HIV epidemiolgy Flashcards
What type of virus is HIV?
Lentivirus, part of the retrovirus family
Single-stranded RNA (ssRNA) virus
What are the two distinct types of HIV?
HIV-1 (most common)
HIV-2 (primarily in West Africa)
Which cells does HIV affect?
CD4+ cells, including:
T lymphocytes
Monocytes
Dendritic cells
What is AIDS?
A progressive decline in the CD4+ Th1 lymphocyte subset
Where is HIV most prevalent?
Asia & Pacific
Sub-Saharan Africa
How have new HIV infections and AIDS-related deaths changed?
New infections dropped from 3.3M → 1.3M
AIDS-related deaths dropped from 2.1M → 630K
What is the UNAIDS strategy?
90% knowledge of HIV status
90% treatment coverage
<500K new infections
<500K AIDS-related deaths
Goal: End AIDS by 2030
Who contributed to the discovery of HIV?
Montagnier (first published but didn’t identify virus)
Gallo (received contaminated samples from Montagnier)
What conditions led to HIV discovery?
Cases of PCP & Kaposi’s sarcoma in gay men
Linked to contaminated blood
What were key steps in HIV identification?
Retrovirus isolated → Cultured, cloned, & characterized
Antibody testing approved
First AZT/Anti-HIV drug approved
FDA approved HIV-sensitive immunoassay
Complete genomic sequence published (1985)
What other viruses are related to HIV?
HIV-2 (found in West Africa by Montagnier)
SIV (found in macaque monkeys)
What are the 4 groups of HIV-1?
Group M (98% of isolates, epicenter: Cameroon)
Group O (Confined to Cameroon/Gabon)
Group N (6 individuals in Cameroon)
Group P (2 individuals in Cameroon)
What is the likely source of HIV-1?
Cross-species transmission from Pan troglodytes (chimpanzees)
SIVcpz found in wild chimpanzees in 2006
How did humans likely contract HIV?
Butchering & meat trade
Chimpanzees are aggressive & SIVcpz is recombinant from other monkey species
What about HIV-1 Groups O & P?
More closely related to SIVgor (found in gorillas)
What is a zoonosis?
A disease that transmits from animals to humans naturally
How many successful cross-species transmission events have occurred?
Only 4
Why did HIV spread despite long-term SIV exposure?
Deforestation
Urbanization
Unsterile needles
Innate immune system vulnerabilities
What was the earliest known HIV case?
Adult male from Congo
12% divergence between early HIV samples
What contributed to HIV’s global spread?
International travel
Blood transfusion
IV drug use
How is HIV transmitted?
Contact with blood or mucous membranes
Sexual contact (major route)
IV drug use
Mother-to-child transmission
Why is sexual transmission inefficient?
Physical barriers
Innate immune defenses
Limited target cells
What increases the risk of transmission?
High viral load
Cuts/abrasions/STDs
Lack of condom use
How common is mother-to-child transmission?
90% of infant HIV cases
Can be as high as 50%
When is the highest risk for transmission?
During delivery
How can transmission be reduced?
Antiviral therapy
Avoiding breastfeeding
Short-course ARTs reduce risk to 2%
