Infectious Diseases - Hiv And Aids

Front 1

What are LTRs?

Back 1

LTRs are long terminal repeat sequences. These are repeating sequences that flank the whole HIV viral genome.

...

There's a lot more to the story here

Front 2

What is the most common mechanism of transmission with HIV?

Back 2

Sexual activity (both heterosexual and homosexual considered together)

Front 3

Why are women 20x more likely than men to get HIV with vaginal intercourse?

Back 3

It is speculated that this is because of the prolonged exposure of the vagina, cervix, and uterus to seminal fluid.

Front 4

To which molecule does the HIV virus bind to on the surface of host cells?

Back 4

HIV binds to CD4 surface receptors. This receptor is present in high concentrations on helper T lymphocytes.

For fusion and translocation of HIV across the cell membrane both a CD4 receptor and a co-receptor, either CCR5 or CXR4, must be present.

Front 5

Other than helper T lymphocytes, name two other cell types that have the surface CD4 receptor.

Back 5

1) Monocytes/macrophages
2) CNS dendritic cells

Front 6

What are CCR5 and CXCR4? What is the significance of these molecules?

Back 6

CCR5 and CXCR4 are normal chemokine receptors present on the surface of human CD4 lymphocytes.

For the HIV virus, these molecules act as co-receptors that facilitate the fusion and translocation of HIV across the cell membrane.

In other words, in order for HIV to gain entry into cells both a CD4 receptor and a CCR5 or CXCR4 co-receptor must be present.

Front 7

Which viral protein binds to the CD4 molecule on the surface of helper T cells?

Back 7

This is the gp 160 glycoprotein (consists of gp 120 and gp 41)

Front 8

In the train analogy of CD4 count and viral load popularized by David Ho, which is the speed of the train and which is the position of the train relative to the cliff?

Back 8

According to this analogy, viral load tells you how fast the train is travelling while the CD4 count is how close you are to the cliff.

It is the CD4 count that determines the person's current risk for developing opportunistic infections. The viral load tells you how fast they're moving towards the edge.

Front 9

What are the four phases in the clinical course of HIV infection?

Back 9

1) Initial infection
2) Acute viral illness (about 1 month later)
3) Clinically latent phase (median 8 years)
4) AIDS (median 2 years)

Front 10

What is the normal CD4 count in a healthy person?

Back 10

1000 cells/microlitre

Front 11

What is malaise?

Back 11

Malaise is a feeling of vague, non-specific physical discomfort, or the absence of the sense of physical well-being.

Another way of putting it is that malaise is the feeling that something is vaguely "not right."

The original word in Old French meant an uncomfortable sense of imperfect health.

Front 12

What are the symptoms of the acute viral illness phase of HIV infection?

When does this phase occur and how long does it last?

Back 12

In about 80% of infected individuals an acute viral illness develops about 1 month after initial infection.

Potential symptoms include fever, malaise, lymphadenopathy, and pharyngitis.

Front 13

Why is describing the generally asymptomatic period that follows infection and acute viral illness as a period of "latency" misleading?

Back 13

It is not a true viral latency without viral replication. HIV continues to replicate in the lymphoid tissue and there is a steady gradual destruction of CD4 T lymphocytes.

Front 14

What is the technical definition of AIDS?

Back 14

AIDS is now defined as having a CD4 T lymphocyte count of less than 200 with serologic evidence of HIV infection

Front 15

What's the average rate at which a person infected with HIV loses CD4 cells?

Back 15

The average infected person loses about 60 CD4 cells per microlitre per year.

Front 16

At what CD4 count do opportunistic infections begin to set in?

How long does it take, on average, for a person infected with HIV to reach this point?

Back 16

400-200 / microlitre

It takes the average infected person 7 years to reach this point.

Front 17

How long does it take, on average, for the CD4 cell count to get to 200 or lower?

Back 17

About 8 years. Reaching a CD4 count of 200 or less marks the end of the clinical latency phases of HIV infection and the beginning of AIDS.

Front 18

Broadly speaking, conditions that arise during the AIDS stage of HIV infection can be divided into two categories. What are they?

Back 18

1) Diseases due directly to virus
-constitutional illness
-neurologic disease

2) Diseases due to immunocompromised state
-malignant neoplasia
-opportunistic infections (bacterial, viral, fungal, protozoal)

Front 19

What are the constitutional symptoms that can be experienced by those with AIDS?

Back 19

1) Fever, chills, rigors

2) Fatigue, weakness, malaise

3) Severe weight loss

4) Generalized lymphadenopathy

Front 20

How does the HIV virus reach the central nervous system?

Back 20

HIV infects monocytes and macrophages, cells which migrate across the blood-brain barrier.

Front 21

What is the predominant HIV-harbouring cell type in the central nervous system?

Back 21

Monocyte/macrophage

Front 22

What is the AIDS dementia complex?

Back 22

...

Front 23

What does ADC refer to?

Back 23

ADC stands for AIDS dementia complex.

Front 24

Name 4 neurological conditions caused by HIV:

Back 24

1) HIV in brain: AIDS dementia complex, also known as HIV dementia or HIV encephalopathy

2) HIV in meninges: aseptic meningitis

3) HIV in spinal cord: myelopathy

4) HIV in peripheral nerves: neuropathy

Front 25

Which conditions that occur in AIDS are due directly to viral infection as apposed to immunodeficiency?

Back 25

1) Constitutional illness (fever, malaise, weight loss, lymphadenopathy)

2) Neurological disease (dementia, meningitis, myelopathy, neuropathy)

Front 26

Which malignancy, common in AIDS sufferers, often presents as a brain mass?

Back 26

B-cell lymphoma

Front 27

Which virus causes Kaposi's sarcoma?

Back 27

Infection with human herpes virus 8, or HHV8, is thought to be related etiologically to the development of Kaposi's sarcoma.

Front 28

What does HHV-8 stand for?

What is its significance for those infected with HIV?

Back 28

HHV-8 is human herpes virus 8, thought to be the causative agent of Kaposi's sarcoma.

Front 29

What is a sarcoma?

Back 29

A sarcoma is a cancer that arises from cells of mesenchymal origin.

Front 30

Describe the presentation of Kaposi's sarcoma.

Back 30

The disease manifests are red to purple plaques or nodules that arise on the skin all over the body.

Front 31

Name 4 cancers that persons with HIV are at particularly increased risk for:

Back 31

1) B cell lymphoma
2) Kaposi's sarcoma
3) non-Hodgkin's lymphoma
4) Hodgkin's lymphoma

Front 32

Name two mycobacterial infections that occur in people with AIDS:

Back 32

1) M. tuberculosis
-CD4 count <500
2) M. avium-intracellulare (MAI)
-CD4 count <100

Front 33

What does MAI refer to?

Back 33

MAI stands for Mycobacterium avium-intracellulare. This mycobacterium can infect people in the late stages of AIDS (CD4 count <100)

Front 34

What does MAC refer to?

Back 34

MAC stands for Mycobacterium avium complex, a group of genetically related mycobacteria that includes the species Mycobacterium avium-intracellulare (MAI).

Front 35

What is Lady Windermere Syndrome?

Why is it called this?

Back 35

...

Front 36

Name five fungal infections that commonly afflict those with HIV/AIDS:

Back 36

1) Candida albicans
-oral thrush
-esophagitis

2) Cryptococcus neoformans
-meningitis

3) Histoplasma capsulatum

4) Coccidioides immitis

5) Pneumocystis jiroveci

Front 37

Name the organism that causes mass lesions in the brain in 15% of AIDS patients?

Back 37

Toxoplasma gondii

Front 38

What does PCP stand for?

Back 38

PCP stands for pneumocystis carinii pneumonia, the most common opprotunistic infection in North America among patients with AIDS.

This condition is not actually caused by pneumocystis carinii, as originally believed, but rather pneumocystis jiroveci.

Front 39

What is the causative organism of PCP?

Back 39

Pneumocystis jiroveci

Front 40

What is the most common opportunistic infection among those with AIDS in North America?

Back 40

PCP, a pneumonia caused by pneumocystis jiroveci but originally thought to be caused by pneumocystis carinii

Front 41

What is OHL?

Back 41

OHL is oral hairy leukoplakia, a condition characterized by white hairlike projections arising from the side of the tongue.

It is caused by Epstein-Barr virus infection.

OHL can be distinguished from Candidal thrush by the fact that OHL will not rub off with a tongue blade.

Front 42

How can oral hairy leukoplakia (OHL) be distinguished from Candidal thrush?

Back 42

Candidal thrush can be rubbed or scraped off with a tongue blade, leaving a red bleeding base behind. Oral hairy leukoplakia (OHL) cannot be scraped off.

Front 43

What is the causative agent or oral hairy leukoplakia (OHL)?

Back 43

Epstein-Barr virus

Front 44

Name three protozoal causes of chronic diarrhea in patients with AIDS:

Back 44

1) Cryptosporidium
2) Microsporidia
3) Isospora

Front 45

Why was the name of the causative organism of PCP changed from Pneumocystis carinii to Pneumocystis jirovecii?

Back 45

At first, the name Pneumocystis carinii was applied to the organisms found in both rats and humans, as it was not yet known that the parasite was host-specific. In 1976 the name Pneumocystis jiroveci was proposed for the first time to distinguish the organism found in humans from variants of Pneumocystis in other animals. The organism was named in honour of Otto Jirovec, who described Pneumocystis pneumonia in humans in 1952.

Front 46

What is the causative organism of toxoplasmosis?

Back 46

Toxoplasma gondii

Front 47

What is the primary mammalian host of Toxoplasma gondii?

Back 47

Cats

Front 48

Since when has HAART been available?

Back 48

1996

Front 49

What does the term "seroconversion" mean?

Back 49

Seroconversion refers to a change from a seronegative to a seropositive state.

A seronegative state implies the absence of antibodies while a seropositive state implies the presence of antibodies.

Front 50

What is an elite controller?

Back 50

"Elite controllers" are HIV-seropositive individuals who have no evidence of viremia, as measured by standard assays (either <50 or <75 copies/mL), and maintain high CD4 cell counts. These patients represent a small minority of HIV-infected individuals (1/300 patients) and the mechanisms that lead to spontaneous virologic control without treatment are unknown.

Front 51

What's another name for ascending cholangitis?

Back 51

Acute cholangitis

Front 52

What is acute/ascending cholangitis?

Back 52

Clinical syndrome of fever, jaundice, and abdominal pain that results from stasis and infection of the biliary tree.

Front 53

Describe the pathophysiology of ascending/acute cholangitis.

Back 53

The cause is almost invariably bacterial infection.

The organisms typically ascend from the duodenum; hematogenous spread from the portal vein is a rare source of infection.

The most important predisposing factor for acute cholangitis is biliary obstruction and stasis secondary to biliary calculi or benign stricture.

Biliary calculi/stricture --> biliary obstruction and stasis --> increased pressure in the biliary tree --> migration of bacteria from portal circulation into biliary tract

Front 54

In ascending cholangitis, how are bacteria able to get from the duodenum into the biliary tree?

Back 54

The sphincter of Oddi normally forms an effective mechanical barrier to duodenal reflux and ascending bacterial infection.

When the barrier mechanism is disrupted, as occurs after endoscopic sphincterotomy, choledochal surgery, or biliary stent insertion, pathogenic bacteria enter the biliary system at high concentrations.