Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Gabon”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed2006

Identification of hepatitis B virus subgenotype A3 in rural Gabon.

An hepatitis B virus (HBV) molecular survey was conducted in five remote villages in the equatorial forest in Gabon, Central Africa. Two hundred seventy out of 311 inhabitants (86.8%) were HBV-infected or had evidence of past HBV infection. Chronic hepatitis corresponding to hepatitis B surface antigen (HBsAg) positivity was suspected in 27 (8.6%) of the HBV-infected subjects. High HBV viral loads were detected mainly in children aged 4-7 years. The pre-S/S domains were sequenced in 13 cases and 12 strains belonged to HBV-A genotype. In one case we found evidence for recombination between genotypes A and E. Phylogenetic analysis revealed that Gabonese HBV strains were distinct from HBV-A subgenotypes (A1 and A2). These new HBV strains from Gabon clustered with previously reported HBV-A3 subgenotype strains from Cameroon and Democratic Republic of Congo. The analysis of the pre-S2 domain allowed us to determine two amino acid substitutions (N/152/S and N/174/T) specific to the Central African HBV-A3 subgenotype strains and one amino acid substitution (P/155/Q) unique to these new Gabonese HBV-A3 subgenotype isolates. Two full genome sequences of two new Gabonese HBV isolates are also presented and confirm the distinctive HBV-Gab-A3 cluster.

Adolescent↗
PubMed1997

Emergence of subtype Zaire Ebola virus in Gabon.

Gabon has recently been struck three times by Ebola hemorrhagic fever. The first isolate originating from the 1994 outbreak has been subjected to molecular characterization of its GP and VP24 genes. Sequence analysis demonstrates that the agent, Gabon-94 virus, belongs to subtype Zaire of Ebola virus. The isolate is closely related to the Kikwit-95 isolate, and both viruses seem to have evolved from a progenitor virus different from that of the Zaire-76 isolates. The relatively close relationship of all subtype Zaire viruses isolated at different geographical locations and up to 20 years apart suggests an extreme conservation in the yet unknown natural reservoir of Ebola viruses. The level of genetic variability in the human host might be different as indicated by the comparison of isolates from a single outbreak (Mayinga-76 and Eckron-76), but needs further investigation on clinical material of patients by PCR since both isolates have different levels of passages in tissue culture.

Animals↗
PubMed2002

A preliminary study on the social relationships in a semi-free ranging colony of sun-tailed monkeys (Cercopithecus solatus), a species recently discovered in Gabon.

In 1984, a species of guenon endemic to Gabon was discovered: the sun-tailed monkey (Cercopithecus solatus). This species is difficult to locate and observe in the wild, and hence to date has been little studied. The Centre International de Recherches Medicales de Franceville (CIRMF), Gabon, houses the world's only breeding colony of C. solatus, on which eco-ethological investigations can be carried out in a semi-free ranging environment. The data reported here present the first results of observations on the social relationships of this colony and support the scant field observations available on this species, showing a basic social unit of one adult male and several females with their offspring. The resident male systematically repulses any second adult male in proximity to the group. A clear hierarchy exists among the females, with mature female offspring eventually acquiring a rank just below that of their mother.

Aggression↗
PubMed2004

In vitro activity of quinolines against Plasmodium falciparum in Gabon.

The assessment of drug sensitivity of Plasmodium falciparum to antimalarial drugs is of vital interest for malaria endemic regions. We conducted a follow-up study to monitor the in vitro activity of the most commonly used quinolines against fresh P. falciparum isolates in Lambaréné, Gabon by measuring schizont maturation inhibition in 2002. Mean 50% effective concentration levels for chloroquine, quinine, and mefloquine were 5.5micromol/l blood, 286nmol/l blood medium mixture (BMM), and 1.1micromol/l blood, respectively. All isolates (n=40) were found to be highly resistant to chloroquine. One isolate was resistant to mefloquine and five isolates were presenting borderline-resistance. All isolates were inhibited by quinine concentrations below the threshold of resistance (n=43). Besides the observation of an increasing number of borderline resistant isolates to mefloquine, an extremly high parasite resistance to chloroquine-still officially the first line antimalarial in Gabon-seems to be of particular concern.

Adolescent↗
PubMed2000

Chloroplast DNA variation in a rainforest tree (Aucoumea klaineana, burseraceae) in Gabon.

One of the dominant savannah colonists in Gabon is Aucoumea klaineana or Okoumé (Burseraceae), an endemic species which belongs to a monotypic genus. Chloroplast DNA (cpDNA) variation was studied in this species by means of PCR amplification of 40 kb of cpDNA sequences, followed by restriction analysis of the resulting fragments. No insertion/deletion events were noted, and a single point mutation was found. The level of differentiation among the 19 populations studied was relatively low (GST = 0.54) compared to other plant species (mean of 0.76), in agreement with the pioneer status of the species. However, cpDNA diversity was geographically structured, with the less frequent haplotype occurring only in populations from southern Gabon. This distribution might suggest either that there were two ancient source populations of Okoumé, one in the north and the other in the south, from which the colonizing process of the savannah began after the last ice age, or alternatively that there was one polymorphic source in the south. The low level of cpDNA diversity could indicate that Okoumé populations in these refugia were quite small.

DNA, Chloroplast↗
PubMed1997

Therapeutic efficacy of clindamycin in combination with quinine for treating uncomplicated malaria in a village dispensary in Gabon.

The efficacy of a 3-day clindamycin-quinine regimen to treat clinical malaria attacks was investigated in 256 children from western Gabon. Treatment was well tolerated by all of the children and its efficacy was higher than 97% by day 20. Thus this 3-day clindamycin-quinine regimen might constitute a potential alternative to chloroquine for treating clinical malarial attacks in children from Gabon.

Adolescent↗
PubMed2002

Analysis of partial pol and env sequences indicates a high prevalence of HIV type 1 recombinant strains circulating in Gabon.

Forty-one HIV-1 strains from Gabonese patients were studied according to the following strategy: nested polymerase chain reaction were performed to obtain an approximately 1,100-bp fragment containing the protease gene and the 5' half of the reverse transcriptase gene. Additional amplifications were carried out to obtain an approximately 700-bp fragment encompassing the C2V3 env gene. Fragments of 600 to 1,200 bp in the gag gene overlapping the pol sequences were used for the study of recombination patterns. Phylogenetic analyses of the different fragments were used to investigate HIV-1 diversity in Gabon. Thirty-one strains were sequenced in the env and pol genes and phylogenetic analyses classified them as subtype A (n = 2), D (n = 4), G (n = 1), H (n = 1), CRF02 (n = 8), and CRF MAL-like (n = 6); in addition, there were 6 unique recombinant forms and 1 unclassified strain, and in 2 cases pol/env sequences classified strains as subtype D whereas gag phylogeny classified them as subtype A. In 10 cases only 1 fragment was available: 4 env (2 subtype D, 1 subtype H, and 1 subtype U) and 6 pol (1 subtype A, 1 subtype C, 2 subtype G, and 2 subtype U). Minor mutations associated with viral resistance to antiretroviral drugs were observed in more than 80% of analyzed strains. Our study confirms the extensive HIV-1 diversity found in Central Africa, with more than 70% of strains from Gabon exhibiting discordant clustering in pol and env genomic regions and less than 60% concordance between sequencing and heteroduplex mobility assay genotyping. These findings highlight the fact that Central Africa represents the epicenter for the origin of HIV-1. The strategy of sequencing pol in association with env has proved to be useful for analysis of the recombinant strains. The main advantage of this approach is that it also allows for evaluation of genotypic susceptibility to antiretroviral drugs without the need for supplementary analyses.

Amino Acid Sequence↗
PubMed2004

A New STLV-1 in a household pet Cercopithecus nictitans from Gabon.

A recent serological survey of wild-born captive monkeys from Gabon, Central Africa, revealed that 1 of 20 Cercopithecus nictitans tested was infected with a new simian T cell lymphotropic virus type 1 (STLV-1). We investigated the molecular relationship between the STLV-1 strain present in this C. nictitans (CN01) and the other available HTLV/STLV strains. Phylogenetic analysis of the env (gp46 and gp21) region showed that the new STLV(nict) clusters with the HTLV-1/STLV-1 group and not with the other nictitans STLVs belonging to the STLV-3 group. Moreover, our new STLV(nict) is closely related to the molecular subtype D, which presently includes five HTLV-1 and three mandrill STLV-1 strains from Gabon and two from Cameroon. These data show that C. nictitans may be the natural carrier of two different molecular types of STLV, one related to STLV-3 and the other possibly one of the simian STLV type 1 counterparts of HTLV-1 subtype D.

Animals↗
PubMed2003

In vitro susceptibility to a new antimalarial organometallic analogue, ferroquine, of Plasmodium falciparum isolates from the Haut-Ogooué region of Gabon.

OBJECTIVES: To assess the activity of a new organometallic chloroquine analogue, ferroquine, against numerous Plasmodium falciparum isolates from Gabon. METHODS: The in vitro susceptibility of 116 P. falciparum isolates to chloroquine and ferroquine was assessed using the isotopic microtest. All isolates were from outpatients in the Franceville and Bakoumba medical centres in the province of Haut-Ogooué, south-east Gabon. RESULTS: The in vitro resistance to chloroquine was 51.8% in Franceville and 96.7% in Bakoumba. The IC50 geometric mean (95% CI) of ferroquine against isolates in Franceville was 16.0 (14.4-17.8) nM, with individual values ranging from 1.0 to 47.0 nM; in Bakoumba it was 27.9 (23.4-33.2) nM, with individual values ranging from 1.0 to 62.0 nM. Compared with chloroquine, ferroquine was 5.3 times more active on isolates susceptible to chloroquine, and 13.3 times more active on isolates resistant to chloroquine. A weak positive correlation was observed between responses of these two drugs, but too low to demonstrate cross-resistance. CONCLUSIONS: Ferroquine may be useful as an alternative drug for treating chloroquine-resistant malaria.

Aminoquinolines↗
PubMed2003

DHFR and DHPS genotypes of Plasmodium falciparum isolates from Gabon correlate with in vitro activity of pyrimethamine and cycloguanil, but not with sulfadoxine-pyrimethamine treatment efficacy.

OBJECTIVES: To assess the relationship between the presence of DHFR and DHPS mutations in Plasmodium falciparum, parasite in vitro resistance, and in vivo efficacy of sulfadoxine-pyrimethamine (SP) treatment. PATIENTS AND METHODS: Measurement of SP treatment efficacy in malaria-infected children in Gabon was combined with in vitro tests of susceptibility to pyrimethamine and cycloguanil, and molecular genotyping at several DHFR and DHPS loci of parasites isolated before treatment. DHFR was studied at codons 108, 51, and 59, whereas DHPS gene was typed at positions 436, 437, 540 and 581. RESULTS: SP treatment was effective in 86% of children by day 28. Seventy-five percent of isolates were in vitro resistant to pyrimethamine and 65.5% to cycloguanil. No mutation was detected at codons 540 and 581 of the DHPS gene. Most isolates (71.8%) presented with the triple mutant DHFR genotype, whereas 64.3% combined at least three DHFR and one DHPS mutations. The increase in the number of DHFR mutations was associated with an increase in in vitro resistance to pyrimethamine and cycloguanil; three DHFR mutations conferred pyrimethamine and to a lesser extent cycloguanil resistance. Treatment failures only occurred with isolates presenting at least two DHFR mutations (S108N and C59R) and one DHPS mutation (S436A or A437G), but SP treatment of infections with such parasites gave treatment success in 82.0% of children. CONCLUSIONS: DHFR mutations that lead to high-level in vitro resistance to pyrimethamine plus 1-2 DHPS mutations are not sufficient to induce in vivo failure of SP treatment in young children from Gabon.

Animals↗
PubMed1996

Epidemiological and molecular characteristics of HIV infection in Gabon, 1986-1994.

OBJECTIVE: To describe trends in the prevalence of HIV-1 infection in different populations in Gabon, and the molecular characteristics of circulating HIV strains. METHODS: Data were collected on HIV prevalence through sentinel surveillance surveys in different populations in Libreville (the capital) and in Franceville. In Libreville, a total of 7082 individuals (hospitalized patients, tuberculosis patients, pregnant women, asymptomatic adults, prisoners) were recruited between 1986 and 1994. In Franceville, we tested 771 pregnant women and 886 healthy asymptomatic adults (1986-1988). Sera were screened for HIV antibodies by enzyme-linked immunosorbent assay (ELISA) and confirmed by Western blot or line immunoassay (LIA). Reactive samples in ELISA were tested for the presence of antibodies to HIV-1 group O viruses by ELISA using V3 peptides from HIV-1 ANT-70 and HIV-1 MVP-5180 followed by confirmation by LIA and a specific Western blot. Seventeen HIV-1 strains were isolated (1988-1993) and a 900 base-pair fragment encoding the env region containing V3, V4, V5 and beginning of gp41 was sequenced and a phylogenetic tree was constructed. RESULTS: HIV prevalence was relatively low and remained stable (0.7-1.6% in pregnant women, 2.1-2.2% in the general population). The prevalence was also stable among prisoners (2.1-2.6%). Among hospitalized and tuberculosis patients prevalence was higher and increased (1.8-12.7% and 1.5-16.2%, respectively). Only three sera had antibodies to HIV-1 group O. The 17 HIV-1 strains represent six different genetic subtypes including type O. CONCLUSION: Our data from 1986 to 1994 show a stable and low HIV prevalence in Gabon, and a high genetic diversity of HIV-1 strains. This, also observed in Cameroon, is in contrast to that found elsewhere in Africa. Differences in rate of spread of HIV infection are probably explained by interplay between numerous factors. The role of different HIV subtypes in the dynamics of the HIV epidemic should be examined further.

Adult↗
PubMed1996

Mother-to-child transmission of human T-cell lymphotropic virus types I and II (HTLV-I/II) in Gabon: a prospective follow-up of 4 years.

SUMMARY: For 4 years. we determined the mode and risk of mother-to-child transmission of HTLV-I in a prospective cohort of 34 children born to seropositive mothers in Franceville, Gabon. We also determined the prevalence of antibodies to HTLV-I/II in siblings born to seropositive mothers. Antibodies to HTLV-I/II were detected by Western blot, and the proviral DNA was detected by the polymerase chain reaction (PCR). The risk of seroconversion to anti-HTLV-I for the 4 years of follow-up was 17.5 percent. Anti-HTLV-I/II and proviral DNA were only detected after age 18 months. We observed a seroprevalence rate of 15 percent among the siblings born to HTLV-I/II seropositive mothers. Furthermore, we report a case of mother-to-child transmission of HTLV-II infection in a population of HTLV-II-infected pregnant women that is emerging in Gabon. The lack of detection of HTLV-I/II proviral DNA in cord blood and amniotic fluid and, furthermore, the late seroconversion observed in the children indirectly indicate that mother-to-child transmission occurred postnatally, probably through breast milk.

Amniotic Fluid↗
PubMed1991

The role of Chlamydia trachomatis and Neisseria gonorrhoeae in the aetiology of ectopic pregnancy in Gabon.

OBJECTIVE: To study the association between ectopic pregnancy and Chlamydia trachomatis and Neisseria gonorrhoeae. DESIGN: A prospective observational study with two comparison groups. SETTING: A general hospital in Franceville, Gabon. SUBJECTS: Forty-five women with ectopic pregnancies and two comparison groups each of 45 women, one at 5 to 12 and the other at 32 to 41 weeks gestation. MAIN OUTCOME MEASURES: Serum levels of IgG and IgA antibodies to C. trachomatis (L1 and rMOMP) and N. gonorrhoeae (pili) in all the women. In the women with ectopic pregnancy peritoneal adhesions were scored and in 40 women samples of tube were cultured for organisms being studied. RESULTS: IgG and IgA antibodies to C. trachomatis (L1) were detected in 84% of the ectopic group and 53 and 39% of the comparison groups (P less than 0.0001). IgG and IgA antibodies to N. gonorrhoeae occurred in 49, 28 and 18% and 49, 28 and 26% of the groups but the differences were not statistically significant. Adhesions were positively associated with the antibodies. C. trachomatis was cultured from the tubes of 71% of the women with ectopic pregnancy. CONCLUSIONS: Infection with chlamydia, and probably with N. gonorrhoeae, is an important factor in the causation of ectopic pregnancy in Gabon.

Antibodies, Bacterial↗
PubMed2006

Cerebral malaria and sequelar epilepsy: first matched case-control study in Gabon.

PURPOSE: Cerebral malaria (CM) is suspected to be a potential cause of epilepsy in tropical areas. The purpose of this article was to evaluate the relationship between CM and epilepsy in Gabon. METHODS: A matched case-control study was carried out on a sample of subjects aged six months to 25 years and hospitalized between 1990 and 2004 in three hospitals in Libreville, Gabon. Cases were defined as patients suffering from epilepsy and confirmed by a neurologist. Controls were defined as patients without epilepsy. The exposure of interest was CM according to WHO criteria. RESULTS: In total, 296 cases and 296 controls were included. Of these, 36 (26 cases and 10 controls) had a CM history. The adjusted odds ratio (aOR) to develop epilepsy after CM was 3.9 [95% CI: 1.7-8.9], p<0.001. Additional risk factors were identified: family history of epilepsy: aOR=6.0 [95% CI: 2.6-14.1], p<0.0001, and febrile convulsions: aOR=9.2 [95% CI 4.0-21.1], p<0.0001. CONCLUSIONS: This first case-control study on that issue suggests that epilepsy-related CM is an underrecognized problem. It emphasizes the need for further studies to better evaluate the role of convulsions during CM.

Adolescent↗
PubMed2007

Women's stories of abortion in southern Gabon, Africa.

The purpose of this study was to explore the reasons women in rural, southern Gabon, Africa, chose to terminate their pregnancies, the methods used to induce abortions, and postabortion effects experienced by these women. Abortion is illegal in this country. A descriptive qualitative design guided the methodology for this study. Five women with a history of induced abortion were interviewed in-depth for their abortion story. Reasons cited for an abortion included lack of financial and partner support. Abortion methods included oral, rectal, and vaginal concoctions of leaves, bark, and water and over-the-counter medications, including misoprostol. Affects were physical, spiritual, and relational. Health care professionals need to provide women with guidance for appropriate contraceptive usage. Abortion after-care of women with physical and spiritual needs is important. Future research is suggested on the use of misoprostol in Gabon to understand its affects on women's reproductive health.

Abortion, Induced↗
PubMed2006

Genital shedding of herpes simplex virus type 2 in childbearing-aged and pregnant women living in Gabon.

The prevalence of genital shedding of herpes simplex virus (HSV)-2 and related risk factors was evaluated in a prospective population of 355 women attending the Maternity Joséphine Bongo, in Libreville, Gabon. We found a high prevalence (66%) of HSV-2 seropositivity, with a high proportion, 14%, of women harbouring HSV-2 DNA shedding in their genital secretions. HSV-2 genital shedding was positively associated with previous episodes of genital blisters, current genital ulcer, current genital blister, HIV seropositivity and HSV-2 seropositivity. The high prevalence of HSV-2 in childbearing-aged population indicates that young women living in Gabon are at high risk for HIV acquisition in HIV-seronegative women sexually exposed to HIV, for HIV transmission in HIV-infected women co-infected by HSV-2 and finally for HSV-2 vertical transmission during pregnancy.

Adult↗
PubMed1995

Hepatitis B, C, D, and E markers in rural equatorial African villages (Gabon).

Serologic markers of hepatitis B virus (HBV), including HBV DNA, and of hepatitis delta virus were measured in three villages in Gabon. Of 303 subjects studied, 19% were carriers of hepatitis B surface antigen (HBsAg); 8.5% of these had anti-delta antibodies. No difference among the three villages was observed. All HBV DNA carriers were children less than 11 years of age. In the 2-9-year-old group, 71% of the HBsAg-positive children tested were HBV DNA carriers. These results indicate that HBV prevalence is high in Gabon and emphasize the importance of horizontal transmission of HBV in Africa. Antibodies to hepatitis C virus, assessed in one of the three villages, were found with a prevalence of 35% with a second generation enzyme-linked immunosorbent assay (ELISA) and 24% with a third generation ELISA. None of 35 subjects tested for antibodies to hepatitis E virus was positive.

Adolescent↗
PubMed1998

Follow-up of the susceptibility of Plasmodium falciparum to antimalarials in Gabon.

The sensitivity of Plasmodium falciparum to chloroquine, mefloquine, quinine, quinidine, halofantrine, artemisinin, and sulfadoxine/pyrimethamine was investigated in Lambarene, Gabon in 1994. The development of in vitro susceptibility has been traced from 1983 or 1992 to 1994 for chloroquine, mefloquine, halofantrine, and quinine. Standard in vitro microtests according to World Health Organization methodology were performed. Of 33 isolates tested for susceptibility to chloroquine, 31 were resistant, one was borderline, and one isolate was sensitive (mean 50% effective concentration [EC50] = 1.38 micromol/L of blood). With mefloquine, all isolates were fully inhibited below the threshold of resistance (mean EC50 = 0.51 micrmol/L of blood). Of 32 isolates tested with quinine, six had borderline resistance (mean EC50 = 0.54 micromol/L of blood medium mixture). Susceptibility to quinidine was higher with a mean EC50 of 0.15 micromol/L of blood medium mixture. With halofantrine, 26 of 32 isolates matured at 3 nmol/L of blood medium mixture (mean EC50 = 1.64 nmol/L of blood medium mixture), indicating a steep decrease in susceptibility in comparison with 1992. For artemisinin, the mean EC50 was 97.92 nmol/L of blood medium mixture. Sulfadoxine/pyrimethamine showed five of 16 resistant isolates with a mean EC50 of 2.46 nmol/L of blood medium mixture. Whereas chloroquine resistance remained stable with a tendency to decrease, susceptibility to mefloquine and quinine was slightly decreased. A significant increase in the mean EC50 and EC90 in comparison with our previous data from Gabon was found for halofantrine.

Animals↗