What needs to be done?(Updated 4 April 2000)

For this lecture, I expect you to read the commentary by Dr. Sylvia Hacker.

How bad is the problem?

• HIV is not VERY contagious
  • 1/500 for heterosexual encounters with HIV positive (vaginal intercourse — anal is higher)
  • asymmetric (M to F 20 times more likely!)
  • time variable: MUCH more infectious early and late
• BUT you can get HIV on first encounter
  • especially if in early or late stage
  • and you’ll spread it before you know it

How much prevention is enough?

• Condoms are probably 90% effective
• without a condom
  • HIV(+) husband to wife 17%
• with condom
  • HIV(+) husband to wife <1%
• Is HIV self-sustaining?

Self sustaining infections

• Three elements
  • number of contacts/time
  • probability of transmission per contact
  • duration of infectious state
• Reduce any or all and you can get to a non-sustainable level of transmission

Herd immunity

• Reduces number of transmissions per contact (“wasted” contacts)
• Real immunity
  • vaccine, natural immunity, etc.
• Virtual immunity
  • education, barriers, quarantine

Silent transmission

• Increases total transmission
• Early detection helps
• Knowing is different from doing
• The quarantine question
  • Cuban experience
  • Typhoid Mary

Condoms

• Do they work?
  • In individual cases?
  • In reducing transmission to non-sustainability?
• Data are not always congruent but trends are there
  • much depends on how you pose the question

Condoms and non-sustainability

• Individual effectiveness might be as low as 60% or as high as 98%.
• Even if only 60%, might be enough to convert epidemic to endemic

Is “safer sex” counterproductive?

• Do education and condom availability lead to more sexual activity?
  • Best data say no.
• Why don’t men use them
• Who should buy them
  • in 1985, women bought 10% of all condoms
  • in 1989, it was 40-50%

Power relations and condoms

• Men are dominant in most cultures
• American young men are embarassed to use condoms
  • “traditions” and “the street”
  • loss of erection
  • loss of spontaneity
  • less sensual
  • religious objection

Oppositon to “safer sex”
The moral conservatives

• Family values
• Need for a threat to prevent sex
• Need for stable families for inheritance of property
• Linkage of sex with economics, children, and male power

Opposition to “safer sex”
Sexual Liberationists

• Barebacking
  • Safe sex is a plot to reduce pleasure
  • lack of risk management in the 90s
    • lawsuits, lack of personal responsibility, the pill and cure
• Bug chasers and Gift givers
  • A terrifying story

Sex and reproduction

• Linkage is relatively new
  • leads to a “new” definition: sex = intercourse
• Result is that both the extreme conservatives and the extreme liberals agree: Sex = intercourse
  • because sex = reproduction
  • because no other way is known

Alternatives to Intercourse

• Abstinence
• “Outercourse”
  • Sylvia Hacker’s commentary
  • Birth control led to its loss in the culture
  • Orgasmic control
• More and less safe versions

What kind of sex is safe(r)?

• Vaginal, Anal, Oral
• Masturbatory and manual
• Mechanical devices
• The viagra paradox
  • longer erection
  • why needed?

Role of Education

• In San Francisco, Gay male transmission is down from 10-20% per year to about 1% per year
• Beginnings of “second wave”
• Failure to address the coming generation
  • educators tired
  • AIDS is no longer “new”

HIV and IV Drug Users

• No spokespersons or focus groups
• Immediacy of need for drugs vs. Planning for safe needles
• Sex for drugs
• General poor health and nutrition

Preventing IDU transmission

• Moral dilemma: needle exchange?
• Same issues as condom use
  • will it increase drug use?
  • is drug use more deadly than AIDS?
  • is it condoning a crime/sin/irresponsible act?
• Major route to heterosexual population
• Major source of orphans and pediatric AIDS

Do needle laws prevent drugs?

• Rule of thumb: the more laws and the more severe the laws, the more prevalent the behaviour
• In other words, laws reflect behavior, they don’t change it much
• “Locks keep honest people out”

A curious correlation

• States with no laws against needles
  • HIV transmission rate = 0.83 per 100,000
• States with syringe possession a felony
  • AIDS rate = 1.63 per 100,000
• States with syringes a felony and requiring a prescription for them
  • AIDS rate = 5.78 per 100,000
• CAUSE OR EFFECT?

Blood transfusions and HIV

• Once a major route of transmission
  • A large dose of HIV via blood (transfusion) is almost certain to result in HIV infection
  • A small dose (needleprick) seldom results in infection (about 1/300)
• Current tests reduced that by more than 99%

Current Blood Tests

• HIV
  • antibodies for HIV-1 and HIV-2
  • misses infections early in the window
  • presence of p24 antigen (since 1996) shows up earlier
    • catches many infections even in the window
• Other pathogens

            1. HIV 1/2 - Test for antibodies to  HIV-1 and HIV-2.
             2.HBc - Test for antibody produced during and after infection
                  with HBV.
             3.HCV - Test for antibody for HCV.
             4.HTLV -I/II - Test for antibodies to   HTLV-I and HTLV-II.
             5.HBsAg (Hepatitis B Surface Antigen) - Screens for HBV.
             6.HIV-1 p24 (HIV-1 p24 Antigen) -  test for HIV antigen.
             7.ABO/Rh - Test for blood type.
             8.Tp (Syphilis) - Test for the agent that causes syphilis.
             9.ALT - Test that measures a liver enzyme found in blood serum.
                Elevated ALT levels may reflect liver inflammation, which
                  may be caused by a hepatitis virus.
            10.Antibody - Test to determine the presence of atypical
                  antibodies that may cause post-transfusion reactions.
            11.CMV - Test for cytomegalovirus - performed on physician 
            12.NAT (Nucleic Acid Testing) -
                NAT is a new technology that can detect the genetic material
                of Hepatitis C and HIV potentially faster and more
                accurately than the current tests,  which react to
                  antibodies of
                those viruses. All of the blood  collected by the American
               Red Cross for transfusion is now  subjected to NAT under an
                Investigational New Drug application submitted to the FDA.

• Blood is very safe now

How safe is blood?

• CDC estimate (1991)
  • 1 in 40,000 to 1 in 250,000
• Red Cross Estimate
  • 1 in 450,000 to 1 in 660,000 (1995)
  • 1 in 1,500,000 (2001)
• For comparison:
  • Death by auto accident: 1 in 5,960
• Death due to surgical complications??

Partneer Notification

History of Contact Tracing

• Began with syphilis in 1937
• Now for many STDs
• Goal is to interrupt the chain of transmission
• Much less palatable when no treatment is available

In Support of Notification

• Break the chain of transmission
• Treat or counsel the partners
• Prevent “guilt” of innocent transmission
• Rights of the uninfected to remain so

Opposition to Notification

• Not cost effective (syphilis marriage test)
• Threat of discrimination
• Revenge
• Will it change any behavior?
• No cure (worse when no effective treatment)
• Homosexuality is a crime