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PubMed1986

Progress in molecular parasitology.

Substantial progress has been made in the last ten years in understanding the structural and functional organization of parasitic protozoa and helminths and the complex physiological relationships that exist between these organisms and their hosts. By employing the new powerful techniques of biochemistry, molecular biology and immunology the genomic organization in parasites, the molecular basis of parasite's variation in surface antigens and the biosynthesis, processing, transport and membrane anchoring of these and other surface proteins were extensively investigated. Significant advances have also been made in our knowledge of the specific and often peculiar strategies of intermediary metabolism, cell compartmentation, the role of oxygen for parasites and the mechanisms of antiparasitic drug action. Further major fields of interest are currently the complex processes which enables parasites to evade the host's immune defense system and other mechanisms which have resulted in the specific adaptations which enabled parasites to survive within their host environments. Various approaches in molecular and biochemical parasitology and in immunoparasitology have been proven to be of high potential for serodiagnosis, immunoprophylaxis and drug design.

Animals↗
PubMed1996

The stage-conversion time of Toxoplasma gondii: interpretation of chemical-biologic data out of parasitologic or host context.

Several published biologic times for the stage conversion of Toxoplasma gondii from tachyzoite to bradyzoite in mice are critically examined. There are several reports of 3 days and many of longer times. Possible errors, related to delay from dissemination of the infection, are pointed out. The time to the appearance of the 36-kDa surface antigen, sometimes used for the diagnosis of bradyzoites, should be compared with the biologic attribute of bradyzoites, inducing the short prepatent period in cats. It is recalled that the development of acid pepsin resistance is not exclusively correlated with the biologic definition of bradyzoites. Reactivation of toxoplasmosis in mice does not necessarily follow the administration of a corticosteroid. The daily dose, the type of corticosteroid, its solubility, whether alcohol or ester, the route of administration, the host, and, probably, other factors are important in giving rise to sufficient immunosuppression for reactivation to occur. The plea is made to examine biologic measurements in the context of parasitologic and host factors.

Animals↗
PubMed2006

[Relevance of parasitological examinations for the clinical course, epidemiology and prevention of alveolar echinococcosis - experiences of more than two decades in Austria].

Alveolar echinococcosis has been known in Austria since 1854. At the beginning of the 20th century the Austrian researcher on echinococcosis, Adolf Posselt, has realized already the enormous medical relevance of serological tests for the diagnosis of alveolar echinococcosis as well as for preventive purposes. Since the beginning of the 1980ies a long-term study about the epidemiology and serodiagnosis of alveolar echinococcosis has started in the Department of Medical Parasitology of the Clinical Institute of Hygiene and Medical Microbiology of the University of Vienna. Today a highly sensitive enzyme-linked immunosorbent assay as well as a highly specific westernblot system are available for the serological diagnosis of human alveolar echinococcosis cases, for the serological monitoring of the disease as well as for seroepidemiological and preventive medical studies. In addition, molecular biological tools for the detection of E. multilocularis (as well as E. granulosus strain) specific DNA in surgical resected and bioptic materials complete our diagnostic spectrum of methods.

Animals↗
PubMed1996

Molecular genetic approaches to parasite identification: their value in diagnostic parasitology and systematics.

A wide range of approaches is available to parasitologists to aid in specific parasite identification and to formulate phylogenetic relationships. This review emphasises the usefulness of molecular genetic techniques, especially DNA-based procedures, in addressing problems of identification, characterisation and phylogeny of parasites. It should be stressed that an understanding of the various DNA approaches, techniques and target genes most likely to be effective in addressing key issues in diagnostic parasitology and systematics is still developing. Nevertheless, DNA methods clearly have great potential with regard to specificity and sensitivity, and applications will increase further with technological advance. Indeed, because of the minimal requirements for material, PCR-based methods especially should prove of immense value in future studies with parasites.

Animals↗
PubMed1983

Serological and parasitological survey of blood donors in Kenya for toxoplasmosis.

322 samples of sera from blood donors in four areas of Kenya were screened for Toxoplasma gondii antibodies by haemagglutination and 54% proved positive. 299 of these were also tested by dye test and 42% were positive, with 5.9% showing high titres indicating possible active infection. Parasitological examination of the buffy coat from donors was also carried out on 100 samples but no Toxoplasma parasites were seen in spite of high antibody incidence. There appears to be little or no clinical toxoplasmosis in Kenya but serological studies indicate a widespread distribution of the parasite in the human population.

Adolescent↗
PubMed1986

Parasitological observations of chronic diarrhoea in suspected AIDS adult patients in Kinshasa (Zaire).

The parasitological profile of chronic diarrhoea in 46 Zairian adults suspected of Aids demonstrated that the frequency of protozoa was five times higher than that of helminths; 86% of the protozoa were sporozoa: Isospora belli was the most frequent (19%), followed by Cryptosporidium isolated for the first time in Zaire (8%) and Blastocystis hominis (2%). 37 of the 46 patients were immunodeficient.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Strongyloides stercoralis: parasitological, immunological and pathological observations in immunosuppressed dogs.

Four specific pathogen-free, two to three-month-old, laboratory-raised beagles were infected with Strongyloides stercoralis and monitored by thrice-weekly faecal examinations. Larvae were not detected in the faeces after the 11th week. During the 14th week, daily oral prednisolone (2.2 mg/kg) was given. This led to weak recrudescence of the infection. During the 21st week, the daily dose of prednisolone was doubled and thereafter two of the four dogs developed severe hyperinfective strongyloidiasis with their adult worm populations markedly exceeding the number of larvae inoculated, as did one dog which remained asymptomatic. One dog died during the 15th week, i.e., before there was time for a marked increase in the parasite population. Three of the four dogs provided evidence of disseminated infection with adult worms occurring in ectopic sites. Parasite-specific cellular and humoral immune responses were monitored weekly. All dogs developed a significant rise in specific IgM titres lasting until the fifth week. From the fourth week, all dogs had detectable parasite-specific IgG antibody levels that persisted throughout the experiment in spite of the immunosuppression. Strongyloides-induced lymphocytic responses in vitro were demonstrated in three dogs from the second to the fifth week of infection, but returned to pre-infection levels thereafter. All animals were necropsied. Relevant pathological lesions were found in the small intestine, the colon and the lungs. Larvae were seen in such ectopic sites as mesenteric nodes and prostate. The observations provide further evidence that canine S. stercoralis infections can be manipulated to reproduce with great fidelity the parasitological and clinico-pathological events occurring in human disseminated strongyloidiasis.

Animals↗
PubMed1987

Filariasis due to Loa loa and Mansonella perstans: distribution in the region of Okondja, Haut-Ogooué Province, Gabon, with parasitological and serological follow-up over one year.

The prevalence of Loa loa and Mansonella perstans filariasis has been determined in 6 rural villages in eastern Gabon. Between 18.9 and 27.2% of people carry L. loa microfilariae with an overall microfilarial rate of 25.1%. The microfilarial rate for M. perstans was more variable, between 33.3 and 62.2% (average 49.1%). No significant difference was seen in the microfilarial rate with age over 15 years for either parasite, but men were infected more frequently than women. Anti-L. loa antibody titres were measured, using a homologous microfilarial antigen in ELISA. Taking the parasitological and immunological evaluations together, only 10% of the sample population appear to be free of these filarial infections. L. loa and M. perstans microfilaraemia and corresponding serology were also investigated twice in 150 people at a one-year interval. 99.1% of the cases who had no circulating L. loa microfilaria in March 1984 still did not show any 12 months later. Similarly, 97.1% of the untreated, microfilaraemic cases still harboured this parasite a year later. The same was not observed for M. perstans, since microfilariae appeared or disappeared in 26.7% of the cases. This suggests different dynamics for the two filarial infections. Variation in individual anti-L. loa antibody titres was low. The possibility of a genetic influence on the expression of loiasis is discussed.

Adolescent↗
PubMed1987

Ketoconazole promotes parasitological cure of mice infected with Trypanosoma cruzi.

Administration of 120 mg/kg/day of ketoconazole for 9 weeks resulted in parasitological cure of at least 78.5% of mice infected with 10(5) blood trypanosomes of Trypanosoma cruzi, strain Y. These results and the fact that ketoconazole is widely used in humans for prolonged therapy of fungal infections without significant side effects strongly suggest that further evaluation of ketoconazole for treatment of Chagas disease is highly desirable.

Animals↗
PubMedDate not supplied

A community trial of ivermectin for onchocerciasis in Sierra Leone: clinical and parasitological responses to four doses given at six-monthly intervals.

Clinical and parasitological responses were studied in villagers receiving all 4 doses of treatment, at 6-monthly intervals, in a placebo-controlled community trial of ivermectin for onchocerciasis in Sierra Leone. Skin microfilarial loads were markedly lowered by ivermectin throughout and there were reductions in the severity, but not the prevalence, of skin lesions. Markers of general health and the prevalences of itching, Onchocerca nodules and visual loss were not significantly reduced during the study period. Despite our inability to demonstrate obvious clinical benefit, treatment with ivermectin was well accepted throughout the study. Simple clinical measures for evaluating the short to medium term impact of the mass distribution of ivermectin on populations with onchocerciasis need further development.

Adult↗
PubMedDate not supplied

Antimonial treatment of hamsters infected with Leishmania (Viannia) panamensis: assessment of parasitological cure with different therapeutic schedules.

The objective of the study was to establish the effective dose and route of administration of Glucantime for treating hamsters infected with Leishmania (Viannia) panamensis and to use this method to test new treatment regimens to attain clinical and parasitological cure. In the first experiments animals were inoculated subcutaneously in the hind foot with 5 x 10(6) promastigotes of L. panamensis (HOM/COL/84/1099) from a 6 d culture. One month after inoculation, Glucantime was administered intramuscularly (i.m.) at 20, 40 or 60 mg/kg/d for 20 d to groups of hamsters. Only 60 mg/kg/d resulted in both clinical improvement and parasite elimination from the skin and draining lymph node. In the second set of experiments, i.m., local and combined antimonial regimens were compared. The local regimen, of 4 intralesional (i.l.) injections of 4 mg of antimony at 5 d intervals, and the combined regimen (i.m. and i.l.), were more efficient at clearing parasites than the systemic (i.m.) schedule, especially when a low dosage of Glucantime (30 mg/kg/d x 20 d) was used. The results suggest that combining local treatment and low systemic dosages of antimonials results in clearance of L. panamensis.

Animals↗
PubMedDate not supplied

Parasitological and clinical aspects of bancroftian filariasis in Kassena-Nankana District, upper east region, Ghana.

A survey of the prevalence of bancroftian filariasis was conducted in August-September 1992 in the northern part of the Kassena-Nankana District, Upper East Region, Ghana. 200 compounds from 3 different communities were randomly selected from the vitamin A trial database. All resident compound members were examined for clinical manifestations of lymphatic filariasis and capillary blood was obtained between 21:00 and 01:00 and examined using the counting chamber technique. 1603 people were examined, 741 males and 862 females. The overall prevalence of microfilaraemia was 32.4% (95% confidence interval 30.1-34.7). Geometric mean microfilaria density (infected persons only) was 794 per mL. The most important clinical manifestation was hydrocele (in 32% of males) followed by limb elephantiasis (in 3.6% of the study population). There was no significant difference between the 3 communities in clinical or parasitological findings.

Adolescent↗
PubMed1986

The evolution of experimental Trypanosoma cruzi cardiomyopathy in rabbits: further parasitological, morphological and functional studies.

Young rabbits (1-2 months of age) inoculated with trypomastigote forms of the Colombia strain of Trypanosoma cruzi have been shown to develop cardiac pathological changes (together with parasitological and immunological alterations) which are very similar to those observed in the acute and chronic phases of Chagas' disease in man. The cardiac alterations in the acute phase are characterized grossly by slight cardiomegaly with dilatation of the right-sided chambers. Microscopically they are characterized by mild focal myocarditis. The chronic phase is characterized by moderate to marked cardiomegaly with hypertrophy and dilatation of both ventricular chambers. There is thinning of the apical region (apical aneurysm), particularly of the left ventricle. Focal myocarditis is seen microscopically with areas of myocytolytic necrosis, atrophic and hypertrophic myofibers, an inflammatory response predominantly composed of mononuclear cells and interstitial fibrosis. Cineventriculography in the left ventricle of rabbits during the chronic phase disclosed regional myocardial dysfunction, with typical apical systolic bulging. The pathogenesis of Chagasic cardiomyopathy is briefly discussed in the light of these findings. Our investigation has further shown that this animal model is particularly suitable for studies on on the mechanisms, pathology and treatment of Chagas' heart disease.

Actin Cytoskeleton↗
PubMed1988

Novel source of parasitological information.

Seldom if ever have parasitological insights been found in the great works of literature. Important observations on the transmammary transmission o f hookworm, however, may be found in a literary manuscript recently discovered in a Parisian archive. The concept of transmammary transmission is now well established, and while canine hookworm species are generally considered incapable of reaching maturity in man, they may well be capable of producing transient patent infections in neonates. The manuscript, to judge by its literary style, is clearly a fragment written by Marcel Proust (1871-1922) for his great seven-part masterpiece A la Recherche du Temps Perdu (Remembrance of Things Past) and perhaps it will appear in future editions. The manuscript was discovered by Professor C.A.M. Bell, who has kindly provided the following translation.

Journal Article↗
PubMed1982

World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guidelines for evaluating the efficacy of anthelmintics in ruminants (bovine and ovine).

During the 8th International Conference of the World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) held in Sydney, Australia, in 1977, President S. Gaafr appointed a committee to prepare international guidelines for evaluating the efficacy of anthelmintic products. The goal was to develop uniform testing standards and registration requirements to expedite the testing and approval of effective products with a minimum of labor, money, and experimental animals without sacrificing scientific validity. Achievement of such a goal would mean that data from investigators in one country could be used in registering drugs in another country. These guidelines, which were approved by the membership at the general meeting of the 9th International Conference of the W.A.A.V.P. on July 16, 1982 in Budapest, Hungary, are only a beginning in the development of uniform international methods for testing the efficacy of anthelmintics. We now propose that they be used by the scientific community recognizing that, at this time, these guidelines have not been officially reviewed or accepted by any government regulatory authority. Investigators are encouraged to evaluate this document critically and to recommend modifications promptly to the Committee so that they may be incorporated in these guidelines before the 10th International Conference to be held in Perth, Australia in 1983.

Animals↗
PubMed1986

World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guidelines for evaluating the efficacy of anthelmintics in swine.

As a follow-up to a previous guideline publication on efficacy evaluation of anthelmintics in ruminants, an expert group of the World Association for the Advancement of Veterinary Parasitology presents similar guidelines for the testing of anthelmintics in swine. The goal of the guidelines is to develop uniform testing standards and registration requirements. Data obtained from investigations according to the guidelines should be internationally accepted in the registering of drugs. Further, the use of the guidelines may contribute towards reducing costs, labor and the number of experimental animals used for drug testing.

Animal Feed↗
PubMed1987

The pathogenicity of haemonchosis in sheep and goats in Iraq: 1. Clinical, parasitological and haematological findings.

The response of Awassi sheep and the local breed of Iraqi goats to primary infection with a prevalent trichostrongylid nematode, Haemonchus contortus, was compared by examining their worm burden and the pathogenic effects of the parasite on these hosts following experimental infection. The results showed that the goats had lower worm burdens and had suffered less severe clinical and haematological disturbances than the Awassi sheep. The worm counts in sheep were higher than in goats but the count of the mucosal phase of the larvae was higher in goats. These differences are possibly immunologic in origin though a genetic resistance may operate, primarily at the level of worm establishment. The pathophysiological changes are correlated with parasitological and clinical observations in the two host species.

Abomasum↗
PubMed1989

Computational veterinary parasitology with an application to chemical resistance.

Mathematical modelling offers an aid to the understanding of parasitic diseases. In the past, computational limitations have meant that the role of many factors influencing the control of disease has had to be ignored or oversimplified. Using computers, these shortcomings can be overcome. Site-specific and environmental modelling offer new prospects for the management of disease. This paper illustrates the approach of computational veterinary parasitology with an application to anthelmintic and acaricidal resistance.

Animals↗