Biomedical subjects

Francis Schaffner

Publications and source records attributed to Francis Schaffner.

6 recordsLinked to original sources

PubMed2005

Phylogeography of Aedes (Stegomyia) aegypti (L.) and Aedes (Stegomyia) albopictus (Skuse) (Diptera: Culicidae) based on mitochondrial DNA variations.

Aedes (Stegomyia) aegypti (l.) and Aedes (Stegomyia) albopictus (Skuse) are the most important vectors of the dengue and yellow-fever viruses. Both took advantage of trade developments to spread throughout the tropics from their native area: A. aegypti originated from Africa and a. albopictus from South-East Asia. We investigated the relationships between A. aegypti and A. albopictus mosquitoes based on three mitochondrial-DNA genes (cytochrome b, cytochrome oxidase I and NADH dehydrogenase subunit 5). Little genetic variation was observed for a. albopictus, probably owing to the recent spreading of the species via human activities. For A. aegypti, most populations from South America were found to be genetically similar to populations from South-East Asia (Thailand and Vietnam), except for one sample from Boa Vista (northern Amazonia), which was more closely related to samples from Africa (Guinea and Ivory Coast). This suggests that African populations of A. aegypti introduced during the slave trade have persisted in Boa Vista, resisting eradication campaigns.

Aedes↗

PubMed2004

Emerging vectors in the Culex pipiens complex.

In the Old World, some mosquitoes in the Culex pipiens complex are excellent enzootic vectors of West Nile virus, circulating the virus among birds, whereas others bite mainly humans and other mammals. Here we show that, in northern Europe, such forms differing in behavior and physiology have unique microsatellite fingerprints with no evidence of gene flow between them, as would be expected from distinct species. In the United States, however, hybrids between these forms are ubiquitous. Such hybrids between human-biters and bird-biters may be the bridge vectors contributing to the unprecedented severity and range of the West Nile virus epidemic in North America.

Animals↗

PubMed2004

First record of Aedes (Stegomyia) albopictus in Belgium.

The 1st record of Aedes albopictus in Belgium was made in a village in Oost-Vlaanderen Province. Two preimaginal stages were collected on October 31, 2000, in the used tire stock of a recycling company that imports tires from the USA and Japan. The species has reproduced on site, and local environmental conditions make its establishment possible. Anopheles plumbeus was a common companion species found in tires in high densities.

Aedes↗

PubMed2003

Genetic differentiation of Anopheles claviger s.s. in Europe.

Two groups of Anopheles claviger sensu stricto Meigen (Diptera: Culicidae) were recently found in France, representing unclear genetic entities. To better understand this situation, sampling was extended to 13 European countries, and 47 samples were analyzed by investigating the polymorphism of 11 autosomal and 1 sex-linked allozyme loci. Genetic differentiation, as measured by F(st), between these two groups was confirmed, with no isolation by distance within each group. Among the twelve loci studied, none had diagnostic alleles. Group I is mainly located in western Europe (UK and south-west of France), and Group II covers eastern France and eastern and northern Europe. Intermediate populations, sampled at the overlapping range between them, do not display a heterozygote deficit, suggesting that these two groups are probably not genetically isolated. The origin of each group and its biological significance is discussed within the context of differentiation in refugia during recent glaciations.

Animals↗

PubMed2003

First record of Ochlerotatus (Finlaya) japonicus japonicus (Theobald, 1901) in metropolitan France.

Ochlerotatus (Finlaya) japonicus japonicus is a potential vector of arboviruses such as Japanese encephalitis virus and West Nile virus. The latter already is present in France. We report the species for the 1st time in metropolitan France and in Europe. Two larvae were collected in July and October 2000 in used tires in a village in northwestern France. Collections were made in a stack of recycled tires from a company that imports from the USA and Japan. The lack of other mutes of introduction for the species confirms tires as a means of worldwide spread. Larval stages found in the area indicate that the species is reproducing locally.

Animals↗

PubMed2003

Polymerase chain reaction-based differentiation of the mosquito sibling species Anopheles claviger s.s. and Anopheles petragnani (Diptera: Culicidae).

A polymerase chain reaction (PCR)-based diagnostic assay was developed that rapidly and reliably differentiates the sibling species of the Anopheles claviger complex, An. claviger s.s. and An. petragnani. The assay makes use of nucleotide differences in the internal transcribed spacer 2 ribosomal DNA sequences to generate PCR products of specific length for each of the two species. In evaluating the test, 580 of 592 field-collected An. claviger s.l. specimens were unambiguously identified as one of the two sibling species. Due to poor DNA quality, the remaining 12 specimens yielded no PCR product. Of the 592 mosquitoes, 407 larval specimens had been identified morphologically prior to species-specific DNA amplification, and in all instances PCR identification corroborated with morphologic identification. Mosquitoes identified as An. claviger s.s. came from various localities all over Europe and from Israel. Those identified as An. petragnani were collected in southern France and Spain. The species-diagnostic PCR assay would facilitate data collection on the temporal and spatial distribution of the two An. claviger sibling species because they represent possible vectors of disease in Europe, the Near and Middle East, and north Africa.

Animals↗