HIV Flashcards
What type of virus is HIV?
retrovirus
What is a retrovirus?
when it makes DNA it uses an enzyme called reverse transcriptase
Out of HIV 1 and 2, what is the most common?
HIV 1
What is the pathophysiology of HIV?
HIV infects CD4 cells
CD4 t helper cells are vital for the induction of the active immune response
therefore there is a disregulated cell response
What effects does HIV have on the immune system?
SUPPRESSION
reduced proliferation of CD4 cells
sequestration of cells in lymphoid tissue leading to reduced circulating CD4 cells
reduction of CD8 cell activation causing dyregulation of cytokine expression and increased susceptibility to viral infections
reduction in antibody class switching
chronic immune activation
What is a normal CD4 count?
500-1600
How does the infection spread in HIV?
infection of the mucosal CD4 cells which is then transported to regional lymph nodes and infection is established within 72 hours
How long do you have to give post exposure prophylaxis for HIV?
72 hours
How does a primary HIV infection present?
2-4 weeks after infection - HIGH RISK OF TRANSMISSION fever maculopapular rash myalgia pharyngitis headache aseptic meningitis
What are some opportunistic infections that are associated with HIV?
pneumocystis pneumonia tuberculosis cerebral toxoplasmosis cytomegalovirus neurocognitive impairment PML - progressive multifocal leukoencephalopathy Skin infections
What organism causes pneumocystis pneumonia?
pneumocystis jiroveci
What is the CD4 threshold in pneumocystis pneumonia?
<200
What is the presentation of pneumocystis pneumonia?
SOB
cough
exercise desaturation - sats go down after 5 mins of exercise
What can be seen on a CXR of pneumocystis pneumonia?
OFTEN NORMAL
interstitial infiltrates
reticulonodular markings
How is pneumocystis pneumonia diagnosed?
bronchioalveolar lavage +/- PCR
How is pneumocystis pneumonia treated?
high dose co-trimoxazole
How is pneumocystis pneumonia prevented?
low dose co-trimoxazole
When does TB occur in those with HIV?
if they are HIV positive when you start anti retrovirals - immune system wakes up and causes TB flare up
What organism causes cerebral toxoplasmosis?
toxoplasma gondii
What is the CD4 threshold in cerebral toxoplasmosis?
<150
What is the pathology of cerebral toxoplasmosis?
reactivation of latent infection
chorioretinitis
multiple cerebral abscesses
What is the presentation of cerebral toxoplasmosis?
headache fever focal neurology seizures reduced conciousness rasied ICP
What is the CD4 threshold for cytomegalovirus?
<50
What does the cytomegalovirus cause?
retinitis
colitis
oesophagitis
What symptoms does cytomegalovirus present with?
reduced visual acuity floaters due to retinitis abdo pain diarrhoea PR bleeding
What must you do for all patients with a CD4 <50?
opthalmic screening
What skin problems are common in those with HIV? How are they different in HIV?
herpes zoster - multidermal and recurrent
herpes simplex - extensive, hypertrophic and aciclovir resistant
HPV - extensive, dysplastic
Penicilliosis
Histoplasmosis
How does HIV associated neurogcognitive impairment present?
HIV 1
reduced short term memory +/- motor dysfunction
What organism causes PML?
JC virus - reactivation of latent infection
What CD4 threshold for PML?
<100
How does PML present?
rapidly progressing focal neurology, confusion and personality change
What is Slims disease?
HIV associated wasting
anorexia
due to malabsorption - gut gets disseminated so is leaky
hypogonadism
What are AIDS related cancers?
Kaposi sarcoma
Non Hodgkins lymphoma
Cervical cancer
What is kaposi sarcoma?
vascular tumour - purply tinge
purple lesions on cutaneous, mucosal or visceral surfaces (GI or pulmonary)
What organism causes kaposi sarcoma?
human herpes virus 8
What treatment can be given for kaposi sarcoma?
HAART
systemic chemo
What organism causes non hodgkins lymphoma?
EBV
How does non hodgkins lymphoma present?
B symptoms - weight loss, fever, night sweats
bone marrow involvement
extra nodal disease
increased CNS involvement
What does every patient with lymphoma get?
HIV test
How is non hodgkins lymphoma treated?
HAART
How is HIV transmitted?
sexual - 95% of infections
parenteral - PWID
mother to baby - 1 in 4 babies get infected
What % of MSM have HIV in the UK?
1 in 17
Who gets tested for HIV?
any medical admission or new patient in a GP in a high prevelance area - subsaharan africa, carribean and Thailand
opt out in clinical settings - TOP, GUM clinics, drug dependency services
screening in high risk groups - PWID, MSM, sex workers, partners of those with HIV or bisexual men
What is an HIV test?
rapid HIV test - finger prick sample, results within 20-30 mins
can do 3rd gen (antibody) or 4th gen (antigen and antibody)
What is the other HIV test?
take a venous sample and look for p24 antigen
How is HIV treated?
HAART - highly active anti-retroviral therapy
What is HAART?
combination of 3 drugs from at least 2 different drug classes from which the virus is susceptible
eg 2 NRTIs and a NNRTI or protease inhibitor
How do antiretrovirals work?
reduce the replication of HIV-1 by targeting = reverse transcriptase, protease, integrase and entry and maturation
How is resistance to antiretrovirals prevented?
adherence
stop-start method of taking them leads to viral breakthrough
if they are going to stop - give them a protease inhibitor
What interactions do HAART have?
Hep C and TB drug regimes
increase cholesterol
affect liver enzymes
How are HIV comorbidities prevented?
HPV vaccinations for women and more regular cervical smears flu vaccine Hep A/B vaccine smoking cessation STI screening
What are the methods of partner notification?
partner referral - partner tells them
provider referral - doctor tells them
conditional referral - doctor tells them if the person doesnt within a certain time etc
At what viral load can HIV not be transmitted?
<200
How can HIV transmission be prevented?
post exposure prophylaxis - PEP pre exposure prophylaxis - PrEP condom use circumcision - reduces by 60% HIV treatment
How can HIV transmission from partner to partner be prevented?
treatment as prevention to the HIV neg partner
PrEP for neg partner
self insemination if male -ve and female +ve = want a baby
How can HIV transmission from mother to baby be prevented?
HAART during pregnancy undetectable load = vaginal delivery detectable load = c/section 4 weeks of PEP for neonate formula feeding only
Where is PrEP avaliable?
only scotland, not england
What is the elidibility criteria for PrEP?
high risk for HIV HIV +ve partner MSM or transwoman >/=16 years HIV negative can commit to 3 monthly follow up reside in scotland
What medication is used in PrEP?
Tenoforir disoproxil/emtricitabine
What is the average effectiveness of PrEP?
86% HIV incidence reduced
How is PEP used for HIV?
3 antiretrovirals
80% effective
start within 72 hours
28 days total
How is PEP used for Hep B?
HBV vaccine up to 7 days later
immunoglobulin if doesnt respond to vaccine
