Feeding systemic insecticides to cattle for control of the tropical horse tick.
Explore the source record for details and available documents.
SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
House-dust-mite allergen is one of the primary causes of asthma. In many instances, asthma is an immunoglobulin gamma E mediated atopy (i.e., allergen-specific hypersensitivity) that leads to non-specific bronchial hyper-reactivity and subsequent symptom manifestations. These symptoms may range from an annoying cough to full-blown respiratory failure. Allergen-avoidance measures should be a primary mode of treatment for atopic asthmatics. This article focuses on the dust-mite allergen and its relationship to asthma. It details specific avoidance measures that should be implemented by the majority of asthmatics. Studies are cited that support the aggressive use of these measures to decrease allergen exposure, and to subsequently prevent or significantly reduce asthma symptoms. When health care providers have a better understanding of avoidance measures and the rationale underlying their use, these measures are more likely to be valued and given greater emphasis in education and treatment plans. Renewed emphasis on an immunomodulatory approach to asthma treatment may help to reverse the rise in asthma morbidity and mortality rates.
Ixodid (hard) ticks are blood-feeding arthropods that require a blood meal to complete each stage of development. However, the hormonal events coordinating aspects of feeding and development are only poorly understood. We have delineated a new neuropeptide-endocrine interaction in the adult tick, Amblyomma hebraeum, that stimulates the synthesis of the moulting hormones, the ecdysteroids. In adult female ticks, ecdysteroid synthesis could be demonstrated in integumental tissue incubated in vitro with a synganglial (central nervous system) extract, but not in its absence. Stimulation by the synganglial extract is both time- and dose-dependent, but is completely abolished by trypsin treatment, suggesting that the activity is due to a peptide/protein. Integumental tissue ecdysteroidogenesis is also stimulated by elevation of the cAMP concentration using forskolin and 3-isobutyl-l-methyl-xanthine, or by 8-bromo-cAMP. This suggests the involvement of at least a cAMP second messenger system in the neuropeptide-ecdysteroidogenesis axis, without precluding a role for other second messengers as well. Despite involving a quite different steroidogenic tissue, the foregoing system has some parallels with the known prothoracicotropic hormone (neuropeptide)-prothoracic gland endocrine axis of insects.
Explore the source record for details and available documents.
The acaricidal efficacy of nine marketed products, i.e. Acardust, Acarosan (foam and powder), Actelic 50, Artilin 3A (spirit and water base), liquid nitrogen, Paragerm AK, and Tymasil, and of intensive vacuum-cleaning have been compared on four different test surfaces: mattress, tufted carpet, gypsum board and rough wooden board, all covered with artificial house dust. They were inoculated with the house dust mite, Dermatophagoides pteronyssinus or the house-dust fungus Aspergillus repens for evaluation of the fungistatic claims of some products. The acaricidal activity of Tymasil did not surpass that of vacuuming; its fungistatic effect was not apparent. The other products showed complete to almost complete eradication on at least one of the substrates tested. Taking into account the results of acaricidal efficacy as well as the data on safety and practicality acquired earlier, Acarosan powder was considered first choice for carpet treatment. Acarosan and liquid nitrogen, were found to be effective in the treatment of mattress, pillow, upholstered furniture and heavy curtains. On wooden surfaces Acarosan was found to be both effective and safe, while Acardust, Actelic 50, Artilin 3A (both fungistatic as well as acaricidal), liquid nitrogen and Paragerm also passed the efficiency test.
Explore the source record for details and available documents.
Most in vivo and in vitro tests with repellents or deterrents against ticks have not considered which sensory channel is being targeted. We have recorded the responses of two hard tick species (Acari: Ixodidae) in vitro to determine if such products can disrupt the perception of an attractant in a repellent assay or the perception of an arrestment stimulus in a deterrent assay. Ethyl butylacetylaminopropionate (EBAAP), N,N-diethyl-methyl-benzamide (deet), permethrin and indalone were chosen to test their capacity to inhibit the attraction of Amblyomma variegatum Fabricius to its aggregation-attachment pheromone. Vapours of each test product plus those from a synthetic blend of the pheromone were delivered to the walking tick in an air stream on a locomotion compensator. Neither EBAAP, deet, permethrin nor indalone could inhibit attraction of A. variegatum even when each of the test products was delivered at 106 times the pheromone. Indalone did decrease the attraction of A. variegatum to the pheromone and induced repulsion of A. variegatum when presented on its own in the air stream. The effect of permethrin, a sodium channel blocker, was also tested in a deterrent assay measuring the arrestment of Ixodes ricinus (L.) adults on its own faeces and faecal constituents. Permethrin deterred arrestment at doses of 670 fg/cm2 to 67 ng/cm2, i.e. at levels five times lower than the dose of chemostimuli present in the arrestment stimulus. This sensitivity to permethrin suggests that it acts via the contact chemoreception channel.
Three in vitro assays for the evaluation of the hatchability of the eggs of the mite Psoroptes ovis (Hering) (Acari: Psoroptidae) are described. Preliminary trials showed that hatching occurs at very high rates when eggs are incubated under conditions of high humidity, on a liquid medium and in agarose dishes. These three protocols were compared, taking into account the ease of preparation, follow-up and accuracy of counting. The best protocol was found to be the use of agarose dishes. It was accurate, easy to carry out and reproducible for further evaluation of existing or potentially new compounds against both adults and eggs of Psoroptes spp. The acaricidal properties of phoxim and amitraz were then evaluated against eggs and adults using the three protocols. Results showed that for both drugs, in vitro adulticidal activity was complete, whereas the in vitro ovicidal activity was only partial. Nevertheless, efficacy of amitraz against both adults and eggs was shown to be higher than that of phoxim.
Explore the source record for details and available documents.
Bovine babesiosis is an important disease caused by Babesia bovis, B. bigemina, and B. divergens. Solid immunity develops after infection and this feature has been exploited with the use of live attenuated organisms as immunogens. Attributes of live vaccines include a durable immunity to heterologous challenge after one vaccination. To overcome disadvantages relating to poor quality control (risk of contamination and adverse reactions), production procedures have been modified to meet the requirements of codes of good manufacturing practice. This includes development of methods to allow production of cryopreserved vaccine and limit antigenic drift. Killed vaccines have also been used on a limited basis and consist of antigens extracted from cultured material or blood of infected calves, and given with adjuvant. The degree and duration of immunity against heterologous challenge is not well documented. Attempts are being made to develop subunit vaccines but the progress has been slow. A better understanding of the mechanisms involved in the expression of protective immunity against Babesia spp will aid in the identification of protective antigens.
Heartwater, a major constraint to improved livestock production in Zimbabwe, threatens to invade areas which have been previously unaffected. To monitor its spread in Zimbabwe, an immunoblotting diagnostic assay based on the responses of animals to the immunodominant, conserved 32-kDa protein of Cowdria ruminantium was evaluated. In this assay, no false reactions were detected with sera known to be positive and negative, but sera from some cattle, sheep, and goats from heartwater-free areas of Zimbabwe reacted strongly with the 32-kDa protein, suggesting that either these animals had previous exposure to heartwater or they were false positives. To investigate the possibility of previous exposure to heartwater, 11 immunoblot-positive and 6 immunoblot-negative sheep from heartwater-free areas of Zimbabwe were compared regarding their susceptibilities to challenge with C. ruminantium. Prior to challenge, C. ruminantium could not be detected in any sheep by transmission to Amblyomma hebraeum ticks or by the polymerase chain reaction (PCR) conducted with plasma samples. All sheep were equally susceptible to the challenge, and infection was confirmed by brain biopsy, necropsy, PCR, and transmission of C. ruminantium to ticks. Our data suggest that the immunoblot-positive reactions of sera from heartwater-free areas were due not to previous C. ruminantium infection but rather to antigenic cross-reactivity between C. ruminantium and another agent(s) such as Ehrlichia species. In conclusion, the immunodominant 32-kDa protein is not antigenically specific to C. ruminantium and its use in serological diagnosis of heartwater requires reevaluation.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.