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Biomedical subjects

H Mehlhorn

Publications and source records attributed to H Mehlhorn.

At least 19 recordsLinked to original sources
PubMed2005

Molecular biological investigations of Brazilian Tunga sp. isolates from man, dogs, cats, pigs and rats.

Twenty-four isolates of Tunga were collected from afflicted humans, dogs, cats, pigs and rats in Brazil. To investigate genetic diversity, a hypervariable section of mitochondrial 16S rDNA was amplified using PCR and subsequently sequenced. In order to compare results with another species of the genus Tunga, three isolates of the recently described Tunga trimamillata were also checked. Whereas eleven isolates (five from cats, three from dogs and three from humans) were of identical sequence, thirteen isolates collected from dogs, humans, pigs and rats showed differences in sequence up to 49%, so that the existence of one or more new species of Tunga may be presumed.

Animals↗
PubMed2005

Effects of a combinations of emodepside and praziquantel on parasites of reptiles and rodents.

A new combination of two anthelmintic compounds containing emodepside and praziquantel (Profender, Bayer AG, Levekusen, Germany) was tested in pet rodents and reptiles. Topical application of the two compounds led to the quick disappearance of nematodes and cestodes from a broad spectrum of hosts including mice, jirds, snakes, anole lizards, turtles, monitor lizards, etc. In reptiles the dosage had to be increased, since the thick outer layer of the epidermis hinders the penetration of the compounds. In animals with an extremely thick epidermis (e.g. monitor lizards, leguans) the new product was applied under the armpits.

Administration, Topical↗
PubMed2005

Efficacy of a combination of imidacloprid and moxidectin against parasites of reptiles and rodents: case reports.

A new compound containing imidacloprid 10% (w/v) and moxidectin 2.5% (w/v) (Advantage multi, Advocate) was applied as a spot-on treatment to mice experimentally infected with Trichuris muris. Case reports of reptiles found positive for nematode and mite infections following parasitological examination and treated with this compound are also discussed. The results demonstrated that the registered, recommended 2.5% moxidectin concentration for use in dogs was sufficient to eliminate nematodes and mites in reptiles. Infections with nematodes were successfully treated with a single application. Mite infestations in reptiles were eliminated using a treatment repeated on 3 consecutive days.

Animals↗
PubMed2005

Experimental quantification of the feline leukaemia virus in the cat flea (Ctenocephalides felis) and its faeces.

Cat fleas (Ctenocephalides felis) were fed via artificial membranes and infected with the feline leukaemia virus (FeLV) from cell cultures. After removing the fleas from the blood source, the quantity of virus in the flea and its faeces was measured over a defined period of time. The virus was detectable in the fleas for up to 30 h at room temperature and up to 115 h at 4 degrees C. In the faeces, the amount of virus decreased much more slowly--after 2 weeks half of the initial amount of virus could still be detected. Thus the faeces might be a source of further infections, e.g. for the flea larvae or the cat itself.

Animals↗
PubMed2005

Field trial of the efficacy of a combination of imidacloprid and permethrin against Tunga penetrans (sand flea, jigger flea) in dogs in Brazil.

In a field trial in Brazil 17 dogs penetrated by females of the jigger flea, Tunga penetrans, were topically treated with a combination of 10% imidacloprid and 50% permethrin (Advantix), while 17 dogs remained untreated. The follow-up controls on days 7, 14, 21 and 28 post-treatment clearly showed that, beginning from day 7, the flea load in treated dogs decreased, so that most of the dogs became free of tungiasis lesions, while in the untreated group the flea load remained high. Since the dogs distribute the flea eggs throughout the village, leading to a high incidence of tungiasis in humans, treatment of dogs probably also decreases the number of cases of tungiasis in the latter.

Animals↗
PubMed2005

Determining a diagnostic dose for imidacloprid susceptibility testing of field-collected isolates of cat fleas (Siphonaptera: Pulicidae).

The susceptibility of four laboratory strains of cat fleas, Ctenocephalides felis (Bouche), to imidacloprid was determined by three different laboratories, by using a standardized bioassay protocol. The probit lines generated by the different laboratories were very similar, with LC50 values ranging from 0.32 to 0.81 ppm. Based on these data, a diagnostic dose (DD) of 3 ppm imidacloprid in larval rearing media was provisionally identified for detecting shifts in tolerance, possibly as a consequence of incipient imidacloprid resistance. None of the larvae from the susceptible laboratory strains survived the DD. Eighteen field-collected isolates were evaluated for their susceptibility to imidacloprid and to validate a DD of 3 ppm. Probit lines from 18 field-collected isolates were very similar, with LC50 values ranging from 0.14 to 1.52 ppm. When exposed to the DD, between 3 and 10% of the exposed larvae emerged as adults from only three of the 18 isolates. All other field isolates gave 100% mortality at the DD. Under the criteria established (>5% survivorship at 3 ppm), two isolates would be established on mammalian hosts and more extensive tests conducted to exclude or confirm the presence of resistance. The DD of 3 ppm is robust enough to eliminate most of the susceptible isolates collected until today, yet low enough to identify possible isolates for further testing.

Animals↗
PubMed2004

Molecular phylogeny of isolates of Ctenocephalides felis and related species based on analysis of ITS1, ITS2 and mitochondrial 16S rDNA sequences and random binding primers.

The phylogenetic relationships among 31 different flea isolates representing seven different species were studied by nucleotide sequence comparison of the internal transcribed spacer 1 (ITS1), internal transcribed spacer 2 (ITS2) and/or mitochondrial 16S ribosomal RNA gene (mt16S-rDNA) to examine the patterns of variation. Results show that all regions are useful in discriminating among flea species. In Ctenocephalides felis and Tunga penetrans, some differences in these gene regions occurred among different isolates within the same species. In the latter case, the differences are in the mt16S-rDNA region, with one isolate showing 48% divergence in nucleotide sequence. The taxonomic implications of this result are unclear at present. The gene regions revealed differences between C. felis isolates only after DNA sequencing the PCR products. Further differentiation among C. felis isolates was obtained using four different random binding primers (decamers) and primers for mammalian aldolase to amplify narrow differences in the genome. Using these primers we were able to discriminate between different C. felis isolates and determine that some of the genetic variation coincided with minor differences in response to the control agent imidacloprid. However, overall findings do not support the existence of subspecies of C. felis.

Animals↗
PubMed2004

[Humanopathogenic parasites--an unwelcome import].

Humanopathogenic parasites represent a health risk for travelers to tropical countries. They can be picked up by direct contact, via contaminated food and drink, the bites of blood-sucking insects and leeches, as also via direct penetration through the skin. Not only the bite and sting wounds themselves are unpleasant. The true danger to the victim is represented, in particular, by the bacteria, viruses or parasites that are transmitted in this way. They can give rise to protracted diseases such as hepatitis B, cutaneous or intestinal disorders. The most effective preventive measure is exposure prophylaxis.

Animals↗
PubMed2003

Evidence of horizontal transmission of feline leukemia virus by the cat flea ( Ctenocephalides felis).

The feline leukemia virus (FeLV) is a naturally occurring and widespread retrovirus among domestic cats. The virus is mainly transmitted horizontally through saliva, blood and other body fluids by close contact between cats. Vectors other than cats, e.g. blood-sucking parasites, have not been reported. This study tested the vector potential of the cat flea ( Ctenocephalides felis) for FeLV. In a first feeding, fleas were fed for 24 h with blood from a FeLV-infected cat with persistent viremia. FeLV could be detected in the fleas, as well as in their feces. Fleas were then divided in two populations and fed in a second feeding for 5 h or 24 h with non-infected non-viremic blood. FeLV was again detected in the fleas and their feces. In addition, the two resulting blood samples of the second feeding were subsequently tested for FeLV and both samples were positive for FeLV RNA. The cat flea transmitted the FeLV from one blood sample to another. In a third feeding, the same populations of fleas were fed again with non-infected blood for 5 h or 24 h. This time FeLV was not detected in the fleas, or in the feces or blood samples. Results show that cat fleas are potential vectors for FeLV RNA in vitro and probably also in vivo.

Animals↗
PubMed2003

Synergistic effects of pyrantel and the febantel metabolite fenbendazole on adult Toxocara canis.

Pyrantel embonate and febantel are both constituents of Drontal Plus and Drontal Puppy broad spectrum anthelmintics for dogs. The effects of pyrantel and the febantel metabolite fenbendazole were investigated against Toxocara canis in-vitro by studying changes in worm motility and tissue damage. Pyrantel and fenbendazole were added to worms incubated in media for 8 h at the following concentrations: pyrantel: 12.2 microg, 25 microg, or 50 microg; fenbendazole: 50 microg, 100 microg or 200 microg; mixture of pyrantel and fenbendazole: 12.2 microg p + 50 microg f, 25 microg p + 100 microg f, 50 microg p + 200 microg f. Following this 8 h incubation period, one group of the worms was immediately fixed and studied by light- and electron microscopical examination. Other groups have been observed for further 8 h periods up to 56 hours and then studied in the same way.

Animals↗
PubMed2003

Electron microscopic study of in vitro cultures of Hammondia heydorni (Berlin 1996) tachyzoites after passages through dogs, mice, rats, guinea pigs and jirds.

This study describes the fine structure and reproduction of tachyzoites of Hammondia heydorni (isolate Berlin 1996) after in vitro cultivation of stages isolated from serial passages between dogs and various intermediate hosts such as mice, rats, guinea pigs, jirds, knock-out mice, goats and sheep. The tachyzoites are identical with respect to their ultrastructural features to the corresponding stages of the NC-1-strain of Neospora caninum. This fact conforms with other already published data and underlines our opinion that the recently redescribed N. caninum Dubey et al. 2002 is a synonym of the previously described H. heydorni (Tadros and Laarman 1976) Dubey 1977.

Animals↗
PubMed2003

No evidence of Wolbachia endosymbiosis with Loa loa and Mansonella perstans.

Endosymbiotic Wolbachia bacteria from different filarial species, including major pathogens of humans such as Wuchereria bancrofti, Brugia malayi and Onchocerca volvulus, seem to play an important role in the development, viability and fertility of these worms. Wolbachia trigger inflammatory host responses as well as adverse reactions against standard treatment regimens and are therefore under investigation as novel treatment targets. We investigated whether Wolbachia are also endosymbiotic in Loa loa and Mansonella perstans. In both male and female adult L. loa, we found no evidence of bacteria by light or transmission electron microscopy. Furthermore, Wolbachia-specific PCR was negative in both L. loa and M. perstans microfilariae. The absence of Wolbachia in both filarial species therefore discourages the use of antibiotics as an adjunct or alternative approach to current treatment concepts for both loiasis and mansonelliasis perstans.

Animals↗
PubMed2003

[Hantavirus-induced acute renal failure. A case report].

A non-ischemic acute renal failure may indicate a hantavirus nephropathy, so that appropriate serological examinations should be done. A 19-year-old man had acutely fallen ill with fever, rhinitis, and arthralgia. Clinically, he presented with a polyuric renal failure as well as hypertension, proteinuria, erythro- and leucocyturia. Serologically, IgG- and IgM-hantavirus antibodies were found against the Central European variant of hantavirus Dobrava. At renal biopsy, tubular epithelial swelling, vacuolization, and necrosis as well as interstitial hemorrhages were seen. Electron microscopically, virion particles with a gridlike surface structure as well as with the shape and dimension evident of hantaviruses could be detected in the nucleus and cytoplasm of renal tubular cells. After a clinical course of 3 weeks, the patient was free of complaints and cured with a restitutio ad integrum.

Acute Kidney Injury↗
PubMed2002

[The tick stings! Observations on a misnomer]].

Dermatology enjoys a unique distinction of visualizing its subject matter and should attain complete unity between a dermatologic term and the clinical concept therewith expressed. Clear and definite terminology seems indispensable. Unfortunately wrong designations sanctioned by daily use are incorporated in official nomenclature. How parasitology tells us that a tick stings and that a "tick bite" is a misnomer is detailed in this article.

Animals↗