HIV Transmission Modes.ppt

health

1. HIV TRANSMISSION
Bonuke Anyona (PhD)

2. Transmission

3. Fluids that can Transmit HIV
Fluids thatDO
transmit HIV:
Blood
Semen
Vaginal Fluid
Breast Milk
(in order of the highest
concentration of HIV)
Fluids that DO NOT
transmit HIV:
Saliva
Tears
Mucus
Urine
Sweat
Feces

4. HIV Transmission
HIV is not transmitted by:
•Public baths
•Handshakes
•Work or school contact
•Using telephones
•Sharing cups, glasses,
plates, or other utensils
•Coughing, sneezing
•Insect bites
•Touching, hugging
•Water, food
•Kissing

5. Major Modes of Transmission of
HIV in Adults
•Sexual contact
•Commercial sex
•Casual sex
•Marital sex
•Men who have sex with men (MSM)
•Injecting drug use
•Blood transfusions
•Medical injections and/or Occupational
exposure

6. Sexual HIV Transmission
•Althoughtherearechallengesinquantifyingrisk
bysexact,studiesconsistentlyreportthatanal
intercourseisahigherriskactthanvaginal
intercourse,whichinturnisahigherriskactthan
oralintercourse
•ThestrongestpredictorofHIVsexual
transmissionisplasmaviralload.
•Asplasmaviralloadincreases,theriskof
transmissionalsoincreases.

7. Sexual HIV Transmission
•MuchofwhatisknownaboutviralloadandHIV
transmissionisderivedfromstudiesof
heterosexualpopulations.Assuch,littleisknown
abouthowviralloadaffectstheriskof
transmissionthroughanalintercourse.
•ThepresenceofaconcomitantSTIhasalsobeen
foundtoaffectHIVtransmission.STIsincrease
susceptibilitytoHIVbyafactorof2to4and
increasetransmissibility2to3times.

8. Sexual HIV Transmission
•Typicalgenitalcoinfections(STIs)inAfrican
countriesarechlamydia,gonorrhea,Treponema
pallidum,andHerpessimplexvirustype2.
•LessfrequentagentsasHaemophilusducreyi,
Klebsiellagranulomatosis,andHTLV-1.
•HTLV-1isawell-knownretrovirusthatis
transmittedcommonlyinAfrica,andwhichcan
acceleratethedeteriorationoftheimmune
functionintheHIV-infected.

9. Sexual HIV Transmission
•Malecircumcisiondecreasestheriskoffemale-
to-malesexualtransmissionofHIVby50%to
60%.
•However,thereislittleepidemiologicalevidence
tosuggestthatcircumcisionreducestheriskof
transmissiontofemalepartnersofcircumcised
menoriseffectiveinthepreventionofHIV
amongmenwhohavesexwithmen(MSM).

10. HIV Transmission among Drug
Users
•Forpeoplewhoinjectdrugs,riskoftransmission
perinjectionfromacontaminatedneedlehasbeen
estimatedtobebetween0.7%and0.8%.
•However,studiesofcontactwithimproperly
discardedneedlesoutsideofthehealthcaresetting
suggestthatsuchexposuresrepresentalowriskfor
HIVtransmission,likelyduetothelowviabilityof
thevirusoutsidethebody.

11. HIV Transmission among Drug
Users
•Sharingancillaryinjectingequipment(eg.filters
orcookers)duringdruginjectionhasbeenshown
toincreasetheriskoftransmission,eveninthe
absenceofsharingneedlesandsyringes.
•OtherfactorsthatincreaseriskofHIV
transmissionforpeoplewhoinjectdrugsinclude:
–Injectinginunsafelocations
–Typeofdrugused
–Frequencyofdruginjection

12. HIV Transmission among Drug
Users
•Peopleusingnon-injectiondrugsarealsoatrisk
ofHIVinfection.
•Drugusecanaltersexualbehavioursby
increasingrisktaking.
•Inaddition,severaldrugshavebeenreportedto
beindependentriskfactorsforHIVtransmission.

13. HIV Transmission by Blood
•TransmissionofHIVandotherblood-borne
virusescanoccurduringtransfusionofblood
components(ie,wholeblood,packedredcells,
fresh-frozenplasma,cryoprecipitate,and
platelets)derivedfromthebloodofaninfected
individual.
•Dependingontheproductionprocessused,blood
productsderivedfrompooledplasmacanalso
transmitHIVandotherviruses,butrecombinant
clottingfactorscannot.

14. HIV Transmission by Blood
•TheriskofHIVtransfusionthroughinfected
bloodproductsexceedsthatofanyotherrisk
exposure.
•NinetypercentofrecipientstransfusedwithHIV
antibody-positivebloodarefoundtobeHIV
infectedatfollow-up.
•The90%probabilityofsero-conversionis
independentoftheageorsexoftherecipient,the
reasonfortransfusion,andthetypeofcomponent
transfused(excludingwashedredbloodcells,
whichtransmitHIVatalowerrate).

15. HIV Transmission by Blood
•HIVdiseaseduetotransfusionprogressesinthe
recipientatratescomparabletothosein
individualsinfectedforsimilardurationbutby
otherroutes.
•Itislikelythathostfactors,particularlythe
recipient'sageandimmunestatus,andperhaps
otheras-yet-undefinedcofactorsinfluencethe
progressiontoAIDS.

16. HIV Transmission by
Occupational Exposure
•TheriskofoccupationalexposuretoHIVismost
closelyrelatedtotheactivitiesanddutiesofthe
healthcareworker.
•Additionally,thegeographiclocationandpractice
settingcanalsoaffecttheriskofexposureandthe
qualityofpostexposurecare.
•Accidentalinfectedneedlepricktoahealthcare
worker;resultsin0.03%transmission.

17. HIV Transmission by
Occupational Exposure
•HIVmaybetransmittedoccupationallytohealth
careworkerswhoare:
–Exposedtobloodandotherpotentiallyinfectious
bodilyfluidsviapercutaneousinjuryor
–Splashexposurestomucousmembranesornonintact
skin.
–Unfamiliarpracticeenvironmentscanputthehealth
careworkeratincreasedriskofexposure.

18. HIV Transmission by
Occupational Exposure
•Inadditiontoblood,cerebrospinalfluid,synovial
fluid,pericardialfluid,pleuralfluid,peritoneal
fluid,amnioticfluid,semen,andvaginal
secretionsareconsideredpotentiallyinfectious.
•Saliva,urine,sputum,nasalsecretions,tears,
feces,vomitus,andsweatarenotconsidered
infectiousforHIVunlesstheyarevisiblybloody.

19. HIV Transmission by
Occupational Exposure
•Typically,exposuresoccurasaresultof
percutaneousexposuretocontaminatedsharps,
includingneedles,lancets,scalpels,andbroken
glass(fromcapillaryortesttubes).
•Skinexposurestopotentiallyinfectiousbodily
fluidsareonlyconsideredtobeatriskforHIV
infectionifthereisevidenceofcompromised
skinintegrity(forexample,dermatitis,abrasion,
oropenwound).

20. HIV TRANSMISSION
IN CHILDREN

21. HIV Transmission in Children
•Abasicdifferencebetweenpediatricandadult
HIVinfectionisthemainrouteoftransmission
whichismothertochild.
•TransmissionofHIVoccursviasexualcontact,
otherexposurestolive-virus-containingfluids
andtissuesincludingverticaltransmission(VT)
frommothertochild.

22. Vertical Transmission
•VTcanoccurbefore(intrauterine),during
(intrapartum),orafterdelivery(mostlythrough
breast-feeding).
•Breast-feedingisresponsiblefor30-50%ofVT
indevelopingcountries
•Breast-feedingisthecauseof90%ofpediatric
HIVgloballyandispredominantlyadiseaseof
resource-poorregions.

23. Breast Feeding and HIV
•Breastfeedingisanefficientmodeof
transmissionofHIVandcanberesponsiblefor
upto50%ofcasesofVTinsomeregions;
between320,000and800,000infectionsperyear
globally.
•Althoughtransmissioncanoccuratanypoint
duringbreastfeeding,thefirst6weeksoflife
entailthegreatestrisk,comprisingabout67%of
transmissions.

24. •Thegreatercellularcompositionofcolostrum
andearlymilkhasbeensuggestedasa
mechanismforhightransmission.
•Thefrequencyofbreast-milktransmissionis
alsoincreasedifthemother’sCD4
+
countisless
than200cells/mL.
Breast Feeding and HIV

25. •TheWorldHealthOrganization(WHO)
recommendsthatwomenbecounseledaboutthe
riskofHIVtransmissionthroughbreastfeeding.
•Whenreplacementfeedingisaffordable,feasible,
acceptable,sustainable,andsafe,avoidanceofall
breastfeedingbyHIV-infectedmothersis
recommended.
Breast Feeding and HIV

26. •Whenreplacementfeedingisnotpossible,
exclusivebreastfeedingisrecommendedand
breastfeedingshouldbediscontinuedassoonas
possible.
•Insomeregionsandcultures,premasticationof
solidfoodsbyanadultpriortofeedingofan
infantoccurs.IftheadultisHIV-infected,this
practicecanresultininfectionofthechild
Breast Feeding and HIV

27. Priority Populations and Programs
Route Population Intervention
Sex work SW and clients Out-reach, condoms, STI Treatment
Casual sex
Youth, military, truckers,
etc.
Out-reach, condoms, STI
Low risk Married couples Promote testing
IDU IDU Risk elimination, harm reduction
MSM MSM Out-reach, condoms, STI Treatment
Injection Patients Sterile needles
Blood Transfusion recipientsScreening
Mother-to-
child
Pregnant women PMTCT

28. References
•http://www.phac-aspc.gc.ca/aids-sida/publication/hivtr-rtvih-eng.php
•http://hivinsite.ucsf.edu/InSite?page=kb-00&doc=kb-07-02-09
•http://wwwnc.cdc.gov/travel/yellowbook/2014/chapter-2-the-pre-travel-
consultation/occupational-exposure-to-hiv