NEW RECORDS OF HELMINTHS OF THE JAGUAR IN MEXICO, WITH AN UPDATED LIST OF SPECIES IN THE AMERICAS.

An inventory of parasites infecting the jaguar (Panthera onca) across its distribution range is relevant for the conservation of this threatened big cat. In this study, we report the occurrence of helminths in a jaguar from Mexico using morphological techniques (cleared and stained mounts and scanning electron microscopy) and partial sequences of the 28S ribosomal RNA (28S rRNA) gene and the cytochrome c oxidase 1 mitochondrial (COI) gene. We also provide an updated list of helminth species reported in jaguars in the Americas. Three helminth taxa are identified in the jaguar examined from Mexico: Toxocara cati, Physaloptera sp., and Taenia sp. The new 28S rRNA sequences of To. cati, Physaloptera sp., and Taenia sp. and the COI sequence of Taenia sp. corroborate the identity of the helminths isolated from this host. One hundred and twenty-nine records of helminths parasitizing jaguars from 49 studies up to May 2023 were identified in the Americas. In most of these studies (73.6%), helminths were identified using coproparasitological techniques. Sixteen helminths (7 nematodes, 5 cestodes, 3 acanthocephalans, and 1 trematode) were identified at the species level in free-ranging and captive jaguars. The study demonstrates the value of an integrative taxonomy approach to increase the accuracy of parasite identification in wildlife, especially when helminth specimens are scarce or poorly fixed.

Description of new species of Trematoda from bats of Southeastern Mexico and a new classification for Brachylecithum rileyi n. comb. (Dicrocoeliidae).

To date, 23 species of trematodes have been reported in bats from Mexico. However, in some regions of Mexico, such as the Yucatan Peninsula, many species of bats do not have helminthological records. Here, we sampled bats in four localities in Southeastern Mexico from April 2017 to February 2022. Parasites were collected from the intestine of four species of bats: Pteronotus fulvus, Eumops nanus, Noctilio leporinus and Nyctinomops laticaudatus. Conventional morphological techniques and molecular tools with the 28S ribosomal gene were used to describe the helminths. We discovered that our parasites represent three new species and a new combination of trematodes. We found that the new species have morphological differences with their congeneric species, and we complement this information whit molecular data. Furthermore, we found morphological and molecular evidence that places Dicrocoelium rileyi within the genus Brachylecithum. This study points out the importance of comparing morphological and phylogenetic information.

Survey on helminths of bats in the Yucatan Peninsula: infection levels, molecular information and host-parasite networks.

Helminth species of Neotropical bats are poorly known. In Mexico, few studies have been conducted on helminths of bats, especially in regions such as the Yucatan Peninsula where Chiroptera is the mammalian order with the greatest number of species. In this study, we characterized morphologically and molecularly the helminth species of bats and explored their infection levels and parasite­host interactions in the Yucatan Peninsula, Mexico. One hundred and sixty-three bats (representing 21 species) were captured between 2017 and 2022 in 15 sites throughout the Yucatan Peninsula. Conventional morphological techniques and molecular tools were used with the 28S gene to identify the collected helminths. Host­parasite network analyses were carried out to explore interactions by focusing on the level of host species. Helminths were found in 44 (26.9%) bats of 12 species. Twenty helminth taxa were recorded (7 trematodes, 3 cestodes and 10 nematodes), including 4 new host records for the Americas. Prevalence and mean intensity of infection values ranged from 7.1 to 100% and from 1 to 56, respectively. Molecular analyses confirmed the identity of some helminths at species and genus levels; however, some sequences did not correspond to any of the species available on GenBank. The parasite­host network suggests that most of the helminths recorded in bats were host-specific. The highest helminth richness was found in insectivorous bats. This study increases our knowledge of helminths parasitizing Neotropical bats, adding new records and nucleotide sequences.

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.

Evaluation of the impact of chemical control on the ecology of Rattus norvegicus of an urban community in Salvador, Brazil.

BACKGROUND: The presence of synanthropic rodents, such as Rattus norvegicus, in urban environments generates high costs of prophylaxis and control, in large part due to the environmental transmission of the pathogenic spirochete Leptospira interrogans, which causes leptospirosis. In Salvador, Brazil, The Center for Control of Zoonosis (CCZ) is responsible for planning and implementing Rodent Control Programs (RCP) which are based on chemical rodenticide. However, these strategies have not been standardized for use in developing countries. AIM: This study aimed to identify the effect of a chemical control campaign on the demographic variables of urban R. norvegicus, analyzing relative abundance, sex structure, body mass, and age of the population, as well as the characterization of spatial distribution among households, rodent capture campaigns and interventions. METHODS: This study was carried out during 2015 in three valleys of an urban poor community in Salvador. Individuals of R. norvegicus were systematically captured before (Pre-intervention) and three months (1st post-intervention) and six months (2nd post-intervention) after a chemical control intervention conducted by the CCZ in two valleys of the study area while the third valley was not included in the intervention campaign and was used as a non-intervention reference. We used analysis of variance to determine if intervention affected demographic variables and chi-square to compare proportions of infested households (Rodent infestation index-PII). RESULTS: During the chemical intervention, 939 households were visited. In the pre-intervention campaign, an effort of 310 trap nights resulted in 43 rodents captured, and in the 1st and 2nd, post-intervention campaigns resulted in 47 rodents captured over 312 trap nights and 36 rodents captured over 324 traps-nights, respectively. The rodent infestation index (PII) points did not show a reduction between the period before the intervention and the two periods after the chemical intervention (70%, 72%, and 65%, respectively). Regarding relative abundances, there was no difference between valleys and period before and two periods after chemical intervention (trap success valley 1: 0,18; 0,19; 0,18 / Valley 3 0,15; 0,17; 0,13/ P>0,05). Other demographic results showed that there was no difference in demographic characteristics of the rodent population before and after the intervention, as well as there being no influence of the application of rodenticide on the areas of concentration of capture of rodents between the campaigns. CONCLUSION: Our study indicates that the chemical control was not effective in controlling the population of R. norvegicus and provides evidence of the need for re-evaluation of rodent control practices in urban poor community settings.

Morphological and molecular identification of helminths of the greater bulldog bat Noctilio leporinus (Quiroptera: Noctilionidae) from Campeche, Mexico.

Surveys on parasites of bats from the Americas have been conducted, but information on helminths is still scarce, especially in the Neotropical region. In Mexico, there are species of bats that lack of a record for helminth species, such as members of the family Noctilionidae. The present study describes for the first time the helminths of Noctilio leporinus in Campeche, Mexico. In 2017, six specimens of N. leporinus were studied for helminths. The species identification of helminths was based on morphological studies and molecular analysis of fragments of the 28S rDNA. All bat specimens were infected for at least one helminth species. Three helminth taxa were identified: the trematode Pygidiopsis macrostomum, and the nematodes Tricholeiperia cf. proencai, and Heligmonellidae gen. sp. The morphological identification of P. macrostomum was confirmed by sequence analysis of 28S rDNA gene. The phylogeny of P. macrostomum grouped our sequence with other sequences of the same species collected in Brazil. The phylogenetic tree of Heligmonellidae gen. sp. indicated that the helminth belongs to clade formed by the species Odilia bainae, Nippostrongylus magnus and Nippostrongylus brasiliensis of the family Heligmonellidae. The phylogenetic analysis of the 28S sequences of T. cf. proencai did not show any similarity or close affinity with nematodes from which that gene has been sequenced to date. The findings of the present study increase the number of helminth species parasitizing bats in Mexico.

The genus Rickettsia in Mexico: Current knowledge and perspectives.

The genus Rickettsia encompasses 35 valid species of intracellular, coccobacilli bacteria that can infect several eukaryotic taxa, causing multiple emerging and re-emerging diseases worldwide. This work aimed to gather and summarise the current knowledge about the genus Rickettsia in Mexico, updating the taxonomy of the bacteria and their hosts by including all the records available until 2020, to elucidate host-parasite relationships and determine the geographical distribution of each Rickettsia species present in the country. Until now, 14 species of Rickettsia belonging to four groups have been recorded in Mexico. These species have been associated with 26 arthropod species (14 hard ticks, three soft ticks, two sucking lice, and seven fleas) and 17 mammal species distributed over 30 states in Mexico. This work highlights the high biological inventory of rickettsias for Mexico and reinforces the need to approach the study of this group from a One Health perspective.

Canine babesiosis: A literature review of prevalence, distribution, and diagnosis in Latin America and the Caribbean.

Canine babesiosis is a tick-borne disease with worldwide distribution and global significance. Traditionally, canine babesiosis was caused by B. canis (large Babesia) and B. gibsoni (small Babesia) based on cytological examination of stained blood smears. Currently, molecular techniques have demonstrated that several Babesia species infect dogs: B. canis, B. vogeli, and B. rossi (large forms) and B. gibsoni, B. conradae, and B. vulpes (small forms). In this study, we compiled and reviewed currently available data on Babesia infections in dogs in Latin America and the Caribbean, as well as on distribution of Babesia species with respect to prevalence, geographic location, and methods of detection. Forty-three studies on canine babesiosis published from 2005 to 2019 were included. The publications retrieved reported three species of Babesia (B. vogeli, B. gibsoni, and B. caballi) based on molecular confirmation of the species. Babesia vogeli was reported in Mexico, Costa Rica, Granada, Haiti, Nicaragua, Saint Kitts and Nevis, Trinidad and Tobago, Argentina, Brazil, Chile, Colombia, Paraguay, Peru, and Venezuela. In contrast, B. gibsoni was recorded in Costa Rica, Nicaragua, Saint Kitts and Nevis, and Brazil. Babesia caballi was found in a dog from Brazil. Babesia prevalence in dogs varied considerably based on parasite species and geographic location, with values close zero to 26.2%. Besides molecular techniques such as PCR, studies included examination of blood smears by microscopy and/or serologic tests. Few countries in the region, e.g., Brazil and Costa Rica, possess profound data availability, whereas the majority of them have scarce information or no data. A deeper understanding of the ecology and epidemiology of Babesia spp. in dogs is needed for the region.

Worldwide overview of human infections with Hymenolepis diminuta.

Hymenolepis diminuta is a zoonotic cestode parasitizing the small intestine of rodents (definitive hosts). Humans can accidentally enter into the life cycle of this tapeworm via the ingestion of infected insects (intermediate hosts) containing cestode cysticercoids in their body cavity. More than two centuries after the first record in humans, there are no accurate estimates of the number of human cases around the world. In order to have a more precise idea about the number of human cases with H. diminuta and the current status of the disease (hymenolepiasis) worldwide, we conducted a literature review of published records on human infection with H. diminuta. One thousand five hundred and sixty-one published records of infection with H. diminuta from 80 countries were identified. This review presents an estimate of the number of human cases with H. diminuta and a current overview of the prevalence, geographic distribution, symptoms, diagnosis, exposure to infective stages, and therapeutic approaches for this underestimated zoonotic tapeworm.

Morphological and molecular identification of hymenolepidid cestodes in children and synanthropic rodents from rural Mexico.

Hymenolepidid cestodes of synanthropic rodents represent a risk for public health. In order to describe the occurrence of hymenolepidids in children and the role of rodents as a potential source of infection, we conducted a morphological and molecular survey on cestodes in two rural villages from Yucatan, Mexico. One hundred and thirty-five stool samples from children (64 from Paraíso and 71 from Xkalakdzonot), 233 Mus musculus (159 from Paraíso and 74 from Xkalakdzonot) and 125 Rattus rattus (7 from Paraíso and 118 from Xkalakdzonot) were analyzed for the presence of cestodes. Three hymenolepidid species were identified morphologically: Hymenolepis nana in 7.8% of children from Paraíso, Hymenolepis microstoma in 4.4% of M. musculus from Paraíso and Hymenolepis diminuta in 15.3% of R. rattus from Xkalakdzonot. The molecular characterization and phylogenetic analysis based on mitochondrial cytochrome c subunit 1 (CO1) gene and ribosomal internal transcribed spacer 1 (ITS1) region, confirmed the identity of the three cestodes isolated from Yucatan. Phylogeny of the CO1 gene identified intraspecific genetic differences within H. nana ranging from 0 to 5%, in H. microstoma from 0 to 0.4%, and in H. diminuta ranged from 0 to 6.5% which suggests, the presence of complex species within H. nana and H. diminuta infecting humans and rodents, as reported by other authors. Based on the morphological and molecular results, and the epidemiological evidence, infections with H. nana suggest a non-zoonotic transmission; however, the presence of H. microstoma and H. diminuta in synanthropic rodents serve as a possible source for human infection.

Occurrence of intestinal parasites in Mayan children from Yucatán, Mexico.

Parasitic intestinal infections occur worldwide and affect the poorest and deprived populations. In Mexico, indigenous peoples live with the highest levels of poverty and marginalization. This study aimed to analyze the occurrence of intestinal parasites among Mayan children from the villages of Xkalakdzonot and Paraíso in Yucatán State. Stool samples from 83 children were examined using two coproparasitological tests (formalin-ethyl acetate concentration and FLOTAC Pellet techniques). The overall prevalence of intestinal parasites in children was 65.1%. Six protozoa and four helminths were identified. Blastocystis sp. (44.6%), Giardia intestinalis (26.5%), and Entamoeba coli (26.5%) were the most prevalent parasites. The prevalence of helminth infections (7.1%) was lower in children from Xkalakdzonot than in Paraíso (29.3%). The study provides relevant information on the occurrence of intestinal parasites in Mayan children from two villages. This data, therefore, can be used by local health authorities to plan appropriate programs for parasite control, considering suitable drug therapies and health education.

A checklist of the helminth parasites of sympatric rodents from two Mayan villages in Yucatán, México.

In this survey, 19 species of helminths including Cestoda (Davaineidae, Hymenolepididae, and Taeniidae), Acanthocephala (Oligacanthorhynchidae), and Nematoda (Trichuridae, Ornithostrongylidae, Heligmonellidae, Oxyuridae, and Gongylonematidae) from Rattus rattus, Mus musculus, Sigmodon toltecus, Heteromys gaumeri, and Peromyscus yucatanicus in two Mayan villages in Yucatán, México, were recorded. Ten species of helminths were collected in both localities. The highest species richness was recorded in R. rattus from Xkalakdzonot (6 taxa). Twelve species are new records for Yucatán and two are registered for the first time in México. This survey constitutes the first checklist of helminth parasites in small rodents in the south-southeast of México.

Survey of intestinal helminths collected from pet rodents in México.

In this survey, intestinal helminths from pet rodents in Mérida, México, were analyzed. A total of 46 mice Mus musculus, 28 hamsters Mesocricetus auratus, 23 rats Rattus norvegicus, and 1 gerbil Meriones unguiculatus were purchased from six pet shops and one black market for wildlife in the city of Mérida. The overall prevalence of helminths in rodents was 61.2% (60/98). Six species of helminths were identified: the zoonotic cestode Rodentolepis nana, and the nematodes Aspiculuris tetraptera, Dentostomella translucida, Syphacia obvelata, Syphacia mesocriceti, and Syphacia muris. Of the 60 infected rodents, 25 (41.7%) harbored 2 or 3 species of helminths. Rodentolepis nana was found in 4.3% of mice and 17.9% of hamsters. This is the first report of infection with S. muris in pet rats. Considering the close physical contact between pet rodents and humans, the presence of R. nana in pets represents a potential risk of transmission, especially to children and immunocompromised individuals.

A new species of Trichuris Roederer, 1761 (Nematoda: Trichuridae) from Heteromys gaumeri 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.

Detection of Rickettsia felis in Wild Mammals from Three Municipalities in Yucatan, Mexico.

The aim of this study was to provide information of the occurrence of Rickettsia felis in wild mammals from three municipalities in Yucatan, Mexico. The reactivity of rodent serum to Rickettsia antigens was detected in 80.9% (17 of 21) samples using immunofluorescence assay. Polymerase chain reaction identified rickettsial DNA in spleens of 43.5% (10 of 23) rodents and 57.1% (4 of 7) opossums. The identification of the rickettsial DNA was confirmed as R. felis by restriction fragment length polymorphism and DNA sequencing. This study comprises the first report of R. felis detection in wild mammals in Yucatan.