54 research outputs found
African Animal Trypanosomiasis: The Problem of Drug Resistance
No full textThe three trypanocides used to control tsetse-transmitted trypanosomiasis in domestic animals in Africa have been in use for over 40 years and, not surprisingly, resistance of trypanosomes to these drugs has emerged. Because of the relatively limited market in Africa and the high costs of developing and licensing new drugs, international pharmaceutical companies have shown little interest in the development of new trypanocides for use in either animals or humans. Therefore, the current challenge is to achieve optimal use of the relatively old existing drugs, and it is in this context that the problem of drug resistance has to be quantified – as discussed here by Stanny Geerts, Peter Holmes, Oumar Diall and Mark Eisler.The three trypanocides used to control tsetse-transmitted trypanosomiasis in domestic animals in Africa have been in use for over 40 years and, not surprisingly, resistance of trypanosomes to these drugs has emerged. Because of the relatively limited market in Africa and the high costs of developing and licensing new drugs, international pharmaceutical companies have shown little interest in the development of new trypanocides for use in either animals or humans. Therefore, the current challenge is to achieve optimal use of the relatively old existing drugs, and it is in this context that the problem of drug resistance has to be quantified – as discussed here by Stanny Geerts, Peter Holmes, Oumar Diall and Mark Eisler
African bovine trypanosomiasis: the problem of drug resistance
No full textThe three trypanocides used to control tsetse-transmitted trypanosomiasis in domestic animals in Africa have been in use for over 40 years and, not surprisingly, resistance of trypanosomes to these drugs has emerged. Because of the relatively limited market in Africa and the high costs of developing and licensing new drugs, international pharmaceutical companies have shown little interest in the development of new trypanocides for use in either animals or humans. Therefore, the current challenge is to achieve optimal use of the relatively old existing drugs, and it is in this context that the problem of drug resistance has to be quantified--as discussed here by Stanny Geerts, Peter Holmes, Oumar Diall and Mark Eisler
TSOL18 vaccine of Taenia solium: development of monoclonal antibodies and field testing of the vaccine in Cameroon
No full textChapter 1 reviews the literature about the immunological aspects of taeniid cestode infections and the existing vaccines against Taenia solium cysticercosis in pigs. One of the most promising vaccines is TSOL18, a protein that has been identified in the oncosphere of Taenia solium and expressed as a recombinant molecule in E. coli. Repeated experimental trials have shown that this vaccine is able to protect up to 100 % of the immunised pigs against a challenge infection with T. solium. Antibodies raised by the vaccine are capable of killing the parasite in in vitro cultures and it is believed that antibody and complement mediated killing of invading parasites is the major protective immune mechanism induced by vaccination with TSOL18.
The identification of the villages with a high risk of T. solium infection, which could subsequently be used in the vaccine trial, is reported in chapter 2. A survey was conducted in 150 households owning 1756 pigs in the rural areas of Mayo-Danay division in the far north region of Cameroon. A questionnaire survey was carried out to collect information on the pig farming system and to identify potential risk factors for T. solium cysticercosis infection in pigs. Blood samples were collected from 398 pigs with the aim of estimating the sero-prevalence of Taenia solium cysticercosis. The results showed that 90.7 % of the pigs were free roaming during the dry season and that 42.7 % of households keeping pigs in the rural areas had no latrine facility.
Seventy six percent of the interviewed pig owners affirmed that the members of the household used open field defecation. ELISA for antigen and antibody detection showed an apparent prevalence of porcine cysticercosis of 24.6 % and 32.2 %, respectively. A Bayesian approach using the conditional dependence between the two diagnostic tests indicated that the true seroprevalence of cysticercosis in Mayo-Danay was 26.6 %. Binary logistic regression analysis indicated that the lack of knowledge of the taeniasis-cysticercosis complex and the absence of a pig pen in the household were associated with pig cysticercosis
Reevaluating Bloom’s Taxonomy: What Measurable Verbs Can and Cannot Say about Student Learning
No full textFaculty and assessment professionals rely on Bloom’s taxonomy to guide them when they write measurable student learning outcomes and describe their goals for developing students’ thinking skills. Over the past ten years, assessment offices and teaching and learning centers have compiled lists of measurable verbs aligned with the six categories that comprise Bloom’s taxonomy. The author analyzed 30 compilations posted on web sites and evaluated how well these verbs aligned with categories in Bloom’s taxonomy. The author discusses the value of Bloom’s taxonomy as a heuristic for writing student learning outcomes and other factors faculty should consider when they articulate learning outcomes to describe levels of expertise attained by students who complete an associate’s, bachelor’s, or graduate degree
Biogeographical patterns of African trypanosomoses for improved planning and implementation of field interventions
No full textSpatially-explicit information is essential for planning and implementing interventions against vector-borne diseases. This is also true for African trypanosomoses, a group of diseases of both humans and animals caused by protozoa of the Genus Trypanosoma, and transmitted by tsetse flies (Genus Glossina).<p>In this thesis the knowledge gaps and the requirements for an evidence-based decision making in the field of tsetse and trypanosomoses are identified, with a focus on georeferenced data and Geographic Information Systems (GIS). Datasets, tools and analyses are presented that aim to fill some of the identified knowledge gaps.<p>For the human form of the disease, also known as sleeping sickness, case detection and treatment are the mainstay of control, so that accurate knowledge of the geographic distribution of infections is paramount. In this study, an Atlas was developed that provides village-level information on the reported occurrence of sleeping sickness. The geodatabase underpinning the Atlas also includes the results of active screening activities, even when no cases were detected. The Atlas enables epidemiological maps to be generated at a range of scales, from local to global, thus providing evidence for strategic and technical decision making.<p>In the field of animal trypanosomosis control, also known as nagana, much emphasis has recently been placed on the vector. Accurate delineation of tsetse habitat appears as an essential component of ongoing and upcoming interventions against tsetse. The present study focused on land cover datasets and tsetse habitat. The suitability for tsetse of standardized land cover classes was explored at continental, regional and national level, using a combination of inductive and deductive approaches. The land cover classes most suitable for tsetse were identified and described, and tailored datasets were derived.<p>The suite of datasets, methodologies and tools presented in this thesis provides evidence for informed planning and implementation of interventions against African trypanosomoses at a range of spatial scales.Doctorat en Sciences agronomiques et ingénierie biologiqueinfo:eu-repo/semantics/nonPublishe
Putting assessment into action: Evolving from a culture of assessment to a culture of improvement
No full textAs assessment work matures, campuses increasingly focus on how to develop structures and processes that facilitate the use of assessment findings and identify opportunities for improvement of curricula, teaching, and student learning.Book ChapterPublishe
TRYPANOSOMOSIS UND TRYPANOZIDRESISTENZ AUF DER HOCHEBENE VON ADAMAOUA IN KAMERUN
No full textDeckblatt-Impressum
persönlicher Dank
Table of contents
Abbreviations
Introduction
Objectives
Literature review
Materials and methods
Results
Discussion
Conclusions and recommendations
Summary
Zusammenfassung
Resumes
References
Annexes
Acknowledgements
SelbständigkeitserklärungTrypanosomosis is among the most devastating diseases in sub-Saharan Africa
and according to FAO it is at the root of poverty, while the tsetse fly is
considered to be one of the most serious pest problems in the world today.
African Animal Trypanosomosis (AAT) has a severe impact on African
agriculture. To control AAT multiple strategies are available including
keeping naturally resistant cattle and vector control, but the most commonly
used strategy is no doubt the use of trypanocidal drugs. However, resistance
to trypanocidal drugs is rapidly emerging and has been reported in many
countries in Africa. A study was carried out on the Adamaoua Plateau Cameroon:
firstly, to assess the trypanosomosis risk using the combination of
entomological, parasitological and serological methods; secondly to determine
the tsetse distribution using traps and fly rounds; thirdly, to assess the
prevalence of trypanocidal drug resistance in the study area. To assess the
trypanosomosis risk a longitudinal survey of trypanosomosis in 9 sentinel
herds was carried out in the 3 study zones, i.e. the plateau, the buffer zone
and the valley. A sero-conversion study was also carried out in cattle during
transhumance in the valley. To determine the tsetse distribution an
entomological survey was organised over a period of one year along 4 transects
traversing the 3 zones of the study area using tsetse traps as well as a
longitudinal survey using fly rounds along two transects in the tsetse
infested valley. To assess trypanocidal drug resistance a questionnaire survey
was carried out on knowledge, attitude and practice of trypanosomosis
management in the study area. Furthermore, a field test was done in two cattle
herds to assess the presence of drug resistant trypanosomes and a study of the
prevalence of drug resistance in trypanosome isolates of the Adamaoua using
the standard test in mice. We found that the trypanosomosis risk on the
plateau was significantly lower than in the buffer zone and the valley. This
may be explained by the regular insecticide treatment of the cattle herds in
the buffer zone which is probably contributing to prevent reinvasion of the
plateau by tsetse flies. Entomological surveys have demonstrated the presence
of G .m. submorsitans and G. tachinoides in the buffer zone and in the valley
whereas no tsetse flies could be captured on the plateau. The distribution of
tsetse in the valley undergoes substantial seasonal changes depending on the
presence or absence of cattle. In the presence of cattle (dry season) large
areas are reinvaded. In the absence of cattle, tsetse distribution is confined
to areas where game is present. We have shown for the first time the presence
of trypanosomes resistant to isometamidium and diminazene in Cameroon using
various techniques (field trial, mouse test). An alarmingly high prevalence of
trypanocidal drug resistance was found in the study area. The data collected
during this study allowed to formulate recommendations for the sustainable
control of African Animal Trypanosomiasis in the Adamaoua region.Die Trypanosomose ist eine der bedeutendsten Viehseuchen südlich der Sahara,
der FAO zufolge verantwortlich für die Armut in weiten Teilen Afrikas. Der
Überträger, die Tsetsefliege wird auch heute noch als eine der weltweit
wichtigsten Vektoren betrachtet. Kontrollmaßnahmen stützen sich auf die
Bekämpfung des Überträgers, die Haltung autochthoner, trypanotoleranter
tauriner Rinderrassen aber vor allem auf den Einsatz trypanozider Medikamente.
In jüngster Zeit häufen sich allerdings Berichte über das Vorkommen
medikamentenresistenter Trypanosomen aus vielen afrikanischen Ländern. Von
2003 2006 wurden auf der Hochebene von Adamaoua Untersuchungen durchgeführt,
um Erstens, mittels entomologischer, parasitologischer und serologischer
Verfahren das Trypanosomose-Risiko zu beurteilen; Zweitens, die Verbreitung
der Tsetsefliegen durch Fallen und fly rounds zu erfassen und Drittens, das
Vorkommen von Trypanozidresistenzen im Projektgebeit zu bestimmen. Die
Untersuchungsgebiete waren: die Hochebene (Plateau, ein in den 90iger Jahren
von Tsetsefliegen befreites Gebiet), ein Übergangsgebiet (die so genannte
Pufferzone) und ein Tal (Valley, ein Trypanosomosis-Endemiegebiet). Zur
Bestimmung ihrer regionalen Verbreitung und Dichte wurden über ein Jahr
mittels Fallen und fly rounds Tsetsefliegenprospektionen im Projektgebiet
durchgeführt: 4 Prospektionen in Form von transects quer durch die 3
Projektgebiete und 2 transects im Tsetsefliegen-infestierten Tal. Eine
Fragebogenerhebung wurde zur Wissens- und Informationsermittlung über die
Rinderhaltung und Trypanosomoseproblematik im Untersuchungsgebiet
durchgeführt. In einer Feldstudie wurden 2 Rinderherden auf das Vorkommen von
trypanozidresistenten Trypanosomen untersucht. Gewonnene Trypanosomenisolate
wurden in Hinsicht auf ihre Trypanozidempfindlichkeit im so genannten Standard
Maustest untersucht. Im Vergleich zur Pufferzone und dem Tal, ergab sich auf
der Hochebene ein signifikant niedrigeres Trypanosomose-Risiko. Reguläre
Behandlungen der Rinderherden mit Insektiziden in der Pufferzone scheinen
dafür verantwortlich zu sein, dass es bisher scheinbar noch zu keiner
Reinvasion durch Tsetsefliegen aus dem Tsetsefliegen-infestierten Tal auf die
Hochebene gekommen ist. In den entomologischen Untersuchungen konnten Glossina
m. submorsitans und G. tachinoides in der Pufferzone und dem Tal nachgewiesen
werden. Auf der Hochebene wurden allerdings keine Tsetsefliegen gefangen. Die
Tsetsefliegenverbreitung unterliegt jedoch in diesen Gebieten erheblichen
saisonalen Schwankungen, in Abhängigkeit des Vorkommens von Rindern. Bei
Vorkommen einer hohen Rinderpopulation (während der Trockenzeit) sind weite
Gebiete in der Pufferzone und im Tal mit Tsetsefliegen besiedelt. In Zeiten,
in denen keine Rinder vorhanden sind, beschränkt sich die
Tsetsefliegenverbreitung auf Gebiete hoher Wildtierdichte. Dies ist der erste
Bericht über ein Vorkommen von Isometamidium- und Diminazen-resistenten
Trypanosomen aus Kamerun, belegt durch verschiedene Untersuchungstechniken
(Felduntersuchungen, Untersuchungen in Mäusen). Die hohe Prävalenz
trypanozidresistenter Populationen im Projektgebiet ist auffällig und
besorgniserregend. Die erhobenen Daten erlaubten die Formulierung von
Managementempfehlungen für eine nachhaltige Kontrolle der bovinen
Trypanosomose in Adamaoua
Effects of hierarchical mentoring on freshman retention in a biology first-year experience course
No full textHigher education must improve student retention and graduation rates to meet increased demand for STEM degrees in the workforce projected for the next ten years. The high rate of attrition among STEM students entering college compels institutions to implement strategies that improve student retention because more states now employ performance-based funding models with increased pressures to improve student outcomes, such as first- and second-year retention rates. We piloted a two-year hierarchical mentoring model as part of a first-year experience course developed for biology students (BioSkills) to increase retention rates among first-time-in-college (FTIC) students. We describe the mentoring structure we adopted and how the design of BioSkills supports and educates future biology professionals. Our findings show that FTIC students who participated in this program earned significantly higher first-year GPAs and were retained at higher rates than students who did not participate, which documents the impact of BioSkills as a successful first-year intervention. However, we were
surprised that the benefit of BioSkills was not replicated among under-represented minority (URM) students. We briefly speculate on explanations for this finding. Lastly, we offer best practice suggestions for future implementation.Journal ArticlePublishe
Studies on the diagnosis, development and distribution of drug-resistant trypanosomes in cattle herds from selected sites of East and West Africa
No full textTitelseite und Inhaltsverzeichnis
1\. Vorwort
Publikationen, die Bestandteil der Habilitationsschrift sind
Einleitung und Ziel der Untersuchungen
2\. Zusammenfassende Darstellung der Ergebnisse
3\. Übergreifende Diskussion
4\. Schlussfolgerungen
5\. Zusammenfassung
6\. Summary
7\. Literaturverzeichnis
8\. Abkürzungen und Definitionen
9\. Darstellung des eigenen Anteils an den Arbeiten
10\. Danksagung
11\. Anhang (Mitteilungen 1-14)Die von Tsetsefliegen zyklisch übertragenen Trypanosomosen der Rinder (Nagana)
bedrohen die landwirtschaftliche Entwicklung in weiten Teilen Afrikas südlich
der Sahara. Seit über 40 Jahren werden bei Rindern das Diamidin
Diminazenaceturat zur Therapie und das Phenanthridinderivat
Isometamidiumchlorid zur Prophylaxe eingesetzt. Die Entwicklung eines
Impfstoffes scheiterte bisher an der ausgeprägten Fähigkeit der Trypanosomen
zur Antigenvarianz. Hinzu kommt, dass trotz des Vorhandenseins effizienter
Methoden die Nachhaltigkeit der Vektorenkontrolle (Tsetsefliegenbekämpfung)
nach wie vor nicht gegeben ist. Auch zukünftig werden deshalb therapeutische
und prophylaktische Behandlungen eine bedeutende Rolle in der Bekämpfung der
Nagana spielen. In jüngster Zeit häufen sich jedoch Berichte über Resistenzen
bei Trypanosomen. Bisher fehlen aber verlässliche Daten über das Vorkommen und
die regionale Verbreitung von Resistenzen. Daher war das Ziel dieser
Untersuchungen, die regionale Verbreitung und Bedeutung von
Medikamentenresistenzen bei Trypanosomeninfektionen in Rinderherden an vier
Standorten Afrikas exemplarisch zu bestimmen. Diese Standorte waren in
Ostafrika Metekel (Nordwest-Äthiopien), Upper Didessa Valley (West-Äthiopien),
Mukono County (Südost-Uganda) und in Westafrika Kénédougou Province (Südwest-
Burkina Faso). In Gebieten mit erhöhtem Infektionsrisiko wurden
Behandlungsstudien durchgeführt, einmal um den Verdacht auf Resistenz zu
bestätigen und zum zweiten um die Häufigkeit resistenter
Trypanosomeninfektionen zu bestimmen. Verschiedene in-vivo- und in-vitro-
Methoden wurden zur Charakterisierung der Medikamentenempfindlichkeit von
Trypanosomenfeldstämmen eingesetzt. Die Polymerase-kettenreaktion (PCR) wurde
vergleichend auf ihre diagnostischen Möglichkeiten und Grenzen zur Kontrolle
von prophylaktischen und therapeutischen Behandlungen bei Trypanosomen-
infektionen überprüft. In Dörfern mit einem erhöhten Infektionsrisiko ergaben
Blockbehandlungsstudien von Rinderherden mit Isometamidiumchlorid in Metekel,
Upper Didessa Valley und Kénédougou Hinweise für ein weit verbreitetes, aber
in seiner Häufigkeit sehr variables Vorkommen von Isometamidium-Resistenzen.
Diese konnten bei weiteren Untersuchungen, sowohl bei der Therapie
experimentell infizierter Rinder, Ziegen und Mäuse als auch unter Einsatz von
in-vitro-Methoden für Isometamidium nicht nur bestätigt, sondern auf Diminazen
ausgeweitet werden. Klone von Trypanosoma congolense-Populationen aus Metekel
und Kénédougou zeigten in Mäusen ausgeprägte Resistenzen gegenüber beiden
Wirkstoffen. Bei einem gehäuften Vorkommen mehrfachresistenter
Trypanosomeninfektionen erscheint die ausschließliche Kontrolle der Nagana
durch Trypanozide langfristig nicht mehr gerechtfertigt. Die Untersuchungen in
Rinderherden von Mukono ergaben keine Hinweise auf Resistenzen bei
Trypanosomen gegenüber Isometamidium und Diminazen. Die zunehmenden Berichte
über Resistenzen aus anderen Regionen sollten allerdings auch in Mukono Anlass
für einen restriktiven Einsatz von Trypanoziden geben. Die
Polymerasekettenraktion (PCR) erwies sich als eine hochempfindliche und
spezifische Methode zur Überprüfung des prophylaktischen und therapeutischen
Erfolgs bei Trypanosomeninfektionen. Unter der Voraussetzung ausreichender
finanzieller Mittel und entsprechender Laboreinrichtungen stellt sie ein
geeignetes diagnostisches Hilfsmittel in epidemiologischen Untersuchungen dar,
sowohl zur verbesserten Risikoabschätzung in Endemiegebieten als auch bei
Erfolgsuntersuchungen in regionalen Bekämpfungsprogrammen. Da aufgrund der
erheblichen Kosten mittelfristig nicht mit der Entwicklung und Zulassung neuer
trypanozider Wirkstoffe für den afrikanischen Nutztiermarkt zu rechnen ist,
sollte zur Verringerung der Gefahr von Resistenzentwicklung ein
Medikamenteneinsatz auf klinisch erkrankte Tiere beschränkt werden. Bei
Nachweis mehrfachresistenter Trypanosomen-populationen ist von einem Einsatz
von Trypanoziden abzuraten. In solchen Regionen sind Maßnahmen zur
Vektorenkontrolle zu intensivieren. Außerdem sollten Einkreuzungen mit
genotypisch trypanotoleranten Rinderrassen angeregt werden.Tsetse transmitted bovine trypanosomosis or nagana is a major constraint to
rural development in much of sub-Saharan Africa. In all these regions the main
control method is to cure the disease in cattle through the administration of
anti-trypanosomal molecules such as the diamidine diminazene aceturate and the
phenanthridine derivative isometamidium chloride. These drugs are in use for
more than 40 years. Due to the phenomenon of antigenic variation no vaccine
has been developed until now. Furthermore, vector control even though
technically feasible, is inherently confronted with problems of
sustainability. Therefore, control of the disease will continue to depend
largely on the use of trypanocidal drugs for the foreseeable future. However,
there have been several reports in recent times indicating an increase of the
drug resistance incidence in trypanosomes. The number of case reports on drug
resistance is growing, yet there is lack of reliable data at regional level on
its true prevalence. The present study aimed to assess the development and
distribution of drug-resistant trypanosomes in cattle herds from selected
sites of East Africa (Metekel, north-west Ethiopia; Upper Didessa Valley, west
Ethiopia; Mukono County, south-east Uganda) and West Africa (province of
Kénédougou, south-west Burkina Faso). Longitudinal field studies were
conducted to estimate the incidence of trypanocidal drug resistance in high
risk areas. Several in vivo and in vitro tests were used to characterize the
drug sensitivity of trypanosome field stocks. The polymerase chain reaction
(PCR) was evaluated and its diagnostic potential to monitor the efficacy of
prophylactic and curative treatments tested. Block treatment of cattle with
isometamidium in high trypanosomosis risk villages in Metekel, Upper Didessa
Valley and Kénédougou indicated that isometamidum resistance in Trypanosoma
congolense was widespread but varied in its incidence between villages,
indicating a relation with trypanosomosis risk and, possibly, other factors.
Field-derived indicators of isometamidium resistance were supported by in vivo
and in vitro demonstration of resistance to both isometamidium and diminazene.
Clones originating from cattle primary isolates of T. congolense from Metekel
and Kénédougou and tested in mice expressed a high level of resistance to both
isometamidium and diminazene. It was concluded that chemotherapeutic agents
per se would not provide a viable option for the control of trypanosomosis at
Metekel and Kénédougou on a long-term basis if such resistance at clonal level
was highly prevalent. In contrast, there appeared to be no resistance of
trypanosomes to the common used drugs in cattle of Mukono. All the same, given
the apparent development of resistance to trypanocidal drugs that has occurred
in other tsetse-infested areas, anti-trypanosomal compounds should be
judiciously applied in Mukono County as well. PCR proved to be a highly
sensitive and specific tool to monitor the therapeutic and prophylactic
efficacy and disease progression in bovine trypanosomosis. Depending on the
availability of financial support, PCR could provide an ideal tool to assess
trypansomosis risk in endemic areas and to monitor the success of tsetse and
trypanosomosis control programmes. Since there is no indication that new
trypanocidal drugs will become available in the near future, it is of greatest
importance that measures be taken to avoid or delay the development of
resistance and to maintain the efficacy of the currently available drugs. The
most efficient way is the reduction in the number of treatments in order to
reduce the selection pressure caused by these drugs. Mass treatments at short
intervals should be avoided, particularly in areas of high challenge. Drug use
should be reduced through vector control and by decreasing host-vector
contact. If resistance to both isometamidium and dimiazene is present at the
level of individual trypanosomes, trypanocidal drug use should be terminated,
except for the treatment of clinical cases. Vector control activities should
be maximised and cross-breeding with trypanotolerant cattle should be
encouraged
Language-dependent access to autobiographical memory in Japanese-English bilinguals and US monolinguals
No full textJapanese bilinguals retrieved autobiographical memories in response to 20 English and 20 Japanese cue words. US monolinguals were cues with 40 English words. All participants reported one earliest memory. Japanese bilinguals retrieved more memories and earlier memories when cued with Japanese words. They also retrieved more memories when the cue language matched either the language of memory encoding or the language of first thought. Although English cues elicited equivalent numbers of English and Japanese memories in the more fluent speakers of English, Japanese words elicited significantly larger numbers of Japanese memories in all Japanese-English bilinguals. The average age of cued memories was significantly earlier for US than for Japanese students but age of the earliest memory did not differ.PublishedJournal Articl
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