AIDS: Lecture #1

(Revised 5 March 2015)

Definitions, Origins, and Prevalence

Some Acronyms

  • AIDS
    • Acquired
    • Immunodeficiency
    • Syndrome
  • HIV
    • Human
    • Immunodeficiency
    • Virus

Acquired

    • AIDS is acquired as the result of a viral infection with HIV. Other immune deficiency syndromes can be hereditary or induced. Thus HIV is an essential part of the definition of AIDS.

Immune Deficiency

    • An infection with HIV usually has few serious symptoms in its early stages — a mild flu and some swollen glands, typically.

Slowly but surely, the HIV infection destroys the ability to mount a protective immune response by killing a special set of cells called T4 lymphocytes (or CD4)

The body is then defenseless vs. infections

Syndrome

    • AIDS is a collection diseases, called opportunistic infections that are often the real cause of disease and death
    • HIV does not cause those diseases, they are the result of the loss of immune defenses
    • The specific subset of opportunistic infections varies with the individual.

Disease vs. Syndrome

  • “HIV disease” refers to the direct effects of the HIV infection, mostly the infection and death of CD4 cells (and a few other types) as well as a later infection of other tissues such as brain.
  • AIDS (a syndrome) is an umbrella for the diseases that occur because of the prior effects of HIV disease (plus a few direct effects of HIV)
  • AIDS is defined by its effects, by a set of symptoms plus a requirement (added more recently) for the presence of HIV
  • HIV disease is defined by its cause, infection with one or more of the Human Immunodeficiency Viruses

Changing Terminology

  • AIDS definitions have changed over time
    • difficulties for statistical measures
  • Political Correctness led to confusion for a while
    • exposed = at risk
    • infected = exposed
    • diseased (patient) = living with (PLWA)

HIV Terms

  • Retrovirus
    • RNA (virus’s genetic material) copied into DNA
    • DNA goes to cell’s chromosomes and becomes a gene — something that all descendants will have
  • two kinds of retrovirus
    • oncornavirus (cause cancer)
    • lentivirus (“slow” viruses, includes HIV)

HIV has several subtypes

  • HIV-1: common in most of the world (almost the only form found in the US)
    • spread from central Africa
    • probably first entered humans about 1950 or a bit earlier
    • oldest knows case (retrospective) 1959
    • about 10 subtypes
  • HIV-2: Confined mostly to West Africa
    • less virulent, but spreading

Origin of HIV

Origin of HIV-2

  • Sooty mangaby monkey of West Africa
  • HIV-2 is much more like SIVsm than it is like HIV-1
  • How is crossed is unknown
    • slaughter of monkeys to feed the lumbermen in the area?
    • no real information

Origin of HIV-1

  • HIV-1 comes from Chimpanzees.
  • Three different transfers
  • probably happened about 1900 in Africa
    • first documented death is 1959 in Leopoldville, Belgian Congo (now Kinshasa, Zaire)
    • similar to the common ancestor of subtypes B and D
    • B is most common in Europe and US

Evolutionary tree for HIV

Timeline for AIDS

  • HIV-1 probably crossed to humans about 1900 (plus or minus 10 years)
  • First known death from AIDS, 1959
  • First AIDS death in Europe
    • Danish surgeon who worked in Zaire
  • First AIDS cases in US 1981
    • Gay men in Los Angeles and New York
    • First confirmed US death, 1969
      • 15-yr old male prostitute with HIV
        • HIV antibodies found in frozen tissue samples

1880-1918

  • German colonization of Cameroon
    • Rubber and Ivory
    • Transported by the Sangha River to Leopoldville (Kinshasa) on the Congo River
      • Slave labor forced to live off the land
    • Germany ceded Cameroon after WWI
      • Rubber price collapsed
      • Sangha route much less important
        • route from site of first transfer closed
    • Map of first transfer from Cameroon to Kinshasa
    • Another map of the region

1920-1960

  • Belgian Congo
    • Property of King Leopold II from 1877-1908
    • Belgian Congo 1908-1960
  • 1920-1940 a time of commerce and railroads
  • By 1940, Kinshasa was a boomtown with lots of commerce
    • “Wild west” type of place
    • Lots of spread of HIV within Kinshasa

1960 to present

  • Wars of independence
  • Transport and trade collapsed
  • Window of opportunity for tansfer of HIV from Kinshasa to rest of Africa closed

And so….

  • Unique circumstances allowed a pandemic spread of HIV throughout Africa
  • Origin in Cameroon
  • Slaves carry ivory and rubber along Sangha to Leopoldville (Kinshasa) in (Belgian) Congo
  • Boomtown leads to spread through the city
  • Roads and railroads spread to other parts of Africa
  • But then chaos closes the normal paths for transfer

And then, Out of Africa

  • Independence in 1960 led to expulsion of francophone Belgian administrators
  • No local administrators, so influx of Haitians
  • Return to Haiti (subtype B) and spread there
  • Then to USA

Indentification of AIDS

“Official Start Date”

  • Michael Gottlieb’s paper in MMWR, June 1981. Pneumocyctis pneumonia (PCP) in (gay) men in Los Angeles
  • Followed by others on Kaposi’s sarcoma and PCP.
  • Usually marked as the first recognition of the pandemic.

34 years later

  • Global total: about 60-70 million infected so far
    • about 20-30 million of those have died
  • US totals: about 1.7 million infected so far,
    • about 1 million estimated to be LIVING with HIV
      • only about 600,000 reported, rest are from estimates
    • about 42,000 new infections per year
    • about 1 million cases of AIDS so far, about half-million deaths so far (2004).

Comparisons worth considering

  • Influenza pandemic of 1918-1919
    • 20 – 40 million deaths from 1 billion infections
  • Black death
    • ?? 30 million??
  • Tuberculosis
    • 3.5 million deaths per year
  • Malaria
    • 3 million deaths per year

Trends 30 years later

  • In US, new infections are leveling off
    • AIDS cases dropping
    • but new HIV infections constant at 50,000/yr
    • Mortality from AIDS dropping (drugs)
  • In “Third World”, the curve is still exponentially increasing
  • In 1980, about twice as many adults in Sub-Saharan Africa were HIV infected as in the US
  • In 1998, it was fourteen times as many!
  • In US, peak of infections was early 1980’s
    • about 150,000 – 200,000 new infections per yr.
    • since 1995, constant at 50,000 new per yr. (incresasing?)

Some worldwide estimates:

Total infections to date (ca. 75 million?)

  • North America: 2 million
  • Latin America: 3 million
  • Western Europe: 1.3 million
  • Sub-Saharan Africa: more than 57 million
  • South and Southease Asia: 9 million

Global Summary as of December 2011

  • Persons living with HIV: 34 million (about 50% are women)
  • Persons newly infected with HIV in 2011: 2.5 million
  • AIDS deaths in 2011: 1.7 million (down from 2.1 million just 5 years earlier)

“If an aspirin and a glass of clean water could cure AIDS, 90% would still die”

Some Sobering Facts

  • In 2011, 1.7 million AIDS deaths but 2.5 million new infections
  • In 2007, our best estimates say that 95% of all those infected with HIV will die of AIDS. (A bit lower now wiht drugs)
  • So the number of deaths per year MUST rise for many years, no matter what else happens!

US data

  • Sharp peak of HIV infections in early 1980s
    • Infections peaked in 1982
    • About 200,000 new infections per year
      • AIDS diagnoses peaked in 1993 (10 years later)
  • By 1988, new infections fell to about 40,000 per year
    • Currently about 42,000 per year

For updates on data

For global data go to unaids.org

For US data go to cdc.gov

For Michigan data, go to michigan.gov/mdch

An excellent single site worth browsing for information is avert.org

Time course of the pandemic

  • persons living with HIV

Impact on life expectancy in 2004

Country without HIV/AIDS with HIV/AIDS
Botswana 74 27
Haiti 62 53
Kenya 68 44
Namibia 69 34
South Africa 68 36
Zambia 59 34
Zimbabwe 71 35

Source: AIDS Update 2004