When the immune system is weakened, the body cannot fight off disease

31.6 Diseases that Weaken the Immune System

When the immune system is weakened, the body cannot fight off disease.

31.6 Diseases that Weaken the Immune System

HIV- Human Immunodeficiency Virus

– Causes AIDS – Retro virus (contains RNA)– Attacks Helper T-cells– Came from butchering

chimps (mutated SIV)

31.6 Diseases that Weaken the Immune System

HIV Structure

CapsidRNA

Reverse Transcriptase

Viral Envelope

Protein

31.6 Diseases that Weaken the Immune System

HIV Replication

31.6 Diseases that Weaken the Immune System

Transmission• Blood• Semen• Vaginal Fluids• Breast Milk

Not Transmitted• Air• Sweat• Saliva• Insect bites• Tears• Urine

How Do You Get HIV?

31.6 Diseases that Weaken the Immune System

HIV infection leads to AIDS

HIV

T celldeadT cell

antibody

activatedB cell

– HIV reproduces in and destroys T cells.– Might NOT have symptoms for 10 years!– AIDS victims do NOT die from HIV they die of

other diseases

31.6 Diseases that Weaken the Immune System

When Helper T-Cell count drops below 200 per mm³ =

Acquired Immune Deficiency Syndrome (AIDS)

31.6 Diseases that Weaken the Immune System

Treatments

• Antiretroviral drugs- reduces

HIV in the body

• Expensive $$$

• No cure but…March 2013 one

child was cured!

31.6 Diseases that Weaken the Immune System

HIV/AIDS Statistics (2010)

• World 34 million infected (3.4 million children)

• USA 1.1 million infected (1 in 5 unaware)

• Africa 23 million infected