Considerable research on ticks has been done since it was discovered that the Rocky Mountain wood tick, Dermacentor andersoni Stiles, was a principal vector of Rocky Mountain spotted fevero Additional disease agents of man are also transmitted by D. andersoni. This tick and a closely related species, Dermacentor parumapertus Neuman, occur commonly in Utah. The two species are often closely associated, although D. andersoni is believed to occur in the mountains, whereas D. parumapertus is in the desert valleys. Diseases affecting animals in nature are transmitted by ticks of both species. Consequently, any interaction between the two may be influential in the maintenance of diseases in nature communicable to man and his domestic animals.

Analysis of Spontaneous Adverse Events Reports after Tick-Borne Encephalitis Vaccine Author: Tereza Brázdová Supervisor: PharmDr. Eva Zimčíková, Ph.D. Consultant: PharmDr. Kateřina Malá, Ph.D. Department of Social and Clinical Pharmacy, Faculty of Pharmacy in Hradec Králové, Charles University Introduction and aim: Tick-borne meningoencephalitis is one of the most frequent causes of viral meningitis in Europe. In recent years, the number of cases of this infection in the Czech Republic has begun to rise. Vaccination is the only reliable protection against infection, but it also comes with some risks. Analysis of spontaneous adverse reaction reports is a key source of information for signal detection, which is used to identify drug risks. The aim of this thesis was to analyse the spontaneous reporting of suspected adverse drug reactions (ADRs), using the data from the Central Database of ADRs provided by the State Institute for Drug Control. Methodology: Descriptive statistics were performed from reporting data in the period from June 2004 to October 2017. For example, the total number of reports, the number of ADRs and the patient characteristics were analysed. We compared the adverse reactions with the Vigibase database and evaluated the expectability of reported reactions. Results: During the...

Climate change will likely have impacts on disease vector distribution. Posing a significant health threat in the 21st century, risk of tick-borne diseases may increase with higher annual mean temperatures and changes in precipitation. We modeled the current and future potential distribution of the Ixodes ricinus tick species in Europe. The Genetic Algorithm for Rule-set Prediction (GARP) was utilized to predict potential distributions of I. ricinus based on current (1990-2010 averages) and future (2040-2060 averages) environmental variables. A ten model best subset was created out of a possible 200 models based on omission and commission criteria. Our results show that under the A2 climate change scenario the potential habitat range for the I. ricinus tick in Europe will expand into higher elevations and latitudes (e.g., Scandinavia, the Baltics, and Belarus), while contracting in other areas (e.g., Alps, Pyrenees, interior Italy, and northwestern Poland). Overall, a potential habitat expansion of 3.8% in all of Europe is possible. Our results may be used to inform climate change adaptation efforts in Europe.

A total of 143 blood samples of nyala (Tragelaphus angasii) from two regions in South Africa were tested for the presence of tick-borne haemoparasites by means of polymerase chain reaction (PCR) and reverse line blot (RLB) hybridisation. While most blood samples taken in EDTA blood turned out negative for the presence of haemoparasites, the majority of blood samples collected on Whatman® filter paper contained several different haemoparasites, often in combination. Samples from the Eastern Cape Province as well as from KwaZulu- Natal turned out positive. Prevalent haemoparasites were Theileria sp. (kudu), T. buffeli, T. bicornis, Theileria sp. (sable), T. taurotragi, Ehrlichia sp. Omatjenne, Anaplasma bovis and A. marginale. This serves as the first report of T. buffeli, T. sp. (kudu), T. bicornis, T. taurotragi, Ehrlichia sp. Omatjenne, A. marginale and A. bovis in nyala. Copyright / Dissertation (MSc (Veterinary Tropical Diseases))--University of Pretoria, 2009. / Veterinary Tropical Diseases / unrestricted

A cross-sectional survey was conducted at six properties in the small-holder and commercial sector in Gwanda district of Matabeleland South Province, Zimbabwe. The study was conducted at Sivume and Nyandeni communal dip-tanks, at Blanket, Double cross, Judds and at Timber farms. The objective of the study was to ascertain the tick infestations, tick species and udder and teat damage of milking cows and heifers from selected cattle herds. The study was important as it would help animalhealth decision makers and farmers in knowing the prevailing tick genera and species in the study area and hence the potential for the occurrence of diseases associated with these ticks. Two hundred and eighty-six cattle were sampled and ticks were collected and sent to the Central Veterinary Laboratory for further characterisation. A total of eight tick species, comprising of Amblyomma hebraeum, Hyalomma truncatum, Hyalomma marginatum rufipes, Rhipicephalus evertsi evertsi, Rhipicephalus (Boophilus) decoloratus, Rhipicephalus appendiculatus, Rhipicephalus zambeziensis and Rhipicephalus simus were identified. 53 % of the sampled cattle had some degree of udder and teat damage but very few farmers (2.6 %) treated their cattle for these conditions. / Dissertation (MSc)--University of Pretoria, 2008. / Veterinary Tropical Diseases / unrestricted

The aim of this study was to investigate three key epidemiological aspects of Theileria parva infections in cattle and African buffalo (Syncerus caffer) in South Africa. The first of these was the possible behavioural change (i.e. transformation) of buffalo-derived T. parva (causing classical Corridor disease in cattle) to what might be considered cattle-derived T. parva (causing classical East Coast fever in cattle) after repeated tick-passage in cattle. For the first time a South African isolate of buffalo-derived T. parva was successfully transmitted using Rhipicephalus zambeziensis for eight passages in non-splenectomised cattle. This was achieved despite most animals developing fatal infections with extremely low piroplasm parasitaemias, and without chemotherapeutic intervention. This finding indicates that, contrary to earlier belief, Corridor disease is not a self-limiting disease in cattle, and given the opportunity, could well become established in a cattle population in the absence of buffalo. Despite repeated tick transmission in cattle of the South African buffalo isolate of T. parva used in this study, it did not exhibit the behavioural changes associated with “transformation” to typical cattle-derived T. parva. Secondly, the potential role of the common waterbuck (Kobus ellipsiprymnus) in the selection of cattle-adapted subpopulations of parasites from buffalo-derived T. parva was investigated. Waterbuck captured in Kruger National Park (KNP) were screened by conventional and molecular diagnostic techniques for Theileria spp. infections. Laboratory-reared R. zambeziensis were fed on captive buffalo confirmed to be naturally infected with T. parva. The ensuing adult ticks were fed on captive waterbuck and cattle. All the waterbuck were found to carry microscopically detectable Theileria sp. piroplasm infections, found by polymerase chain reaction (PCR) diagnosis to belong to a hitherto uncharacterised Theileria species. R. zambeziensis adults which fed as nymphs on the buffalo transmitted fatal T. parva infections to cattle. However, no transmission of T. parva to the waterbuck could be demonstrated clinically or by PCR diagnosis. Also, R. zambeziensis nymphs that were subsequently fed on the waterbuck failed to transmit T. parva to cattle in the ensuing adult stage, confirming the absence of T. parva-group infections in the waterbuck. The results suggest that buffalo in KNP probably do not carry T. parva-group parasites which are readily transmissible to common waterbuck and waterbuck are therefore unlikely to play an important role in the epidemiology of T. parva-group infections in cattle in South Africa. Thirdly, to investigate the carrier state of buffalo-derived T. parva infections in cattle, blood from infected non-splenectomised and splenectomised carrier cattle was subinoculated to splenectomised cattle. T. parva infections were successfully transmitted by subinoculation of 1000 ml of blood at various intervals after infection to splenectomised recipient cattle. Donor animals comprised of recovered intact cattle, reacting intact cattle or splenectomised recovered cattle. Microscopically detectable piroplasm parasitaemias were detected in all recipients after inoculation. One splenectomised recipient developed a moderate clinical reaction, accompanied by a moderate schizont parasitosis, but recovered spontaneously, confirming persistence of schizonts in some T. parva carrier animals. By contrast, a T. parva piroplasm infection, persisting in a treated recovered splenectomised bovine, in the apparent absence of circulating schizonts, was serially (consecutively) passaged in splenectomised cattle. Seroconversion occurred in all recipient cattle. With the exception of the recipient which developed a clinical reaction and circulating schizonts, none of the recipients showed any clinical signs of T. parva infection. Upon homologous sporozoite challenge with T. parva, two out of three recipient animals with only microscopically detectable piroplasm parasitaemias developed fatal T. parva infections and one recovered after exhibiting severe clinical signs. These findings confirm the stage-specific immunity in T. parva and, contrary to popular belief, the possibility of long-term maintenance of piroplasm parasitaemias in the absence of schizonts in carrier cattle. The technique of subinoculating and establishing virulent T. parva carrier infections in splenectomised cattle also provides a method whereby buffalo-derived parasite stocks may be isolated and maintained for characterisation and the preparation of sporozoite stabilates for inclusion in T. parva vaccines. Copyright / Dissertation (MSc)--University of Pretoria, 2011. / Veterinary Tropical Diseases / unrestricted

Society requires better insights into how disturbances will alter the global carbon cycle. Ecosystem models help us understand the carbon cycle and make predictions about how the terrestrial land sink will change under future climate regimes. Disturbances drive ecosystem cycling, but modeling disturbances has unique challenges, particularly in incorporating heterogeneity and parameter uncertainty. In this dissertation, I explore two questions. 1) How can we capture disturbance ecology in models?, which I explore in my first and second chapters, and 2) How can we use those models to make projections for the Southeastern US?, which I explore in my third and fourth chapters. Both my first and second chapters point to the practical trade-offs in model structure and realism. In my first chapter, I found that representing spatially implicit contagious disturbances in terms of shape and frequency accurately captured structural changes over time and separated the disturbance regimes of different regions. Representing spatially implicit disturbances in terms of shape and frequency sacrificed the specificity of a space-based approach but may be more computationally efficient. In my second chapter, I developed a framework for calibrating models based on an iterative cycle between uncertainty analysis and literature synthesis, targeted field campaigns, and statistical constraint. I found that targeted field work and statistical constraint reduced parameter uncertainty until structural uncertainty began to dominate. Models that capture disturbance dynamics can help us anticipate effects of global change factors like climate change and invasive species. In my third chapter, I found that elevated temperatures reduce cogongrass biomass, and that cogongrass facilitates pine dominance over oaks in a mixed pine-oak stand. This suggests that cogongrass mediates inter-species competition at an ecosystem scale. Prescribed burns are a management technique used to suppress cogongrass and has an add-on benefit of reducing tick populations. However, climate change may threaten how frequently prescribed fires can be safely deployed. In my fourth chapter, I found that tick populations are most sensitive to leaf litter and humidity, which allows for management strategies as an alternative to prescribed burns.

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Tick-borne diseases represent major public and animal health issues worldwide. Ixodes ricinus, primarily associated with deciduous and mixed forests, is the principal vector of causative agents of viral, bacterial, and protozoan zoonotic diseases in Europe. Recently, abundant tick populations have been observed in European urban green areas, which are of public health relevance due to the exposure of humans and domesticated animals to potentially infected ticks. In urban habitats, small and medium-sized mammals, birds, companion animals (dogs and cats), and larger mammals (roe deer and wild boar) play a role in maintenance of tick populations and as reservoirs of tick-borne pathogens. Presence of ticks infected with tick-borne encephalitis virus and high prevalence of ticks infected with Borrelia burgdorferi s.l., causing Lyme borreliosis, have been reported from urbanized areas in Europe. Emerging pathogens, including bacteria of the order Rickettsiales (Anaplasma phagocytophilum, “Candidatus Neoehrlichia mikurensis,” Rickettsia helvetica, and R. monacensis), Borrelia miyamotoi, and protozoans (Babesia divergens, B. venatorum, and B. microti) have also been detected in urban tick populations. Understanding the ecology of ticks and their associations with hosts in a European urbanized environment is crucial to quantify parameters necessary for risk pre-assessment and identification of public health strategies for control and prevention of tick-borne diseases.

This dissertation consists of three essays in applied financial economics. The unifying theme is the use of financial regulation as quasi-experiments to understand the interrelationship between derivatives and the underlying assets. The first two essays use different quasi-experimental econometric techniques to answer the same research question: how does option listing affect the return volatility of the underlying stock? This question is difficult to answer empirically because being listed on an options exchange is not random. Volatility is one of the dimensions along which the options exchanges make their listing decisions. This selection bias confounds any causal effect that option listing may have. What is more, the options exchanges may list along unobservable dimensions. Such omitted variable bias can also confound any causal effect of option listing. My first essay overcomes these two biases by exploiting the exogenous variation in option listing that is created by the SEC-imposed option listing standards. Specifically, the SEC mandates that a stock must meet certain criteria in the underlying market before it can trade on an options exchange. For example, a stock needs to trade a total of 2.4 million shares over the previous 12 months before it can be listed. Since 2.4 million is an arbitrary number, stocks that are “just above” the 2.4 million threshold will be identical to stocks that are “just below” it, the sole difference being their probability of option listing. Accordingly, I use the 2.4 million threshold as an instrument for option listing in a fuzzy regression discontinuity design. I find that option listing causes a modest decrease in underlying volatility, a result that corroborates many previous empirical studies. My second essay attempts to estimate the effect of option listing for stocks that are “far away from” the 2.4 million threshold. I overcome the aforementioned omitted variable bias by fully exploiting the panel nature of the data. I control for the unobserved heterogeneity across stocks by implementing a two-way fixed effects model. Unlike most previous studies, I control for individual-level fixed effects at the firm level rather than at the industry level. My results show that option listing is associated with a decrease in volatility. Importantly, these results are only statistically significant in a model with firm-level fixed effects; they are insignificant with industry-level fixed effects. My third essay is a policy evaluation of the SEC’s Penny Pilot Program, a mandated decrease of the option tick size for various equity options classes. Several financial professionals claimed that this decrease would drive institutional investors out of the exchange-traded options market, channeling them into the opaque, over-the-counter (OTC) options market. I empirically test an implication of this hypothesis: if institutional investors have fled the exchange-traded options market for the OTC market, then it may take longer for information to be impounded into a stock’s price. Using the `price delay’ measure of Hou and Moskowitz (2005), I test whether stocks become less price efficient as a result of being included in the Penny Pilot Program. I perform this test using firm-level fixed effects on all classes that were included in the program. I confirm these results with synthetic control experiments for the classes included in Phase I of the Penny Pilot Program. Generally, I find no change in price efficiency of the underlying stocks, which suggests that the decrease in option tick size did not materially erode the price discovery that takes place in the exchange-traded equity options market. I also find evidence that the decrease in option tick size caused an increase in short selling for the piloted stocks. / Economics