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PubMedDate not supplied

[Echography, principles, techniques and applications to tropical and parasitological medicine (author's transl)].

After recalling the principles and general basis of ultrasounds, the authors consider the various modes of medical echographic exploration. A. mode, T.M. mode (time-motion); B. mode (bidimensional); D. mode (dynamic or in real time); Döppler mode. The technique of the examination, and the required preparation of the patients, are briefly reported. The basic echographic semiology is studied, considering the echos given by four main structures: 1) purely liquid with non echo, 2) non purely liquid with variable echos, 3) parenchymatous with many mixed echos (non perfect and non homogenous echos), 4) solid structures (bones, calculi) having complete impermeability to ultrasounds. Both parasitological and tropical medicine offer many and good opportunities for the use of echography in various controls: --liver: primitive tumors or parasitic abcesses, cysts, --gall ducts and bladder, --pancreas: pancreatitis, pseudocysts, --splenomegalies and cases of portal hypertension, --large vessels: ectasy, thrombosis, --kidneys: enlargement and cases of deceiving urography, --genital duct: sterility and pelvic tumors, --pregnancy: surveillance of pregnancy, hemorrhage, placenta praevia, foetal malformations, --heart: this chapter will not be considered in this paper. With regard to such a wide range of indications and to be low cost of its use, echography might be very useful in both tropical and parasitological medicine, when correctly applied and interpreted.

Diagnosis, Differential↗
PubMed1993

[Epidemiology of trypanosomiasis caused by T. evansi in camels in mali: results of parasitological and clinical survey].

An epidemiological study of trypanosomiasis was conducted in the rearing areas of dromedary camels in Mali. According to the parasitological and clinical surveys performed, the overall infection rates were 9.5% (29/305) in Western Sahel (region I) and 4.5% (28/627) in the areas of Tombouctou and Gao (region II). The proportion of contaminated herds was 55% in region I and 68% in region II and in some herds the infection rate exceeded 50%. The surveys showed a trend for increasing parasitological prevalence with age. While it was almost nonexistent in young camels less than one year old, it increased with age and reached a maximum in 2 to 5-year old camels. The authors showed that the infection has a significantly negative effect on PCV and on the overall status of the animals, confirming the pathogenicity of Trypanosoma evansi in dromedary camels. This trypanosome is almost the only species detected in the dromedary camel in Mali and it does not seem to cause infections in other animals reared in the same environment.

Aging↗
PubMed1993

Parasitological and clinical studies on human scabies in Cairo.

This study is a parasitological and clinical study on human scabies. This study was carried out on 100 patients attending the Dermatology Outpatient Clinic at Ain Shams University Hospitals, including 54 males and 46 females. All patients were subjected to detailed history taking, complete dermatological examination including Skin Scraping Test and Burrow Ink Test. Younger patients attended the dermatology clinic earlier than older patients, who usually delayed their visits until complications occurred. Scratching, erythematous papules and secondary infected lesions were the commonest lesions. The hands, wrist and external genitalia were the most frequently affected sites while the feet, ankles, knees and back were the least affected. Burrows could only be detected in 40% of patients. The most frequent sites were the web spaces, external genitalia, and finger sides. Burrow Ink Test was positive among 85% of patients with burrows while mites could be identified by Skin Scraping Test in 55% of patients. The most frequent clinical manifestations in the parasitologically positive patients were itching, burrows, and papules, and the most frequent sites were the web spaces, and the finger sides. Multiple sites affection was the characteristic feature among the preschool age children who represented 14% of cases.

Age Factors↗
PubMed1993

[Malaria in the Saharan region of Senegal. 2. Parasitological indices].

The malaria parasitological indexes have been studied in three villages situated in the Senegal river central valley. Near one of them an irrigated rice field has been operational since July 1989. Each village has its own health care unit and the consumption of antimalarial drugs, especially chloroquine, is important. The parasitological indexes in children 0 to 9 years old and in patients presenting with symptoms evocative of malarial attacks are low. Irrigation of the rice field area does not seem to be an increasing factor for the malaria parasite rates in the area.

Animals↗
PubMed1996

Using molecular tools for diagnosis in veterinary parasitology.

The development of molecular biology has made available tools that identify parasites which are important in veterinary parasitology. PCR (polymerase chain reaction) is the most frequently used tool. Target sequences are ribosomal DNA and RNA as well as fragments derived from RAPD (random amplified polymorphic DNA). The most studied protozoan genera have been: Eimeria, Babesia, Theileria, Trypanosoma and Cryptosporidium. Trichinella species and ruminant Trichostrongylid parasites have been the most investigated helminths. The use of molecular tools for identification in veterinary parasitology, however, remains a research technique rather than one that is currently used in the field for diagnostic purposes.

Animals↗
PubMed2006

[An introduction into bioethics and parasitology].

Bioethical considerations increasingly affect the process of integrating scientific and medical findings into the moral conceivabilities of a society and, consequentially, into the stock of laws. In a natural science like parasitology a social consensus must be reached in the areas of species protection, of the red biotechnology, of human prenatal diagnosis, and of animal experiments. The crucial problem is the social value of an individual's dignity and the conjoined question of the admissibility of an exploitation of a creature. The responsibility of man for other organisms, in that particular case parasites and their hosts, is brought up for discussion in a bioethic debate.

Animal Experimentation↗
PubMed1990

Parasitological serendipity: from Schistocephalus to Echinococcus.

Attention is drawn to the situation nowadays, whereby workers are encouraged to undertake research which appears useful or of economic importance, although the History of Science indicates that many major discoveries have been the result of 'serendipity'--'the chance observation falling on the receptive eye'. Some of the more important examples in Medicine and Parasitology are reviewed. The author then relates how he was given a stickleback infected with the plerocercoid of Schistocephalus solidus, an episode which eventually led to the successful in vitro culture of the adult of this species. Attention is also drawn to the largely unrecognized work of the Danish Veterinarian, P. C. Abildgaard, who in 1789 demonstrated that this species completed its life cycle in a bird, thus establishing, for the first time, the transmission of a parasite from one host to another. The in vitro culture of S. solidus led to the development of successful in vitro techniques for Ligula intestinalis and for Echinococcus granulosus and E. multilocularis. The observation that E. granulosus of horse origin failed to grow in vitro led eventually to the concept of physiological 'strains' of E. granulosus, now a subject of much international research.

Animals↗
PubMed1989

Texas fever, two-headed calves and the Hatch Act--100 years and counting for veterinary parasitology in the United States.

The structure, historical development and major research problems confronting veterinary parasitology in the U.S.A. are reviewed 100 years after the cooperative federal-state experiment station system was authorized through passage of the Hatch Act by the U.S. Congress in 1887. The story of Texas cattle fever eradication from the American south exemplifies historical and functional aspects of the experiment station system. The distribution and importance of parasite problems of livestock, companion animals and parasitic zoonoses are summarized in the context of larger national agricultural issues.

Animals↗
PubMed1999

The Galton-Watson branching process as a quantitative tool in parasitology.

Stochastic growth processes abound in the biology of parasitism, and one mathematical tool that is particularly well suited for describing such phenomena is the Galton-Watson branching process. Introduced more than a century ago to settle a debate over the rate of disappearance of surnames in the British peerage, branching processes are applied today in fields as diverse as quantum physics and theoretical computer science. In this article, Dale Taneyhill, Alison Dunn and Melanie Hatcher provide a simple introduction to branching processes, and demonstrate their uses in quantitative parasitology.

Animals↗
PubMed2001

The role of molecular biology in veterinary parasitology.

The tools of molecular biology are increasingly relevant to veterinary parasitology. The sequencing of the complete genomes of Caenorhabditis elegans and other helminths and protozoa is allowing great advances in studying the biology, and improving diagnosis and control of parasites. Unique DNA sequences provide very high levels of specificity for the diagnosis and identification of parasite species and strains, and PCR allows extremely high levels of sensitivity. New techniques, such as the use of uniquely designed molecular beacons and DNA microarrays will eventually allow rapid screening for specific parasite genotypes and assist in diagnostic and epidemiological studies of veterinary parasites. The ability to use genome data to clone and sequence genes which when expressed will provide antigens for vaccine screening and receptors and enzymes for mechanism-based chemotherapy screening will increase our options for parasite control. In addition, DNA vaccines can have desirable characteristics, such as sustained stimulation of the host immune system compared with protein based vaccines. One of the greatest threats to parasite control has been the development of drug resistance in parasites. Our knowledge of the basis of drug resistance and our ability to monitor its development with highly sensitive and specific DNA-based assays for 'resistance'-alleles will help maintain the effectiveness of existing antiparasitic drugs and provide hope that we can maintain control of parasitic disease outbreaks.

Animals↗
PubMed2003

World Association for the Advancement of Veterinary Parasitology (WAAVP) guidelines for evaluating the effectiveness of anthelmintics in chickens and turkeys.

These guidelines have been prepared to assist in the planning, operation and interpretation of studies designed to assess the effectiveness of drugs against helminth parasites of chickens and turkeys. They are the first to be compiled under the auspices of the World Association for the Advancement of Veterinary Parasitology (WAAVP) for these parasites. The advantages and disadvantages of the widely used critical and controlled tests are discussed. Information is provided on the selection of animals for experiments, animal housing, feed, dose determination studies, confirmatory and field trials, record keeping and necropsy procedures. This document should help investigators and those involved in product approval and registration in conducting and evaluating studies concerned with determining the effectiveness and safety of anthelmintic drugs.

Animal Husbandry↗
PubMed1997

Alternatives to animal experimentation in parasitology.

In parasitology, several measures can contribute to the aims of 3R (Reduction, Refinement and Replacement of animal experimentation). These include legal regulations, international guidelines for evaluating antiparasitic drugs, the refinement of animal models for parasitic infections, cryopreservation and cultivation of parasites in vitro or in chicken eggs, the maintenance of arthropods by artificial feeding, and the use of immunological and molecular in vitro techniques (e.g. the production of recombinant antigens for vaccines). Considerable progress has been achieved in the development of alternative techniques but both their standardisation and validation are not far advanced. A wider acceptance and use of alternative methods will only be achieved if research can offer economic alternatives that are as effective and reliable as animal experiments. Great efforts are needed for further progress.

Animal Testing Alternatives↗
PubMed1997

Application of molecular biology in veterinary parasitology.

The number of applications of molecular biology in veterinary parasitology is increasing rapidly. The techniques used with eukaryotic cells are generally applicable to the study of parasites and their hosts. The polymerase chain reaction is particularly important for identification and diagnosis of parasites, as well as for many other applications. With species and type specific probes or primers, sensitivities and specificities unheard of with conventional techniques can be achieved. The accumulation of more information on the DNA sequences of parasites will reveal many more unique sequences which can be used for identification, diagnosis, molecular epidemiology, vaccine development and for studying the evolutionary biology and the physiology of parasites and the host-parasite relationship. Similarly, the completion of genome projects on host organisms will greatly assist efforts to select for hosts that are genetically resistant to parasite infection. The study of the molecular biology of antiparasitic drug receptors, potential targets for chemotherapy, and the molecular genetics of drug resistance will allow molecular screens to be used with combinatorial chemistry in the search for new antiparasitic drugs, improvements to existing chemotherapeutic families and better diagnosis and monitoring of drug resistance. While there is a proliferation of molecular biology techniques, the availability of simple kits and of automated techniques and services for sequencing, library construction and oligonucleotide synthesis and other procedures is making it easier for non-specialists to apply many of the common techniques of molecular biology. Molecular biology and the benefits from its application are relevant for veterinary parasitologists in developing countries as well as developed countries and we should introduce aspects of molecular biology to the teaching and training of veterinary parasitologists.

Animals↗
PubMed2004

The nurse of parasites: gender concepts in Patrick Manson's parasitological research.

Patrick Manson (1844-1922), the so-called father of tropical medicine, played a pivotal role in making that discipline into a specialty. During his early career in China he discovered that the mosquito was the intermediate host of the filarial parasite and he somewhat peculiarly called the mosquito the "nurse" of the filarial worm. The discovery contributed greatly to the intellectual foundation of modern parasitology. In this paper I situate Manson's nomenclature in the context of nineteenth-century biological research on reproductive mech-anisms and argue that Manson's concept of the "nurse" was derived from nineteenth-century theories of sexual division of labor in nature's economy. The way he framed the relation between the mosquito and the parasite, moreover, can be understood in the terms of the domestic arrangement of the colonial European household. Manson's research demonstrates the significant exchange between medical concerns over European women's procreative role in the tropics and biological studies of parasitic reproduction.

Animals↗
PubMed1999

Molecular parasitology goes cellular.

Application of molecular genetics is an increasingly feasible undertaking in parasitology; however, an understanding of the phenotypes of various mutants generated by this approach will ultimately rely on cellular approaches to resolve the function of various proteins. In addition to the advances in understanding the biology of parasitism, such studies probably will uncover fundamental aspects of how eukaryotic cells communicate and regulate their responses to the environment. Thus, parasites may one day provide useful biological tools, just as viruses and bacterial toxins have done in the past, towards probing the biology of mammalian cells.

Animals↗
PubMed1993

[Parasitological evaluation of the stool].

The parasitologic investigation performed without clinical orientation in a routine laboratory allowed to identify the most common parasites, often cysts of protozoa, using a minimal technique. A more accurate investigation (e.g.: concentration, extraction and flotation) was hampered by a too large number of systematic specimens. The use of an immersion objective improves the detection and identification of cysts of protozoa. There is still some controversy on the virulence of small amoebae, flagellates, Blastocysts and Entamoeba coli, the infection being often massive. AIDS should predispose to new parasitic diseases such as cryptosporidiosis and strongyloidosis. A careful examination of stools for parasites has become mandatory in view of the wide geographical origin of patients with a parasitic disease.

Animals↗
PubMed2003

The design and analysis of microarray experiments: applications in parasitology.

Microarray experiments can generate enormous amounts of data, but large datasets are usually inherently complex, and the relevant information they contain can be difficult to extract. For the practicing biologist, we provide an overview of what we believe to be the most important issues that need to be addressed when dealing with microarray data. In a microarray experiment we are simply trying to identify which genes are the most "interesting" in terms of our experimental question, and these will usually be those that are either overexpressed or underexpressed (upregulated or downregulated) under the experimental conditions. Analysis of the data to find these genes involves first preprocessing of the raw data for quality control, including filtering of the data (e.g., detection of outlying values) followed by standardization of the data (i.e., making the data uniformly comparable throughout the dataset). This is followed by the formal quantitative analysis of the data, which will involve either statistical hypothesis testing or multivariate pattern recognition. Statistical hypothesis testing is the usual approach to "class comparison," where several experimental groups are being directly compared. The best approach to this problem is to use analysis of variance, although issues related to multiple hypothesis testing and probability estimation still need to be evaluated. Pattern recognition can involve "class prediction," for which a range of supervised multivariate techniques are available, or "class discovery," for which an even broader range of unsupervised multivariate techniques have been developed. Each technique has its own limitations, which need to be kept in mind when making a choice from among them. To put these ideas in context, we provide a detailed examination of two specific examples of the analysis of microarray data, both from parasitology, covering many of the most important points raised.

Analysis of Variance↗
PubMed1994

Proficiency testing in parasitology. An educational tool to improve laboratory performance.

In 1977, the Laboratory Proficiency Testing Program began testing laboratories that examine samples for gastrointestinal parasites and operated with little change in the subsequent 17 years. Four surveys, each containing four samples, are distributed each year to every currently licensed medical laboratory in Ontario. Participation is mandatory. Survey results indicate a remarkable improvement in laboratory performance during this period. Improvement is believed to result from a combination of the voluntary withdrawal from testing by laboratories with poor performance and the improved performance of the others. The extensive educational services devised and carried out by the Parasitology Committee is believed to have been a significant factor leading to this improvement.

Data Collection↗