ACQUIRED IMMUNE
DEFICIENCY SYNDROME (AIDS)
EPIDEMIOLOGY
By Emmanuel E Nkwogu
Liberty University Online, Lynchburg, Virginia USA
DEFINITIONS
•
AIDS (Acquired immune deficiency syndrome)
diagnosis;── stage 3 HIV infection
• HIV (Human immunodeficiency virus) infection;
ranges from asymptomatic to advanced
disease
• Two types of HIV:
(a) HIV-1; major cause of HIV
infection worldwide
(b) HIV-2; less virulent and mainly
in West Africa
Etiology
• HIV/AIDS─ of zoonotic origin1
• Switched from primates to humans
• Switched from chimpanzees and gorillas from
West Central Africa
• HIV -1 identified in a serum from 1959 and a
biopsy from 1960 in Democratic Republic of
Congo (DRC)
Transmission/Spread
• One of the most serious health problems f the 21st century
• Globally, major source of spread are heterosexual
(>75%), and mother to child (5%-10%)
• HIV present in blood, semen and breast milk
• Course of infection defined by changes in the CD4+ TLymphocyte (helper T-cells)
• CD8 Cytotoxic T cell lymphocytes most
important for recognizing and lysing of CD4 cells
• Exact mechanism not fully understood.
The Phylogenetic Relationships of Lentiviruses
The phylogenetic relation of lentiviruses in man and non-human primates
Adapted from Simon V.,Ho DD., and Karim QA. HIV/AIDS epidemiology,
pathogenesis,
prevention and treatment.
The Lancet, Volume 368, issue 9534 2005 489-504
http://dx.doi.org/10.1016/so140-6736(06)69157-5
The Course of HIV-1 Infection
The course of HIV-1 infection defined by the level of viral replication, Plasma viraemia (top)
And dynamic changes of the CD4+ T-Lymphocyte components (bottom. Primary infection
charcterized by high plasma viraemia (red line top), Low CD4…
Adapted from Simon V.,Ho DD., and Karim QA. HIV/AIDS epidemiology, pathogenesis,
prevention and treatment.
The Lancet, Volume 368, issue 9534 2005 489-504
http://dx.doi.org/10.1016/so140-6736(06)69157-5
Worldwide Prevalence and
Incidence
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•
•
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A Modern Day Plague: A global security threat3
First recognized in 1981
AIDS takes about 2-15 years to develop
34.2 million people living with HIV/AIDS
worldwide
• 2.5 million New cases (including 330,000 children )
in 2011
• More than 25 million people have died from
HIV/AIDS
Worldwide Distribution of HIV-1 Infection
Adapted from Simon V., Ho DD., and Karim QA. HIV/AIDS epidemiology, pathogenesis,
prevention and treatment.
The Lancet, Volume 368, issue 9534 2005 489-504
http://dx.doi.org/10.1016/so140-6736(06)69157-5
Worldwide distribution of HIV-1 infections, modes of transmission, and HIV-1 subtypes.
HS=Heterosexual, MSM= Men who have sex with men, IDU= Injection drug users.
Based on Joint UNAIDS and WHO AIDS epidemic update, December 2005
Deaths from AIDS in 2005
totaled 2.3 million3
Source: UNAIDS Report on the Global AIDS Epidemic, 2012
HIV/AIDS Timeline
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1981- a new syndrome AIDS was discovered among
homosexuals in the United States of America.
1983 – HIV identified as the etiologic agent for AIDS.
By mid-1980’s it was discovered that the virus had spread
unknowingly throughout most of the world.
HIV/AIDS pandemic consists of separate epidemics
Separate in terms of geography, specific populations affected,
different risk behaviors and practices
Sub-Saharan Africa most affected
Most explosive epidemic in Southern Africa 2
Botswana and Swaziland have the highest prevalence level
HIV among Pregnant women
in Developing Countries
Source: UNAIDS_WHOPaper 2: Workshop on HIV/AIDS and adult mortality
In Developing Countries ─September 2003
Strategies for Surviving
HIV/AIDS epidemic7
Source: Mutangadura, et al., 1999:17
HIV/AIDS epidemic in
Addis Ababa, Africa2
Source: SimonV, Ho DD, Karim QA. HIV/AIDS epidemiology… The Lancet Vollume 368, issue 9534
HIV/AIDS IN THE USA
• Dr D Gallo and co-workers discovered HTLV1 and HTLV-2 between 1976 and 1982
• Initially referred to the disease as GRID (Gayrelated immune deficiency)
• Later known as Acquired immune deficiency
syndrome (AIDS)
HIV/AIDS in the USA,
cont’d
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•
•
•
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•
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STATISTICAL OVERVIEW:
At the end of 2009 1,148,200 persons living with
HIV/AIDS6
207,600 (18.1%) undiagnosed
In 2010 incidence of HIV=47,500
Two-thirds of these were in gay and bisexual men
Blacks/ African American men and women had HIV
incidence 8 times that of whites
In 2010, number of deaths from AIDS=15529
Cumulative AIDS diagnoses through 2010=636,048
In 2011 HIV incidence: 49,273 (men-38,825,Women=10257
HIV/AIDS in the USA cont’d
Diagnoses OF HIV INFECTION BY AGE
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
Data Source: Center for Disease Control and Prevention (CDC)-Statistical Overview
HIV/AIDS in the USA cont’d
DIAGNOSES OF HIV INFECTION , BY RACE/ETHNICITY
25000
20000
15000
10000
5000
0
Data Source: Center for Disease Control and Prevention (CDC)- Statistical Overview
HIV/AIDS in the USA cont’d
HIV DIAGNOSES, BY TOP 10 STATES/DEPENDENT AREAS
7000
6000
5000
4000
3000
2000
1000
0
Data Source: Center for disease Control and Prevention (CDC)- Statistical Overview
Core Indicators of Global AIDS
Response
• Reducing sexual transmission of HIV by 50% by 2015
• Eliminate new HIV infections among children by 2015 and substantially
reduce AIDS-related maternal deaths.
• Reducing transmission of HIV among people who inject drug by 50% by
2015
• Reach 15 million people living with HIV with lifesaving antiretroviral
treatment by2015.
• Reduce tuberculosis deaths in people living with HIV by 50% by 2015.
• Close the global AIDS resource gap by 2015 and reach annual global
investment of US$ 22$ billion in low- and middle income countries.
• Eliminating gender inequalities, stigma and discrimination and travel
restriction
• Strengthening HIV integration.
Some AIDS-defining Diagnoses
Kaposi Sarcoma
Adapted from Natural History and Clinical features by Lewthwait P, &
Wilkins E. 2009 Elsevier Ltd.
Kaposi sarcoma
Pneumocystis Jirovecii
pneumonia
Source: Lewthwaite p and Wilkins E.
Natural History of HIV/AIDS
Herpes simplex
Current Hypotheses
RISK FACTORS
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Risky Sexual behavior
Unsafe blood transfusion,
High prevalence of STD,
Absence of circumcision,
Use of non sterile needles,
Human density in forest areas,
Increasing transport between urban and rural areas,
Human migration,
Increase in commercial sex
Gaps in Knowledge
Mechanism of destruction of
Mode of Transmission
CD4
• Many people do not know
the mode of transmission of
HIV/AIDS; and thus are
uncomfortable associating
with people with
HIV/AIDS.
• The exact mechanism of the
destruction of CD4
lymphocytes is not well
Viral load/CD4 Changes over time following
HIV infection
understood yet.
Source: Natural History and Clinical features by
Lewthwait P, & Wilkins E. 2009 Elsevier Ltd.
Further
Epidemiologic
Research
Focus on understanding the:
•Exact mechanism of the destruction of
CD4 lymphocytes
• All that is involved in the transmission of
the HIV/AIDS.
• With a fuller understanding of the mode
and mechanism of transmission, there will be
hope that a vaccine would be developed
against HIV/AIDS.
• Although the current Antiretroviral drugs
are active in reducing the effects of
HIV/AIDS
•Research into development of new drugs is
still important as the HIV is known to have a
high capacity to mutate.
Source: UNAIDS Report on the Global AIDS Epidemic,2012
Appraisal of the data as a
whole:
• According to CDC and from the data as a
whole, the battle against HIV/AIDS is yielding
to science and worldwide commitment.
• This is also illustrated below by UNAIDS
2012 report.
• Progress in Fighting the Epidemic:
• 50% reduction in New HIV infections between
2001 and 2011 in 25 countries
Appraisal of the Data as a
Whole, cont’d
• 43% decline in new HIV infections in children from
2003 to 2011, with over half of that decline occurring
within the last two years
• 50% or greater drop in HIV/AIDS-related deaths
between 2005 and 2011 in 14 countries, with another 29
countries achieving a reduction of 25-49%
• 25% decline in TB-related deaths worldwide and 28%
decline in sub-Saharan Africa between 2004 and2011.
• The progress is reflected in terms of longer life span
due to antiretroviral treatment. The progress is
illustrated in the figures below.
Cumulative Life-Years Gained from
Antiretroviral Drugs, 1996-2011
Source: UNAIDS World AIDS Day Report, 2012
HIV/AIDS Programmatic
Tipping Point in 2011
Source: UNAIDS World AIDS Day Report, 2012
References 1
1. Martine P., Steve AM., Eitel MN., Eric D. Origin of HIV and risk for ongoing zoonotic
transmissions from nonhuman primates to humans. July 2010: P.387: http://dx doi.org.
Epoxy.liberty.edu. 2048/102217/hiv10332.
2. Simon V., Ho DD., Karim QA. HIV/AIDS epidemiology, pathogenesis, prevention and treatment.
The Lancet, Aug 5-Aug 11, 2006; 368, 9534 ProQuest Central P.489. Accessed from
www.ncbi.nlm.nih.gov on June 3, 2013.
3. WHO Global AIDS Response 2013. 2011 UN Political Declaration on HIV/AIDS.
www.who.int/hiv/pub/progress_report 2011
4. A History of the HIV/AIDS Epidemic with Emphasis on Africa. UNAIDS and WHO
www.un.org/esa/population/publications...UNAIDS.
5. Tekoa F. The economic impacts of HIV/AIDS morbidity and mortality on households in Addis
Ababa, Ethiopia. AIDS care, Volume 20 issue 8 doi. 10.108/09540120701777256 P.995
6. CDC’s HIV Surveillance Report: Diagnosis of HIV Infection and AIDS in the United States and
Dependent areas 2011. Centers for Disease Control and Prevention. Statistics Review.
(/ hiv/library/report/surveillance/2011/Surveillance Report vol. 23.html) vol.23 retrieved from
7. Naidu V., Harris G. The Impact of HIV/AIDS on morbidity and mortality on households. A review
of household studies. South African Journal of Economics Vol. 73 2005, Special issue on
HIV/AIDS. Doi: 10.11 11/saje.2005.73.issue-s1/issue toc, www.demographic research.org
/volume/vol. 27
References 2
8. CDC and the fight against Global HIV/AIDS. Accessed on June 3, 2013 from
www.cdc.gov/globalaids/publications/CDC-Global-HIV-Update-2013.pdf
9. Fauci AS, Kasper DL, Long DL, Hauser S, Jameson J, Lascalzo J. HIV Infection and
AIDS. Harrison’s Principles of Internal Medicine, 18th ed., McGraw-Hall, Health
Professions Division, New York.2011.
10. Guyton, A.C., Hall, J. E. (2001). Resistance of the body to Infection: Immunity and
Allergy. Text Book of Medical Physiology, 10th ed., W.B. Saunders Company, A
Harcourt Health Sciences Company, The Curtis Center, Independence Square West,
Philadelphia, Pennsylvania 19106, 2010
11. Jacques Initiative; Institute of Human Virology, University of Maryland School of
Medicine. Accessed from www.jacques.umaryland.edu
12. Sullivan LM. Essentials of Biostatistics in Public Health, 2nd ed. Burlington,
Massachusetts, MA; Jones and Bartlett Learning, LLC: 20128.
13. Friis RH, Seller AT. Epidemiology for Public Health Practice, 4th ed. Sudbury,
Massachusetts, MA;
14. Lewthwaite P and Wilkins E. Natural History Clinical features of HIV/AIDS ,
Elsevier Ltd.,2009.