RESUMEN
The Companion Animal Parasite Council hosted a meeting to identify quantifiable factors that can influence the prevalence of tick-borne disease agents among dogs in North America. This report summarizes the approach used and the factors identified for further analysis with mathematical models of canine exposure to tick-borne pathogens.
Asunto(s)
Enfermedades de los Perros/parasitología , Enfermedades por Picaduras de Garrapatas/veterinaria , Animales , Perros , Modelos Biológicos , Prevalencia , Factores de Riesgo , Sociedades Científicas , Infestaciones por Garrapatas/epidemiología , Infestaciones por Garrapatas/veterinaria , Enfermedades por Picaduras de Garrapatas/epidemiología , Garrapatas/clasificación , Estados Unidos/epidemiología , Medicina Veterinaria/organización & administraciónRESUMEN
Lyme disease, the most common vector-borne disease in the United States, is caused by a tick-borne infection with Borrelia burgdorferi. Currently, Ohio is considered by the Centers for Disease Control and Prevention (CDC) to be non-endemic for Lyme disease. The low incidence of Lyme disease in this state was largely attributed to the absence of the transmitting vector, Ixodes scapularis, commonly known as the blacklegged tick. However, a tick surveillance program established by Ohio Department of Health indicated that the number of I. scapularis in Ohio had increased sharply in recent years, from 0 - 5 ticks per year during 1983-2008 to 15 in 2009, 40 in 2010, and 184 in 2011. During the fall deer hunting season, examination of deer heads submitted to Ohio Department of Agriculture found 29 I. scapularis from 7 counties in 2010 and 1,830 from 25 counties in 2011. As of 2012, the tick had been found in 57 of the 88 counties of Ohio. In addition, all three active stages (larva, nymph, and adult) of I. scapularis were found in Tiverton Township of Coshocton County, demonstrating the presence of established tick populations at this central Ohio location. Of 530 nymphal or adult I. scapularis analyzed by quantitative polymerase chain reaction (qPCR), 32 (6.1%) tested positive for the B. burgdorferi flaB gene, ranging from 36 to 390,000 copies per tick. Antibodies to B. burgdorferi antigens were detected in 2 of 10 (20%) field-captured Peromyscus leucopus from Tiverton Township, and in 41 of 355 (11.5%) dogs residing in Ohio. Collectively, these data suggest that the enzootic life cycle of B. burgdorferi has become established in Ohio, which poses risk of Lyme disease to people and animals in the area.
Asunto(s)
Borrelia burgdorferi/aislamiento & purificación , Ixodes/crecimiento & desarrollo , Ixodes/microbiología , Animales , Anticuerpos Antibacterianos/sangre , Borrelia burgdorferi/genética , Ciervos/parasitología , Perros , Femenino , Flagelina/genética , Masculino , Ohio , Peromyscus/microbiología , Reacción en Cadena en Tiempo Real de la PolimerasaRESUMEN
Doxycycline is the treatment of choice for canine monocytic ehrlichiosis (CME), a well-characterized disease and valuable model for tick-borne zoonoses. Conflicting reports of clearance of Ehrlichia canis after treatment with doxycycline suggested that the disease phase during which treatment is initiated influences outcomes of these treatments. The purpose of this study was to evaluate the efficacy of a 28-day doxycycline regimen for clearance of experimental E. canis infections from dogs treated during three phases of the disease. Ten dogs were inoculated with blood from E. canis carriers and treated with doxycycline during acute, subclinical, or chronic phases of CME. Daily rectal temperatures and semiweekly blood samples were monitored from each dog, and Rhipicephalus sanguineus ticks were acquisition fed on each dog for xenodiagnosis. Blood collected from dogs treated during acute or subclinical CME became PCR negative for E. canis as clinical parameters improved, but blood samples collected from dogs treated during chronic CME remained intermittently PCR positive. R. sanguineus ticks fed on dogs after doxycycline treatments became PCR positive for E. canis, regardless of when treatment was initiated. However, fewer ticks became PCR positive after feeding on two persistently infected dogs treated with doxycycline followed by rifampin, suggesting that antibiotic therapy can reduce tick acquisition of E. canis.
Asunto(s)
Antibacterianos/uso terapéutico , Enfermedades de los Perros/tratamiento farmacológico , Doxiciclina/uso terapéutico , Ehrlichiosis/tratamiento farmacológico , Animales , Perros , Ehrlichia canis/genética , Ehrlichia canis/fisiología , Reacción en Cadena de la PolimerasaRESUMEN
Cimex lectularius (the "bedbug") is an insect that feeds nocturnally, taking a requisite blood meal from a sleeping human or other parasitized host. Immunological reactions to bedbug saliva vary, but typically, bites yield erythematous and pruritic papules. The face and distal extremities, areas uncovered by sleeping clothes or blankets, are preferentially involved. Until the late 1990s, bedbug infestations in the United States were declining. Resurgence is attributed to increased travel and resistance to insecticides. Although hepatitis or human immunodeficiency virus is not effectively transmitted by the bedbug, pruritus and the fear and perceived violation of an infestation can be debilitating. Bedbugs are small but robust, and their ability to remain ensconced in crevices within the bedroom makes eradication difficult. As more patients present with bedbug bites, physicians must possess the knowledge to diagnose, treat, and educate with regard to bedbug bites and bedbug infestations.
Asunto(s)
Chinches/parasitología , Mordeduras y Picaduras de Insectos/terapia , Animales , Vectores Artrópodos/parasitología , Ropa de Cama y Ropa Blanca/parasitología , Eritema/parasitología , Humanos , Mordeduras y Picaduras de Insectos/diagnóstico , Prurito/parasitología , Estados UnidosRESUMEN
The ehrlichioses have been subject to increasing interest from veterinary and public health perspectives, but experimental studies of these diseases and their etiologic agents can be challenging. Ehrlichia canis, the primary etiologic agent of canine monocytic ehrlichiosis, is relatively well characterized and offers unique advantages and opportunities to study interactions between a monocytotropic pathogen and both its vertebrate and invertebrate hosts. Historically, advances in tick-borne disease control strategies have typically followed explication of tick-pathogen-vertebrate interactions, thus it is reasonable to expect novel, more sustainable approaches to control of these diseases as the transmission of their associated infections are investigated at the molecular through ecological levels. Better understanding of the interactions between E. canis and its canine and tick hosts would also elucidate similar interactions for other Ehrlichia species as well as the potential roles of canine sentinels, reservoirs and models of tick-borne zoonoses. This article summarizes natural exposure studies and experimental investigations of E. canis in the context of what is understood about biological vectors of tick-borne Anaplasmataceae.
Asunto(s)
Vectores Arácnidos/fisiología , Ehrlichia canis/fisiología , Ehrlichiosis/epidemiología , Ixodidae/microbiología , Ixodidae/fisiología , Animales , Enfermedades de los Perros/microbiología , Enfermedades de los Perros/transmisión , Perros , Ehrlichiosis/transmisiónRESUMEN
The association between house dust mites (HDMs) and atopic dermatitis (AD) has long been a contested issue in both dermatology and allergy/immunology. As AD continues to burden millions of individuals and even whole societies, the commercial availability of a HDM allergen mix for epicutaneous testing has revived efforts to identify a definitive link between HDMs and AD. Conclusive evidence of a role for HDMs in the pathogenesis of AD would justify patch testing with mite allergens and would further the use of allergen-specific immunotherapy in the management of such patients; an absence of involvement would refocus our investigative efforts on other conspirators. We present a thorough review of the dissenting scientific evidence and expert opinions on this controversial topic. The association of HDMs with AD has remained elusive, and additional investigation is necessary to resolve this vexing riddle.
Asunto(s)
Alérgenos/efectos adversos , Dermatitis Atópica/etiología , Hipersensibilidad Tardía/etiología , Pyroglyphidae , Adulto , Alérgenos/química , Alérgenos/inmunología , Animales , Células Presentadoras de Antígenos/inmunología , Niño , Dermatitis Atópica/inmunología , Humanos , Hipersensibilidad Tardía/diagnóstico , Hipersensibilidad Tardía/inmunología , Pruebas del Parche , Pyroglyphidae/química , Pyroglyphidae/inmunología , Linfocitos T Colaboradores-Inductores/inmunologíaRESUMEN
The tropical cattle tick, Rhipicephalus (Boophilus) microplus, is an important ectoparasite of livestock in Thailand that causes economic losses due to the direct effects of tick feeding and by the pathogens they transmit. Intensive acaricide use has several drawbacks, which spurred efforts to develop anti-tick vaccines. Vaccines targeting concealed antigens localized in the tick midgut result in reduced tick fecundity, but molecules localized in the tick salivary glands, which could play a role in pathogen transmission, remain largely unexplored for R. microplus. Calreticulin (CRT) is a protein found in tick salivary glands and saliva, and CRT might facilitate tick feeding and pathogen transmission through anti-thrombotic and complement-inhibition activities. This then suggests that CRT should be evaluated as a vaccine candidate antigen to control cattle ticks in Thailand. The objective of this work was to clone, sequence, and analyze cDNA encoding CRT from salivary glands of R. microplus indigenous to Thailand. Nucleotide sequence analysis showed an open reading frame of 1233 bp. Comparison of the amino acid sequence showed 65-99% identities to other known CRTs from Oryctolagus cuniculus, Rattus norvegicus, Homo sapiens, Bos taurus, R. sanguineus, and R. microplus. The N- and P-domains of CRT were the most conserved, whereas the C-domain was high acid and more variable. CRT primary sequences were most conserved among mammals. Further investigations are warranted to determine whether immunization with Thai B. microplus CRT can affect tick performances and experimental pathogen transmission.
Asunto(s)
Calreticulina/química , Proteínas de Insectos/química , Glándulas Salivales/química , Garrapatas/química , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Calreticulina/genética , Clonación Molecular , Cartilla de ADN , ADN Complementario , Electroforesis en Gel de Agar , Proteínas de Insectos/genética , Datos de Secuencia Molecular , Homología de Secuencia de Aminoácido , TailandiaRESUMEN
Ehrlichia canis is the etiologic agent of canine monocytic ehrlichiosis (CME) and is a useful model for zoonotic tick-borne pathogens, many of which infect dogs. The purpose of this study was to evaluate rifampin and doxycycline regimens for clearance of E. canis infections in addition to alleviation of CME. Beagles were infected with E. canis by intravenous inoculation with carrier blood and treated with either rifampin or doxycycline after the acute phase of CME. Improved hematological values demonstrated that both treatments effectively relieved signs of the disease. Peripheral blood from all dogs became PCR negative after antibiotic treatment, suggesting that these infections were eliminated and that rifampin is an effective alternative chemotherapeutic agent for treatment of CME.
Asunto(s)
Enfermedades de los Perros/transmisión , Doxiciclina/farmacocinética , Ehrlichia canis/metabolismo , Ehrlichiosis/transmisión , Rifampin/farmacocinética , Animales , Enfermedades de los Perros/sangre , Perros , Ehrlichiosis/sangre , FemeninoRESUMEN
Human monocytic ehrlichiosis (HME) is a zoonotic emerging tick-borne disease with clinical signs that range from mild symptoms to multiple organ failure and death. Ehrlichia chaffeensis, the aetiologic agent of HME, is reported to infect a divergent range of mammals. Although cattle are common hosts of the primary vector of this pathogen, the susceptibility of this host to E. chaffeensis has not been reported to date. This study was undertaken to determine if cattle could provide a useful infection model of E. chaffeensis. Dairy calves were injected with DH82 cells infected with the Arkansas, St Vincent or 91HE17 strain of E. chaffeensis, and monitored for signs of clinical ehrlichiosis and for infection of peripheral blood and ticks by PCR assay. Splenectomized and spleen-intact calves were injected with cryopreserved stabilates of E. chaffeensis-infected DH82 cells for the first experiment. Mild clinical signs were occasionally observed among these calves, and only two blood samples were PCR-positive, while several ticks fed on each calf tested PCR-positive. The second experiment involved injection of normal calves with active cultures of the same E. chaffeensis strains. Interestingly, three of six calves inoculated with active cultures became recumbent and died or had to be euthanized. All of the surviving calves in this experiment tested PCR-positive on multiple dates, but fewer ticks fed on these calves were PCR-positive. These results suggest that a bovine disease model could facilitate the understanding of factors that affect the severity of HME.
Asunto(s)
Susceptibilidad a Enfermedades/veterinaria , Ehrlichia chaffeensis/patogenicidad , Ehrlichiosis/veterinaria , Animales , Bovinos , Ehrlichiosis/microbiología , Ehrlichiosis/patología , Humanos , Modelos Animales , Reacción en Cadena de la Polimerasa/veterinariaRESUMEN
Doxycycline generally alleviates clinical monocytic ehrlichiosis, but its efficacy in the control of monocytotropic ehrlichial pathogens requires further investigation. In this study, Ehrlichia canis was detected in dogs treated with doxycycline for 14 days and in ticks fed on these dogs, suggesting that treated dogs can remain reservoirs for E. canis.
Asunto(s)
Antibacterianos/uso terapéutico , Enfermedades de los Perros/tratamiento farmacológico , Doxiciclina/análogos & derivados , Ehrlichia canis , Ehrlichiosis/tratamiento farmacológico , Ehrlichiosis/veterinaria , Rhipicephalus sanguineus/microbiología , Animales , Vectores Arácnidos , Enfermedades de los Perros/microbiología , Perros , Doxiciclina/uso terapéutico , Ehrlichiosis/microbiología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Rhipicephalus sanguineus/crecimiento & desarrolloRESUMEN
The acquisition and transmission of rickettsial pathogens by different tick developmental stages has important epidemiological implications. The purpose of this study was to determine if male Rhipicephalus sanguineus can experimentally acquire and transmit Ehrlichia canis in the absence of female ticks. Two trials were performed where nymphal and male R. sanguineus were simultaneously acquisition fed on the same infected donor hosts, and transstadially or intrastadially exposed male ticks were fed on separate pathogen-free dogs as a test for transmission. A single-step p30-based PCR assay was used to test canine and tick hosts for E. canis infections before and after tick feeding. E. canis was detected after either intrastadial or transstadial passage in male ticks, the organism remained detectable in both tick groups after transmission feeding, and both tick groups transmitted the rickettsia to susceptible dogs. Infection of dogs via tick feeding resulted in milder clinical signs and lower antibody titers than intravenous inoculation of carrier blood, but further investigation is needed to understand the mechanisms responsible for this observation. These results demonstrate that male R. sanguineus can take multiple feedings, and that they can both acquire and transmit E. canis in the absence of female ticks. This tick development stage could be important in transmission of E. canis, and perhaps related pathogens, between vertebrate hosts under natural and experimental conditions.
Asunto(s)
Vectores Artrópodos/microbiología , Enfermedades de los Perros/microbiología , Enfermedades de los Perros/transmisión , Ehrlichia canis/crecimiento & desarrollo , Ehrlichiosis/transmisión , Ehrlichiosis/veterinaria , Ixodidae/microbiología , Animales , Anticuerpos Antibacterianos/sangre , Temperatura Corporal , ADN Bacteriano/química , ADN Bacteriano/genética , Enfermedades de los Perros/sangre , Perros , Ehrlichia canis/genética , Ehrlichiosis/sangre , Ehrlichiosis/microbiología , Femenino , Técnica del Anticuerpo Fluorescente/veterinaria , Hematócrito/veterinaria , Recuento de Leucocitos/veterinaria , Masculino , Recuento de Plaquetas/veterinaria , Reacción en Cadena de la Polimerasa/veterinaria , Organismos Libres de Patógenos EspecíficosRESUMEN
House dust mite allergens cause allergy and asthma in sensitized individuals. The allergens they produce are known to resist decay under natural household conditions and are thought to accumulate until removed. We sought to evaluate the effects of high temperature (96 degrees C) generated by a hard surface cleaner on live mite populations of American house dust mites, Dermatophagoides farinae Hughes and their allergens in carpet and mattresses. Statistically significant (P < 0.05) mite mortality (100%) was observed in response to treatment in both textile surfaces. Similar effects were observed on Der f1 fecal allergen. Allergen reductions in carpet with two or five pass treatment regimes were 61.4 and 100%, respectively. These results demonstrate the potential of employing a hard surface steam cleaner as a novel method to eliminate house dust mite populations and their allergens in a residential setting and appeal particularly promising as an environmental control strategy.
Asunto(s)
Alérgenos/aislamiento & purificación , Dermatophagoides farinae , Calor , Textiles/parasitología , Animales , Dermatophagoides farinae/inmunología , Desnaturalización Proteica , Industria Textil/métodosRESUMEN
Detection of Ehrlichia chaffeensis is necessary to study interactions between the parasite and its vertebrate and invertebrate hosts. The purpose of this study was to develop a sensitive, specific PCR assay for E. chaffeensis based on the outer membrane protein gene, p28. Candidate primer sets were identified and ranked based on annealing scores, similarities to three major p28 sequence clusters, dissimilarity to E. canis p30, an ortholog of p28, and the proximities of flanking primer sequences for nested PCR. The relative sensitivities of five optimized single-step and two nested PCR assays were determined, and the most sensitive assay was found to be a single-step PCR that was as much as 1000-fold more sensitive than a standard 16S rDNA-based nested PCR assay. This p28-based PCR assay amplified the target amplicon from isolates representative of all three major clusters of known p28 sequences, and this assay did not amplify template prepared from either of the two species most closely related to E. chaffeensis, E. canis and E. muris. These results indicate that this sensitive, specific and isolate-universal single-step PCR assay will be a useful tool in characterizing the transmission of this important zoonotic pathogen.
Asunto(s)
Proteínas de la Membrana Bacteriana Externa/genética , Cartilla de ADN , Ehrlichia chaffeensis/aislamiento & purificación , Ehrlichiosis/diagnóstico , Reacción en Cadena de la Polimerasa/métodos , Ehrlichia chaffeensis/genética , Humanos , Sistemas de Lectura Abierta/genéticaRESUMEN
OBJECTIVE: To use an amplified ELISA technique to document the presence and quantify the concentration of the house dust mite allergen, Der f 1, in skin and coat dust samples collected from dogs. ANIMALS: 29 pet dogs of various breeds. PROCEDURE: Dogs were weighed, and body surface area in square meters was determined. Skin and coat dust samples were obtained by vacuuming dogs. Collected dust was analyzed by use of standard and amplified ELISA techniques. RESULTS: By use of the standard ELISA technique, Der f 1 was detected in skin and coat dust samples from 6 of 29 (21%) dogs. Mean concentration of Der f 1 in the 6 samples with positive assay results was 16.16 ng/mL (range, 5.61 to 31.24 ng/mL). Samples with negative assay results were retested for dust mite allergen by use of an amplified ELISA technique; an additional 14 dogs had positive assay results. Mean concentration of allergen was 0.36 ng/mL (range, 0.19 to 2.20 ng/mL). Combining both techniques, 20 of 29 (69%) dogs had positive assay results for Der f 1. CONCLUSIONS AND CLINICAL RELEVANCE: Results of our study indicate that house dust mite allergens are present on the skin and in the coat of dogs, and this source of allergen may act as a reservoir for allergen exposure in hypersensitive dogs. Use of an amplified ELISA technique to determine environmental concentrations of house dust mite allergens in homes and on dogs will help to identify the relationship between immunologic findings and environmental exposures in dogs with atopic dermatitis.
Asunto(s)
Alérgenos/análisis , Antígenos Dermatofagoides/análisis , Ensayo de Inmunoadsorción Enzimática/métodos , Cabello/parasitología , Pyroglyphidae/inmunología , Piel/parasitología , Alérgenos/inmunología , Animales , Antígenos Dermatofagoides/inmunología , Proteínas de Artrópodos , Cisteína Endopeptidasas , Perros , Polvo , Cabello/inmunología , Piel/inmunologíaRESUMEN
Detection of vector-borne pathogens is necessary for investigation of their association with vertebrate and invertebrate hosts. The ability to detect Ehrlichia spp. within individual experimentally infected ticks would be valuable for studies to evaluate the relative competence of different vector species and transmission scenarios. The purpose of this study was to develop a sensitive PCR assay based on oligonucleotide sequences from the unique Ehrlichia canis gene, p30, to facilitate studies that require monitoring this pathogen in canine and tick hosts during experimental transmission. Homologous sequences for Ehrlichia chaffeensis p28 were compared to sequences of primers derived from a sequence conserved among E. canis isolates. Criteria for primer selection included annealing scores, identity of the primers to homologous E. chaffeensis sequences, and the availability of similarly optimal primers that were nested within the target template sequence. The p30-based assay was at least 100-fold more sensitive than a previously reported nested 16S ribosomal DNA (rDNA)-based assay and did not amplify the 200-bp target amplicon from E. chaffeensis, the human granulocytic ehrlichiosis agent, or Ehrlichia muris DNA. The assay was used to detect E. canis in canine carrier blood and in experimentally infected Rhipicephalus sanguineus ticks. Optimized procedures for preparing tissues from these hosts for PCR assay are described. Our results indicated that this p30-based PCR assay will be useful for experimental investigations, that it has potential as a routine test, and that this approach to PCR assay design may be applicable to other pathogens that occur at low levels in affected hosts.