High-resolution prediction models for Rhipicephalus microplus and Amblyomma cajennense s.l. ticks affecting cattle and their spatial distribution in continental Ecuador using bioclimatic factors.

In Ecuador, the main tick species affecting cattle are Rhipicephalus microplus and Amblyomma cajennense sensu lato. Understanding their spatial distribution is crucial. To assess their distribution, data from 2895 farms visited between 2012 and 2017 were utilized. Ticks were collected during animal inspections, with each farm's location georeferenced. Bioclimatic variables and vapor pressure deficit data were obtained from Climatologies at High resolution for the Earth´s Land Surface Areas (CHELSA) dataset. They were overlaid to develop predictive maps for each species using Random Forest (RF) models. The cross-validation results for RF prediction models showed high accuracy for both R. microplus and A. cajennense s.l. presence with values of accuracy = 0.97 and 0.98, sensitivity = 0.96 and 0.99, and specificity = 0.96 and 0.93, respectively. A carefully selected subset of bioclimatic variables was used to describe the presence of each tick species. Higher levels of precipitation had positive effect on the presence of R. microplus but a negative effect on A. cajennense s.l. In contrast, isothermality (BIO3) was more important for the presence of A. cajennense s.l. compared to R. microplus. As a result, R. microplus had a broader distribution across the country, while A. cajennense s.l. was mainly found in coastal areas with evident seasonality. The coexistence of both species in some regions could be attributed to transitional zones, whereas high altitudes limited tick presence. This information can aid in developing appropriate tick management plans, particularly considering A. cajennense s.l.'s broad host range species and R. microplus's specificity for cattle. Moreover, the predictive models can identify areas at risk of associated challenging hemoparasite, requiring special attention and mitigation measures.

Widespread resistance to macrocyclic lactones in cattle nematodes in Ecuador.

The aim of the present study was to assess the resistance status of bovine gastrointestinal nematodes (GINs) against ivermectin (IVM) and fenbendazole (FBZ) in Ecuador. The study involved five cattle farms located in different topographic zones of the country. Anthelmintic efficacy was assessed by calculating the percentage of fecal egg counts reduction (FECR) after treatment. Additionally, DNA from pooled larval cultures was screened to ascertain benzimidazole resistance alleles. For animals treated with IVM, FECR percentages ranged from 0 to 68%, indicating the presence of highly resistant worms. The opposite was found for animals treated with FBZ, where FECR percentages were above 90% on all the farms tested. Pooled coprocultures revealed that Cooperia spp. were the predominant species pre and post-treatment although minor proportions of Haemonchus spp. and Ostertagia spp. were also identified. No mutations conferring resistance to benzimidazoles were identified in the beta-tubulin isotype 1 gene of the isolated Cooperia spp. worms, which is in line with the results of the FECR performed with FBZ. Overall, the present study highlights widespread resistance of bovine GINs to IVM but no to FBZ in Ecuador.

Systematics and geographical distribution of Galba species, a group of cryptic and worldwide freshwater snails.

Cryptic species can present a significant challenge to the application of systematic and biogeographic principles, especially if they are invasive or transmit parasites or pathogens. Detecting cryptic species requires a pluralistic approach in which molecular markers facilitate the detection of coherent taxonomic units that can then be analyzed using various traits (e.g., internal morphology) and crosses. In asexual or self-fertilizing species, the latter criteria are of limited use. We studied a group of cryptic freshwater snails (genus Galba) from the family Lymnaeidae that have invaded almost all continents, reproducing mainly by self-fertilization and transmitting liver flukes to humans and livestock. We aim to clarify the systematics, distribution, and phylogeny of these species with an integrative approach that includes morphology, molecular markers, wide-scale sampling across America, and data retrieved from GenBank (to include Old World samples). Our phylogenetic analysis suggests that the genus Galba originated ca. 22 Myr ago and today comprises six species or species complexes. Four of them show an elongated-shell cryptic phenotype and exhibit wide variation in their genetic diversity, geographic distribution, and invasiveness. The remaining two species have more geographically restricted distributions and exhibit a globose-shell cryptic phenotype, most likely phylogenetically derived from the elongated one. We emphasize that no Galba species should be identified without molecular markers. We also discuss several hypotheses that can explain the origin of cryptic species in Galba, such as convergence and morphological stasis.

Prevalence of Fasciola hepatica infection in Galba cousini and Galba schirazensis from an Andean region of Ecuador.

Some Lymnaeid snails are intermediate hosts of the liver fluke Fasciola hepatica, the causal agent of fasciolosis, a zoonotic parasitic disease. Human and livestock fasciolosis has been reported in a highland community located in the Chimborazo Province of the Ecuadorian Andes. However, no previous study has been carried out to identify which snail species act as intermediate host/s of F. hepatica. This study first aimed to identify the intermediate snail species and secondly to determine the prevalence of natural infection with F. hepatica in 230 lymnaeid snails sampled from irrigation and drainage canals in this area. The first objective entailed observations of shell morphology and internal organs as well as sequencing of the cytochrome oxidase subunit 1 (COI) gene. For the second objective, we used classic parasitological methods (observation of rediae and cercarial emission) and PCR amplification specie-specific to F. hepatica. COI haplotype networks were built to elucidate phylogeographic relationships between the snail populations from this highland community with other American and worldwide populations. We identified two lymnaeid Galba cousini and Galba schirazensis and found high infection rates of F. hepatica in G. cousini, but these differed according to the method used, with PCR showing a higher rate (61 ± 20%) compared to rediae observation (29 ± 17%). F. hepatica in G. schirazensis was identified only by DNA amplification. G. cousini populations were genetically structured by geographic distance whereas G. schirazensis populations showed very low genetic diversity. The higher abundance and infection rate of G. cousini compared to G. schirazensis suggests that the former is likely the specie responsible for F. hepatica transmission in this region.

Serological evidence of Coxiella burnetii infection in cattle and farm workers: is Q fever an underreported zoonotic disease in Ecuador?

Background: Q fever is an underreported zoonotic disease of cattle and men in most countries of the world. Very little information about the prevalence of Coxiella burnetii infection in animals and humans comes from South and Central America and systematic studies are lacking. Methods: A seroprevalence survey for Q fever amongst cattle, farm workers and students was conducted in Ecuador using a commercial ELISA kit. Results: Survey results showed an unexpectedly high prevalence of Coxiella burnetii antibodies in dairy cattle (43%) and in farm workers (34%). In addition, a clinical case in a human of acute Q fever in the convalescent stage was detected. Conclusion: We conclude that the disease is endemic in Ecuador but is overlooked by medical and laboratory personnel. Q fever should be considered a public health issue in Ecuador and further research into the clinical relevance of this infection is recommended.

Bayesian Evaluation of Three Serological Tests for Detecting Antibodies against Brucella spp. among Humans in the Northwestern Part of Ecuador.

Brucellosis is an important but neglected zoonosis that causes serious economic losses both in livestock and human populations. The aim of the present study was to estimate the true prevalence of brucellosis together with diagnostic sensitivity and specificity of three serological tests in humans of the northwestern part of Ecuador using a Bayesian approach adjusted for the dependencies among the multiple tests to avoid any misinterpretation. In addition, the causal agent responsible for human brucellosis was also identified. Using a total of 3,733 samples collected from humans in this area between 2006 and 2008, the prevalence of human brucellosis and the diagnostic test characteristics of the Rose Bengal fast agglutination test (RBT), Wright's slow agglutination test with ethylenediaminetetraacetic acid disodium salt dehydrate (EDTA) (SAT-EDTA), and indirect ELISA (iELISA) were estimated using a Bayesian approach. The estimated true prevalence of human brucellosis was 1% (credibility interval: 0.4-1.6). The sensitivities of iELISA and RBT were higher than and similar (95.1% and 95.0%, respectively) to those of SAT-EDTA (60.8%). Even though all tests indicated a high specificity (> 99.0%), the specificity of SAT-EDTA was highest (99.9%). The circulating strain in this study area was identified to be Brucella abortus biotype 4 based on culture and microbiological characterization. The RBT and the iELISA are recommended for estimating the true prevalence of human brucellosis and/or for surveillance programs following their high sensitivities and specificities. The proposed strategy supports evidence-based medicine for clinicians and policy-makers to ensure appropriate preventive and control program of brucellosis worldwide.

A new multiplex PCR assay to distinguish among three cryptic Galba species, intermediate hosts of Fasciola hepatica.

A molecular tool described here allows in one step for specific discrimination among three cryptic freshwater snail species (genus Galba) involved in fasciolosis transmission, a worldwide infectious disease of humans and livestock. The multiplex PCR approach taken targets for each species a distinctive, known microsatellite locus which is amplified using specific primers designed to generate an amplicon of a distinctive size that can be readily separated from the amplicons of the other two species on an agarose gel. In this way, the three Galba species (G. cubensis, G. schirazensis, and G. truncatula) can be differentiated from one another, including even if DNA from all three were present in the same reaction. The accuracy of this new molecular tool was tested and validated by comparing multiplex PCR results with species identification based on sequences at mitochondrial and nuclear markers. This new method is accurate, inexpensive, simple, rapid, and can be adapted to handle large sample sizes. It will be helpful for monitoring invasion of Galba species and for developing strategies to limit the snail species involved in the emergence or re-emergence of fasciolosis.

Gastrointestinal parasites in captive and free-ranging Cebus albifrons in the Western Amazon, Ecuador.

Currently, there is a lack of surveys that report the occurrence of gastrointestinal parasites in the white-headed capuchin monkey (Cebus albifrons). We therefore assessed the presence and richness (= number of different parasite genera) of parasites in C. albifrons in wildlife refuges (n = 11) and in a free-ranging group near a human village (n = 15) in the Ecuadorian Amazon. In the 78 samples collected (median of 3 samples per animal), we identified a total of 6 genera of gastrointestinal parasites, representing protozoa, nematodes, acanthocephalans and cestodes. We observed a high prevalence (84%) across the 26 individuals, with the most prevalent parasite being Strongyloides sp. (76.9%), followed by Hymenolepis sp. (38.5%) and Prosthenorchis elegans (11.5%). We found Entamoeba histolytica/dispar/moskovskii/nuttalli and Capillaria sp. in only a minority of the animals (3.8%). In addition, we observed unidentified strongyles in approximately one-third of the animals (34.6%). We found a total of 6 parasite genera for the adult age group, which showed higher parasite richness than the subadult age group (5) and the juvenile age group (3). Faecal egg/cyst counts were not significantly different between captive and free-ranging individuals or between sexes or age groups. The free-ranging group had a higher prevalence than the captive group; however, this difference was not significant. The only genus common to captive and free-ranging individuals was Strongyloides sp. The high prevalence of gastrointestinal parasites and the presence of Strongyloides in both populations support results from previous studies in Cebus species. This high prevalence could be related to the high degree of humidity in the region. For the free-ranging group, additional studies are required to gain insights into the differences in parasite prevalence and intensity between age and sex groups. Additionally, our study demonstrated that a serial sampling of each individual increases the test sensitivity.

Is Galba schirazensis (Mollusca, Gastropoda) an intermediate host of Fasciola hepatica (Trematoda, Digenea) in Ecuador?

Fasciolosis is a widely distributed disease in livestock in South America but knowledge about the epidemiology and the intermediate hosts is relatively scarce in Ecuador. For three months, lymnaeid snails were sampled (n = 1482) in Pichincha Province at two sites located in a highly endemic area. Snails were identified (based on morphology and ITS-2 sequences) and the infection status was established through microscopic dissection and a multiplex polymerase chain reaction (PCR)-based technique. Techniques based on morphology were not useful to accurately name the collected snail species. Comparison with available DNA sequences showed that a single snail species was collected, Galba schirazensis. Live rediae were observed in 1.75% (26/1482) and Fasciola sp. DNA was detected in 6% (89/1482) of collected snails. The COX-1 region permitted identification of the parasite as Fasciola hepatica. The relative sensitivity and specificity of the microscope study, compared to PCR results, were 25.84% and 99.78%, respectively. The mean size of the snails recorded positive for F. hepatica through crushing and microscopy was significantly higher than the mean size of negative snails, but there was no such difference in PCR-positive snails. The role of G. schirazensis as an intermediate host of F. hepatica in Ecuador is discussed and the hypothesis of an adaptation of the parasite to this invasive snail is proposed. For the first time, an epidemiological survey based on molecular biology-based techniques assessed the possible role of lymnaeid snails in the epidemiology of fasciolosis in Ecuador.

Incidence of human Taenia solium larval Infections in an Ecuadorian endemic area: implications for disease burden assessment and control.

BACKGROUND: Human cysticercosis is a zoonotic disease causing severe health disorders and even death. While prevalence data become available worldwide, incidence rate and cumulative incidence figures are lacking, which limits the understanding of the Taenia solium epidemiology. METHODOLOGY/PRINCIPAL FINDINGS: A seroepidemiological cohort study was conducted in a south-Ecuadorian community to estimate the incidence rate of infection with and the incidence rate of exposure to T. solium based on antigen and antibody detections, respectively. The incidence rate of infection was 333.6 per 100,000 person-years (95% CI: [8.4-1,858] per 100,000 person-years) contrasting with a higher incidence rate of exposure 13,370 per 100,000 person-years (95% CI: [8,730-19,591] per 100,000 person-years). The proportion of infected individuals remained low and stable during the whole study year while more than 25% of the population showed at least one antibody seroconversion/seroreversion during the same time period. CONCLUSIONS/SIGNIFICANCE: Understanding the transmission of T. solium is essential to develop ad hoc cost-effective prevention and control programs. The estimates generated here may now be incorporated in epidemiological models to simulate the temporal transmission of the parasite and the effects of control interventions on its life cycle. These estimates are also of high importance to assess the disease burden since incidence data are needed to make regional and global projections of morbidity and mortality related to cysticercosis.

Human brucellosis in northwest Ecuador: typifying Brucella spp., seroprevalence, and associated risk factors.

Human brucellosis in Ecuador is underreported and based only on passive surveillance. Since 2008, brucellosis was removed from the list of communicable diseases in the country. Until now, the true human brucellosis picture has not yet been determined. The aim of this study was to determine the seroprevalence of the disease, identify risk factors associated with brucellosis seropositivity in humans, and isolate circulating strains of Brucella spp. in the northwestern part of Ecuador. Between 2006 and 2008, a large transect survey was conducted, based on blood sampling of people from the northwestern part of Ecuador (n=3733) together with an epidemiological inquiry. On the basis of three diagnostic tests used in parallel, the overall seroprevalence was estimated as 1.88% (95% confidence interval [CI] 1.48-2.38). Based on a multivariable random effects logistic regression analysis, the main risk factors associated with human brucellosis seropositivity were contact with livestock (odds ratio [OR]=3.0; CI 1.25-7.08), consumption of fetus and placenta (OR=2.5; CI 1.18-5.22), and involvement in activities at risk for brucellosis infection (OR=1.8; CI 1.00-3.35). Noticeable variation in brucellosis seropositivity among humans within cantons was observed. The circulating strain was Brucella abortus biotype 4. This study emphasized that contact with livestock, consumption of fetus and placenta, and occupational hazard group were all significant risk factors for the transmission of brucellosis among individuals in the northwestern part of Ecuador. Alongside encouraging the launching of educational campaigns against brucellosis, especially in rural areas where 36% of the population lives, controlling this zoonotic disease in animals will directly benefit its prevention in humans, especially because there is no safe and efficacious vaccine against brucellosis in humans.

Comparative intradermal tuberculin test in dairy cattle in the north of Ecuador and risk factors associated with bovine tuberculosis.

We studied the prevalence of bovine tuberculosis (BTB) in Mejia canton, the major dairy cattle production area in northern Ecuador. Twenty dairy herds comprising 2,022 cattle were selected. In 2007, each animal was tested using the comparative intradermal tuberculin test (CITT). In 2008, a follow-up test was performed in the same herds. The true annual incidence was 1.70%, and the true prevalence was 7.41% and 7.13% in 2007 and 2008, respectively. The prevalence was 0.27% and 0.57% in medium-sized herds in 2007 and 2008, respectively, compared with 8.63% and 8.43% in large herds (P < 0.01). The number of skin test-positive cases also increased significantly with age (P = 0.03), contacts with other species of animals (P < 0.01), and introduction of new cattle (P = 0.04). Herd prevalence was 55% in 2007 and 65% in 2008. This study shows the lack of knowledge in cattle farmers about this zoonosis and the necessity for a national BTB control program in Ecuador.