1. The external morphology of all stages in the life cycle of B. decoloratus is described with the aid of scanning electron micrographs. 2. The biological activities of B. decoloratus during its parasitic cycle are examined with special reference to the course of feeding of all stages, and to the influence of the pharate nymph and adult conditions in accelerating the completion of the cycle. 3. The pattern of dropping of replete females is considered in relation to their weight and their time of drop-off. 4. The adult male population structure is described. Two distinct weight groups are reported and the taxonomic significance of these is discussed. 5. The preoviposition period duration of B .decoloratus was studied under laboratory conditions and found to be temperature dependent and humidity independent. Female size, as implied by their engorged weights, influenced the duration of the oviposition period: ticks weighing less than 20 mg possessed longer preoviposition periods. 6. The preoviposition period of B.decoloratus females under fluctuating macroclimatic conditions was studied and found to be long in duration. The implications of this are discussed in relation to laboratory findings and the summer build-up of this species in nature. 7. The duration of the oviposition period of B. decoloratus and the number of eggs produced during this period were studied under laboratory and field conditions. Both these parameters were found to be temperature dependent and uninfluenced by humidity. The significance of a temperature dependent oviposition period is discussed. 8. The minimum amount of 'blood' required by female ticks for oviposition of eggs was found to be approximately 16 mg. under laboratory conditions. 9. The oviposition behaviour of B. decoloratus females has been described and the water relations of ovipositing and non-ovipositing females were examined and discussed . 10. The effects of handling female ticks during their oviposition period was studied and females which were handled were found to produce significantly fewer eggs. The significance of this is discussed. 11. During preliminary experiments on the incubation period of B. decoloratus it was found that the viability of eggs laid during the first half of the oviposlting period was greater than for eggs laid in the second half of the period. The critical temperature of the 'wax' coating of eggs was found to be 42⁰C while the critical humidity was approximately 70% R.H. (7,53 mmHg) at 26⁰C. The implications of these findings are discussed. 12. The development of eggs, traced throughout the incubation period by monitoring the build-up of guanine spectrophotometrically, was studied under different humidity conditions . Successful development was found to be dependent on the water content of the eggs at the time of laying. As eggs were also found to be unable to take up water vapour from the atmosphere this finding is important evidence to support the suggestion that the survival of the egg stage largely determines the spacial distribution of larvae in the field. 13. Results of work done at constant, alternating and naturally fluctuating temperatures and humidities demonstrated that the duration of the incubation period of B.decoloratus is temperature dependent and humidity independent. The significance of this is discussed in relation to the findings of previous workers and to the biology of the species. 14. Egg viability (percentage hatch) was found to be humidity dependent and temperature independent. The implications of these findings are discussed. 15. Some of the problems associated with the assessment of the effects of climatic conditions on ticks are discussed. Special reference has been made to the advocation of using saturation deficit instead of relative humidity as the parameter indicative of environmental humidity in any biological study involving fluctuating humidity conditions. 16. The problems associated with having three variables (e.g. temperature, saturation deficit and incubation period duration) are discussed and reasons given for why contour diagrams have been used in this investigation. 17. A model of the interactions between the main abiotic factors of the environment (temperature and humidity) and the biological parameters studied during the second part of this investigation is presented. 18. The effects of climatic conditions on the life cycle and distribution of B.decoloratus are discussed. Special reference has been made to the available evidence explaining the summer build-up in tick numbers known to occur in nature and the way in which the present findings have helped in an understanding of the spacial distribution of B.decoloratus in the field.

Commercial (high-grade) BaS04 selectively adsorbs two proteins from crude 0. savignyi salivary gland extracts. They co-purify during reversed-phase HPLC, but can be separated by hydrophobic-interaction chromatography. Both proteins have been characterized in terms of their molecular mass, amino acid composition and one partial internal amino acid sequence was determined. Their molecular masses were established through electro-spray mass spectrometry as 9333 Da and 9173 Da, respectively. The 9.3 kDa protein was designated BSAP1 and the 9.1 kDa protein BSAP2. Their amino acid compositions shows significant differences, in particular the presence of 6-7 and 8 cysteine residues in BSAP1 and BSAP2, respectively. It is therefore unlikely that these proteins are isoforms. All of the cysteine residues are involved in the formation of disulphide bonds, the only possible exception being one residue in BSAP1. Both proteins appear to be N-terminally blocked. An internal amino acid sequence Asp/Ser-Gly-Gly-Xxx-Xxx-Ile-Leu-Gly was obtained by sequencing a fragment of the cyanogen bromide cleaved BSAP2. It was suspected that these proteins might exhibit anticoagulant activity. The prothrombin time (PT) and activated partial thromboplastin time (aPPT) in the presence of the presumptive inhibitors were therefore evaluated. The aPPT was not significantly prolonged. The PT however did indicate a slight delay in the clotting time. This delay is not due to inhibition of factor VII, one of only two unique coagulation factors in the extrinsic pathway. The other factor is thromboplastin, also known as tissue factor. The nature of the protein adsorption to BaS04 was examined. From literature it is known that ϒ-carboxyglutamic acid-containing proteins, as well as some hydroxyproline and hydroxylysine-rich glycoproteins adsorb selectively to BaS04. The BSAPs were analysed for the presence of these modified amino acids, but all tests proved negative. The absence of Gla residues was determined using a Gla-specific stain on a polyacrylamide gel and was confirmed by performing mass spectrometry on native and decarboxylated protein samples. The absence of hydroxyproline and hydroxylysine was demonstrated by amino acid analysis. Both BSAPI and BSAP2 bind to neutral and negative membranes. BSAPI binds neutral and negative membranes more strongly than BSAP2. Its affinity for negative membranes is however much lower than its affinity for neutral membranes. In contrast, BSAP2 binds both membranes equally strongly. The binding of the proteins to the membranes was significantly lowered upon pre-incubation with Ca2+. / Dissertation (MSc (Biochemistry))--University of Pretoria, 2006. / Biochemistry / unrestricted

Host-parasite relationships are one of the most common symbiotic relationships present in a diverse array of ecosystems. There are numerous factors that impact the dynamics of these relationships. Major factors that can influence the degree of parasitism include host sex, hormonal state, reproductive condition, and behavior. It has been observed in several vertebrate taxa that males have higher ectoparasite intensities than females and males with increased testosterone have increased ectoparasite intensities. One potential reason for these observations is that testosterone concentrations are elevated in males, particularly during the breeding season, and when circulating concentrations increase males become more vulnerable to ectoparasitism. Here I first tested the hypothesis that higher circulating testosterone concentrations in male western fence lizards (Sceloporus occidentalis) induce higher tick intensities. To examine this hypothesis I implanted male lizards with either testosterone or blank implants in the field. The testosterone-implanted males had significantly higher tick intensities compared to the control males. However, in contrast, control males had significantly higher mite intensities compared to testosterone-implanted males. These results are consistent with other studies suggesting that testosterone impacts certain aspects of host-parasite relationships. However, the exact mechanism for how testosterone influences parasite intensities remains unclear. There are two major current hypotheses for how testosterone influences ectoparasite intensities on males, the first involving immunosuppression and the second involving behavioral patterns and movement. However, another potential reason for why male lizards, particularly those with high circulating testosterone, have higher ectoparasite intensities than female and low testosterone male lizards is that the parasites preferentially choose their host. Furthermore, it has been demonstrated that vitellogenic female lizards have diminished immune function and this could potentially lead to increased ectoparasitism in much the same way that testosterone does in male lizards. Therefore, it is possible that a host preference is also present with vitellogenic versus non-vitellogenic female lizards. Although there have been a few interspecific studies done on this topic there have been no such studies on parasite host preference in reptiles to date. Here I tested three hypotheses: 1. Ticks prefer male lizards to female lizards. 2. Ticks prefer male lizards with high testosterone concentrations to male lizards with normal testosterone concentrations. 3. Ticks prefer vitellogenic female lizards to non-vitellogenic female lizards. All three experiments demonstrated no preference of host by ticks, which suggests they will attach to any suitable host they come across. However, during the male versus female host choice experiment ticks fed faster on vitellogenic female lizards than male lizards and non-vitellogenic female lizards. These results, taken together with previous studies showing higher tick intensities on male lizards, lizards with experimentally elevated testosterone, and reproductive female lizards, provide evidence that ticks do not preferentially choose their host, but instead are found in higher numbers on certain hosts due to some other reason. Other potential explanations include differences in immune function, microhabitat use, and behavioral patterns. One of the major hypotheses as to why male lizards, particularly those with high testosterone concentrations, have higher ectoparasite intensities than female lizards and male lizards with low testosterone concentrations is that these lizards perform more territorial behaviors, have increased movements, and larger home range sizes, thus exposing them to more parasites. Several studies have shown testosterone to increase the frequency of behaviors, movement, and home range size in lizards, but few, if any, have related it to ectoparasite intensities. Here I tested two hypotheses: 1. High testosterone male lizards have larger home ranges than male lizards with lower testosterone concentrations and female lizards. 2. High testosterone male lizards perform a higher frequency of territorial behaviors than male lizards with lower testosterone concentrations and female lizards. To test these hypotheses I implanted male lizards with either testosterone or blank-control implants, left female lizards unaltered, and performed behavioral observations in the field for 25 days. At the end of this time period, home range sizes were calculated as minimum convex polygons and ectoparasite intensities were quantified. Results of this study revealed no significant difference in ectoparasite intensities between high and low testosterone male lizards, but male lizards did have significantly higher ectoparasite intensities than female lizards. Furthermore, home range size and frequencies of territorial behaviors were not significantly different between high and low testosterone male lizards. However, male lizards did have larger home ranges and performed more territorial behaviors and movements than female lizards. These results suggest that home range, movement, and territorial behavior frequency contribute to higher ectoparasite intensities on male lizards, particularly those on males with high circulating testosterone. However, future studies need to address the behavioral and physiological mechanisms responsible for the observed effects of testosterone on parasitism, including parasite intensity, immunosuppression, and parasitic effects on host fitness.

No description available.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2005. / Bibliography: leaves 65-76.

Ticks "are not merely annoying pests but surpass all other anthropods in the number and variety of disease agents for which they are carriers (Chandler 1955). This statement is certainly true of Boophilus decoloratus (Koch), the blue tick, which is probably one of the most important ticks in South Africa. Various studies have been made on the blue tick in Africa, among which are investigations on taxonomy (Hoogstraal 1956); distribution (Theiler 1949 and 1962); ecology (Kraft 1961); disease transmission (Neitz and du Toit 1938; du Toit 1947; Neitz 1956 a and b); control and resistance to insecticides (du Toit, Graf and Bekker 1941; Whitnall and Bradford 1947; Whitehead 1958 and 1959) To date, the behaviour of Boophilus decoloratus has not been studied to any extent. The aim of the present work is to analyse the behaviour of the unfed larvae into its constituent patterns in order to determine what are the significant environmental factors which affect this behaviour. It is also hoped that the present laboratory studies might help in understanding their behaviour in the field. Intro., p. 1.

Tick-borne diseases cause in enormous burden on human, livestock, and wildlife health globally and are driven by the increasing abundance and geographic expansion of medically important tick species. More recently, tick-borne disease emergence is occurring in urban landscapes due to complex feedbacks between the environment, humans, wildlife, and ticks. In this dissertation, I focus on the ecological conditions that allow for tick-borne disease emergence in a city. I use a combination of spatial landscape modeling, empirical data collection, wildlife movement tracking to determine drivers of zoonotic hazards in New York City, NY, and employ vector genomics to examine vector dispersal in the northeastern United States. In chapter one, I pair tick collection throughout the five boroughs of New York City with landscape connectivity modeling to examine how green space connectivity and habitat availability affects the density and infection of questing nymphs – an important epidemiological measure of human risk for tick-borne diseases. I found that green spaces that were highly connected for deer had higher nymph density and infection prevalence for Borrelia burgdorferi sensu stricto, the etiologic agent of Lyme disease. In chapter two, I use camera trapping, live trapping, and tick collection on Staten Island, NY, to examine how landscape fragmentation – through changing habitat size and connectivity – shapes the host community available for questing Ixodes scapularis nymphs. Further, I examined whether patterns in host species abundance and activity correlate with the density of nymphs and their infection prevalence with three different pathogens that vary in host-specificity, B. burgdorferi, Babesia microti, and Anaplasma phagocytophilum. I found associations between host species and the size and connectivity of the park habitat, identified host species which amplified and removed ticks in the environment, and determined links between host activity and abundance and the infection prevalence of nymphs with host-specific pathogens. In chapter three, I utilize movement data from 59 white-tailed deer on Staten Island, NY, to assess the drivers of movement and its impact on tick-borne disease hazard across the landscape. I found that white-tailed deer avoid anthropogenic development at fine spatial scales when establishing home ranges but select for anthropogenic resources within their home range, increasing the potential to distribute ticks into environments that interface with humans. Finally in chapter four, I use double digest Restriction Associated DNA sequencing to examine the genetic differentiation of six I. scapularis populations across the Northeast region. I found high levels of gene flow across a spatial scale of 400 km, likely resulting from frequent host-mediated dispersal events combined with large I. scapularis populations. Taken together, this work emphasizes that host movement and ecology are critical determinants of urban tick-borne disease emergence through directing vector and pathogen dispersal, serving as pathogen reservoirs in urban habitats, and interfacing with humans in unique ways that increase human exposure to zoonotic hazards.

There are about 1500 cases of Lyme borreliosis (LB) registered annually in Lithuania, the average morbidity rate was 34/100 000 in 1991-2006. The high incidence of LB determines the high attention to the epidemiological situation. The analysis of the diseases patterns and causative factors is needed for management of the situation, development of disease preventive strategies, improving the diagnostics, providing recommendations and etc. The aim of the study is to assess epidemiological patterns of LB and the main factors (natural-climatic and social) leading to them in Lithuania 1995-2006. In this study LB incidence trends and risk factors are evaluated, correlation of various risk factors with LB incidence and abundance of ticks are assessed, the prevalence of tick bites and risk factors among the population are determined. This study has evaluated the possible ecological significance of newly formed biotope‘s to the LB spread. After molecular tests the prevalence and genotypes of Borrelia in Ixodes ricinus nymphs collected from different biotopes was determined. This study succeeded to detect until now not detected in Lithuania Borrelia miyamotoi belonging to relapsing fever group. The study results showed that nymps’ infectivity in Lithuania is 14.8%. The climatic (air temperature and snow cover) risk factors are the most important ones influencing the LB. LB natural habitat has the property to expand at the expense of areas where the incidence rate was previously low. / Lietuvoje kasmet registruojama apie 1500 susirgimų Laimo borelioze (LB), 1991-2006 m. vidutinis sergamumo rodiklis buvo 34/100 000 gyventojų. Aukštas sergamumo LB lygis sąlygoja didelį dėmesį šios ligos epidemiologinei situacijai. Jos dėsningumų ir priežastinių veiksnių analizė reikalinga situacijos valdymui, planuojant ir rengiant prevencines strategijas, gerinant diagnostiką, teikiant rekomendacijas visuomenei ir kt. Šio darbo tikslas – įvertinti LB epidemiologinius dėsningumus ir juos sąlygojančius svarbiausius veiksnius (gamtinius-klimatinius ir socialinius) Lietuvoje 1995–2006 m. Darbe išnagrinėti ir aprašyti LB sergamumo dėsningumai, įvertintos sergamumo tendencijos, atlikta LB rizikos veiksnių analizė ir nustatytos sąsajos su LB sergamumu ir erkių gausa, nustatytas erkių įkandimų ir rizikos veiksnių paplitimas tarp Lietuvos gyventojų. Šiame darbe įvertinta naujai susiformavusių biotopų galima ekologinė reikšmė LB plitimui, atlikus molekulinius tyrimus, nustatytas borelijų paplitimas ir genotipai Ixodes ricinus nimfose, surinktose skirtinguose biotopuose bei išaiškinta nauja, iki šiol Lietuvoje neaptikta grįžtamosios karštinės borelijų grupei priklausanti Borrelia miyamotoi. Šio darbo rezultatai parodė, kad nimfų infekuotumas Lietuvoje yra 14,8 proc.; svarbiausi sergamumą LB sąlygojantys rizikos veiksniai yra klimatiniai (vidutinė oro temperatūra bei sniego danga); LB gamtinis arealas turi savybę plėstis teritorijų, kuriuose sergamumas anksčiau buvo žemas, sąskaita.

Lietuvoje kasmet registruojama apie 1500 susirgimų Laimo borelioze (LB), 1991-2006 m. vidutinis sergamumo rodiklis buvo 34/100 000 gyventojų. Aukštas sergamumo LB lygis sąlygoja didelį dėmesį šios ligos epidemiologinei situacijai. Jos dėsningumų ir priežastinių veiksnių analizė reikalinga situacijos valdymui, planuojant ir rengiant prevencines strategijas, gerinant diagnostiką, teikiant rekomendacijas visuomenei ir kt. Šio darbo tikslas – įvertinti LB epidemiologinius dėsningumus ir juos sąlygojančius svarbiausius veiksnius (gamtinius-klimatinius ir socialinius) Lietuvoje 1995–2006 m. Darbe išnagrinėti ir aprašyti LB sergamumo dėsningumai, įvertintos sergamumo tendencijos, atlikta LB rizikos veiksnių analizė ir nustatytos sąsajos su LB sergamumu ir erkių gausa, nustatytas erkių įkandimų ir rizikos veiksnių paplitimas tarp Lietuvos gyventojų. Šiame darbe įvertinta naujai susiformavusių biotopų galima ekologinė reikšmė LB plitimui, atlikus molekulinius tyrimus, nustatytas borelijų paplitimas ir genotipai Ixodes ricinus nimfose, surinktose skirtinguose biotopuose bei išaiškinta nauja, iki šiol Lietuvoje neaptikta grįžtamosios karštinės borelijų grupei priklausanti Borrelia miyamotoi. Šio darbo rezultatai parodė, kad nimfų infekuotumas Lietuvoje yra 14,8 proc.; svarbiausi sergamumą LB sąlygojantys rizikos veiksniai yra klimatiniai (vidutinė oro temperatūra bei sniego danga); LB gamtinis arealas turi savybę plėstis teritorijų, kuriuose sergamumas anksčiau buvo žemas, sąskaita. / There are about 1500 cases of Lyme borreliosis (LB) registered annually in Lithuania, the average morbidity rate was 34/100 000 in 1991-2006. The high incidence of LB determines the high attention to the epidemiological situation. The analysis of the diseases patterns and causative factors is needed for management of the situation, development of disease preventive strategies, improving the diagnostics, providing recommendations and etc. The aim of the study is to assess epidemiological patterns of LB and the main factors (natural-climatic and social) leading to them in Lithuania 1995-2006. In this study LB incidence trends and risk factors are evaluated, correlation of various risk factors with LB incidence and abundance of ticks are assessed, the prevalence of tick bites and risk factors among the population are determined. This study has evaluated the possible ecological significance of newly formed biotope‘s to the LB spread. After molecular tests the prevalence and genotypes of Borrelia in Ixodes ricinus nymphs collected from different biotopes was determined. This study succeeded to detect until now not detected in Lithuania Borrelia miyamotoi belonging to relapsing fever group. The study results showed that nymps’ infectivity in Lithuania is 14.8%. The climatic (air temperature and snow cover) risk factors are the most important ones influencing the LB. LB natural habitat has the property to expand at the expense of areas where the incidence rate was previously low.

A emergência e reemergência de doenças transmitidas por artrópodes são desafios para as medicina Veterinária e Humana. Cães domésticos estão frequentemente expostos as diferentes espécies de carrapatos, os quais fazem destes animais bons sentinelas para riquetsioses que afetam os humanos. O Estado do Maranhão está localizado na região Nordeste do Brasil, numa área de transição dos biomas Amazônia e Cerrado. Neste contexto, no presente estudo, objetivou-se avaliar infecções por riquétsias em cães e carrapatos. Durante o perído de 2011 a 2013, amostras de sangue foram coletadas aleatoriamente de 1560 cães, sendo de áreas urbanas e rurais de oito municípios: Açailândia, Balsas, Barreirinhas, Caxias, Cururupu, Grajaú, São Bento e São Domingos. As amostras foram testadas pela reação de imunofluorescência indireta para cinco espécies de riquétisas: Rickettsia rickettsii, Rickettsia parkeri, \"Candidatus Rickettsia amblyommii\", Rickettsia rhipicephali e Rickettsia bellii. Os carrapatos foram coletados sobre os cães, identificados morfologicamente e submetidos a pesquisa de riquétsias, quase todos os carrapatos foram submetidos ao teste de hemolinfa e tentativa de isolamento de riquétsia. Do total, 12,6% (196/1560) dos cães foram sororreativos a Rickettsia spp. Noventa e dois soros mostraram títulos para Rickettsia parkeri, \"Candidatus Rickettsia amblyommii\", Rickettsia rhipicephali and Rickettsia bellii pelo menos quatro vezes maior do que aqueles outros antígenos de riquétisa. Desta forma, considera-se que os cães foram infectados por Rickettsia parkeri (1 soro), \"Candidatus Rickettsia amblyommii\" (73 soros), Rickettsia rhipicephali (6 soros) and Rickettsia bellii (12 soros), com títulos variando de 128 a 16.384. Novecentos e cinquenta e nove carrapatos foram coletados sobre os cães, Rhipicephalus sanguineus, Amblyomma cajennense sensu lato, Amblyomma ovale, Amblyomma parvum, Amblyomma oblongoguttatum, Amblyomma rotundatum, Rhipicephalus (Boophilus) microplus, Haemaphysalis juxtakochi e Amblyomma sp. Produtos da reação em cadeia pela polimerase de 17 carrapatos foram sequenciados e mostraram corresponder a \"Candidatus Ricketsia andeanae\", Rickettsia bellii and \"Candidatus Rickettsia amblyommii\". Estes resultados sugerem que estas riquétsias ou uma cepa muito próxima estão infectando cães no Estado do Maranhão, ressaltando o potencial patogênico destas espécies de riquétsias no Nordeste do Brasil. Ao mesmo tempo, diferencia-se do Sudeste do Brasil, onde hospedeiros sentinelas como os cães, tendem a ter maiores títulos para Rickettsia rickettsii ou Rickettsia parkeri, os agentes da febre maculosa no Sudeste do Brasil. / The emergence and reemergence of diseases transmitted by arthropods are challenges for the Veterinary and Human medicine. Domestic dogs are often exposed to different tick species, what makes these animals good sentinels for rickettsial diseases that affect humans. The state of Maranhão is located in the northeastern region of Brazil, in a transition area from Amazon to Savannah biomes. In this context, the present study aimed to evaluate rickettsial infection in dogs from this state. During the period 2011 to 2013 blood samples were randomly collected from 1560 domestic dogs, being from urban and rural areas of eight municipalities of Maranhão: Açailândia, Balsas, Barreirinhas, Caxias, Cururupu, Grajaú, São Bento and São Domingos. Samples were tested by indirect imunofluorescence assay against 5 Rickettsia species: Rickettsia rickettsii, Rickettsia parkeri, \"Candidatus Rickettsia amblyommii\", Rickettsia rhipicephali and Rickettsia bellii. Ticks were collected on dogs to morphological taxonomic identification and to rickettsia research, almost ticks were submitted to hemolymph test and shell vial attempting to isolate rickettsia. Overall, 12.6% (196/1560) of the dogs were seroreactive to Rickettsia spp. Ninety-two sera showed titers to Rickettsia parkeri, \"Candidatus Rickettsia amblyommii\", Rickettsia rhipicephali and Rickettsia bellii at least 4- fold higher than those observed to the other rickettsial antigens. In this way, we considered that these dogs were infected by Rickettsia parkeri (1sera), \"Candidatus Rickettsia amblyommii\" (73 sera), Rickettsia rhipicephali (6 sera) and Rickettsia bellii (12 sera), with titers ranging from 128 to 16,384. Nine hundred and fifty-nine ticks were collected on dogs (Rhipicephalus sanguineus, Amblyomma cajennense sensu lato, Amblyomma ovale, Amblyomma parvum, Amblyomma oblongoguttatum, Amblyomma rotundatum, Rhipicephalus (Boophilus) microplus, Haemaphysalis juxtakochi and Amblyomma sp). Polymerase chain reaction products of at least seventeen of these ticks were sequenced and also showed to correspond to \"Candidatus Ricketsia andeanae\", Rickettsia bellii and \"Candidatus Rickettsia amblyommii\". These results suggest that these ricketsias or close-related strains are infecting dogs in Maranhão state, highlighting the potential pathogenicity of these Rickettsia species in northeastern Brazil. At the same time, it differentiates from southeastern Brazil, where sentinel hosts like dogs tend to have higher titers to Rickettsia rickettsii or Rickettsia parkeri, the agents of spotted fever in southeastern Brazil.