RESUMEN
Infrared thermography has been used to help in diagnosing lameness. It is hypothesized that, if used in a routine basis, it could help in understanding musculoskeletal modifications during race training. This study aimed to evaluate thermal variation in the musculoskeletal regions of young Thoroughbred (TB) horses during their initial months of race training. Thermographic examinations were performed once every 2 weeks on 16 (10 male, 6 female) two-year-old TB racehorses, from arrival to the racetrack in June 2016, until January 2017, for a total of 16 evaluations. Thermographic imaging was performed using the appropriate protocol. Temperature (°C) was measured at the dorsal and palmar/plantar aspects of specific regions of interest (fetlock, metacarpal, metatarsal, carpal, tarsal, thoracolumbar, sacroiliac spine, and both hips). Initially, we found a thermal balance and all regions demonstrated a positive correlation with one another. However, a significant difference was noted between the left and right sides as training progressed. Four horses were withdrawn from the study after 50% of evaluations because of metacarpal conditions associated with training. Thermographic examination revealed changes before the clinical manifestation of these conditions. In conclusion, this study demonstrated that infrared thermography is an image technique that can facilitate understanding of musculoskeletal system modifications to race training and should be further investigated as a predictive tool to anticipate the occurrence of lesions.
Asunto(s)
Huesos del Metacarpo , Huesos Metatarsianos , Aclimatación , Animales , Femenino , Caballos , Articulaciones , Masculino , Termografía/veterinariaRESUMEN
The present experiment was conducted to evaluate and compare the impact of Ageratum conyzoides plant extract (ACE) with routinely used synthetic acaricides i.e., amitraz and coumaphos on the oogenesis of engorged adult females of Rhipicephalus microplus tick. On the day of dropping from the host, panoistic ovary of R. microplus appeared white in colour, horseshoe shaped, hollow tubular organ with immature oocytes predominantly in dorsal groove. Different developmental stages of oocytes (I-V) proceed simultaneously and asynchronously. Oocytes showed gradual increase in size, deep brown colored with accumulation of eggs in oviduct during 24-72â¯hours of development.At LC90 concentration a highly significant (pâ¯<â¯0.001) cessation of egg laying after exposure to amitraz and ACE while significant reduction (pâ¯<â¯0.01) of egg laying in coumaphos treated ticks was observed. Upon dissection of treated ticks, uterus and oviduct packed with eggs, which failed to pass out was observed. The histo-architectural alterations including presence of extensive vacuolation, alteration of oocyte morphology, deformation of chorion and disorganization of yolk granules were observed in the treated ovaries. Histochemically, low level of storage or synthesis of essential elements viz., proteins, polysaccharides and lipids in treated oocytes responsible for reduction of fertility and inhibition of progress of vitellogenesis was observed.
Asunto(s)
Acaricidas/farmacología , Ageratum/química , Cumafos/farmacología , Extractos Vegetales/farmacología , Rhipicephalus/efectos de los fármacos , Toluidinas/farmacología , Animales , Relación Dosis-Respuesta a Droga , Femenino , Oogénesis/efectos de los fármacos , Oogénesis/fisiología , Extractos Vegetales/química , Rhipicephalus/fisiologíaRESUMEN
INCOGARR is a thematic network recently approved to be financially supported by the Ibero-American Program of Science and Technology for Development (CYTED). The objectives of this Network are the design and evaluation of an efficient and feasible anti-tick vaccine candidate from the technical and economical points of view and also sharing experiences in the immunological control of ticks as part of an Integrated Control Program. The Network consists of seven laboratories and one company from six countries. The first meeting of the Network took place with the representation of each laboratory involved. In the meeting, general and specific objectives and activities of the Network were discussed and it was a very nice example of international collaboration to address an unsolved worldwide topic on tick control in which laboratories with different competencies and expertise join their efforts in a common goal.
Asunto(s)
Nanopartículas del Metal/química , Control de Ácaros y Garrapatas/métodos , Infestaciones por Garrapatas/prevención & control , Vacunas/uso terapéutico , Animales , Bovinos , Enfermedades de los Bovinos/prevención & control , Femenino , Seda/química , Vacunas/químicaRESUMEN
Rhipicephalus sanguineus sensu lato (s.l.) is a very common ectoparasite of domestic dogs able to transmit several pathogens of human and veterinary importance. Tick infestations and tick-borne diseases (TBDs) remain a serious and persistent problem, due to the lack of efficient control measures. It is therefore vital that novel approaches to control are pursued. Whilst vaccination is recognised as a potential control method to reduce tick infestation, no anti-R. sanguineus vaccine is available. Ticks depend on their blood meals to obtain nutrients and to achieve sexual maturity, which exposes them to vast amounts of iron. Although an essential molecule for several biological processes, its excess can lead to oxidative stress. Iron homeostasis is achieved with the help of iron-binding proteins called ferritins, among others, present in several tick tissues and developmental stages. These evolutionarily conserved proteins regulate iron homeostasis by storing and releasing iron in a controlled manner. In this study the R. sanguineus ferritin 1 gene was silenced through RNA interference (RNAi) in adult females exposed to an experimental infection with Ehrlichia canis. The purpose of this study was to assess the role of this protein in tick feeding, ovary development, oogenesis, and pathogen acquisition. Our data has shown that silencing ferritin 1 alters tick competence to normally engorge and causes morphologic and histochemical changes in the ovaries (OV) and oocytes. Furthermore, our data revealed that no E. canis DNA was found in either experimental group. Determining the function of molecules that act in key biological processes, such as blood digestion or reproduction, and that could be considered potential tick antigens will contribute towards the improvement of current control measures against these ectoparasites and the pathogens they vector.
Asunto(s)
Ehrlichia canis/fisiología , Ferritinas/metabolismo , Interferencia de ARN , Rhipicephalus sanguineus/metabolismo , Rhipicephalus sanguineus/microbiología , Animales , Ferritinas/genética , Regulación de la Expresión Génica , Interacciones Huésped-Patógeno , Masculino , ARN Mensajero/genética , ARN Mensajero/metabolismo , Rhipicephalus sanguineus/ultraestructuraRESUMEN
In this study, different geographical populations of Rhipicephalus sanguineus sensu lato were compared by molecular, biological, and morphometric methods. Phylogenetic trees were constructed using 12S and 16S rDNA sequences and showed two distinct clades: one composed of ticks from Brazil (Jaboticabal, SP), Cuba (Havana) Thailand (Bangkok) and the so-called "tropical strain" ticks. The second clade was composed of ticks from Spain (Zaragoza), Argentina (Rafaela, Santa Fe) and the so-called "temperate strain" ticks. Morphometric analysis showed good separation between females of the two clades and within the temperate clade. Males also exhibited separation between the two clades, but with some overlap. Multiple biological parameters revealed differences between the two clades, especially the weight of the engorged female. These results confirm the existence of at least two species under the name "R. sanguineus".
Asunto(s)
Rhipicephalus sanguineus/genética , Animales , ADN/genética , Conducta Alimentaria , Femenino , Masculino , Filogenia , ARN Ribosómico/genética , Reproducción/fisiología , Rhipicephalus sanguineus/fisiología , Rhipicephalus sanguineus/ultraestructuraRESUMEN
The sloth's giant tick Amblyomma varium Koch, which is a neotropical species that inhabits tropical rainforests, is the largest tick reported to date. The adult stage of this tick parasitizes mammals from the families Bradypodidae and Magalonychidae (Xenarthra) nearly exclusively. This study aimed to describe morphological and histological features of the reproductive system and the oocyte maturation process of this tick species. The ovary of A. varium is a long single tubular organ that is horseshoe-shaped, winding and arranged in the posterior part of the body. Two oviducts are connected to the ovary on each side; these thicken at certain region forming the uterus (common oviduct), followed by a muscular connecting tube, vagina and genital aperture. A large number of oocytes at different stages of development are attached to the ovary wall by the pedicel, as they reach maturity they are released into the ovary lumen and from there to the genital aperture. These oocytes develop simultaneously and asynchronically along the ovary. Amblyomma varium oocytes were classified into five development stages (i.e., I-V), and specific characteristics were observed; the processes of yolk and chorion deposition begin early in oocytes stage II, and oocytes V exhibit a very thick chorion and eggs of a large size. These characteristics are likely adaptations that enhance the survival and the reproductive success of this extremely host-specific tick, which is limited to a particular environment.
Asunto(s)
Ixodidae/anatomía & histología , Perezosos/parasitología , Animales , Brasil , Femenino , Histocitoquímica , Ixodidae/ultraestructura , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Oocitos/ultraestructura , Ovario/anatomía & histologíaRESUMEN
Ovarian development and egg maturation are essential stages in animal reproduction. For bisexual ixodid ticks, copulation is an important prerequisite for the completion of the gonotrophic cycle. In this study, we aimed to characterize the morpho-histological changes in the ovary and oocytes of the tick Rhipicephalus sanguineus, together with the identification of feeding and reproductive parameters associated with mating. Virgin and cross-mated females (with R. turanicus males) weighed 60% less at full engorgement than females mated conspecifically. In addition, the oocytes of these females did not develop to the same advanced stages as those of the conspecifically mated females. Sequencing of a 250-bp ITS-2 fragment in eggs that originated from a cross between an R. sanguineus female and an R. turanicus male showed a genotype similar (except by a deletion of 1 thymine) to that observed in the mother, arguing against fertilization by a trans-specific male. These findings suggest that male sex peptides are species-specific molecules that influence both full engorgement and oocyte maturation. Mechanical stimulation of the gonopore alone was insufficient for the completion of the entire process of vitellogenesis.
Asunto(s)
Copulación , Ixodidae/fisiología , Ovario/crecimiento & desarrollo , Animales , Cruzamiento , Femenino , Ixodidae/genética , Ixodidae/crecimiento & desarrollo , Masculino , Oocitos/citología , Oocitos/crecimiento & desarrollo , Oocitos/metabolismo , Ovario/citología , Ovario/metabolismo , Conejos , Especificidad de la Especie , Espermatozoides/metabolismo , VitelogénesisRESUMEN
Oocyte maturation in the thelytokous parthenogenetic tick Amblyomma rotundatum was examined for the first time using light and scanning electron microscopy. The panoistic ovary lacks nurse and follicular cells and is a single continuous tubular structure forming a lumen delimited by the ovarian wall. Oocytes of tick species are usually classified according to cytoplasm appearance, the presence of germinal vesicle, the presence of yolk granules, and the chorion. However, for this species, we also use oocyte size as an auxiliary tool since most oocytes were in stages I-III and were histologically very similar. Oocytes were classified into five development stages, and specific characteristics were observed: mature oocytes with thin chorion, pedicel cells arranged forming an epithelium with two or more oocytes attached by the same structure, and a large number of oocytes in the process of reabsorption.
Asunto(s)
Ixodidae/citología , Oocitos/citología , Animales , Femenino , Humanos , Ixodidae/crecimiento & desarrollo , Ixodidae/ultraestructura , Microscopía Electrónica de Rastreo , Oocitos/crecimiento & desarrollo , Oocitos/ultraestructura , Ovario/citología , Partenogénesis , VitelogénesisRESUMEN
Tick-borne zoonoses (TBZ) are emerging diseases worldwide. A large amount of information (e.g. case reports, results of epidemiological surveillance, etc.) is dispersed through various reference sources (ISI and non-ISI journals, conference proceedings, technical reports, etc.). An integrated database-derived from the ICTTD-3 project ( http://www.icttd.nl )-was developed in order to gather TBZ records in the (sub-)tropics, collected both by the authors and collaborators worldwide. A dedicated website ( http://www.tickbornezoonoses.org ) was created to promote collaboration and circulate information. Data collected are made freely available to researchers for analysis by spatial methods, integrating mapped ecological factors for predicting TBZ risk. The authors present the assembly process of the TBZ database: the compilation of an updated list of TBZ relevant for (sub-)tropics, the database design and its structure, the method of bibliographic search, the assessment of spatial precision of geo-referenced records. At the time of writing, 725 records extracted from 337 publications related to 59 countries in the (sub-)tropics, have been entered in the database. TBZ distribution maps were also produced. Imported cases have been also accounted for. The most important datasets with geo-referenced records were those on Spotted Fever Group rickettsiosis in Latin-America and Crimean-Congo Haemorrhagic Fever in Africa. The authors stress the need for international collaboration in data collection to update and improve the database. Supervision of data entered remains always necessary. Means to foster collaboration are discussed. The paper is also intended to describe the challenges encountered to assemble spatial data from various sources and to help develop similar data collections.
Asunto(s)
Vectores Arácnidos/microbiología , Bases de Datos como Asunto , Enfermedades por Picaduras de Garrapatas/microbiología , Garrapatas/microbiología , Zoonosis/microbiología , Animales , Países en Desarrollo , Geografía , Humanos , Enfermedades por Picaduras de Garrapatas/diagnóstico , Enfermedades por Picaduras de Garrapatas/epidemiología , Clima Tropical , Zoonosis/epidemiologíaRESUMEN
Histological features of Rhipicephalus sanguineus ticks fed on dog, a non resistant host, and on guinea pig, a resistant host, were compared. Unfed ticks and ticks from each host species were collected during first and third infestation and processed for histology. Many ticks from guinea pigs, especially during third infestation, were unattached, dehydrated and small. Only the midgut of ticks fed on guinea pigs had host leukocytes. Vacuolization of midgut cells was observed in all ticks, with exception of those fed on dogs for more than 96 h. Ticks of guinea pigs, particularly from third infestation, had vacuolated tracheae and swelling of malpighian tubules. Solely ticks from third infestation of guinea pigs displayed vacuolization of oocytes. Ticks fed on guinea pigs also had an increased number of guanine spherules. Observed alterations in ticks from guinea pigs are discussed.
Asunto(s)
Enfermedades de los Perros/parasitología , Rhipicephalus sanguineus/fisiología , Infestaciones por Garrapatas/veterinaria , Animales , Perros , Femenino , Tracto Gastrointestinal , Cobayas , Interacciones Huésped-ParásitosRESUMEN
OBJECTIVE: This study compared the histopathology of canine distemper virus (CDV)-induced keratoconjunctivitis sicca (KCS) to non-infectious KCS in conjunctival tissues. ANIMALS STUDIED: Forty mongrel dogs were assigned to three distinct groups: (i) non-infectious KCS (G1, n = 10), (ii) CDV-induced KCS (G2, n = 20), and (iii) healthy animals without any ocular alterations (G3, n = 10). PROCEDURE: IgG titers and physical and ophthalmic examinations (e.g. Schirmer tear test [STT], tonometry, biomicroscopy, indirect biomicroscopy, and fluorescein test) were performed on all dogs. Conjunctival biopsies were collected and examined microscopically. RESULTS: Non-infectious and CDV-induced KCS demonstrated similar histopathological changes. Both types of KCS correlated with low STT, conjunctival hyperemia, mucopurulent ocular discharge, predominant lymphoplasmacytic infiltration, and acantholysis and keratinization of the ocular surface. G1 had lower conjunctival goblet cell counts than G3. Inclusion bodies were sporadically found in conjunctival samples of dogs from G2. The severity of ocular lesions in G1 and G2 did not correlate with the histopathological findings. CONCLUSIONS: Dogs with non-infectious and CDV-induced KCS had very similar conjunctival histopathology. Our findings suggest that the pathophysiology of CDV-induced KCS is likely to be the same as non-infectious KCS, that is, a result of lacrimal deficiency and inflammation of the ocular surface.
Asunto(s)
Moquillo/complicaciones , Queratoconjuntivitis Seca/veterinaria , Animales , Anticuerpos Antivirales/sangre , Moquillo/patología , Virus del Moquillo Canino , Perros , Queratoconjuntivitis Seca/patología , Queratoconjuntivitis Seca/virologíaRESUMEN
Although Amblyomma brasiliense Aragão 1908 has been reported as one of the most aggressive ticks to humans in Brazil, information about the biology of this tick species is virtually inexistent. This work reports data on the life cycle of A. brasiliense fed on rabbits and pigs and maintained in an incubator at 20 degrees C, 90% RH and 12 h of light for off-host development. Tick yield of adult females fed on pigs and rabbits was 81.2% and 58.3%, respectively. Females fed on pigs had mean engorgement weight of 862.3 mg and egg mass of 208 mg, while females fed on rabbits had mean engorgement weight of 606.1 mg and egg mass of 160 mg; these values did not differ statistically between host species. Feeding period of female ticks fed on pigs (10 days) was significantly shorter than that on rabbits (17 days). Mean preoviposition period was slightly longer (35.9 days) for ticks fed on pigs than on rabbits (30 days). The minimum incubation period of eggs of ticks from both host species was similar and over 100 days. Egg production efficiency was low for females fed on both hosts (less than 30% and 20% for ticks from pigs and rabbits, respectively). More than 55% of larvae and 79% of nymphs fed on rabbits, set free inside the feeding chambers, engorged successfully. These ticks attained an engorgement weight of 1.3 and 18.2 mg, respectively, and fed for approximately 5 days. The minimum pre-molt period was 30 days for engorged larvae and over 44 days for nymphs. Molting success was low, less than 50% in the case of larvae and less than 20% for nymphs. Further studies are required to better determine the off-host requirements of this tick species.
Asunto(s)
Ixodidae/fisiología , Alimentación Animal , Animales , Animales de Laboratorio , Peso Corporal , Brasil/epidemiología , Femenino , Humanos , Ixodidae/crecimiento & desarrollo , Ixodidae/patogenicidad , Oviposición , Infestaciones por Garrapatas/epidemiologíaRESUMEN
The acquisition of resistance in goats against Amblyomma cajennense after repeated infestations and the role of inflammatory cells in this mechanism were investigated. Ten naive goats aged 6 months were distributed into two groups: test (n= 5), infested thrice at 30-day intervals; and control (n= 5), infested once. Nymphs (n= 115 per animal per infestation) were released inside alimentary chambers glued to the animal's dorsum and the following biological parameters were evaluated: yielding rate, nymphal engorgement weight, engorgement period, ecdise rate, and ecdise period. Skin fragments of tick bite sites were collected at 24, 48, 72, and 120 h post attachment for histopathology and inflammatory cells counts. The engorgement weight decreased significantly (P < 0.05) from the first infestation onward; nymphs weighed 41.7% and 37.1% less after the second and third infestations, respectively, as compared to those collected after the first infestation (12.55 mg +/- 3.21). Furthermore, the ecdise period increased significantly (P < 0.05) in the third infestation (18 days +/- 2.83) in comparison with the first infestation (15 days +/- 0.82) and the ecdise rate was significantly lower after the second infestation (71.91%+/- 17.38) in comparison with the first infestation (96.89%+/- 3.38). There were no significant differences with regard to both the engorgement period and yielding rate. A cutaneous basophilia was evidenced between 48 and 72 h (P < 0.05) after both the second and third infestations. We conclude that goats develop resistance against nymphs of A. cajennense and that basophils may play an important role in such a mechanism.
Asunto(s)
Basófilos/inmunología , Cabras/inmunología , Enfermedades de la Piel/inmunología , Garrapatas/fisiología , Animales , Basófilos/citología , Femenino , Masculino , Enfermedades de la Piel/patología , Garrapatas/crecimiento & desarrolloRESUMEN
This study investigated the development of resistance in guinea pigs to nymphs of Amblyomma triste ticks after repeated infestations. Guinea pigs were infested thrice, at 30-day intervals, with 30 nymphs of A. triste per animal per infestation. Acquisition of resistance was evaluated by determining: nymph yielding rate, engorgement period, and weight. Skin biopsies of tick bite sites were collected at 24, 48, and 96 h after tick attachment for inflammatory cell counts. Engorged nymphs weighed 5.53 mg +/- 1.9 in re-infested hosts (56.6% less than in primary infestation) and took 6.9 days +/- 2.16 to feed in the third infestation (14.5% more than in the first infestation). Guinea pigs yielded 78%+/- 7.2 of nymphs in the re-infestation (11.6% less than in the primary infestation). In addition, a marked increase in basophil influx was observed from the first infestation onward; 69% of infiltrated cells were basophils in re-infested hosts 24 h after tick attachment. No basophils were seen at this time in primary infested animals. That number increased to 84.7% 48 h post attachment in re-infested hosts (73.2% more than in the primary infested ones) and decreased markedly 96 h post attachment in both groups (2.6% and 1% of basophils in the third and first infestation, respectively). We conclude that guinea pigs acquire resistance against nymphs of A. triste ticks after repeated infestations and that a cutaneous basophilia must play a crucial role in such a mechanism.
Asunto(s)
Basófilos/inmunología , Enfermedades de la Piel/inmunología , Garrapatas/fisiología , Animales , Basófilos/citología , Femenino , Cobayas , Enfermedades de la Piel/patologíaRESUMEN
In this work, the biology, mitochondrial DNA and fertility of hybrids from two strains of Rhipicephalus sanguineus, from Brazil and Argentina, were compared. Engorged larvae, nymphs and adults from Argentina weighed more and the engorgement period of adult females was significantly longer than those of their Brazilian counterparts, whereas adult female tick yield rate was higher for the Brazilian strain. High intraspecific divergence of mitochondrial DNA was detected between R. sanguineus from Brazil and Argentina. On the other hand, a strong genetic relationship was detected between European and Argentinean R. sanguineus populations while the Brazilian population appeared to be related to the African Rhipicephalus turanicus. Adult hybrid females laid eggs, which were mostly unviable, whereas a mean of more than 1400 larvae hatched per egg mass from pure Brazilian and Argentinean strains. These results showed that differences between these strains are greater than previously assumed and that the biosystematic status of R. sanguineus ticks from South America should be re-evaluated. Wide variations, such as these might account for the reported worldwide differences in biology and vector capacity of this species.
Asunto(s)
Enfermedades de los Perros/parasitología , Ixodidae/clasificación , Animales , Argentina , Secuencia de Bases , Peso Corporal , Brasil , Cruzamientos Genéticos , ADN Mitocondrial/química , ADN Mitocondrial/genética , Perros , Conducta Alimentaria , Femenino , Fertilidad , Ixodidae/genética , Ixodidae/fisiología , Masculino , Datos de Secuencia Molecular , Filogenia , Reacción en Cadena de la Polimerasa/veterinaria , ARN Ribosómico/química , ARN Ribosómico/genética , Conejos , Alineación de Secuencia , Infestaciones por Garrapatas/parasitologíaRESUMEN
Casos de demodicose bovina foram observados em um rebanho da raça Sindhi no período de dezembro 1989 a janeiro 1992. Ambas as formas, localizada e generalizada, foram diagnosticadas. Este é o primeiro relato da forma generalizada no Brasil. Nos dois primeiros anos, a demodicose foi diagnosticada somente em animais < 2 anos, enquanto que nos dois últimos anos, animais de todas as idades estavam positivos. A prevalência variou de 20,4 por cento (11/54) a 53,1 por cento (26/49) e 13,2 por cento (12/91) a 14,8 por cento (9/61) nos animais com menos e mais de 2 anos de idade, respectivamente. Os sinais clínicos variaram de pequenos nódulos a espessamento da pele com nódulos grandes e moles, nas formas localizada e generalizada, respectivamente. Os principais achados histopatológicos dos nódulos cutâneos na forma generalizada foram: acantose com hiperqueratose, adenite sebácea crônica, necrose muscular subcutânea e degeneração focal de células da camada basal da epiderme, além da presença de grande número de ácaros de localização intraluminal nos terços médio e inferior de folículos pilosos dilatados. Observou-se ainda perifoliculite crônica, caracterizada por infiltrado celular predominantemente linfoplasmocitário contendo ainda macrófagos e neutrófilos, que envolvia bulbos pilosos. O estado nutricional precário dos animais e o estresse provocado pela longa estiagem, provavelmente, contribuíram para aumentar a suscetibili-dade do rebanho à infestação pelos ácaros.
Asunto(s)
Bovinos , Enfermedades Parasitarias en Animales/epidemiología , Infestaciones por Ácaros/epidemiologíaRESUMEN
In the present study we compared the immunological reactions between Rhipicephalus sanguineus tick-infested susceptible (dogs and mice) and tick-resistant hosts (guinea pigs), elucidating some of the components of efficient protective responses against ticks. We found that T-cells from guinea pigs infested with adult ticks proliferate vigorously in the presence of concanavalin A (ConA), whereas ConA-induced cell proliferation of tick-infested mice and dogs was significantly decreased at 43.1 and 94.0%, respectively, compared to non-infested controls. Moreover, cells from mice and dogs submitted to one or three successive infestations did not exhibit a T-cell proliferative response to tick antigens, whilst cells from thrice tick-infested guinea pigs, when cultured with either a tick extract or tick saliva, displayed a significant increase in cell proliferation. Also, we evaluated the response of tick-infested mice to a cutaneous hypersensitivity test induced by a tick extract. Tick-infested mice developed a significant immediate reaction, whereby a 29.9% increase in the footpad thickness was observed. No delayed-type hypersensitivity (DTH) reaction was detected. Finally, the differential cell count at the tick attachment site in repeatedly infested mice exhibited a 6.6- and 4.1-fold increase in the percentage of eosinophils and neutrophils, respectively, compared to non-infested animals, while a decrease of 77.0-40.9 in the percentage of mononuclear cells was observed. The results of the cutaneous hypersensitivity test and the cellular counts at the tick feeding site for mice support the view that tick-infested mice develop an immune response to R. sanguineus ticks very similar to dogs, the natural host of this species of tick, but very different from guinea pigs (resistant host), which develop a DTH reaction in addition to a basophil and mononuclear cell infiltration at the tick-attachment site. In conclusion, saliva introduced during tick infestations reduces the ability of a susceptible animal host to respond to tick antigens that could stimulate a protective immune response. As a consequence, the animals present a lack of DTH response and disturbed cellular migration to tick feeding site, which can represent a deficient response against ticks.
Asunto(s)
Antígenos/inmunología , Enfermedades de los Perros/inmunología , Enfermedades de los Perros/parasitología , Ixodidae/inmunología , Infestaciones por Garrapatas/inmunología , Infestaciones por Garrapatas/veterinaria , Animales , División Celular/inmunología , Concanavalina A/metabolismo , Susceptibilidad a Enfermedades/inmunología , Susceptibilidad a Enfermedades/parasitología , Susceptibilidad a Enfermedades/veterinaria , Perros , Femenino , Cobayas , Interacciones Huésped-Parásitos/inmunología , Hipersensibilidad/inmunología , Hipersensibilidad/parasitología , Hipersensibilidad/veterinaria , Masculino , Ratones , Ratones Endogámicos C3H , Saliva/inmunología , Saliva/parasitología , Piel/inmunología , Piel/parasitología , Linfocitos T/citología , Linfocitos T/inmunología , Linfocitos T/parasitología , Infestaciones por Garrapatas/parasitologíaRESUMEN
The dog is considered to be the natural host of Rhipicephalus sanguineus and is unable to develop appreciable resistance even after repeated feedings. The guinea pig develops strong resistance after one infestation with adult ticks. Antibody (IgG) titres against tick salivary gland antigens (SGAs) and blood leukocyte numbers in dogs and guinea pigs undergoing experimental R. sanguineus tick infestations were measured to detect a possible correlation with susceptibility or resistance of hosts. Since infested dogs develop an immediate hypersensitivity reaction to R. sanguineus antigens, total and anti-R. sanguineus SGA IgE levels were also measured in this host species. IgG and IgE antibody levels were determined by an enzyme-linked immunosorbent assay (ELISA) along three consecutive infestations of both hosts. Most dogs and guinea pigs displayed low IgG levels against R. sanguineus SGAs, though marked differences in individual response were observed. Although dog's total serum IgE levels increased significantly after infestations, no change in the amount of anti-salivary gland IgE was detected. Total and differential blood cell counts were determined in dogs and guinea pigs during primary and secondary infestation. In dogs, a tertiary infestation and a subsequent higher infestation level were also evaluated. Infested dogs did not display any alteration in blood leukocyte counts throughout the experiment. Guinea pigs, on the other hand, developed a significant basophilia during primary infestation which increased further during secondary infestation. These data reveal similarities and differences in the reactions of resistant and non-resistant hosts to ticks. They contribute for the understanding of such host-parasite relationships and will hopefully aid in the development of immune control of ticks.
Asunto(s)
Enfermedades de los Perros/inmunología , Enfermedades de los Perros/parasitología , Ixodidae/inmunología , Leucocitos/inmunología , Leucocitos/parasitología , Infestaciones por Garrapatas/inmunología , Infestaciones por Garrapatas/veterinaria , Animales , Enfermedades de los Perros/sangre , Perros , Ensayo de Inmunoadsorción Enzimática/veterinaria , Femenino , Cobayas , Hematócrito/veterinaria , Hemoglobinas/metabolismo , Interacciones Huésped-Parásitos/inmunología , Inmunoglobulina E/sangre , Inmunoglobulina G/sangre , Recuento de Leucocitos/veterinaria , Masculino , Glándulas Salivales/inmunología , Glándulas Salivales/parasitología , Infestaciones por Garrapatas/sangre , Infestaciones por Garrapatas/parasitologíaRESUMEN
This study was conducted in October 1998 and November 1999 in the Emas National Park (131,868 ha), a savanna-type cerrado region situated in the far south of Goias State, Brazil, near the geographic center of South America (15 degrees -23 degrees S; 45 degrees -55 degrees W). Animals were captured with the aid of nets and anesthetized (15 mg/kg ketamine + 1 mg/kg xylasine) in order to collect ticks for identification and to establish laboratory colonies. They included giant anteaters (Myrmecophaga tridactyla) (n = 4) and yellow armadillos (Euphractus sexcinctus) (n = 6). Free-living ticks (larvae, nymphs, and adults) were collected from the field by using a 1 x 2-m flannel cloth. Free-living ticks were identified as Amblyomma sp., A. cajennense, and A. triste. Adult ticks collected from anteaters were identified as Amblyomma cajennense and A. nodosum and from armadillos as A. pseudoconcolor and A. nodosum. The relevance of these host-tick relationships to possible mechanisms underlying emergence of tick-borne pathogens of importance to public health is discussed.
Asunto(s)
Armadillos/parasitología , Ixodidae/clasificación , Infestaciones por Garrapatas/veterinaria , Xenarthra/parasitología , Animales , Animales Salvajes , Brasil/epidemiología , Femenino , Interacciones Huésped-Parásitos , Humanos , Larva , Masculino , Ninfa , Salud Pública , Infestaciones por Garrapatas/epidemiología , Infestaciones por Garrapatas/parasitología , Enfermedades por Picaduras de Garrapatas/epidemiología , Enfermedades por Picaduras de Garrapatas/transmisión , Enfermedades por Picaduras de Garrapatas/veterinariaRESUMEN
Corneal degeneration may occur with a deposition of lipids or calcium, or both. Calcareous and lipid degeneration may be either primary or secondary, associated with systemic diseases such as primary hyperlipidemia, hyperlipidemia associated with hyperadrenocorticism, and hypothyroidism. The authors report a case of bilateral corneal lipid and calcium degeneration in a 7-year-old female Poodle with hyperadrenocorticism. The condition worsened with Lysodren therapy but responded to surgical excision.