RESUMO
Wildlife diseases have implications for ecology, conservation, human health, and health of domestic animals. They may impact wildlife health and population dynamics. Exposure rates of coyotes (Canis latrans) to pathogens such as Yersinia pestis, the cause of plague, may reflect prevalence rates in both rodent prey and human populations. We captured coyotes in north-central New Mexico during 2005-2008 and collected blood samples for serologic surveys. We tested for antibodies against canine distemper virus (CDV, Canine morbillivirus), canine parvovirus (CPV, Carnivore protoparvovirus), plague, tularemia (Francisella tularensis), and for canine heartworm (Dirofilaria immitis) antigen. Serum biochemistry variables that fell outside reference ranges were probably related to capture stress. We detected antibodies to parvovirus in 32/32 samples (100%), and to Y. pestis in 26/31 (84%). More than half 19/32 (59%) had antibodies against CDV, and 5/31 (39%) had antibodies against F. tularensis. We did not detect any heartworm antigens (n = 9). Pathogen prevalence was similar between sexes and among the three coyote packs in the study area. Parvovirus exposure appeared to happen early in life, and prevalence of antibodies against CDV increased with increasing age class. Exposure to Y. pestis and F. tularensis occurred across all age classes. The high coyote seroprevalence rates observed for CPV, Y. pestis, and CDV may indicate high prevalence in sympatric vertebrate populations, with implications for regional wildlife conservation as well as risk to humans via zoonotic transmission.
Assuntos
Coiotes , Vírus da Cinomose Canina , Cinomose , Doenças do Cão , Infecções por Parvoviridae , Parvovirus Canino , Peste , Tularemia , Yersinia pestis , Animais , Cães , Humanos , Peste/epidemiologia , Peste/veterinária , Tularemia/epidemiologia , Tularemia/veterinária , Cinomose/epidemiologia , Estudos Soroepidemiológicos , New Mexico , Anticorpos Antivirais , Infecções por Parvoviridae/epidemiologia , Infecções por Parvoviridae/veterinária , Animais SelvagensRESUMO
BACKGROUND: The Hemagglutination assay (HA) is widely used in plague diagnosis, however, it has a subjective interpretation and demands high amounts of antigen and other immunobiological supplies. On the other hand, the conventional Anti-IgG ELISA is limited by the need of specific conjugates for multiple plague hosts, which leaves a gap for new diagnostic methods able to cover both the diagnosis of human cases and the epidemiological surveillance of multiple sentinel species. METHODS: We developed an ELISA Protein A-peroxidase method to detect anti-F1 antibodies across several species, including humans. To determine the cut-off and performance rates, HA results from 288 samples (81 rabbits, 64 humans, 66 rodents and 77 dogs) were used as reference. Next, we evaluated the agreement between Protein A-ELISA and Anti-IgG ELISA in an expanded sample set (n = 487). RESULTS: Optimal conditions were found with 250ng/well of F1 and 1:500 serum dilution. Protein A-ELISA showed high repeatability and reproducibility. We observed good correlation rates between the Protein A and IgG ELISAs optical densities and a higher positive/negative OD ratio for the Protein A-ELISA method. The overall sensitivity, specificity and area under the curve for Protein A-ELISA were 94%, 99% and 0.99, respectively. Similar results were observed for each species separately. In the analysis of the expanded sample set, there was a strong agreement between Protein A and IgG assays (kappa = 0.97). Furthermore, there was no cross-reaction with other common infectious diseases, such as dengue, Zika, Chagas disease, tuberculosis (humans) and ehrlichiosis, anaplasmosis and leishmaniasis (dogs). CONCLUSIONS: Altogether, the Protein A-ELISA showed high performance when compared both to HA and Anti-IgG ELISA, with a polyvalent single protocol that requires reduced amounts of antigen and can be employed to any plague hosts.
Assuntos
Peste , Animais , Cães , Ensaio de Imunoadsorção Enzimática/métodos , Humanos , Imunoglobulina G , Peste/diagnóstico , Peste/veterinária , Coelhos , Reprodutibilidade dos Testes , Roedores , Sensibilidade e Especificidade , Proteína Estafilocócica A , Zika virus , Infecção por Zika virusRESUMO
Plague is a flea-borne zoonosis that affects a wide range of mammals and still causes outbreaks in human populations yearly across several countries. While crucial for proper treatment, early diagnosis is still a major challenge in low- and middle-income countries due to poor access to laboratory infrastructure in rural areas. To tackle this issue, we developed and evaluated a new Fraction 1 capsular antigen (F1)-based rapid diagnostic test (RDT) as an alternative method for plague serological diagnosis and surveillance in humans and other mammals. In this study, 187 serum samples from humans, dogs, rodents and rabbits were retrospectively assessed using the plague RDT method. To calculate its performance, results were compared to those obtained by traditional hemagglutination (HA) and ELISA, which are well-established methods in the plague routine serodiagnosis. Remarkably, the results from RDT were in full agreement with those from the ELISA and HA assays, resulting in 100% (CI 95% = 95.5-100%) of sensitivity and 100% (CI 95% = 96.6-100%) of specificity. Accordingly, the Cohen's Kappa test coefficient was 1.0 (almost perfect agreement). Moreover, the RDT showed no cross-reaction when tested with sera from individuals positive to other pathogens, such as Y. pseudotuberculosis, Yersinia enterocolitica, Anaplasma platys, Ehrlichia canis and Leishmania infantum. Although preliminary, this study brings consistent proof-of-concept results with high performance of the Plague RDT when compared to HA and ELISA. Although further human and animal population-based studies will be necessary to validate these findings, the data presented here show that the plague RDT is highly sensitive and specific, polyvalent to several mammal species and simple to use in field surveillance or point-of-care situations with instant results.
Assuntos
Peste , Yersinia pestis , Animais , Testes Diagnósticos de Rotina , Cães , Humanos , Mamíferos , Peste/diagnóstico , Peste/epidemiologia , Peste/veterinária , Coelhos , Estudos RetrospectivosRESUMO
Plague is a low incidence flea-borne zoonosis that is often fatal if treatment is delayed or inadequate. Outbreaks occur sporadically and human cases are often preceded by epizootics among rodents. Early recognition of epizootics coupled with appropriate prevention measures should reduce plague morbidity and mortality. For nearly a century, the flea index (a measure of fleas per host) has been used as a measure of risk for epizootic spread and human plague case occurrence, yet the practicality and effectiveness of its use in surveillance programs has not been evaluated rigorously. We sought to determine whether long-term monitoring of the Xenopsylla flea index on hut-dwelling rats in sentinel villages in the plague-endemic West Nile region of Uganda accurately predicted plague occurrence in the surrounding parish. Based on observations spanning ~6 yr, we showed that on average, the Xenopsylla flea index increased prior to the start of the annual plague season and tended to be higher in years when plague activity was reported in humans or rodents compared with years when it was not. However, this labor-intensive effort had limited spatial coverage and was a poor predictor of plague activity within sentinel parishes.
Assuntos
Epidemias , Peste/epidemiologia , Peste/veterinária , Ratos , Espécies Sentinelas , Vigilância de Evento Sentinela/veterinária , Xenopsylla/fisiologia , Animais , Densidade Demográfica , Estações do Ano , Uganda/epidemiologiaRESUMO
Plague is a zoonosis caused by Yersinia pestis, whose cycle is based on a reservoir system composed of mammals and their fleas. Its transmission cycle presents long enzootic periods with undetected cases, sometimes misleading that the cycle is extinct. While surveillance activities in Brazil are being carried out only in some focal areas, the serologic results confirm the persistence of Y. pestis in all monitored areas. We studied the small mammal assembly and Y. pestis presencein the Borborema Plateau Focus within the state of Paraíba, which staged the last Brazilian plague outbreak (1986-1987), through aninventory and Y. pestis detection survey of small mammals in peridomestic and sylvatic areas from two municipalities in the state of Paraíba.The field sampling captured 45 specimens (27 marsupials, 18 rodents), of 10 species. Only two species (one marsupial, one rodent) were captured in both peridomestic and sylvatic ecotopes. The sylvatic ecotope had higher richness and abundance. No evidence of circulation of the pathogen was detected, however, this result does not discard the necessity of continuous epidemiological surveillance due to the risk of rekindling the foci after long dormant periods, especially given the current epidemiological transition occurring on a Global scale.
Assuntos
Reservatórios de Doenças/parasitologia , Mamíferos/parasitologia , Peste/veterinária , Sifonápteros/microbiologia , Yersinia pestis/isolamento & purificação , Animais , Brasil , Reservatórios de Doenças/classificação , Mamíferos/classificação , Marsupiais/microbiologia , Peste/transmissão , Roedores/microbiologia , Vigilância de Evento Sentinela/veterináriaRESUMO
Abstract INTRODUCTION: In Brazil, the plague is established in several foci located mainly in the northeastern part of the country, where it alternates between active and quiescent periods. These foci in the State of Ceará have high epidemiological importance. In addition to other plague detection activities, plague areas can be monitored through serological surveys of dogs and cats (domestic carnivores), which, following feeding on plague-infected rodents, can develop mild to severe forms of the disease and produce long-lasting antibodies. This study aimed to characterize the circulation dynamics and spatial distribution of Yersinia pestis antibodies in dogs and cats in plague foci areas of Ceará. METHODS: An ecological study was conducted to analyze the temporal series and spatial distribution of secondary data obtained from domestic carnivore serum surveillance in Ceará's plague areas from 1990 to 2014. RESULTS: Joinpoint analysis revealed that the overall trend was a reduction in antibody-positive animals. The mean proportion of antibody-positivity during the whole study period was 1.5% (3,023/203,311) for dogs, and 0.7% (426/61,135) for cats, with more than 4% antibody-positivity in dogs in 1997 and 2002. Antibody titers ranging from 1/16 to 1/64 were frequent. Despite fluctuations and a significant reduction, in recent years, there were antibody-positive animals annually throughout the study period, and the localities containing antibody-positive animals increased in number. CONCLUSION: Yersinia pestis is actively circulating in the study areas, posing a danger to the human population.
Assuntos
Animais , Gatos , Cães , Peste/veterinária , Yersinia pestis/imunologia , Doenças do Gato/epidemiologia , Doenças do Cão/epidemiologia , Anticorpos Antibacterianos/sangue , Peste/diagnóstico , Peste/imunologia , Peste/epidemiologia , Brasil/epidemiologia , Doenças do Gato/diagnóstico , Doenças do Gato/imunologia , Estudos Soroepidemiológicos , Vigilância da População , Prevalência , Doenças do Cão/diagnóstico , Doenças do Cão/imunologia , Análise Espaço-TemporalRESUMO
INTRODUCTION: In Brazil, the plague is established in several foci located mainly in the northeastern part of the country, where it alternates between active and quiescent periods. These foci in the State of Ceará have high epidemiological importance. In addition to other plague detection activities, plague areas can be monitored through serological surveys of dogs and cats (domestic carnivores), which, following feeding on plague-infected rodents, can develop mild to severe forms of the disease and produce long-lasting antibodies. This study aimed to characterize the circulation dynamics and spatial distribution of Yersinia pestis antibodies in dogs and cats in plague foci areas of Ceará. METHODS: An ecological study was conducted to analyze the temporal series and spatial distribution of secondary data obtained from domestic carnivore serum surveillance in Ceará's plague areas from 1990 to 2014. RESULTS: Joinpoint analysis revealed that the overall trend was a reduction in antibody-positive animals. The mean proportion of antibody-positivity during the whole study period was 1.5% (3,023/203,311) for dogs, and 0.7% (426/61,135) for cats, with more than 4% antibody-positivity in dogs in 1997 and 2002. Antibody titers ranging from 1/16 to 1/64 were frequent. Despite fluctuations and a significant reduction, in recent years, there were antibody-positive animals annually throughout the study period, and the localities containing antibody-positive animals increased in number. CONCLUSION: Yersinia pestis is actively circulating in the study areas, posing a danger to the human population.
Assuntos
Anticorpos Antibacterianos/sangue , Doenças do Gato/epidemiologia , Doenças do Cão/epidemiologia , Peste/veterinária , Yersinia pestis/imunologia , Animais , Brasil/epidemiologia , Doenças do Gato/diagnóstico , Doenças do Gato/imunologia , Gatos , Doenças do Cão/diagnóstico , Doenças do Cão/imunologia , Cães , Peste/diagnóstico , Peste/epidemiologia , Peste/imunologia , Vigilância da População , Prevalência , Estudos Soroepidemiológicos , Análise Espaço-TemporalRESUMO
Invasive transformer species change the character, condition, form, or nature of ecosystems and deserve considerable attention from conservation scientists. We applied the transformer species concept to the plague bacterium Yersinia pestis in western North America, where the pathogen was introduced around 1900. Y. pestis transforms grassland ecosystems by severely depleting the abundance of prairie dogs (Cynomys spp.) and thereby causing declines in native species abundance and diversity, including threatened and endangered species; altering food web connections; altering the import and export of nutrients; causing a loss of ecosystem resilience to encroaching invasive plants; and modifying prairie dog burrows. Y. pestis poses an important challenge to conservation biologists because it causes trophic-level perturbations that affect the stability of ecosystems. Unfortunately, understanding of the effects of Y. pestis on ecosystems is rudimentary, highlighting an acute need for continued research.
La Bacteria de la Peste como una Especie Transformadora en los Perritos de las Praderas y los Pastizales del Oeste de Norteamérica Resumen Las especies invasoras transformadoras cambian el carácter, la condición, la forma o la naturaleza de los ecosistemas y merecen atención considerable por parte de los científicos de la conservación. Aplicamos el concepto de especie transformadora a la bacteria de la peste Yersinia pestis en el oeste de Norteamérica, en donde el patógeno fue introducido alrededor de 1900. Y. pestis transforma los ecosistemas de pastizal al disminuir severamente la abundancia de los perritos de las praderas (Cynomys spp.) y por lo tanto causa declinaciones en la abundancia y diversidad de las especies nativas, incluidas las especies amenazadas y en peligro; altera las conexiones de las redes alimenticias; altera la importación y exportación de nutrientes; causa la pérdida de resiliencia del ecosistema ante las plantas invasoras; y modifica las madrigueras de los perritos. Y. pestis es un reto importante para los biólogos de la conservación ya que causa perturbaciones de nivel trófico que afectan la estabilidad de los ecosistemas. Desafortunadamente, el entendimiento de los efectos de Y. pestis sobre los ecosistemas es rudimentario, lo que resalta una necesidad aguda de investigación continua.
Assuntos
Cadeia Alimentar , Pradaria , Peste/veterinária , Doenças dos Roedores/microbiologia , Sciuridae , Yersinia pestis/fisiologia , Animais , Canadá , Conservação dos Recursos Naturais , Espécies Introduzidas , México , Peste/microbiologia , Estados UnidosRESUMO
If a parasite is not detected during a survey, one of two explanations is possible: the parasite was truly absent or it was present but not detected. We fit occupancy models to account for imperfect detection when combing fleas (Siphonaptera) from black-tailed prairie dogs (Cynomys ludovicianus) during June-August 2012 in the Vermejo Park Ranch, New Mexico, USA. With the use of detection histories from combing events during monthly trapping sessions, we fit occupancy models for two flea species: Oropsylla hirusta (a prairie dog specialist) and Pulex simulans (a generalist). Detection probability was <100% for both species and about 21% lower for P. simulans. Pulex simulans may be especially difficult to detect because it is about half the size of O. hirusta. Monthly occupancy (prevalence) for P. simulans was estimated at 24% (June, 95% confidence intervalâ=â19-30), 39% (July, 32-47), and 56% (August, 49-64) in new prairie dog colonies, and 43% (32-54), 61% (49-71), and 79% (70-87) in old colonies. These results suggest P. simulans can attain high prevalence on prairie dogs, especially in old colonies. If P. simulans is highly prevalent on prairie dogs, it may serve as a "bridge vector" between Cynomys and other mammalian hosts of the plague bacterium Yersinia pestis, and even function as a reservoir of Y. pestis between outbreaks.