AIDS Ch5 Epidemiology

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    The Epidemiology of AIDS

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    WHO definition:

    •  Epidemiology is the study of the distriution !nd

    determin!nts of he!lth"rel!ted st!tes or e#ents $in%luding

    dise!se&' !nd the !ppli%!tion of this study to the %ontrol of

    dise!ses !nd other he!lth prolems(

    •)!rious methods %!n e used to %!rry out epidemiologi%!l

    in#estig!tions: sur#eill!n%e !nd des%ripti#e studies %!n e

    used to study distriution* !n!lyti%!l studies !re used tostudy determin!nts(

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    AIDS !nd Epidemiology

    In +une ,-.,' do%tors !t the CDC:

     – Described five cases of Pneumocystis pneumonia in homosexual men inLos Angeles. – Received several requests for pentamidine isethionate, which is used to

    treat Pneumocystis pneumonia. – Received reports of an unusual number of cases of Kaposi’s sarcoma and

    suppressed immune sstems in patients(

    /y the end of ,-.0' epidemiologists h!d n!med the dise!se

    !%1uired immune defi%ien%y syndrome $AIDS&( – !urmised that there was a common denominator among cases in separate


     – As data on the long incubation period emerged, the guessed a larger

    group was infected and would manifest smptoms in the future.

     – "sed case control studies to gather additional data.

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    A %!se"%ontrol study is !n !n!lyti%!l study 2hi%h %omp!res

    indi#idu!ls 2ho h!#e ! spe%ifi% dise!se $3%!ses3& 2ith !

    group of indi#idu!ls 2ithout the dise!se $3%ontrols3&( Theproportion of e!%h group h!#ing ! history of ! p!rti%ul!r

    e4posure or %h!r!%teristi% of interest is then %omp!red(

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    Epidemiologists g!thered enough d!t! to prep!re ! %!se

    definition for AIDS in ,-.(

     – 6!de re%ommend!tions for !#oiding the dise!se(

     – Physi%i!n reporting pointed to lood !nd semen !s

    prin%ip!l sour%es of the dise!se !gent(

    C!se %ontrol studies en!led epidemiologists to sho2:

     – 7umer !nd fre1uen%y of se4u!l p!rtners !mong

    homose4u!l men 2ere f!%tors in the in%iden%e of AIDS(

     – Se4u!l p!rtners of homose4u!l !nd ise4u!l men 2ere

    !t ris8 !nd th!t more th!n 09 of %!ses o%%urred in

    men 2ho h!d ! se4u!l rel!tionship 2ith !n infe%ted


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    HI) #irus(

     – Disintegr!tes outside the ody( – C!nnot resist en#ironment!l pressures(

    Tr!nsmission re1uires e4%h!nge of ody fluids to spre!d

     – A l!rge numer of #ir!l p!rti%les must e p!ssed during


     – P!rti%le %ounts in s!li#!' te!rs' !nd s2e!t !re too lo2 to

    !ffe%t HI) tr!nsmission(

    Semen !nd lood rem!in the m!;or

    tr!nsferring sust!n%es of HI)(

    Other %ontriuting ris8 f!%tors: – )olume of fluid introdu%ed into

    the re%ipient(


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    35.3million [32.2 million – 38.8 million]32.1million [29.1 million – 35.3 million]

    17.7million [16.4 million – 19.3 million]

     3.3million [3.0 million – 3.7 million]

    2.3million [1.9 million – 2.7 million]

    2.0 million [1.7 million – 2.4 million]


    1.6million [1.4 million – 1.9 million]

    1.4 million [1.2 million – 1.7 million]


    Number of people living wit !"#

    $eople newl% infe&te' wit !"# in 2012

    (")* 'e+t, in 2012



    /il'ren 15 %e+r,



    /il'ren 15 %e+r,



    /il'ren 15 %e+r,

    Global summary of the AIDS epidemic  2012


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    Total: 35.3 million [32.2 million – 38.8 million]

    Western&Central Europe


    Middle East & Nort !"ri#a260000


    $u%$aaran !"ri#a25.0million

    [23.5million – 26.6 million]

    Eastern Europe& Central !sia

    1.3million[1.0million – 1.7 million]

    $out & $outEast !sia3.9million

    [2.9million – 5.2 million]



    Nort !meri#a1.3million


    (atin !meri#a1.5million

    [1.2million – 1.9 million]

    East !sia880000




    Adults and children estimated to be living with HI  2012

      WHO, UNAIDS, UNICEF 2014

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    Epidemi% in the =nited St!tes

    CDC  MMWR +une ,5' 09,0: Estim!ted numer of persons !ged >, ye!rs li#ing

    2ith di!gnosed !nd undi!gnosed HI) infe%tion? !nd per%ent!ge 2ith undi!gnosedHI) infe%tion@ 7!tion!l HI) Sur#eill!n%e System' =nited St!tes' ,-.5B099.

    # $%& prevalence estimates were based on national $%& surveillance data for persons aged '() ears at diagnosis

    reported through *une +( using extended bac-calculation.

    / 0he number of undiagnosed $%& infections was calculated b subtracting the estimated number of diagnosed $%&

    infections in living persons from the estimated overall $%& prevalence.

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    Epidemi% in the =nited St!tes

    • (.) million

    Americans had been

    diagnosed with

    A%D! or found to be

    $%&positive in

    +1.• Rates of new $%&

    infections and deathsfrom A%D! have not


    changed in the ".!.

    since (223.

    • 4radual shift awa

    from sexuall activehomosexual men and

    toward blac-s,

    $ispanics, and


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     !reas )it te i*est estimated rates o" persons

    li+in* )it dia*nosed ,- in"e#tion at te end o"

    2/0/ )ere the District of Columbi !2,"04#$%, Ne&

     'or( !)10#0%, the U#S# *ir+i Isl-s !.."#1%,

    /rl- !.$2#%, Flori- !2#"%, 3uerto ico

    !)4#$%, Ne& 5erse !4))#2%, 6ouisi !41#"%,- 7eor+i !42)#)%#

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    Estim!ted 7e2 HI) Infe%tions in the =nited St!tes' 09,9' for

    the 6ost Affe%ted Supopul!tions $CDC&

    Estim!ted ne2 AIDS di!gnoses !s of 

    09,, y geogr!phi% distriution :

    • South 5• 7orthe!st 0

    • West ,-• 6id2est ,

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    Annu!l Pre#!len%e of Adults i#ing 2ith HI) Dise!se'

    ,--5"09,0' lorid!

    As result of -eclii+ -eths, ul HI*8AIDS -i+oses h9e e:cee-e- -eths sice 1,

    - the umber of ;ersos re;orte- &ith HI*8AIDS tht re ;resume- to be li9e hs bee

    icresi+# Sice the er 1, ;re9let cses h9e icrese- b 4.)

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    3o;ultio EstimtesN=1.,10,)42

    6i9i+ A-ult HI*8AIDS CsesN=),21

    Note> I this s;shot of li9i+ -ult HI*8AIDS cses throu+h 2012, 4< re blc(, &heresol 14< of Flori-?s -ult ;o;ultio re blc(# @his i-ictes -is;rit of HI*8AIDS i the blc(;o;ultio#

    Source> 3o;ultio estimtes re ;ro9i-e- b Flori-CHA@SOther iclu-es Asi83cific Isl-ers - Nti9e Als(s8Americ I-is#

    Adults i#ing 2ith HI) Dise!se' !nd

    St!te Popul!tion?' y R!%eFEthni%ity'

    Reported through 09,0' lorid!

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    3ersos 6i9i+ &ith HI* Diseseb Selecte- Demo+r;hics - is( Fctors

    U#S# !2010% - Flori- !2012%

    Note> />F rtio> U#S#, $#0>1# F6, 2#4>1

    Source> U#S# -t> HI* Sur9eillce e;ort, 2011 !most recet 9ilble% *ol# 2$, @ble 1 !HI*

    -t for ll 0 sttes% htt;>88&&c-c#+o98hi98to;ics8sur9eillce8resources8re;orts8i-e:#htm 

    Flori- -t> F6 De;rtmet of Helth, HI*8AIDS - He;titis Sectio, li9e - re;orte- throu+h

    2012, s of 0.8$081$#

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    HI) !nd AIDS in 2omen

    Women represent 09 of !ll di!gnoses of HI) infe%tion in the

    =nited St!tes (!pread of $%& through highris- heterosexual contact is on the rise because

    women are more susceptible than men to the spread of $%& through

    heterosexual activit, and most sex events in the human population are


    • !uggests that $%& distribution in the ".!. ma become predominantl heterosexual and female.

    Pre#ention %h!llenges for 2omen

    • "naware of partner’s ris- factors for $%& infection.• Relationship dnamics 5fear of phsical abuse or abandonment if the

    insist on condom use6• $istor of sexual abuse ma lead to the use of drugs as a coping

    mechanism.• 7a exchange sex for drugs or engage in highris- sexual activities.

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    )!gin!l infe%tions• 8acterial vaginosis increases a woman’s susceptibilit to $%& infection

     because it interferes with the normal metabolism of cells lining the vaginal


    • 9pportunistic diseases are equall prevalent in $%&infected women andmen 5except for cervical cancer and Kaposi’s sarcoma6

    • 4necological complications associated with !0Ds require special attention

    HI* - AIDS i &ome

    HI) infe%tion !nd pregn!n%y

    • $AAR0 or even A:0 intervention can interrupt viral passage to the fetus.

    • During deliver, an obstetrician will postpone rupture of the amniotic

    membranes or other potentiall invasive procedures that might encourage

    $%& transmission.

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    HI) !nd AIDS in in;e%tion drug users

    • !haring of bloodstained needles and sringes• Rinsing the syringe !nd needle in ! le!%h solution %!n elimin!te the

    #irus !nd interrupt tr!nsmission(

    • !haring needles and sringes that contain a drugblood mixture that is not

    entirel removed before use b the next person.• In 09,9' - of HI) infe%tions 2ere !ttriut!le to the use of in;e%tion


    eg!l needle e4%h!nge progr!ms

    •  ;ot available in all states.•  ;eedles and sringes ma still be hard to come b.• African Americans.

    • AIDS epidemi% is gr!du!lly t!8ing on so%iologi%!l' politi%!l' !nd

    e%onomi% o#ertones th!t differ from those of the p!st(

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    The Spre!ding Epidemi% in the =nited St!tes

    ? E!rly high pre#!len%e of HI) in the !%ti#e homose4u!l

    popul!tion suggests th!t HI) entered the =(S( homose4u!lpopul!tion #ery e!rly in the epidemi% here(


    HI) in the =(S(

    ? CDC re%ommends !nnu!l HI) testing for men 2ho h!#e se42ith men(

    ? Tr!nsgender %ommunities in the =(S( !re !mong the groups !t highest ris8

    for HI) infe%tion(

    • 0ransgender refers to individuals who do not conform to the traditional

    definition of gender based on external genitalia or their sex assigned at

     birth.• %dentifing transgender people can be challenging.• $igh levels of $%& ris- behavior have been reported among transgender


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    HI) !nd AIDS in g!y !nd ise4u!l men !nd

    tr!nsgender indi#idu!ls

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    HI) !nd AIDS in heterose4u!ls

    @or heterosexuals, the ris- of contracting A%D! can be substantial, depending

    on circumstances.

    HI) ris8s from heterose4u!l inter%ourse: fem!les

    • ounds, lesions, or abrasions along the vaginal lining.• &irus can pass through the lining of the uterus if vaginal intercourse

    occurs at the beginning of or during a woman’s menstrual period.

    • 7acrophages ma also be able to pass through the tissue of the cervix.HI) ris8s from heterose4u!l inter%ourse: m!les

    • Lesions on the outside surface of the penis.• &iruses or infected 0lmphoctes can enter the urethra at the conclusion

    of e=aculation.

    Abstinence is the most sensible and efficient method of preventing $%&


    Bondom use and limiting the number of sexual partners are also recommended.

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    In the ,-.9s' most di!gnosed older Ameri%!ns %ontr!%ted HI) !s ! result

    of ! %ont!min!ted lood tr!nsfusion(

    • Burrentl, the vast ma=orit have become infected as a result of

    heterosexual contact.

     ;umber of cases and deaths in this group is expected to increase because of

    new treatments that prolong life.

    9bstacles include overcoming denial and stigma.

    Aul 3re9lece of A-ult /les

    6i9i+ &ith HI* Disese, b

    Curret A+e, 1B2012, Flori-

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    HI) !nd AIDS in %orre%tion!l


     – %ncarcerated men and women are

    often first diagnosed with $%& in a

    correctional setting.

     – BDB recommends $%& screening

    upon entr into prison and beforerelease, in addition to voluntar $%&

    testing periodicall during


     – 0esting hesitanc is common due tothe stigma associated with a positive

    diagnosis and concern that

    confidentialit will not be


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    HI) !nd AIDS in s%hools !nd %olleges

    %ncidence in schoolage children and teenagers is rel!ti#ely lo2' but the potential

    for exposure exists.

    • Experimenting with drugs and sexualit is common.9bstacles

    • %gnorance and feelings of invincibilit.

    BDB is wor-ing on a multifaceted approach to interventions, including the use of

     prevention messages on cell phones, gaming sstems, websites, and social media.

     'ou+ ;eo;le +e- 1$ to 1 i the

    U#S# re t hi+h ris( for HI*

    ifectio !CDC 2011%#

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    HI) !nd AIDS in ne2orns

    Women %!n p!ss HI) to their !ies:

    • During pregn!n%y(• During deli#ery(• Through re!st"feeding(

    /y 099G' the CDC h!d reports of more th!n -'999 %umul!ti#e

    %onfirmed %!ses of pedi!tri% AIDS in =S(

    Testing of ne2orns e%!me possile 2ith the de#elopment of

    the #ir!l lo!d test(

    7e2 HI) infe%tions !mong %hildren h!#e de%lined sin%e 099(6ore th!n -9 of the %hildren 2ho !%1uired HI) in 09,, li#e

    in su"S!h!r!n Afri%!(

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    Studies sho2 th!t r!pid implement!tion of AT tre!tment

    %!n lo%8 tr!nsmission to the fetus(• ed to ! steep de%line of pren!t!lly !%1uired AIDS(

    • =n%le!r 2hy these drugs !re more effe%ti#e in lo%8ing

    the spre!d to the inf!nt %omp!red 2ith the effe%t on the!dult(

    !ome newborns appeared to neutraliFe $%& before it became

    entrenched in the tissues ? ;ow attributed to maternal antibodiesthat eventuall cleared the neonnates’ sstem, not genuine $%&


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    Pedi!tri% AIDS


    ? !ilure to thri#e• Do not demonstrate expected growth patterns after birth.• Do not respond to aggressive nutritional therap.• Experience weight loss that does not reverse itself.• Decreased cognitive s-ills.

    ? C!ndidi!sis

    ? ymph!denop!thy

    ? S2ollen s!li#!ry gl!nds

    ? Opportunisti% dise!ses

     – "suall have a bacterial source.•   Salmonella species 5intestinal infections6

    • !treptococci 5respirator infections6• !taphlococci 5s-in and blood infections6

    ? Only %ommon denomin!tor is ! %ompromised immune system(

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      WHO, UNAIDS, UNICEF 2014

    Western&Central Europe


    Middle East & Nort !"ri#a20000


    $u%$aaran !"ri#a2.9million

    [2.7million – 3.3 million]

    Eastern Europe& Central !sia


    $out & $outEast !sia200000




    Nort !meri#a4500


    (atin !meri#a40000


    East !sia8200



    16000 ]14000–19000[

    !hildren "#1$ years% estimated to be living with HI  2012

    Total: 3.3 million [3./ million – 3.1 million]

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    Elimin!tion efforts

     – In 099-' the +oint =nited 7!tions Progr!mme

    on HI)FAIDS %!lled for the #irtu!l elimin!tion

    of mother"to"%hild tr!nsmission $6TCT& of


     – In 09,9' the World He!lth Org!ni!tion $WHO&

    pulished ! set of guidelines for est s%ientifi%'

    progr!mm!ti% tools' !nd ne2 !d#i%e for s!ferinf!nt feed to elimin!te 6TCT(

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    HI) !nd AIDS in Afri%!

    • Dr!m!ti% in%re!ses in !ntiretro#ir!l ther!py %o#er!ge h!#e

    o%%urred in su"S!h!r!n Afri%!(• Afri%! rem!ins the h!rdest"hit %ontinent(

     – As mu%h !s G. of the 5 million people 2ith HI)

    infe%tion or AIDS !re li#ing in su"S!h!r!n Afri%!

     – Blaims ( million lives annuall in sub!aharan Africa.

    Different p!ttern of spre!d th!n in Western Europe !nd the

    =nited St!tes J 6ost tr!nsmissions t!8e pl!%e during

    heterose4u!l #!gin!l inter%ourse(

    • Attributed in part to lesions and sores from !0Ds.• Refusal to circumcise males also a contributing factor.• Bultural practice of Cdr sex in certain communities.• 0raditional attitudes against condom use.

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    Total: 35.3 million [32.2 million – 38.8 million]

    Western&Central Europe


    Middle East & Nort !"ri#a260000


    $u%$aaran !"ri#a25.0million

    [23.5million – 26.6 million]

    Eastern Europe& Central !sia

    1.3million[1.0million – 1.7 million]

    $out & $outEast !sia3.9million

    [2.9million – 5.2 million]



    Nort !meri#a1.3million


    (atin !meri#a1.5million

    [1.2million – 1.9 million]

    East !sia880000



    250000 ]220000–280000[

    Adults and children estimated to be living with HI  2012

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    KSlim dise!seL – !mptoms include r!pid 2eight loss' intr!%t!le di!rrhe!' fe#er' !nd loss

    of !ppetite(

     – 7an patients are infe%ted 2ith the protoo!l p!r!sites Cryptosporidium and Isospora.

     – HI) h!s !lso een lo%!ted in intestin!l m!%roph!ges, which ma reduce the

     bod’s natural defenses.

    • Other %onditions – Tuer%ulosis is the most pre#!lent opportunisti% dise!se in Afri%!( – Kaposi’s sarcoma is found in both infected and noninfected individuals. –   Pneumocystis pneumonia is relativel rare.

    • 0he epidemic is largel confined to urban

    centers, where malaria is also widespread.

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    World He!lth Org!ni!tion $WHO& !nd the =nited

    7!tions Progr!m on AIDS $=7AIDS&

     – Wor8 to promote physi%!l' ment!l' !nd so%i!l he!lth in

    peoples of the 2orld(

     – Colle%t !nd distriute d!t! on epidemi%s(

     – Est!lish intern!tion!l progr!ms for de!ling 2ith epidemi%s(

    St!tisti%s – )G million people worldwide live with $%&. – +12 countries are involved in the pandemic.

     – Annual new $%& infections fell +(H between (22I and +(. –

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    HI) !nd AIDS in the World

    Se#er!l %ountries do not fit the de%lining trend(• Su"S!h!r!n Afri%!• E!stern Europe• Centr!l Asi!

    The C!rie!n h!s the se%ond highest HI) pre#!len%e'

    ut the epidemi% there h!s slo2ed signifi%!ntly sin%e

    the mid",--9s(

    In Asi!' pre#!len%e of HI) is !mong popul!tions !t

    higher ris8 of infe%tion(

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    Three m!;or p!tterns of tr!nsmission

    Centr!l Europe

    • Simil!r to th!t in the =nited St!tes' 2ith the

    m!;ority of %!ses o%%urring in homose4u!l men

    !nd in;e%tion drug users(

    E!stern Europe' the Russi!n eder!tion' !nd =8r!ine

    • In;e%tion drug use is the le!ding %!use(

    !tin Ameri%! !nd su"S!h!r!n Afri%!

    • Prim!rily tr!nsmitted y heterose4u!l %ont!%t(

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     – Se%ond to South Afri%! in the tot!l numer of %!ses of

    HI) infe%tion !s of 099(

     – Dise!se is highly stigm!tied(

    Chin! – o2 in%iden%e' prim!rily from in;e%tion drug use(

     – Con%erns !re rel!ted to the gro2ing se4 industry !nd

    disd!in for %ondoms' !s 2ell !s %ont!min!ted lood

    ot!ined !t %ommer%i!l %olle%tion %enters(

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    WHO !nd =7AIDS

    Committed to pre#enting ne2 HI) infe%tionsthrough:

    • Edu%!tion

    • /lood s%reening

    • Tre!tment for in;e%tion drug users

    See8 to ring support !nd %!re to the !ffli%ted 2hile

    lin8ing together n!tion!l !nd intern!tion!l efforts tore!8 the %h!ins of tr!nsmission(