roedores infectados con Trypanosoma cruzi capturados en barrios suburbanos de Mérida, México

Introduction: Trypanosoma cruzi is the causal agent of the American trypanosomiasis, an endemic disease in México. The commensal rodents Mus musculus and Rattus rattus are reservoirs of this parasite, which invades cardiac fibers and develops parasite nests causing various lesions. Histopathological studies in naturally infected rodents are scarce.Objective: To describe the types and frequencies of microscopic lesions in cardiac tissue of M. musculus and R. rattus infected with T. cruzi captured in Mérida, México.Materials and methods: The rodents were captured in suburban environments of Mérida. Cardiac tissue was extracted and processed by the paraffin inclusion technique and hematoxylin and eosin stained. The observation was made with a conventional microscope and all the lesions, as well as their degree, were identified.Results: Eight tissue samples of M. musculus and seven of R. rattus were studied. Parasite nests were found in 7/15, specifically 3/8 in M. musculus and 4/7 in R. rattus. The inflammatory infiltrate was the most frequent lesion. Other lesions were: Degeneration of cardiac fibers (8/15), congestion of blood vessels (6/15), and necrosis (5/15).Discussion: The lesions we observed have been described in experimental animal models and in humans with American trypanosomiasis. The inflammatory infiltrate has been identified as the most significant lesion in humans and reservoirs in the chronic stage of the disease.Conclusion: The lesions we described are associated with T. cruzi infection, which confirms that the rodents studied are reservoirs of this parasite.Introducción. Trypanosoma cruzi es el agente causal de la tripanosomiasis americana, enfermedad endémica en México. Los roedores Mus musculus y Rattus rattus son reservorios del parásito, el cual invade las fibras cardiacas y desarrolla nidos parasitarios produciendo diversas lesiones. Los estudios histopatológicos en roedores naturalmente infectados son escasos.Objetivo. Describir los tipos y las frecuencias de las lesiones microscópicas en muestras de tejido cardiaco de M. musculus y R. rattus infectados con T. cruzi capturados en Mérida, México.Materiales y métodos. Los roedores se capturaron en los barrios suburbanos de Mérida. Se extrajo el tejido cardiaco y se procesó por la técnica de inclusión en parafina y tinción con hematoxilina y eosina. Su examen se hizo con un microscópico convencional y se determinaron todas las lesiones y su grado de afección.Resultados. Se trabajaron ocho muestras de tejido de M. musculus y siete de R. rattus. Se encontraron nidos parasitarios en siete del total de las muestras: en 3 de las 8 de M. musculus y en 4 de las 7 de R. rattus. Se observaron infiltrados inflamatorios en todas las muestras. Otras lesiones fueron la degeneración de las fibras cardiacas (8/15), la congestión de los vasos sanguíneos (6/15) y la necrosis (5/15).Discusión. Las lesiones observadas están descritas en los modelos animales experimentales y en los&nbsp; humanos con tripanosomiasis americana. Los infiltrados inflamatorios se han descrito como la lesión más significativa en los humanos y en los reservorios en la etapa crónica de la enfermedad.Conclusión. Las lesiones observadas están asociadas con la infección con T. cruzi, lo cual confirma que los roedores estudiados son reservorios de este parásito

Morphological and molecular characterization of Trichuris muris (Nematoda: Trichuridae): studies from two commensal rodent species

In this paper we re-describe Trichuris muris based on morphological data following isolation from two commensal rodent species, Mus musculus from Mexico and Rattus rattus from Argentina. Furthermore, we provide a molecular characterization based on mitochondrial (cytochrome c oxidase subunit 1 mitochondrial gene) and nuclear (internal transcribed spacer 2 region) markers in order to support the taxonomic identification of the studied specimens of T. muris from M. musculus. We distinguished T. muris from 29 species of Trichuris found in American rodents based on morphological and biometrical features, such as the presence of a spicular tube, length of spicule, size of proximal and distal cloacal tube and non-protrusive vulva. We suggest that spicular tube patterns can be used to classify Trichuris species in three groups. Considering that the diagnosis among the species of this genus is mainly based on morphometry, this proposal represents a relevant contribution. We provide molecular studies on two markers, making this the first contribution for T. muris in the Americas. This study makes an important contribution to the integrative taxonomy of cosmopolitan nematode species, and its correct determination from the parasitological study of commensal rodents.Fil: Panti May, Jesús Alonso. Universidad Autonoma de Yucatan (uady);Fil: Gómez Muñoz, María de Los Ángeles. Universidad Nacional del Nordeste; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Yeh Gorocica, A. B.. Universidad Autonoma de Yucatan (uady);Fil: Hernández Betancourt, S.. Universidad Autonoma de Yucatan (uady);Fil: Milano, F.. Universidad Nacional del Nordeste; ArgentinaFil: Galliari, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Robles, Maria del Rosario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; Argentin

Prevalence of Human Intestinal Entamoeba spp. in the Americas: A Systematic Review and Meta-Analysis, 1990–2022

Among the seven species of Entamoeba known to infect humans, E. histolytica is widely recognized as a pathogen. It is reported that Entamoeba infections are common in the developing world, but rare in developed countries. The best way to diagnose these protozoan parasites is to detect antigens or DNA in the stool. This study aimed to review the prevalence, distribution, and diagnosis methods of Entamoeba spp. infecting humans in the Americas between 1990 and 2022. A systematic review and meta-analysis were performed, including 227 studies on Entamoeba infections from 30 out of 35 American countries. The pooled prevalence of each species of Entamoeba was calculated using the random-effects model. The assignment of Entamoeba species was mainly performed by microscopy. The most widely distributed and prevalent species was E. coli (21.0%). Of the studies, 49% could not differentiate the species of the Entamoeba complex. The pathogenic species E. histolytica was distributed among 22 out of 30 American countries studied, with a pooled prevalence of 9%. Molecular data on Entamoeba species are still scarce. This is the first study that reviewed and summarized data on the prevalence of this protozoan genera among American countries.Centro de Estudios Parasitológicos y de Vectore

Population Characteristics of Human-Commensal Rodents Present in Households from Mérida, Yucatán, México

Anthropocommensal rodents live in close proximity to humans in many habitats around the world. They are a threat to public health because of the pathogens they carry. Recent studies in Mérida, Yucatán, México, have shown that commensal rodents harbor potential zoonotic pathogens such as bacteria, helminths, and viruses. In this study, we describe reproductive and demographic parameters of house mice and black rats present in households from Mérida, Yucatán, México, a municipality located in a tropical region in southern México. Rodents were trapped in 142 households within the municipality of Mérida from 2011 to 2014. A total of 832 rodents were trapped, constituting 556 (66.8%) house mice (Mus musculus) and 276 (33.2%) black rats (Rattus rattus). The sex ratio in mice was different than parity, while in rats it was 1:1. Mice in the weight class 8.1–12 g were most abundant in both females (52.9%) and males (57.2%). On the other hand, rats weighing ≤ 40 g (25% of females and 28.6% of males) were most abundant. The percentage of pregnancy in mice was 46.7%, whereas in rats it was 21.3%. The mean number of embryos was 4.7 and 5.8 in mice and rats, respectively. This study provides relevant demographic information on the ecology of commensal rodents from a tropical region of Latin America. We consider that our findings could be useful as a first step toward understanding the ecological behavior of rodent populations in tropical regions

Helminths of small rodents (Heteromyidae and Cricetidae) in the Yucatan Peninsula, Mexico: an integrative taxonomic approach to their inventory

In this survey, we inventoried the helminths of heteromyid and cricetid rodents captured in the Yucatan Peninsula from 2017 to 2019. Helminths were identified using morphological techniques (clearing, staining, and scanning electron microscopy). Also, the 28S rRNA gene of individuals from several helminth taxa was successfully amplified and sequenced. To confirm the identification at the generic level, and in some cases at the specific level, and the genealogical relationships of the parasites, phylogenetic analyses were performed with the new 28S sequences. We identified 22 species of helminths including three trematodes (Brachylaimidae, Dicrocoeliidae, and Microphallidae), five cestodes (Davaineidae, Hymenolepididae, and Taeniidae), and 14 nematodes (Trichuridae, Ancylostomatidae, Ornithostrongylidae, Heligmonellidae, and Oxyuridae) from Heteromys gaumeri (Heteromyidae), Ototylomys phyllotis, Oligoryzomys fulvescens, Peromyscus yucatanicus, Sigmodon toltecus, and Reithrodontomys gracilis (Cricetidae). The overall frequency of infection in small rodents was 84.1% (143/170); all specimens of H. gaumeri, S. toltecus and Ol. fulvescens were infected with helminths. In total, we provided 46 new sequences of the 28S gene from 17 species of helminths. Seven species are likely undescribed species, six are reported for the first time in rodents from Mexico, and 12 are new host records in the Americas. Before this study, 87 taxa of helminths had been reported from 35 cricetid and 12 heteromyid species in 21 Mexican states. Our findings increase to 93 the helminth taxa in these rodents, and to 36 the cricetid species parasitized by helminths. This large scale-survey is the first to use an integrative approach to inventory the helminths of wild small rodents in Mexico.Fil: Panti May, Jesús Alonso. Universidad Autónoma de Yucatán;Fil: Moguel Chin, Wilson Isaias. Universidad Autónoma de Yucatán;Fil: Hernández Mena, David Iván. Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional; MéxicoFil: Cárdenas-Vargas, Miguel Humberto. Universidad Autónoma de Yucatán; MéxicoFil: Torres Castro, Marco. Universidad Autónoma de Yucatán;Fil: García Prieto, Luis. Universidad Nacional Autónoma de México; MéxicoFil: Digiani, Maria Celina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología Invertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Hernández Betancourt, Silvia F.. Universidad Autónoma de Yucatán;Fil: Vidal Martínez, Víctor Manuel. Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional; Méxic

Population Characteristics of Rattus rattus and Mus musculus present in rural communities in Yucatán, México

The aim of this study was to describe the abundance, weight and body length structures, and reproductive and health status of the black rat Rattus rattus and the house mouse Mus musculus from Yucatán, México. Rodents were trapped from May to September 2016 in rural households in the communities Xkalakdzonot (XKA) and Paraíso (PAR). A total of 236 M. musculus and 127 R. rattus were trapped over 3880 trap-nights. In XKA, R. rattus was more abundant than M. musculus, whereas in PAR, M. musculus was notably dominant over R. rattus. The sex ratio was 1:1 in both rodent species. Rattus rattus in classes 40.1?80 g and 120?139 mm were more abundant, whereas M. musculus in classes 8.1?12 g and 70?79 mm were more abundant. Mus musculus had similar weight, body length and reproductive and health parameters between communities. The majority of specimens of trapped rodents had a good body condition and few individuals had wounds. The information generated in this study is basic for understanding the ecology of commensal rodents, the dynamics of rodent-associated zoonosis transmission, and to design of integrated control programs for rodents.Fil: Panti May, Jesús Alonso. Universidad Autonoma de Yucatan; MéxicoFil: Gurubel González, Yessica M.. Universidad Autonoma de Yucatan; MéxicoFil: Palomo Arjona, Eduardo E.. Universidad Autonoma de Yucatan; MéxicoFil: Cetina Trejo, Rosy C.. Universidad Autonoma de Yucatan; MéxicoFil: Machain Williams, Carlos. Universidad Autonoma de Yucatan; MéxicoFil: Robles, Maria del Rosario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Hernández Betancourt, Silvia F.. Universidad Autonoma de Yucatan; Méxic

Perceptions of rodent-associated problems: an experience in urban and rural areas of Yucatan, Mexico

Rodents are a threat to agriculture and homes, and are a public health risk. Local perceptions about rodents and the damage they cause are vital, as a first step, to the design and implementation of rodent control or educational programs. A total of 111 interviews were conducted in two urban neighborhoods and two rural villages in Yucatan, Mexico. More than 90% of the interviewed inhabitants perceived rodents as a problem. The fear of rodents (57%), damage to food and stocks (56%), and damage to clothes (34%), were the most cited problems. In the urban neighborhoods, the use of rodent control methods was more frequent (57%) than in the villages (33%) in this study. In addition, the percentage of damage to domestic appliances was lower in villages (10%) than in neighborhoods (33%). Our preliminary results suggest that rodent pests represent a threat to human health and to human food security in the studied sites.Facultad de Ciencias Naturales y MuseoCentro de Estudios Parasitológicos y de Vectore

Rickettsia typhi en roedores de una comunidad con antecedentes de tifo murino, de Yucatán, México.

Objetivo. Determinar la presencia de Rickettsia typhi en roedores sinantrópicos capturados en la comunidad rural de Bolmay, Yucatán, México, con antecedentes de tifo murino en sus habitantes. Materiales y métodos. Se examinaron 37 roedores: 30 Mus musculus, 6 Rattus rattus y 1 Heteromys gaumeri. Se obtuvo ADN total del bazo de los roedores. La identificación de R. typhi se realizó a través de la amplificación de un fragmento del gen htrA (proteína 17-kDa) por PCR punto final. Los productos positivos fueron purificados y enviados a secuenciación para su análisis de alineamiento con la herramienta BLAST. Resultados. La identificación de ADN rickettsial se logró en un 27% (10/37) de los roedores: siete M. musculus y 3 R. rattus. El análisis de alineamiento obtuvo porcentajes de identidades y coberturas del 97 - 99% para R. typhi, respectivamente. Conclusiones. El presente estudio sugiere la participación de los roedores sinantrópicos en el ciclo de transmisión del tifo murino en la región. Se describe la primera evidencia molecular de R. typhi en M. musculus de Yucatán, México