Biomedical subjects

F Rodhain

Publications and source records attributed to F Rodhain.

At least 37 records · Page 2Linked to original sources

PubMed1998

Two-dimensional gel analysis of midgut proteins of Anopheles stephensi lines with different susceptibility to Plasmodium falciparum infection.

Little is known about the composition of the mosquito midgut which plays a central role in the development and subsequent transmission of malaria parasites. As a first step towards the characterization of mosquito midgut molecules involved in the transmission of malaria parasites, we analysed two-dimensional gel electrophoresis patterns of the midgut proteins of sugar-fed and blood-fed Anopheles stephensi lines of different susceptibility to P. falciparum infection. Two lines fully susceptible and one line (Pb3-9A) of reduced susceptibility were used. In the refractory line ookinetes do develop but are only inefficiently transformed into oocysts (Feldmann & Ponnudurai, 1989). The protein profiles of midguts from all sugar-fed mosquito lines were similar. However, after blood feeding, the midgut of the fully susceptible lines contained proteins not found in the midgut of line Pb3-9A. Twenty-nine such proteins were detected and are candidates for involvement in the interaction between the mosquito midgut and P. falciparum.

Animals↗

PubMed1998

Spiroplasma turonicum sp. nov. from Haematopota horse flies (Diptera: Tabanidae) in France.

Strain Tab4cT, a helical prokaryote that was isolated from the body of a Haematopota sp. fly collected in Champchevrier, Indre-et-Loire, Touraine, France, was found to be a member of the class Mollicutes. The cells of strain Tab4cT were small, motile helices that were devoid of a cell wall. The organism passed through filters with mean pore diameters as small as 0.20 mm. Strain Tab4cT grew rapidly in liquid SP-4 medium at both 30 and 37 degrees C. The organism fermented glucose but did not hydrolyse arginine or urea, and did not require serum for growth. In preliminary electrophoretic analyses, the cell protein patterns of strain Tab4cT were distinct from those of 14 other spiroplasmas found in mosquitoes, deer flies and horse flies from Europe and the Far-East. In reciprocal metabolism inhibition and deformation serological tests, employing antigens and antisera representative of spiroplasma groups I-XXXIII (including all sub-groups), plus ungrouped strains BARC 1901 and BARC 2649, no serological relationship with Tab4cT was found. The G + C content of the DNA of strain Tab4cT was about 25 +/- 1 mol% and its genome size was 1.305 kbp. It is proposed that spiroplasma strain Tab4cT be assigned to group XVII (presently vacant) and that strain (ATCC 700271T) is the type strain of a new species, Spiroplasma turonicum.

Animals↗

PubMed1998

[Joseph Désiré Tholozan and the Persian relapsing fever].

In the year 1879, Tholozan seems to have been convinced of the danger caused by the bites of ornithodores in Persia, as a result of very careful observations of sick persons suffering from iranian relapsing fever due to Borrelia persica. Among the ticks collected by him and sent to entomologists in France was the true vector, named Argas (presently Ornithodoros) tholozani by Laboulbene and Megnin. Tholozan's contribution to our knowledge on persian relapsing fever is really important. He was one of the first to provide a good clinical description of the disease and to involve an argasid tick in its transmission. He discovered the real vector species which is now called after him.

Animals↗

PubMed1998

[The idea of natural reservoir in arbovirology].

Aboviruses usually have extremely complex epidemiological cycles since their circulation involves successively a susceptible vertebrate and an hematophagous arthropod acting as vector. Natural reservoirs for arboviruses can belong to two different categories of organisms: Vertebrate reservoirs, with as main characteristics: a susceptible population but showing no symptoms of disease or only a benign one, an abundant and prolific population, the infected animal must show an efficient viremia, a population with strong and frequent contacts with vector populations. Two factors tend to oppose these characteristics: the pathogenicity of the virus and infection-induced immunity. Many groups of wild vertebrates (birds and mammals) act as usual reservoirs for arboviruses. Domestic or commensal mammals, as well as human beings, are rarely involved as reservoirs. Invertebrate reservoirs: arthropods are involved in the maintenance of many arboviruses for two main reasons: their longevity and the possibility of vertical transmission of the virus. An infected arthropod remains infected throughout its life, in spite of successive moultings. This lifetime can be long, especially for ticks. Vertical transmission is known in some virus-vector systems, but its frequency appears to be very variable. The epidemiological importance of the phenomenon is specially high in the case of cold-resistant or dry-resistant eggs. These facts lead to a large variety of epidemiological situations according to virus and region. Studying epidemiological situations also shows up the evolution of these systems, as a response to environmental modifications, often resulting from human activities. Furthermore, the repeated passages of an arbovirus in reservoir hosts could induce modifications of the viral genome, for example by facilitating the emergence of reassortants during coinfections. Finally, for many different reasons, it seems difficult, for the moment, to imagine efficient preventive measures levelled at any kind of natural reservoirs.

Arbovirus Infections↗

PubMed1997

Prevalence of antibodies to Borrelia burgdorferi in forestry workers of Ile de France, France.

A cross-sectional sero-epidemiological study was conducted on forestry workers, a high risk population for Lyme borreliosis. The prevalence of seropositive forestry workers (indirect immuno fluorescence assay) is 15.2% (n = 211). Almost 70% of participants reported a history of tick bite. Among districts, high seroprevalences were observed in Fontainebleau and Rambouillet; two sites of high risk for Lyme borreliosis. However, clinical prevalence of the disease is very low. During the investigation no active Lyme borreliosis was observed. Thus, asymptomatic infection predominates.

Adult↗

PubMed1997

Three spiroplasmas isolated from Haematopota sp. (Diptera:Tabanidae) in France.

On August 1991, three spiroplasmas (Tab 2A, Tab 2B and Tab 4C) were isolated from Haematopota sp. flies collected from Indre-et-Loire, France. Isolations were made at 28 degrees C in MD1 medium from ground individual flies, but not from external washings. All isolates adapted well to SP4 medium at 30 and 37 degrees C and were triple cloned before serological identification. Using the cross deformation test, the 3 isolates were compared with 42 known spiroplasmas isolated from diseased plants, flowers, various insects and ticks belonging to 25 serological groups. Each isolate cross-reacted with others and exhibited weak 1-way reactions with TABS-2 or PLHS-1, two spiroplasmas isolated in the United States from respectively Tabanus abactor Philip and Panorpa helena L, a scorpion-fly. These results suggest that Tab 2A, Tab 2B and Tab 4C together with TABS-2 and PLHS-1 may represent, members of a new serological supergroup.

Animals↗

PubMed1997

Aedes polynesiensis in the Society Islands: environmental correlates of isoenzyme differentiation.

Isoenzyme genetic differentiation of Aedes polynesiensis mosquitoes in Raiatea island, French Polynesia, was evaluated by two models of population structure based on seven gene-enzyme systems: Ak, Est, Got, Gpi, Hk, Mdh and Pgm. The ecological model tested whether genetic differentiation is congruent with habitat differences. The isolation model evaluated whether genetic differentiation is proportional to geographical distribution. The ecological model found no significant differentiation between populations of Ae.polynesiensis from beach and forest ecotopes, whereas the isolation model was consistent with the data. However, incipient speciation is opposed by the source-sink system of population dynamics in such small neighbouring islands, where Ae.polynensiensis extinction is readily followed by reinvasion causing considerable gene flow between island populations.

Aedes↗

PubMed1997

[First Algerian case of human otomyiasis from Chrysomya bezziana].

In Algeria, Human myiasis, essentially ophtalmomyiasis, are known for a long time. Most of cases are due to Oestrus ovis. In this papers the authors report, in a shepherd, the first case of otomyiasis due to Chrysomya bezziana larvae, a species still unknown in North Africa. This observation which indicates the presence of the species in a Northern part of Algeria is also the first report of the insect outside of its endemic traditional area.

Adolescent↗

PubMed1996

Use of enzyme-labelled protein G assay for the detection of anti Borrelia burgdorferi antibodies in wild animal sera.

A modified ELISA was developed for the detection of anti-Borrelia burgdorferi (Bb) IgG antibodies in wild animal sera based on an Enzyme-Labelled-protein G Assay (ELGA). Microplates were coated with an extract of Bb sensu stricto strain (SVI) as antigen. Specific antibodies of the serum samples were detected by a peroxidase-labelled-protein G. Using comparative immunodiagnosis by means of a passive hemagglutination test (HA), ELGA was tested on 82 roe-deer blood samples. A correlation was found between the two methods (r = 0.66). Good reproducibility of titers was observed by ELGA technique. A minimal cross-reactivity was discovered with Leptospira. ELGA could facilitate the recognition of specific antibodies in collections of wild animal sera.

Animals↗

PubMed1996

Infection of Ixodes ricinus (Acari:Ixodidae) by Borrelia burgdorferi in Ile de France.

Free-living nymphs and adults from Rambouillet and Fontainebleau, 2 major forests of Ile de France, were collected to determine the infection rates of Ixodes ricinus L. by Borrelia burgdorferi (Johnson, Schmid, Hyde, Steigerwalt & Brenner). Field-collected I. ricinus nymphs and adults were screened for the presence of B. burgdorferi using direct fluorescent antibody assay. The infection rates of nymph, male and female were 12.4% (314), 2.8% (35), and 2.9% (34). No difference in infection rates of nymphs among sites were detected. Spirochetes was isolated from both sites. Isolates from Rambouillet and Fontainebleau were identified as B. burgdorferi sensu stricto and B. garinii, respectively (Baranton, Postic, Saint-Girons, Boerlin, Piffaretti, Assous, and Grimont).

Animals↗

PubMed1996

Phylogenesis of relapsing fever Borrelia spp.

The phylogenetic relationships of 20 relapsing fever (RF) Borrelia spp. were estimated on the basis of the sequences of rrs genes. Complete sequences were aligned and compared with previously published sequences, and the similarity values were found to be 97.7 to 99.9%. Phylogenetic trees were constructed by using the three neighbor-joining, maximum-parsimony, and maximum-likelihood methods. The results of the comparative phylogenetic analysis divided the RF Borrelia spp. into three major clusters. One cluster included Borrelia crocidurae, Borrelia duttonii, Borrelia recurrentis, and Borrelia hispanica. Another cluster comprised tow main branches with Borrelia coriaceae, Borrelia lonestari, and Borrelia miyamotoi on one side and Borrelia parkeri, Borrelia turicatae, and Borrelia hermsii on the other side. Borrelia anserina constituted the third cluster. The phylogenetic position of Borrelia persica was more uncertain. These results suggested that the taxonomy of these spirochetes should be revised. To overcome the problems of culturing the spirochetes, RF Borrelia primers were defined. Following PCR amplification of the rrs gene, restriction length fragment polymorphism could be used to distinguish between RF Borrelia strains.

Animals↗

PubMed1996

[Zoo-anthroponoses involving rodents: epidemiologic considerations].

A large number of zoo-anthroponoses is known, in the natural cycle of which are involved rodents or lagomorphs. This is mainly related to the numerical importance of rodents, their ecological plasticity, their relationships with man. Thus, it is important, for the epidemiologist, to differentiate synanthropic rodents living in close contact with man and often spread by him, which are at the origine of frequently urban diseases, from wild rodents usually having only few contacts with man in rural areas only. The events allowing the passage of an infectious agent from rodent to man appear varied, as are epidemiological schemes in which these animals can play different roles: they can act, alone or together with other animals, as natural reservoirs, or, on the contrary, they are only occasionally infected, and the transmission can occur by direct contact, by bite, through the environment, or with the help of an arthropod vector. It is particularly interesting to follow the evolution of some of these epidemiological systems, in order to evaluate the impact of human activities, such as deforestations, new technics for agriculture and cattle breeding, urbanization, increasing transportation, development of leisure activities. In order to reduce this infectious risk, we should look for the means of a correct balance between rodent and human populations, by joining the control of epidemiologically dangerous species, modification of some of our behaviours, a relevant health information, together with the care of the protection of natural ecosystems.

Animals↗

PubMed1996

[Ecology of Aedes aegypti in Africa and Asia].

Aedes aegypti is originated from Africa and expanded around the tropical World with a pantropical distribution in 1930. Because of mosquito control, this extension decreased, but is still very important and threatening because of disease transmission. Eggs of Ae. aegypti can survive unfavorable conditions. Larvae and pupae of Ae. aegypti breed into natural or artificial containers, the last being the most important. Artificial breeding-sites are mostly water storage containers and discarded containers. The water storage containers, called "canaris" in West Africa, can assume different shape according to the human populations in which they are found. In Asia, water is stored everywhere, including in large towns. The adult females of Ae. aegypti are mostly diurnal and indoor feeders. Adult densities are variable and can reach huge numbers. Active dispersion of females is weak, one female usually visit one or two houses in its life. At the opposite, passive dispersion is extreme. The mean life duration of a female is about 2 to 3 weeks, thus when infected with dengue viruses, because of the duration of the extrinsic cycle of the viruses, a female has a low probability to survive enough to transmit the disease. Nevertheless, the system works quite well. Although Ae. aegypti is a "domestic" mosquito, its ecology remains largely misunderstood.

Aedes↗

PubMed1996

[Problems posed by the spread of Aedes albopictus].

Ae. albopictus is originated from Asia, and is known as a natural vector of dengue in South-East Asia. Since about 10 years, Ae. albopictus has spread all around the world. It was introduced into the Americas: United States, Mexico, Brazil, Barbados and the dominican Republic; into some Pacific islands as Solomons, Fidji and Australia; into Africa in Nigeria; and finally into Europe: in Italy and Albany. These introductions were made primarily through imported tyres containing eggs and/or larvae of Ae. albopictus. The tyre international trade plays a significant role in the expansion of Ae. albopictus. Furthermore, this mosquito species has a broad ecological spectrum and found suitable conditions either into tropical and temperate countries. In some situations in the Americas, Ae. albopictus has displaced Ae. aegypti. The spread of Ae. albopictus is of great concern because it can experimentally transmit several arboviruses and filarial worms.

Aedes↗

PubMed1996

[The situation of dengue in the world].

The situation of dengue in the world can be summarized as follows: 2,5 billions persons at risk, 60 millions cases per year, and 30 000 deaths per year. The four dengue serotypes, DEN-1, DEN-2, DEN-3 and DEN-4 are nearly human-specific. Clinical symptoms of dengue vary from unapparent infection, mild febrile manifestations to hemorrhagic forms with or without shock syndrome. Dengue viruses are transmitted by Aedes mosquitoes, the most important vectors being Aedes aegypti and Aedes albopictus. The epidemiology of the disease can be divided into endemo-epidemic situations occurring in South-East Asia, and epidemic situations found in Pacific islands, Africa and Tropical America. Maintenance of dengue is supported by an increasing demography, uncontrolled urbanization and climatic conditions favorable to the vectors. Spread of dengue is primarily caused by modern transportation means, especially the aircraft. The geographical distribution of dengue is pantropical, except for Madagascar and some african regions. Because no vaccine and no specific treatment actually exist against dengue viruses, mosquito control is the only way to reduce the incidence of dengue around the world. However, the evolution of the dengue situation is not satisfactory.

Dengue↗

PubMed1995

Aedes albopictus: a potential problem in France.

Aedes albopictus, a mosquito of Asian origin, has been rapidly spreading in all the continents since a decade: it is now established in North and South America, Africa, Oceania and even in Europe where it was detected in Albania, 1979 and in Italy, 1990. The international shipping trade of used tires provides to Ae. albopictus an ideal mechanism of dissemination, and everywhere the tire stocks constitute an extremely productive ecological niche. Now, this mosquito is present in several localities in Northern and Central Italy, and it is a real threat for other Mediterranean countries, particularly Southern part of France (French Riviera and Corsica) where climatic conditions are very suitable for its establishment. In addition, the tolerance exhibited by some natural populations of Ae. albopictus for low temperatures allows this species to occupy an area much further north than Ae. aegypti. Ae. albopictus is a very competent vector for many arboviruses, particularly the four dengue serotypes, with the possibility of a vertical transmission; we also know that it can act as an experimental vector for many other viruses. The consequences of its introduction into France would lie in an increased level of transmission of autochthonous viral or filarial (canine dirofilariasis) infections, along with the spread of viruses presently unknown in the region (like dengue, Rift Valley fever, Batai, etc.). For these reasons, it is necessary to set up a permanent entomological surveillance in all the threatened areas in order to detect immediately such an introduction and to be able to quickly eliminate the mosquito.

Aedes↗

PubMed1994

Experimental infection of Aedes aegypti mosquitoes, suckling mice, and rats with four mosquito spiroplasmas.

Four mosquito spiroplasmas, Spiroplasma culicicola, Spiroplasma sabaudiense, Spiroplasma taiwanense, and an isolate designated CUAS-1 were nonpathogenic for suckling mice and suckling rats inoculated either intracerebrally or intraperitoneally. S. culicicola persisted as long as 14 days in the brain of intracerebrally inoculated mice but did not replicate. The three other spiroplasmas were not reisolated from inoculated rats or mice. S. culicicola replicated in vitro at 37 degrees C in M1D media. A low but clear-cut immune response was elicited in suckling rats inoculated with S. sabaudiense. S. culicicola and S. taiwanense were pathogenic (life span reduced) for Aedes aegypti females inoculated intrathoracically. The progeny of Ae. aegypti females inoculated with S. sabaudiense had a significantly reduced emergence rate in one of two trials and a significant distortion of the sex ratio in two of two trials (increased percentage of males). Female Ae. aegypti inoculated with S. culicicola had a significantly reduced fecundity rate.

Animals↗

PubMed1994

[A serological survey regarding Flaviviridae infections on the island of Réunion (1971-1989)].

Serological prevalence of Flaviviridae was studied on Reunion Island by testing 2,507 human sera from a randomised sample. Each serum was tested against 5 viruses (yellow fever, dengue type 1 and 2, West Nile and Wesselsbron) using haemagglutination inhibition test: 42.68% of human sera were found positive. The multivalent reactions represent practically three fourths of the positive ones. A severe dengue type 2 outbreak on the island in 1977-1978 and the possible circulation of a Flavivirus may explain these data. Among the tested subjects, positivity frequencies vary according to their age and their living surrounding. These results were compared with those of a previous serosurvey performed in 1971 and showed an important increase in the serological prevalence largely explainable by the 1977-1978 epidemic.

Adolescent↗