HIV: Pathophysiology Flashcards
What type of virus is HIV and where did it originate
retrovirus
HIV 2- west African Sooty mangabey
HIV 1- central/west African chimpanzees
What immune cell is the target site for HIV
CD4 receptors found on immune cells particularly T helper cells, dendritic cells, macrophages and microglial cells
What effect does HIV have on the immune response
reduced circulating CD4 cells Reduced proliferation of cd4 cells reduced CD8 cell activation reduction in antibody class switching CHRONIC IMMUNE ACTIVATION
What are people with HIV more susceptible yo
viral infections
fungal infections
mycobacterial infections
infection induced cancer
what are the normal cd4 parameters
500-1600 cells/mm3
at what CD4 count is someone at risk of opportunistic infections
less than 200
what are the main phases of HIV infection
primary infection
asymptomatic infection
symptoms of AIDS
what is the average time between infection and death without treatment
9-11 yrs
what are the features of primary hiv infection
usually onsets 2-4 weeks after infection
flu like illness- rash, fever, myalgia, pharyngitis etc
high risk of transmission at this point
what are the features of asymptomatic infection
ongoing viral replication
ongoing cd4 count depletion
ongoing immune activation
risk of onward transmission of undiagnosed
what is an opportunistic infection
an infection caused by a pathogen that does not normally produce disease in a healthy indicidual
which organism causes pneumonia often in patients with HIV
pneumocystis jiroveci
what is the treatment of pneumocystis pneumonia
high does co-trimoxazole (give low dose for prophylaxis)
+/- steroid
What is cerebral toxoplasmosis
a parasitic infection resulting in multiple cerebral abscesses causing headache, fever, focal neurology, seizures, reduced consciousness and raised intracranial pressure
at what cd4 count can toxoplasmosis infection occur
less than 150
at what CD4 count can you get cytomegalovirus
less than 50
how can CMV present
preduced visuall acuity
floaters
abdo pain, PR bleeding
what skin infectiosn are common in HIV
herpes zoster herpes simplex HPV pencilliosis Histoplasmosis
what virus causes HIV associated neurocognatice impairement
HIV 1
what organism causes Progressive multifocal leukoencephelopathy and at what CD4 threshold
JC virus
less than 100
Name some AIDS related cancers
Kaposi’s sarcoma (vascular tumour)
Non hodgkins lymphoma
cervical cancer
what virus causes kaposi’s
human herpes virus 8
what organism can cause non hodgkins
EBV
what kind of things may a patient with symptomatic HIV present with
mucosal candidiasis seborrhoeic dermatitis diarrhoea fatigue psoriasis lymphadenopathy parotitis STIs, hep B or C
what haematological conditions occur in those with HIV
anaemia
thrombocytopenia
how is HIV most commonly transmitted
sexual
51 percent (MSM)
49 percent between men and woman
what factors increase transmission risk
anoreceptive risk
trauma
genital ulceration
concurrent STI
name another mode of transmission
parenteral= IVDU infected blood products iatrogenic mother to child= in utero delivery breast feeding
which group of people are most likely to present late with HIV
heterosexual men
how many people in the UK living with HIV are undiagnosed
1/4
when is universal (opt out) testing implimented
in high prevelance areas in the uK ie HIV rate is locally more than 0.2 percent of population
where is and opt out HIV test always offered in the UK
TOP services GUM clinic drug dependency services antenatal services assisted conception
what groups of people are deemed high risk and should be offered screening
MSM female partners of bisexual men IVDU partners of people with HIV adults/children/sexual partners from endemic areas history of iatrogenic exposure
