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Biomedical subjects

H Schulz-Key

Publications and source records attributed to H Schulz-Key.

79 records · Page 5Linked to original sources
PubMed1975

[Investigations on the filariidae of the cervidae in Southern Germany. 3. The filariidae of roe deer (Capreolus capreolus) and fallow deer (Dama dama) (author's transl)].

Roe deer in southern Germany are frequently infected with W. rugosicauda. The adult worms are found subcutaneously in the connective tissues of the back of the host. The microfilariae concentrate in a considerable distance near the nose, in smaller numbers also in the ears and in the skin of the legs. The vector is probably Ixodes ricinus. In fallow deer C. wenki are found intradermally and subcutaneously. The microfilariae remain in the skin near the site of the adult worms. Skin inhabiting microfilariae of another filariid worm are found which cannot be associated with the described species of Cervidae. The host specificity of the filariid forms of roe deer, fallow deer and red deer is indicated, the development of the microfilarial distribution patterns is discussed.

Animals↗
PubMedDate not supplied

Efficacy of ivermectin in the treatment of concomitant Mansonella perstans infections in onchocerciasis patients.

As part of an ivermectin dose-ranging study of onchocerciasis patients in Togo, 55 onchocerciasis patients with concomitant mansonelliasis received single oral doses either of ivermectin (100 to 200 micrograms/kg body weight) or placebo. As expected, Onchocerca volvulus microfilariae in the skin were greatly reduced in number soon after drug treatment, but microfilariae of Mansonella perstans reacted differently. Microfilarial densities of M. perstans were assessed with a filtration technique both before, and 4 times after, treatment. In untreated patients microfilarial densities were stable until the end of the study at 6 months. In patients receiving ivermectin, microfilarial densities dropped on average to less than 60% of the pre-treatment level and remained there until the final post-treatment examination. This partial reduction was probably not caused by a microfilaricidal effect of ivermectin, but rather by an altered distribution of microfilariae in the peripheral blood and in a suspected microfilarial reservoir.

Animals↗
PubMedDate not supplied

Density-dependent parasite establishment suggests infection-associated immunosuppression as an important mechanism for parasite density regulation in onchocerciasis.

The modulation of human immune response by filarial parasites has yielded contradictory experimental findings and attracted much controversy. We address the unresolved question of acquisition, establishment and accumulation of Onchocerca volvulus by using a modelling approach that relates computer simulations to cross-sectional data concerning parasite burdens in 913 West African onchocerciasis patients. It is shown that the acquisition of O. volvulus is not constant with host age; instead, the analysis of age profiles of parasite burdens strongly indicate the operation of immunosuppressive processes within the human host, associated with the presence of adult parasites or microfilariae. It is suggested that these processes suppress immunity against incoming infective larvae (L3), which themselves act as an immune modulating component once they have successfully overcome the barrier of concomitant immunity. Suppression of parasite-specific immunity leads to parasite establishment rates which increase along with the parasite burden, but which hardly depend on hyperendemic annual transmission potentials. Children, still immunocompetent due to low parasite burdens, acquire 0.1-0.5 adult female parasites per year, whereas older people, immunosuppressed due to high burdens, acquire 2-4 adult female parasites per year. Differences in parasite establishment between the forest and the savannah strains of O. volvulus are quantified and dynamic aspects of density-dependent parasite establishment discussed.

Adolescent↗
PubMedDate not supplied

A DNA sequence specific for forest form Onchocerca volvulus.

Onchocerciasis, or river blindness, is caused by infection with Onchocerca volvulus, a filarial parasite which infects about 40 million people in Africa and Latin America. Epidemiological, clinical, entomological and serological studies of African onchocerciasis led to the hypothesis that Onchocerca volvulus exists in different forms in the forest and savannah. It is uncertain if these differences are due to genetic differences within O. volvulus itself, or to epigenetic factors, such as differences in the host populations. To date no basic biochemical differences between the forest and savannah populations of O. volvulus has been found, although isoenzyme studies have shown that differences in allele frequency between forest and savannah populations exist. Here we describe the isolation of a DNA sequence that seems to be specific for the forest form of O. volvulus, the first indication of a basic genetic difference between the savannah and forest forms.

Base Sequence↗