Questions: Know what is happening in each stage of an untreated HIV infection. Which stage does death typically result? Why? How do people die from AIDS? Bacterial pneumonia is the most common cause of death. What are two known bacterial pathogens that cause AIDS-associated pneumonia?

To address the question, let's break it down into its components and answer each part step by step.

1. Stages of Untreated HIV Infection:

   • Acute HIV Infection: This is the initial stage that occurs 2-4 weeks after the virus enters the body. Symptoms may resemble those of the flu, including fever, swollen lymph nodes, sore throat, rash, muscle and joint aches, and headache. During this stage, the virus multiplies rapidly, and the person is highly infectious.
   • Chronic HIV Infection (Clinical Latency Stage): This stage can last for several years. The virus is still active but reproduces at very low levels. People may not have any symptoms or only mild ones. Without treatment, the virus will eventually progress to the next stage.
   • AIDS (Acquired Immunodeficiency Syndrome): This is the final and most severe stage of HIV infection. The immune system is severely damaged, and the body becomes vulnerable to opportunistic infections and certain cancers. Symptoms can include rapid weight loss, recurring fever, extreme tiredness, prolonged swelling of the lymph glands, and more.

2. Stage Resulting in Death:

   • Death typically results during the AIDS stage. This is because the immune system is so weakened that it can no longer fight off infections and diseases that a healthy immune system could manage.

3. How People Die from AIDS:

   • People with AIDS die from opportunistic infections or cancers that their weakened immune system cannot combat. These infections and cancers take advantage of the body's compromised immune defenses.

4. Bacterial Pathogens Causing AIDS-Associated Pneumonia:

   • Two known bacterial pathogens that cause AIDS-associated pneumonia are:
     • Streptococcus pneumoniae: This bacterium is a common cause of bacterial pneumonia in people with AIDS.
     • Haemophilus influenzae: This bacterium is another frequent cause of pneumonia in individuals with compromised immune systems, including those with AIDS.

Summary: Untreated HIV infection progresses through three stages: acute HIV infection, chronic HIV infection, and AIDS. Death typically occurs in the AIDS stage due to the immune system's inability to fight off opportunistic infections and cancers. Bacterial pneumonia, often caused by Streptococcus pneumoniae and Haemophilus influenzae, is a common cause of death in people with AIDS.