HIV: Pathophysiology and Presentation Flashcards
What is the target site for HIV?
CD4+ receptors
What is CD4?
a glycoprotein found on the surface of a range of cells
What cells have CD4 on them?
T help lymphocytes (CD4+ cells); dendritic cells; macrophages and microglial cells
What is the function of CD4+ cells?
recognition of MHC2 APCs; activation of B cells; activation of CD8+ cells; cytokine release
What effect does HIV infection have on immune response?
sequestration of cells in lymphoid tissues; reduced proliferation of CD4+ cells; reduction cyctotoxic T cell activation; reduction in antibody class switching; chronic immune activation
What is the effect of sequestering of cells in lymphoid tissue in HIV?
reduced circulating CD4+ cells
Waht si the effect of reduced cytotoxic T cell activation in HIV?
dysregulated expression of cytokines and increasing susceptibility to viral infections
What is the the effect of a reduction in antibody class switching in HIV?
reduces affinity of antibodies produced
What types of infections are patients with HIV more susceptible to?
viral; fungal; mycobacterial infections and infection-induced cancers
What is the normal range of CD4+ cells?
500-1600cells/mm3
Below what level of CD4+ cells is there a risk of opportunistic infections?
<200
How long does it take to create a new generation of HIV virus?
every 6-12 hours
How long does it take someone to die with HIV without treatment?
9-11 years
What cells are initially infected iwth HIV?
infection of mucosal CD4 cells- Langerhans and Dendritic cells
How long does it take for HIV to become established after entry?
3 days
When does primary HIV infection usually occur after infection?
2-4 weeks
What are the symptoms of priamry HIV infection?
fever; rash (maculopapular); myalgia; pharyngitis; HA/aseptic meningitis
What organism causes pneumocystis pneumonia?
pneumocystis jiroveci
What is the typical sign with pneumocystis pneumonia?
exercise desaturation
How is PCP diagnosied?
BAL and immunofluorescence +/- PCR
What is the treatment for PCP?
co-trimoxazole
What are the symptoms of cerebral toxoplasmosis?
HA; fever; focal neurology; seizures; reduced consciousness; raised intracranial pressure
What is the CD4 threshold for cerebral toxoplasmosis?
<150
What is the CMV CD4 threshold?
<50
What is the presentaiton of CMV?
reduced visual acuity; floaters; abdo pain; diarrhoea and PR bleeding
What is done to monitor CMV in HIV patients?
ophthalmic screening for all individuals CD4<50
Waht is the presentation of HIV-associated neurocognitive impairment?
reduced short term memory +/- motor dysfunction
What is the presentation of progressive mulifocal leukoencephalopathy?
rapidly progressing; focal neurology; confusion; personality change
What causes progresive multifocal leukoencephalopathy?
JC virus
Waht is the CD4 threshold for PML?
<100
What are the causes of HIV-assocaited wasting?
chronic immune activation; anorexia; malabsorption/diarrhoea; hypogonadism
What causes Karposi’s sarcoma?
human herpes virus 8
What is Karposi’s sarcoma?
vascular tumour
What virus causes non-hodgkins lymphoma?
EBV
What is the presentation of non-hodgkins lymphoma?
B symptoms; bone marrow involvement; extranodal disease; increased CNS involvement
What organism is responsible for cervical cancer?
HPV
What are the non-opportunistic problems associated iwth HIV?
mucosal candidiasis; seborrhoeic dermatitis; diarrhoea; fatigue; worsening psoriasis; lypmhadenopathy; parotitis
What factors increase the transmission risk of HIV?
anoreceptive sex; trauma; genital ulceration; concurent STI
WHat is the risk of mother to child transmission if viral laod is undetected at delivery?
<0.1%
What group is most likely to be undiagnosed and present late?
heterosexual men
How many people in Scotland with HiV are unaware of their infection?
1 in 6
What is a high prevalence area in the UK?
> 0.2%
When should a patient be tested for HIV if incapacitated?
only if in patients best interests but if safe, wait until patient regains capacity
Is consent from relatives required to do an HIV test on an incapacitated patient?
no
What markers are used to detect HIV infection?
viral RNA; capsule protein p24-antigen; antibody
What do thrid generation HIV tests look at?
HIV-1 and HIV-2 antibody- IgM and IgG
What is the window period for third generation HIV antibody test?
20-25 days
What do 4th generation HIV tests test?
combined antibody and antigen
What is the window period for 4th generation HIV tests?
14-28days
How long does it take to get results with rapid HIV tests?
20-30mins
What is the function of recent infection testing algorithms?
used to identify if an infection occurred within the preceding 4-6 months by looking at measuring different types of antibodies or stregth of antibody binding
