Utilizou-se técnicas de geoprocessamento e imagens geradas pelo Sistema Landsat 7 - ETM+, para identificar áreas favoráveis ao crescimento das populações de Amblyomma cajennense e, conseqüentemente, o risco de infestação humana pelo carrapato no Município de Piracicaba, São Paulo, Brasil. As imagens de satélite permitiram determinar os valores de temperatura e do Índice de Vegetação por Diferença Normalizada (NDVI) que, em associação com as variáveis, densidade de eqüinos e modelo preditivo de distribuição de capivaras (Hydrochoerus hydrochaeris), foram utilizadas para construir um modelo de risco multivariado identificando assim áreas favoráveis ao crescimento de populações do carrapato. Verificou-se que a população humana exposta às regiões altamente desfavoráveis ou desfavoráveis ao crescimento de populações de A. cajennense é de, no mínimo, 70,14% podendo chegar a 96,16%. Por outro lado, de 0,04% a 15,23% da população está exposta a áreas favoráveis ou altamente favoráveis ao longo do ano. / Geoprocessing techniques and Landsat 7 - ETM+ images were used to identify suitable areas for the development of Amblyomma cajennense populations and the resulting risk of human infestation by that tick in Piracicaba, São Paulo, Brazil. Temperature and Normalized Difference Vegetation Index (NDVI) were calculated based on satellite images, and those data were later associated with horse density and a predictive model of spatial distribution of capybaras (Hydrochoerus hydrochaeris) to build a multi-variant risk model. It was observed that the human population exposed to extremely unsuitable or unsuitable areas ranges from 70.14% to 96.16%. On the other hand, 0.04% to 15.23% of the human population is exposed to suitable or extremely suitable areas throughout the year.

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No. of bitstreams: 1 paulahocayendepaula.pdf: 483329 bytes, checksum: fb02e4ccca0d774566f707ecf9a8926d (MD5) Previous issue date: 2000-04-25 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A descrição do comportamento de queda de fêmeas ingurgitadas do carrapato Boophilus microplus foi feita em experimento realizado na Estação Experimental da Embrapa Gado de Leite, em Coronel Pacheco- MG com o objetivo de avaliar as vantagens da modificação do horário de ordenha dos animais, em relação à higienização do pasto, em se tratando do carrapato. O experimento constou de uma fase de verão, com fotoperíodo maior e outra de inverno com fotoperíodo menor. Foram realizadas doze repetições semanais, de vinte e quatro horas de duração, em cada fase, onde oito vacas secas 7\8 holandês x zebu naturalmente infestadas por carrapato B. microplus e mantidas em regime de pasto, eram levadas à área experimental no dia em que se daria a observação, onde ficavam confinadas em baias individuais. A cada hora, durante o período de vinte e quatro horas, as fêmeas ingurgitadas dos carrapatos, desprendidas naturalmente, eram coletadas em cada baia. Os resultados mostraram diferenças significativas no ritmo de queda de fêmeas ingurgitadas entre as fases de verão e inverno. No verão, as fêmeas ingurgitadas apresentaram maior porcentagem de queda entre 7 e 10 horas (35,3%) com pique de queda às 9 horas e no inverno entre 6 e 9 horas (19,69%) com pique de queda às 6 horas e entre 14 e 17 horas (21,79%) com pique de queda às 15 horas. A porcentagem de queda de fêmeas ingurgitadas no período em que os animais estariam estabulados para ordenha é de 35,15% para o sistema atual de ordenha (de 5-8h e 13-16h) e de 45,48% para o sistema de ordenha em estudo para o Brasil-Central (de 8-11h e 16-19h), durante os meses de verão. Nos meses de inverno o porcentual de queda é de 40,51% e de 32,71% para os dois horários de ordenha respectivamente. Considerando o tempo que os animais permanecem estabulados para a suplementação no cocho durante o período entre as ordenhas na época seca do ano na região (maio a setembro), a porcentagem de queda de fêmeas ingurgitadas é de 55,83% para o sistema de ordenha atual (de 5 a 16h) e de 52,36% para o sistema de ordenha em estudo (de 8 a 19h). A correlação entre a queda de fêmeas ingurgitadas e o fotoperíodo foi significativa apenas para o tratamento de verão. Em relação à temperatura média e umidade relativa do ar, não houve correlação significativa tanto para o verão como para o inverno. / A description of the drop-off behaviour of engorged females of the tick Boophilus microplus was carried out as a result of an experiment at the Experimental Station, Embrapa Gado de Leite, Coronel Pacheco, MG, Brazil. Its objective was to evaluate any repercussions of changing the time of milking of cattle in terms of reduced recontamination of the pastures with the tick. Such possible changes in this daily cattle management routine have recently become a reality since the advent of refrigerated on-farm storage of the milk and non-daily collection by tanker truck. The field experiment consisted of a phase in summer, with a longer photoperiod, and in winter, with a shorter photoperiod. Twelve weekly experimental repetitions, of 24 hours duration, were carried out in each of these seasons. For each repetition, eight non-lactating, 7/8 Holstein-Friesian x Zebu cows, naturally infested with B. microplus and maintained on pastures, were removed to an experimental area on the day on which the observations were to be made and maintained in individual stalls. At each hour, over 24 hours, all fully engorged ticks that had dropped off naturally from the cattle were collected from the stalls. The results showed a significant difference in the rhythm of their drop-off in the summer compared to winter. In the summer the greater proportion of ticks dropped off between 07:00 and 10:00 (35.3%) with a maximum at 09:00. In winter, there were two daily periods of greater drop-off of ticks, the first between 06:00 and 09:00 (19.69%) with a maximum at 06:00, and the second between 14:00 and 17:00 (21.79%) with a maximum at 15:00. The percentage of ticks dropping off during the traditional milking time (05:00-08:00 and 13:00-16:00) would have been 35.15%, while those falling during an alternative sytem under consideration for Central Brazil (08:00-11:00 and 16:00-19:00) would be 45.48%, during the summer. During the winter, the proportion of ticks falling from the cattle is 40.51% and 32.71% for the two times of milking, respectively. Considering the time that the animals remain in stalls for feed supplement during the period between milkings during the dry season (May to September), the proportion of ticks falling would be 55.83% for the traditional system (05:00-16:00) and 52.36% for the milking period under consideration (08:00-19:00). The correlation between drop-off of ticks and photoperiod was significant only for the summer, but not so for mean air temperature nor relative humiditty for either of the seasons compared.

Please read the abstract in the thesis / Thesis (PhD)--University of Pretoria, 2013. / gm2013 / Biochemistry / unrestricted

The cattle tick, Rhipicephalus microplus, has a debilitating effect on the livestock industry worldwide, owing to its being a vector of the causative agents of bovine babesiosis and anaplasmosis. In South Africa, co-infestation of livestock with R. microplus and R. decoloratus occurs. An alternative to chemical control methods is sought in the form of an anti-tick vaccine. Using microarray technology, this study aimed at identifying genes that are shared between midgut tissues of adult female R. microplus and R. decoloratus ticks. In addition, results from another study were used and a reverse vaccinology pipeline was devised to identify putative novel vaccine candidates. Using a custom oligonucleotide microarray comprising 13 477 R. microplus sequences, 2476 genes were found to be shared between the two abovementioned tick species. In addition, 136 were found to be more abundantly expressed in R. decoloratus and 1084 in R. microplus. Chi-square analysis revealed that genes involved in lipid transport and metabolism are significantly over-represented in R. microplus and R. decoloratus. With vaccine design in mind, considering genes that are expressed in the midgut of both tick species, 6730 genes were identified and of these, 1224 are predicted to contain membrane-spanning helices. One major limitation to anti-tick vaccine discovery in the past has been a lack of candidates to evaluate, combined with limited knowledge of the transcriptome of R. microplus. This study identified a large pool of transcripts that are expressed in the midgut of both R. microplus and R. decoloratus adult females. Of these, those that are expressed in larvae, nymphs and the midgut were identified in another study and an in silico pipeline was used to predict membrane-bound protective antigens using an alignment-free approach, which led to the identification of seven proteins that were predicted to be both glycosylphosphatidylinositol (GPI)-anchored and more likely than Bm86 to be protective antigens. Finally, epitopes were predicted and corresponding synthetic peptides were evaluated using enzyme-linked immunosorbent assay (ELISA), resulting in the identification of three epitopes that are recognized to a greater extent than previously published Bm86 epitopes, when using murine serum raised against membrane proteins from the midgut of R. microplus. These results are significant because novel R. microplus proteins that are also present in R. decoloratus were identified. Trials using recombinant protein are under way and this will ultimately validate the experimental methodology discussed in this dissertation. Finally, regardless of whether the next-generation anti-tick vaccine has been discovered, this study also led to the identification of novel reference genes that can be used for real-time PCR experiments. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Biochemistry / Unrestricted

This thesis focuses on the molecular characterization of tick-borne parasites of dogs in South Africa. Emphasis is placed on Babesia, Erhlichia, incidental and novel parasite infections that may cause morbidity or mortality in infected dogs. An outbreak of canine babesiosis in the Netherlands is also reported in this thesis. Molecular techniques were employed to isolate, amplify and characterize genomic DNA of these parasites to species level. During preliminary screening of blood samples collected from various sites in the country, that included the Onderstepoort Veterinary Academic Hospital, SPCAs and private clinics throughout seven provinces in South Africa, it was discovered that domestic dogs harboured a wide variety of tick-borne pathogens. The most frequently encountered parasites in South Africa were Babesia rossi, a novel Theileria species of dogs, B. vogeli and Ehrlichia canis respectively. The parasites occurred as single or mixed infections. Incidental infections that included B. gibsoni and Trypanosoma congolense were also detected using PCR. Although it was anticipated that zoonotic Ehrlichial infections of dogs would be detected, none were found. Babesia vogeli was reported for the first time in South Africa although, without any clinical significance. An outbreak of autochthonous canine babesiosis in the Netherlands was confirmed to have been caused by Babesia canis. Dermacentor reticulates was implicated in the transmission of the parasite to naïve dogs. Clinical significance of B. rossi and the novel Theileria sp. of dogs was evaluated. Babesia rossi was found to be of significant clinical importance. Genotyping of B. rossi isolates revealed that parasite genotypes could be correlated to disease phenotype. Additionally, specific genotypes could also be associated with fatalities. Although the characterization of the Theileria sp. in dogs was a first report in South Africa, the clinical significance of this infection in dogs appeared to be poorly resolved. The dangers of having non-endemic species becoming established in South Africa was highlighted with the incidental finding of a B. gibsoni infection in an imported dog. The results of this thesis have shown therefore that populations of dogs that live in tickendemic areas are exposed to single or multiple tick-borne pathogens. These pathogens continue to cause morbidity and mortality in susceptible dogs. Correct diagnosis (supported by molecular diagnostic tools) followed by appropriate treatment offers a better understanding and management of these tick-borne pathogens. Preventative measures should be fully evaluated and applied to prevent these tick-borne pathogens from adversely affecting the canine population in South Africa and elsewhere. / Thesis (PhD)--University of Pretoria, 2008. / Veterinary Tropical Diseases / unrestricted

No description available.

No description available.

This study was conducted to understand the occurrence, diversity and epidemiology of tickborne diseases (TBDs) in a transhumant pastoral area of Karamoja Region, Uganda. We used participatory epidemiology (PE), involving focus group discussions (n = 24) with livestock keepers, 30 key informant interviews, review of previous surveillance data, clinical examinations, and laboratory confirmation of cases of TBDs, to define and prioritise cattle diseases, evaluate current control activities, and identify constraints to the control of TBDs. The livestock keepers regarded TBDs, particularly East Coast fever (ECF) and anaplasmosis, as the most important health problems in their cattle, based on morbidity and mortality rates, rates of transmission, treatment costs, difficulty in accessing the correct treatment, difficulty to control, and inadequate knowledge to manage the diseases. The main constraints to the control of TBDs were inadequate knowledge, inadequate veterinary services and limited availability of drugs. Hand picking of ticks was done by all pastoralists while hand spraying was done with under-strength acaricides, often at irregular intervals and with little acaricide wash. We determined the endemic status of TBDs in 20 randomly-selected cattle herds by estimating the proportion of annual ECF and anaplasmosis cases in different age groups of cattle using participatory approaches and clinical examinations, determining the diversity and abundance of ticks (161 cattle in 20 herds), and establishing the seroprevalence of antibodies to Theileria parva and Anaplasma marginale among cattle (n = 397 in 20 herds). Clinical examinations and informant interviews showed that TBDs affected all age groups of cattle. Two-thirds of the cattle were infested with moderate (37.3%, 11-50 ticks) to abundant (28.6%, > 50 ticks) numbers of ticks. Out of the 10,923 ticks collected, Rhipicephalus appendiculatus (54.4%) was the most abundant species followed by R. decoloratus (17.7%), Amblyomma variegatum (12%) and A. lepidum (11.6%). We collected tick species that are either rare in Uganda (A. lepidum, Hyalomma truncatum, A. gemma) or were not known to be present in the country (R. pulchellus). The true seroprevalence of antibodies to A. marginale was high (95.1%, 95% confidence interval [CI] 91.3% - 98.5%), while that of T. parva was low (16.5%, 95% CI 12.9% - 19.6%). We determined the presence of tick-borne haemoparasites among cattle and the prevalence of infections using reverse line blot (RLB) hybridisation and quantitative real-time polymerase chain reaction (qPCR), and characterised Theileria and Babesia species by sequence and phylogenetic analyses of the full-length 18S rRNA gene. The RLB hybridisation assay demonstrated the presence of tick-borne haemoparasites in most cattle (99.6%), mostly as mixed infections (97.5%). The most frequently-detected species were Theileria mutans (88.3%, 95% CI: 84.6-92.1%), A. marginale (73.8%: 68.3-79.2%), T. velifera (71.3%: 65.8-76.7%) and Anaplasma sp. Omatjenne (63.3%: 57.5-68.8%). Other virulent pathogens, namely Babesia bigemina (5.0%) and T. parva (2.9%), were also detected with RLB, but Ehrlichia ruminantium was not detected. The proportions of qPCR positive samples were 82.9% (A. marginale), 12.1% (A. centrale), 3.3% (T. parva), and 1.7% (E. ruminantium). Variations (5 to 9 nucleotides) in the 18S rRNA gene sequences of B. bigemina were identified as compared with previously published sequences. We assessed the 16S rRNA gene phylogeny of Anaplasma species from cattle and analysed the msp1α gene sequences of A. marginale to identify genotypes. There was genetic heterogeneity within A. marginale in cattle in the study area. Most A. marginale sequences (16/19) were closely related (99- 100% identities) and clustered with A. marginale strain Veld from cattle in South Africa, with strong bootstrap support, while three sequences clustered (100% identity) with A. marginale strain from Virginia, USA. The A. centrale sequences were closely related (100% identity) and clustered with the Israel vaccine strain. We found four different kinds of MSP1a tandem repeat sequences (UP39-F-M2-3) that correspond to one A. marginale strain unique to Uganda. One tandem repeat (UP39) was unique to Karamoja cattle. The findings from this study provide knowledge on the diversity and epidemiology of TBDs, which can be used to support diagnosis and strategic control of TBDs, and consequently improve cattle productivity and the livelihoods of pastoralists. More effective control and prevention measures against ticks and TBDs should urgently be implemented in the region. There is need to facilitate and promote immunisation of cattle against ECF. Given the scarcity of veterinarians in the region, the activities of community-based animal health workers [CAHWs] should be strengthened. The local governments in Karamoja Region should facilitate a more favourable business environment to attract private companies, who could scale-up veterinary drug supplies to the region. Pastoralists should be sensitised to improve their ecological knowledge of the seasonal activity of ticks for strategic tick control. / Thesis (PhD)--University of Pretoria, 2017. / Agricultural Technology and Agribusiness Advisory Services (ATAAS) / The National Agricultural Research Organisation (NARO) of Uganda / Veterinary Tropical Diseases / PhD / Unrestricted

Relapsing fever Borrelia are transmitted through saliva of argasid ticks. Given the 10 to 60 minute long bloodmeal, we characterized the rapidity of Borrelia turicatae transmission from their vector Ornithodoros turicata. Infection rates were compared in mice when cohorts of ticks fed to repletion on animals in which groups of O. turicata were removed 15 seconds after attachment. Infection was evaluated by examining the blood by dark field microscopy, quantitative PCR, and serological responses generated against B. turicatae. Scanning electron microscopy was also performed on cryofractured tick salivary glands to determine spirochete localization. Dissemination of B. turicatae into murine blood was evaluated by removing the bite site after ticks engorged. Our findings indicate that B. turicatae is localized in the lumen of salivary gland acini of O. turicata and transmission to and dissemination in the mammal occur shortly after tick attachment and do not require a complete bloodmeal.

Parasites often have profound effects on the survival and evolution of their hosts, and hence on the structure and health of entire ecosystems. Yet basic questions, such as the degree of virulence of a given parasite on its host, and factors influencing which hosts in a population are at the greatest risk of infection, are vexingly difficult to resolve. The western blacklegged tick-western fence lizard (Ixodes pacificus-Sceloporus occidentalis) system is important, primarily because I. pacificus, a vector of the Lyme disease spirochete Borrelia burgdorferi, is dependent on S. occidentalis for blood meals in its subadult stages, and this lizard possesses an innate immune response that removes the Lyme disease pathogen from attached ticks. My study focused on two aspects of the I. pacificus-S. occidentalis interaction. In Chapter 1, I investigated factors correlating with the intensity of I. pacificus infestations on S. occidentalis. Infection intensity (parasites per host) is often highly variable within a host population, though certain individuals, such as males, tend to be more heavily infected. Previous work in the I. pacificus-S. occidentalis system suggests that differences in behavior, such as the frequency of territorial patrols, may contribute to variation in tick intensity among lizards. I therefore hypothesized that lizard traits that correlate with dominance would also correlate with infestation intensity. Specifically, I predicted that larger and more colorful males would have higher infestation intensities than less impressive animals. In this chapter, I also focused on site selection by ticks infesting S. occidentalis. Skin folds on the necks of these lizards (nuchal pockets) may function to divert ectoparasites away from eyes, ears, and other potentially vulnerable structures. I therefore also looked for factors correlating with tick attachment in these pockets. I sampled ticks on adult male S. occidentalis in the spring and summer, which is the seasonal peak for both S. occidentalis territorial behavior and subadult I. pacificus abundance. After determining the site of infestation and intensity of ticks on these lizards, I re-infested lizards with laboratory-reared I. pacificus larvae, and again quantified tick intensity and attachment location. Contrary to expectation, no host traits correlated with tick intensity among ticks naturally infesting lizards, and lab-reared larval intensity was negatively correlated with lizard body size. As expected, ticks acquired by lizards naturally concentrated inside nuchal pockets, and I also observed this site preference among ticks in lab-based experimental infestations. Although the general pattern, lab-reared ticks were more varied in the sites on which they fed. There was a negative correlation between infestation intensity and the proportion of ticks attached in nuchal pockets. Unsurprisingly, the most reliable predictor of tick intensity and site selection was the season. In Chapter 2, I explored how tick attachment affects male S. occidentalis contest behavior. I. pacificus infestation has been shown to have negative physiological impacts on S. occidentalis, but mechanisms linking physiological changes to ultimate fitness consequences have been largely underexplored. I hypothesized that tick infestation reduces male S. occidentalis fighting ability by reducing O2 carrying ­­capacity­, or by obstructing or damaging vulnerable structures on their hosts. I held fifty half-hour trials between pairs of size- and ventral badge-matched male S. occidentalis, with one male in each pair infested with lab-reared I. pacificus larvae. I found that tick infestation negatively correlated with aggressive behavior in these staged contests. In support of reduced O2 capacity as the mechanism of reduced aggression, my ecologically relevant infestation intensities seemed to cause significant declines in hematocrit among experimentally infested lizards relative to controls. However, the site at which ticks attached did not significantly correlate with the aggressiveness of their lizard hosts. This is one of only a handful of studies to address the direct effect of I. pacificus on S. occidentalis. My study demonstrates that tick infestation can be detrimental to the fitness of their lizard hosts even without the transmission of pathogens. This insight may prove informative in future work on the ecology of I. pacificus-borne diseases in the western United States. This study is also one of only a few to use parasite infection to induce an asymmetry in fighting ability in intrasexual contests.