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F Rodhain

Publications and source records attributed to F Rodhain.

At least 19 recordsLinked to original sources
PubMed1992

The Alsatian tick-borne encephalitis focus: presence of the virus among ticks and small mammals.

An extensive epidemiologic survey was carried out from 1970 to 1974 in order to understand the condition of circulation of tick-borne encephalitis virus between ticks and small mammals in the Alsatian focus, France. The virus has been isolated from Ixodes ricinus adult ticks (30 lots out of 369, representing a total of 5617 ticks), and from Ixodes ricinus nymphs (4 lots out of 251, representing a total of 8587 ticks). The virus has also been isolated from 11 pools of rodent organs (out of 3361 rodents), and HI antibodies were detected in 21 out of 8735 rodent specimens. The virus has never been detected in rodent blood, nor in 10,298 ticks collected engorged from 1505 vertebrate hosts. These results show that Alsatian tick-borne encephalitis focus is stable since the activity of the virus is detected every year, and that the focus is an extended one since the virus is isolated from 5 of 6 study sites, as well as in several control sites.

Animals↗
PubMed1992

Oral susceptibility of Aedes albopictus to dengue type 2 virus: a study of infection kinetics, using the polymerase chain reaction for viral detection.

Female Aedes albopictus mosquitoes, aged 1 week, were infected with DEN-2 dengue virus. The kinetics of infection in mosquito brain and mesenteron were monitored using DNA probes with polymerase chain reaction (PCR) amplification of target DNA sequences coding for DEN-2 virus envelope protein, compared with the standard immunofluorescence assay technique (IFA). Rates of virus detection in the mesenteron of orally infected mosquitoes rose to 38% by day 4 post-inoculation, then declined until day 8, followed by irregular peaks around days 11-14 and subsequently. In mosquito head squashes, virus was detected from day 4 onwards, reaching 38% positive by day 18. Salivary glands of all the same females were found to be positive for virus by day 8 onwards. Parenterally infected Ae.albopictus females were all positive for DEN-2 in the brain and salivary glands 8 days post-inoculation. In every case, results obtained with the PCR matched those from the IFA. Our DNA probe with PCR procedure can therefore be utilized as a sensitive and reliable method for studies of DEN-2 vectors.

Aedes↗
PubMed1992

[Recent data on the epidemiology of dengue fever].

Because of its haemorrhagic forms often with shock syndrome, dengue fever is presently one of the most important pediatric health problems, particularly in South-east Asia. The natural reservoir of dengue is now constituted by urban human populations; travellers are the only dissemination factor of the viruses from one country to another, and all vectors are domestic species of the genus Aedes; in these mosquitoes, a vertical transmission can take place. The persistence mechanisms of dengue fever are closely related to demographic explosion, uncontrolled growth of towns and deterioration of urban environment which comes of it. The spreading mechanisms of outbreaks are related to dramatic increase of travels and the variable susceptibility of the natural Aedes populations to the viruses. All these factors appear to be directly connected with human activities; they were submitted to considerable changes since World War II and the epidemiology of the disease has been widely modified; the incidence of the disease is continuously growing year after year, building up a very worrying situation, more especially as we have no etiologic treatment nor vaccine against it.

Asia, Southeastern↗
PubMed1991

Analysis of inheritance of oral susceptibility of Aedes aegypti (Diptera: Culicidae) to dengue-2 virus using isofemale lines.

Isofemale lines were compared to determine possible genetic variation in oral susceptibility within the Fare strain of Aedes aegypti (L.) to dengue-2 (DEN-2) virus. Three groups of 12 isofemale lines each were tested statistically using the SAS CATMOD procedure of analysis of variance. The "isofemale line" effect was highly significant, demonstrating genetic variability in oral susceptibility among females. The length of time eggs were stored before hatching influenced the oral susceptibility of the adult mosquitoes for DEN-2 review.

Aedes↗
PubMed1991

[Functioning of virus-vector systems].

The transmission of viruses by arthropod vectors is a very complex biological phenomenon, and a very efficient one epidemiologically speaking; it takes place in three successive stages: arthropod infection, virus replication and dissemination within the arthropod, transmission to the vertebrate with, possibly, trans-stadial, vertical and/or venereal transmission. Many factors influence this transmission: endogenous factors, specific of the two components of the system (physiology, biology, genetics of the virus as well as the arthropod) determining vectorial competence, and exogenous environmental factors, which, along with previous ones, condition vectorial capacity. These facts have important consequences on arbovirus evolution, through different mechanisms for segmented or non-segmented genome viruses. They also have practical implications on epidemiology of arbovirus infections, through selective pressures exerted on each development stage of these viruses. These considerations lead us to state some directions for future researches: exact mechanisms of the different virus development stages within their vectors and type of their genetical control, defense reactions of arthropods and pathogenic effects of the viral infection, possible interference with other micro-organisms or with homologous or heterologous antibodies,.. Researchers working in that field should approach the problem not only with "arboviruses" and their vectors, but with consideration for all virus-arthropod relationships, and should take in account the necessity of not too much wandering from conditions of the nature in their experiments.

Animals↗
PubMed1991

[Experimental infection of Aedes albopictus mosquitoes by a spiroplasma strain isolated from Culex annulus in Taiwan].

Two Aedes albopictus strains are infected by one of the four presently known mosquito spiroplasma strains, the CUAS-1 strain isolated from Culex annulus from Taïwan. An infection by intra-thoracic inoculation leads to a pathogenic effect, dose-dependent, the longevity of mosquitoes being shortened. This pathogenicity is observed at various time after inoculation depending of the mosquito strain. On the other hand, an oral infection has no consequence on the longevity of infected females. However, the replication of spiroplasma has been demonstrated with both infection procedures.

Aedes↗
PubMed1991

[The Borrelia of ornithodoros in tropical Africa: value and limits of cross protection tests in the mouse].

The identification of Borrelia strains isolated from ticks or relapsing fever patients is not easy. Seizing the opportunity of recent isolation of such strains from Western Africa, we tried to evaluate the interest and the limits of a method classically proposed for that aim; cross protection test in mouse. This technique is proving rather difficult to perform because of different technical reasons; the results are critical to read. In some cases, these results seem undeniable, but the observed differences in protection levels are often weak, inconstant, insufficiently reliable to constitute a diagnostic tool. So it appears important to develop other identification methods, based on molecular analysis of Borrelia DNA, which will be more subtle and more specific.

Africa, Western↗
PubMed1990

Variation among strains of Aedes aegypti in susceptibility to oral infection with dengue virus type 2.

We compared 18 Aedes aegypti strains for oral susceptibility to dengue virus type 2 (DEN-2) using a feeding protocol in which all parameters remained constant, including the titer of the infectious bloodmeal. For most strains, no significant variation between replicates was observed. Comparisons between pairs of strains showed variation of different degrees, and allowed us to characterize the strains with respect to their oral susceptibility to DEN-2.

Aedes↗
PubMed1990

[Comparative study of dengue 2 virus replication and isoenzymes in two strains of Aedes aegypti].

This study, dealing with two strains of Aedes aegypti from Vietnam and French Guiana, shows the variability of the genes coding for 11 isoenzymatic systems and the replication of the dengue 2 virus in parenterally infected mosquitoes. Slight differences are observed in the characteristics of viral replication. No clear correlation is shown with enzymatic patterns which appear widely different from one strain to the other with four of the enzymes studied.

Aedes↗
PubMed1990

[The presence of Aedes (Stegomyia) albopictus in the Fiji Islands].

An entomological survey conducted at the international airports of the Fiji Islands showed Aedes albopictus breeding in the protective area of Nadi airport. No Aedes aegypti nor Anopheles accidentally imported have been seen during the visit. Aedes vexans, A. pseudoscutellaris, A. burnetti, A. vigilax, Culex annulirostris, C. quinquefasciatus and a species of the pipiens complex have been collected incidentally out of airport areas. Due to the presence of Aedes albopictus, a new and important epidemiological risk must be considered now in Fiji Islands. Vector control measures must be taken urgently. These results demonstrate the necessity to maintain a strict vector surveillance in international airports.

Aedes↗
PubMed1989

[Lyme disease: epidemiology].

Lyme disease, known primarily from North America, with three main foci in the United States, and from temperate Europe, particularly in France, seems to be increasing in incidence. Wherever it is known to exist, it has become the most prevalent tick-borne disease of man. The natural cycle of the etiologic agent, Borrelia burgdorferi, involves ticks as vectors and wild rodents as reservoirs. In infected areas, everyone walking or, especially, working in forested areas is at risk of tick bites, especially from May to October.

Animals↗
PubMed1989

[Transmission cycles of the West-Nile virus in Madagascar, Indian Ocean].

Virological, serological and entomological research conducted in Madagascar since 1975, reveal the wide-spread presence of West-Nile virus on the island. This arbovirus has been isolated from humans, parrots and egrets. Vectors belong to the genus Culex (e.g. Cx. decens, Cx. quinquefasciatus, Cx. antennatus, Cx. univittatus), however the virus has also been isolated from Aedes and Anopheles. Serological tests carried out on over 1,600 human and almost 1,000 animal sera, revealed that human beings could be infected throughout the island. Other potential vertebrate hosts, apart from birds, are oxen and bats. Insectivores, rodents and lemurs are probably involved in the transmission cycles only to a very small extent.

Animals↗
PubMed1989

[Tick-borne relapsing fever in Madagascar: an eradicated disease?].

Since about thirty years, no relapsing fever due to Borrelia duttoni is recorded from Madagascar. A survey was conducted in the formerly endemic area, between Soalala and Majunga, in order to collect data on possible cases and to look if the vector, Ornithodoros moubata is still present. No mention of the disease was recorded; all Ornithodoros seem to have completely disappeared in the area, without any clear reason. However, a few O. moubata specimens were recorded from piggeries in Mahasolo, 150 km west of Tananarive, outside the endemic area.

Animals↗