Aeschlimann, André

1995, Toutoungi, Lina Naïme, Aeschlimann, André

1993, Toutoungi, L. N., Gern, Lise, Aeschlimann, André

A rearing method for Ixodes (Pholeoixodes) hexagonus, the hedgehog tick, was established which enabled the life cycle of immature stages to be studied under laboratory conditions. Larvae were fed on Swiss mice and nymphs on the cars of New Zealand rabbits. The feeding time of the larvae and nymphs on both hosts was 4–17 days. Larvae moulted to nymphs 15–21 days after detachment from mice. The premoulting period was 13–26 days for newly emerged males and 15–27 days for females. Engorged nymphs which developed into males weighed less (5.64±0.91 mg) than those that developed into females (6.019±88mg). The sex ratio (male: female) under laboratory conditions was 1:1.13.

1992, Gern, Lise, Burgdorfer, Willy, Aeschlimann, André, Krampitz, H. E.

1991, Zhu, Z., Gern, Lise, Aeschlimann, André

A peritrophic membrane was found in all three stages of Ixodes ricinus at no later than 18 h after their placement on rabbits. It was found to remain intact until at least 11, 30 and 10 days after repletion in larvae, nymphs and females, respectively. In blood-feeding I. ricinus, the peritrophic membrane is an uneven single layer with a thickness of about 0.03–0.48 μm in larvae, 0.03–0.79 μm in nymphs and 0.04–0.93 μm in females. It covers the whole surface of the midgut epithelium at a distance of about 0.2–0.8 μm. After repletion, the peritrophic membrane becomes thicker and thicker and more and more winding and simultaneously becomes multi-layered mainly in its arched parts. The distance between the peritrophic membrane and the midgut epithelium increases considerably and in the arched parts can reach as much as about 13 and 16 μm in metamorphosing larvae and nymphs, respectively and 25 μm in ovipositing females.

1994, Marval, Floriane de, Aeschlimann, André

1993, Humair, Pierre-François, Turrian N., Aeschlimann, André, Gern, Lise

The infestation of birds by immature Ixodes ricinus was studied during 6 months in a Swiss woodland, where Lyme borreliosis is endemic. Thirteen passerine species were found to be parasitized by /. ricinus subadults and specially Turdus merula, T, philomelos and Erithacus rubecula. Overall, 300 larvae and 162 nymphs were collected on 95 avian hosts. Prevalence of infestation of nymphs on birds was higher in spring; larvae peaked in summer. The infection of birds by Borrelia burgdorferi was also studied using blood cultivation and examinations of ticks. Motionless spirochetes were isolated from two E. rubecula. Infected ticks were removed from five species of passerines, and mainly three species of Turdidae (T. merula, T. phllomelos and E. rubecula}. Infection rate of larvae and nymphs by spirochetes averaged 16.3% and 21.7%, respectively. These percentages, compared to the infection rate of questing ticks collected through dragging, suggest that some Turdidae may play a role as amplifying hosts for spirochetes in the focus.

1991, Liz, Jorge S., Aeschlimann, André, Pfister, Kurt

1993, Beati, Lorenza, Péter, Olivier, Burgdorfer, Willy, Aeschlimann, André, Raoult, Didier

We propose the name Rickettsia helvetica sp. nov. for a rickettsial serotype of unknown pathogenicity isolated in 1979 in Switzerland from Ixodes ricinus ticks and designated the Swiss agent. The growth characteristics and the results of microimmunofluorescence serologic typing, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting (immunoblotting) with specific mice sera, and a polymerase chain reaction followed by restriction fragment length polymorphism analysis confirmed previously reported preliminary findings which suggested that this rickettsia, to which a name was given provisionally, does represent a new member of the spotted fever group of rickettsiae. The type strain is C3 (Reference Center for Rickettsioses, Marseille, France).

1993, Cordas, T., Aeschlimann, André, Morel, P. C.

Le rôle épidémiologique de certaines espèces de tiques du genre Ixodes est actuellement bien démontré. La nécessité de mieux connaître leur morphologie nous a donc conduit à mener une étude au microscope électronique à balayage (M.E.B.) des Ixodes de Suisse, dans le but d'identifier les espèces avec sûreté quelque soit le stade évolutif considéré. I. ricinus, 1. apronophorus, I. trianguliceps, I. hexagonus, I. canisuga, I. rugicollis, I. arboricola, I. lividus et I. vespertilionis ont pu être étudiés. La plupart des spécimens proviennent de la « collection AESCHLIMANN » déposée au Musée Zoologique de Lausanne. Les principales caractéristiques morphologiques ont été passées en revue et sont illustrées par des photographies, tandis que les résultats sont résumés sous forme de clés de détermination., The epidemiological importance of some ticks of the genus Ixodes has already been proved. Necessity of a better knowledge of their morphology has led us to undertake a scanning electron microscope (S.E.M.) study of Ixodes ticks in Switzerland, in order to be able to accurately identify the species independent of the development stage examined. I. ricinus, I. apronophorus, I. trianguliceps, I. hexagonus, I. canisuga, I. rugicollis, I. arboricola, I. lividus and I. vespertilionis have been studied. Most of these tick specimens were from the « collection AESCHLIMANN » deposited at the Lausanne Zoological Museum. The main morphological features are illustrated by micrographs, and results presented in determination keys.

1991, Gern, Lise, de Marval, F., Aeschlimann, André

In Switzerland, the spirochete Borrelia burgdorferi and tick-borne encephalitis virus infect the human population. These infections may cause serious pathogenic effects to men and domestic animals. The tick Ixodes ricinus is the vector of both microorganisms. The distribution of the virus is concentrated in small foci scattered in some regions. In these areas, the infection occurs in less than 1 % of the ticks. The distribution of the spirochete is larger and more regular in the Swiss territory and B. burgdorferi is present in 5 to 50 % of/, ricinus. It is the aim of this paper to try to explain how both types of foci occur, considering especially the problem of small mammals as reservoirs for the bacterium and the virus.