Présentation au sujet: "2) LES MODES DE TRANSMISSION ET LEUR IMPORTANCE"— Transcription de la présentation:
1 2) LES MODES DE TRANSMISSION ET LEUR IMPORTANCE L’INFECTION A VIH SIDA2) LES MODES DE TRANSMISSIONET LEUR IMPORTANCE
2 RISQUES TRANSMISSION DE L’INFECTION HIV T SANGUINE PAR TRANSFUSION # 100%T MERE-ENFANT à 30%T MERE-ENFANT(AVEC ARV) 5 à 10%T PAR ALLAITEMENT 10 à 15%T PAR ECHANGE DE SERINGUE 1 à 10 p1000T PAR AES p1000T PAR RAPPORT SEXUELHOMOSEXUEL 5 à 8 p1000HETEROSEXUEL(FEMME) 2 à 3 p1000 HETEROSEXUEL(HOMME) p1000
3 PRESENCE DU VIRUS HIV DANS LES VOIES GENITALES SPERME 30 à 60% (1/3 à 1/2)COL 30 à 50% (1/3)VAGIN 15% (1/6)
4 - absent + rare ++ présent +++ abondant DENSITE DES CELLULES CIBLES POTENTIELLES AU VIH DANS LES MUQUEUSES GENITO-URINAIRE,ANALE,RECTALE ET ORALE,ET DISTRIBUTION DES CELLULES M.CELLULES RF c +CELLULES EPITHELIALES HLA II+CELLULES MONONUCLEEES CD4 + (LAMINA PROPRIA)CELLULES DE LANGERHANSCELLULES MMUQUEUSE VAGINALE-+++EXOCERVICALE+++ZONE DE TRANSITION (CERVIX)MUQUEUSE ENDOCERVICALEMUQUEUSE PREPUCIALE++ à +++MUQUEUSE URETHRALE MASCULINEMUQUEUSE ANALENRMUQUEUSE RECTALEMUQUEUSE ORALE- (1)- absent + rare ++ présent +++ abondantNR non rapporté (1) Les amygdales posséderainet de rares cellules M
5 TRANSMISSION PROBABILITY BY SEXUAL INTERCOURSE (PER 1000 ) POPULATIONPRIMARY INFECTIONASYMPTOMATIC STAGESYMPTOMATIC STAGEALL COUPLE2,10,71,5MALES-FEMALESVAGINAL INTERCPURSEANAL INTERCOURSE2,90,81260,9171,30,6321FEMALES-MALES-0,43
7 LOCAL AND GENERAL RISK FACTORS FOR HIV SEXUAL TRANSMISSION GENERAL COFACTORS INFECTIVITY SENSITIVITYInfection StagePrimary Infection ++Severe Immune depression +Clinical stage 3 orHigh viral load +Chronic stimulation of immune System (infections? STDs?) +HIV coreceptors abnormalities -Age : Women ≥ 45 years ? +Girls < 13 years ? +
8 LOCAL AND GENERAL RISK FACTORS FOR HIV SEXUAL TRANSMISSION GENERAL COFACTORS INFECTIVITY SENSITIVITYLOCAL COFACTORSSTDSBACTERIAL VAGINOSIS ? +GENITAL TRACT INFLAMMATIONCERVICAL ECTOPY ? +LACK OF CIRCUMCISION ? +HIV VARIANTS +(?)LOCAL CONTRACEPTIONI U D ±(?)
9 PRESENCE DU VIRUS HIV DANS LES VOIES GENITALES Variations avec CD4 ± pas de parallélisme parfaitAvec Tt ARV ± pas de obligatoirement (secteur différent)(d’ailleurs le virus sanguin et le virus sexuel ne sont parfois pas totalement identiques)AVEC DEFICIT VITAMINE A ( AU NIVEAU DU COL)x 12 – ( selon l’intensité du déficit )
11 Role des MST dans la transmission du VIH Role épidémiologique Fonction de l’incidence Syndrome / MaladieEstimation du risqueMoyenneIntervalleChancre mou4,73,3-18,2Syphilis (sérologique)3,02,0-9,9Herpès Génital3,31,9-8,5Chlamydia4,53,2-5,7Gonorrhée3,5-8,5Trichomonase2,7?Condylomes3,7Source : Wasserheit J;Holmes K.K.; En Germain A. et coll. : Reproductive tract infections
12 Manifestations liées au MST indiquant une excrétion génitale accrue de VIH Sécrétions cervico-vaginaleCervicite mucopurulenteUlcération cervicaleUlcération vaginaleLeucocytes N. gonorrhoeaC. trachomatisSpermeUrétritesLeucocytes N. gonorrhoeaSource :OMS Dpt VIH/SIDA
19 HETEROSEXUAL TRANSMISSION COMPARAISON EUROPA/ AFRICA The risk of contamination for a young africanIs 500 fold higher (1/5-10)than in Europe (1/ )CAUSES= STD median RR:4PREVALENCE 10 TO 15 FOLD HIGHER (x50)=Multiple silmultaneous partnership (x10)=Role of some HIV1 subtypes such as C or E (?)
21 SEROPREVALENCE COMPAREE SELON LES SEXES ET L’AGE A KISUMU (KENYA) ET NDOLA (ZAMBIE) EN %HOMMES FEMMES FILLES GARCONS à 49 ANS 15 à 49 ANS 15 à 19 ANS 15 à 19 ANS KISUMU NDOLASource –différence dans la propagation du VIH dans quatre villes d’Afrique subsaharienne
22 Probability of HIV-1 TRANSMISSION PER COITAL ACT IN MONOGAMOUS ,HETEROSEXUAL,HIV-1-DISCORDANT COUPLES IN RAKAI ,UGANDASUMMARYBACKGROUND the probabilityof HIV-1 transmission per coital act in representative African populations in unknown. We aimed to calculate this probability overail ,and to estimate how it is affected by various factors throught to influence infectivity.Methods 174 monogamous couples ,in wich one partner was HIV-1 positive,were retrospectively identified from a population cohort in RAKAI ,OUGANDA.Frequency of intercourse and reliability of reporting within couples was assessed prospectively. HIV-1 seroconversion was determined in the uninfected partners,and HIV-1 viral load was measured in the infected partners.RESULTS the mean frequency of intercourse was 8-9 per month,wich declined with age and HIV-1 viral load.Members of couples reported similar frequencies of intercourse. The overail unadjusted probability of HIV-1 transmission per coital act was (95% CI ). Transmission probabilities increased from per act at 38 500 copies/ml or more (p=0.002) and were with genital ulceration versus without (p=0.02). Transmission probabilities per act did not differ significantly by HIV -1 subtypes A and D ,sex, STDs ,or symptoms of discharge or dysuria in the HIV-1 positive partner
25 ASSOCIATION BETWEEN METHOD OF CONTRACEPPTION AND HIV-1 SEROCONVERSION HAZARD RATIO95 % CONFIDENCE INTERVALPMODEL 1 (UNIVARIATE)None/ tubal ligation1.0DMPA2.2.001ORAL CONTRACEPTIVES1.5.1LOW-DOSE.2HIGH-DOSE2.3IUD1.3.7MODEL 2 (MULTIVARIATE)contraceptive method2.0.003.3.42.61.2
26 COMPLICATIONS OF USE OF INTRAUTERINE DEVICES AMONG HIV-1 INFECTED WOMEN. (Samuel K Sinei,Charles S Morrison,Christine Sekadde-Kigondu,Melissa Allen,Donald Kokonya)SUMMARY,BACKGROUNDA: WHO expertgroup and the international planned Parenthood Federation recommend against use of intrauterine devices(IUDS) in HIV 1 infected women based on theoreticalconcerns about pelvic infection and increased blood loss.We investigated whether the risk of complications after IUD insertion is higherin HIV 1 infected women than in non-infected women .METHOD 649 (156 HIV 1 infected 493 non infected) women in NAIROBI,KENIA ,who requested and met local eligibility criteria for insertion of an IUD were enrolled.We gathered informationon IUD related complications , incluning pelvic inflammatory disease,removals due to infection,pain,or bleeding expulsions,and pregnancies at1and 4months after insertion.Patients HIV 1 status was masked from physicians.FINDINGS Complications were identified in 48 of 615 women ( %- HIV 1 infected women, %-non infected).Incident pelvic inflammatory disease (two -1.4%-HIV 1 infected , one -0.2%-non infected) and infected related complications (any tenderness,removal of IUD for infection or pain; (ten-6.9% HIV 1 infected , %-non infected) were also rare and similar in the two groups.Complication rates were similar by CD4 (immune) status.Multivariate analyses suggested no association between HIV 1 infection and increased risks for overall complications (odds ratio % CI ) or infection-related complications ( ). adjusted for marital status,study site,previous IUD use ,ethnic origin,and frequency of sexual intercourse,but a slight increase cannot be ruled out .INTERPRETATION Our data suggest that IUDS may be a safe contraceptive method for appropriately selected HIV 1 infected women with continuing access to medical services
27 MALE CIRCUMCISION, SEXUALLY TRANSMITTED DISEASE, AND RISK OF HIV A cross-sectional study in KIGALI ,the capital of RWANDA , with 837 married men who volunteered for HIV testing and counselling.Despite the low-risk profile, uncircomcised men had a higher prevalence of HIV infection than circumcised men (29% versus 21% HIV positive, p=0.02), which was most marked in men reporting five or more lifetime sex partners (36% versus 23% HIV positive,p=0.005) or contact with prostitutes (35% versus 23% HIV positive , p=0.009). Circumcision remained a predictor of HIV infection in multivariate analyses (multivariate odds ratio 1.69, 95% confidence interval ( ).
28 THE ASSOCIATION BETWEEN LACK OF MALE CIRCUMCISION AND RISK FOR HIV INFECTION: A REVIEW OF THE EPIDEMIOLOGICAL DATAThirty epidemiological studies identified in the literature that investigated the association between male circumcision status and risk for HIV infection were reviewed.RESULTS: EIGHTEEN cross-sectional studies from six countries reported a statistically significant association, fout studies from four countries found a trend toward an association. Four studies from two countries found no association. Two prospective studies reported significant associations, as did two ecological studies.In studies in which significant associations were demonstrated, measures of increased risk ranged from 1.5 to 8.4. The groups in which positive associations were found included sexually transmitted disease(STD) clinic and hospital patients, outpatient clinic and HIV screening clinic attenders, long-distance truck drivers and general community members .
29 MUCOSAL AND SYSTEMIC HIV-1 SPECIFIC IMMUNITY IN HIV- 1 EXPOSED BUT UNINFECTED HETEROSEXUAL MEN Sergio Lo Caputo,Daria Trabattoni,Francesca Vichi,Stefania Piconi,Lucia Lopalco,Maris Luisa Villa,Franscesco Mazzotta And Mario Clerici.BACKGROUND: Despite multiple, repeated exposures to HIV -1,some individuals never seroconvert. Mucosal and systemic immune correlates of this condition have been analysed in HIV-1 exposed women but no data are available concerning mucosal immunity and HIV -1 specific immune responses in exposed but uninfected men.DESIGN: We analysed cellular and humoral immune parameters in peripheral lymphocytes ,seminal fluid and urethral swabs of 14 recently HIV -1 exposed seronegative (ESN) heterosexual men ,seven HIV seropositive patients and seven healthy controls.RESULTS: HIV1 specific IGA were detected in urethral swabs of 11 out 14 ESN and of six of seven HIV seropositive patients ; Env- and Gag specific IFNγ producing CD4 and CD8 peripheral lymphocytes were present in ESN and HIV seropositive patients; seminal lymphocytes , but not peripheral blood lymphocytes , of ESN were enriched in actived populations (CD8CD38RO and CD4CD25). P24-specific cytotoxic T lymphocytes were correlated with the percentage of CD4 in the HIV seropositive partners. High urethral concentrations of HIV1 specific IgA were seen in those ESN with the most recent unprotected sexual episode.CONCLUSIONS: this is the first report of HIV specific mucosal immunity in ESN men .These data add to the body of knowledge of the immune correlates present in exposed , uninfected individuals and might be important in vaccine design.
30 Plan de l’intervention de Mwanza Formation et supervisionDistribution de médicamentsEducation sanitaire sur la demande de soinsSource :OMS Dpt VIH/SIDA