HIV Flashcards
What diseases can the HIV virus cause?
- Acquired Immunodeficiency Syndrome (AIDS)
- Opportunistic Infections
- AIDS-related cancers
People with treated HIV have a “near normal” life expectancy. TRUE/FALSE?
TRUE
HIV infection is preventable. TRUE/FALSE?
TRUE
What are the two main types of HIV virus?
- HIV-2 originated in West Africa
- Less virulent
- HIV-1 originated in Central/West African chimpanzees
- HIV-1 group M responsible for global pandemic starting in 1981
What is CD4 in relation to HIV?
CD4 (Cluster of Differentiation)
- glycoprotein receptor found on the surface of cells
- target site for HIV
What types of cells have CD4 receptors on their surface and therefore are susceptible to HIV infection?
- T helper lymphocytes (“CD4+ cells”)
- Dentritic cells
- Macrophages
- Microglial cells
What do CD4+ T lymphocytes do?
Induce adaptive immune response: => Recognition of MHC Class II antigen-presenting cell => Activation of B-cells => Activation of cytotoxic T-cells (CD8) => Cytokine release
How does HIV change the immune response?
- Reduced circulating CD4 cells
- Reduced proliferation of CD4 cells
- Reduced CD8 T cell activation
- Dysregulated cytokines
- Reduced affinity of Ab produced
- Chronic Immune Activation
HIV effect on the immune response makes people more susceptible to what types of infection?
- Viral infections
- Fungal infections
- Mycobacterial infections
- Infection-induced cancers
What are the normal parameters for CD4 T cells?
500-1600 cells/mm3
What CD4 levels would indicate the potential for opportunistic infection?
<200
What is meant by opportunistic infection?
Infection caused by a pathogen that could collonise and not cause disease in a healthy individual
When does replication occur during HIV infection?
- Rapid replication in very early and very late infection
- New generation every 6-12 hours
What is the average time to death if no treatment is given in HIV infection?
9-11 years
What happens to the CD4 count during and after acute HIV infection?
CD4 count goes down in initial acute infection then comes back up before steady decline
Explain how the virus gets from initial infection to dissemination
Infection of mucosal CD4 cell
Transport to regional lymph nodes
Infection established within 3 days of entry
Dissemination of virus
What percentage of Primary HIV infections present symptomatically and within how long?
80%
onset usually within 2-4 weeks
What symptoms may appear with disseminated HIV?
- Fever
- Rash
- Myalgia
- Pharyngitis
- Headache/aseptic meningitis
What pneumonia do HIV patients often get and what CD4 count usually causes this?
Pneumocystis jiroveci
CD4 threshold: <200
WHat are the symptoms and signs of pneumocystis pneumonia in patients with HIV?
insidious onset
SOB
Dry cough
Signs: exercise desaturation - get tachy and sats decrease rapidly after 5 mins of exercise
A CXR for pneumocystis pneumonia in HIV may be normal. Why is this?
Diffuse infiltrates => no clear sign of lobar consolidation
What tests are used to diagnose pnuemocystis pneumonia?
Bronchoalveolar Lavage and immunofluorescence +/- PCR
What treatment is used for pneumocystis jirovecii?
- Treatment: high dose co-trimoxazole (+/- steroid)
- Prophylaxis: low dose co-trimoxazole
What features of TB are more common in patients with positive HIV infection?
- Symptomatic primary infection
- Reactivation of latent TB
- Lymphadenopathies
- Extrapulmonary TB
- drug resistant TB
- Immune reconstitution syndrome
Cerebral toxoplasmosis is caused by what microorganism and at what CD4 count?
Cerebral toxoplasmosis
Toxoplasma gondii
CD4 threshold: <150
How does cerebral toxoplasmosis appear on neuro-imaging?
Multiple cerebral abscess
What symptoms and signs may indicate a toxoplasmosis infection
Headache Fever Focal neurology Seizures Reduced consciousness Raised intracranial pressure
What CD4 count causes HIV patients to be susceptible to CMV?
CD4 threshold: <50
What does CMV infection cause and how do patients present?
Causes: retinitis, colitis, oesophagitis
Presentation:
- Reduced visual acuity
- Floaters
- Abdo pain, diarrhoea, PR bleeding
What skin infections may indicate that a patient may have HIV?
Herpes Zoster
- If rash appears in Multiple dermatomes
- If frequently recurrent
Herpes Simplex
- If extensive
- If Aciclovir resistant
Human Papilloma Virus
- Extensive
- Dysplastic
HIV can cause neurocognitive impairment. At what CD4 count does this present and what symptoms can occur?
No CD4 threshold - can happen at any level of immunosuppression
Causes
- Reduced short term memory
- potentially motor dysfunction also
What is Progressive multifocal leukoencephalopathy, and what virus causes this?
Caused by: JC virus
Affects frontal lobe of brain =>
- Rapidly progressing
- Focal neurology
- Confusion
- Personality change