7.2 HIV Flashcards
define HIV ?
human immunodeficiency virus
define AIDS?
acquired immunodeficiency syndrome
define viral tropism?
ability of different viruses to infect different cellular types
define ART?
antiretroviral therapy
define MSM?
men who have sex with men
define POCT ?
point of care test
define PWID?
people who inject drugs
define STI?
sexually transmitted infection
define TasP?
treatment as prevention
HIV
1. type of RNA virus ?
2. tyupe of virus ?
3. …. kb genome
4. … genes encoding ….. viral proteins
- enveloped single-stranded
- retrovirus
- 9
- 9 , 15
what is HIV capsid ?
HIV’s core that contains HIV RNA
what is HIV envelope?
outer surface of HIV
what is HIV enzymes ?
proteins that carry out steps in the HIV life cycle
what is HIV glycoproteins ?
protein ‘spikes’ embedded in the HIV envelope
what is HIV RNA ?
HIV’s genetic material
Examples of variety of body fluids that can be exchanged from infected people to transmist HIV ?
- blood
- breast milk
- semen
- vaginal fluids, including menstrual blood
How can a HIV be transmitted from mother to child ?
- during pregnancy
- delivery
- breastfeeding
What substances don’t have sufficient viral loads to cause infection ?
- saliva
- sweat
- urine
Individuals on …1…. with an undetectable viral load do not transmit HIV
- ART = antiretroviral therapy
How is HIV not passed on ?
- spitting
- kissing
- biting
- contact with unbroken, health skin
- sneezing
- sharing baths, towels or cutlery
- using the same toilets or swimming pools
- mouth-to-mouth resuscitation
- contact with animals or insects like mosquitoes
Transmission of HIV includes what ?
- unprotected anal or vaginal sex
- sharing contaminating needles, syringes, other injecting equipment and drug solutions when injecting drugs
- receiving unsafe injections, blood transfusions , tissue transplanation and medical procedures that involve unsterile cutting or piercing
- experiencing accidental needle stick injuries, including among health workers
- vertically from mother to child
Stages of HIV infection ?
- primary HIV infection
- asymptomatic stage
- advanced HIV infection
- AIDS
Symptoms that are common to primary HIV (PHV) infection
- fevers
- sore throat
- maculopapular rash
- malaise
- lethargy
- arthralgia
- myalgia
- lymphadenopathy
- oral, genital, perianal ulcers
Less common symptoms of primary HIV infection
- headache
- meningitis
- cranial nerve palsies
- diarrhoea
- weight loss
What’s the name of the illness involved in primary HIV infection ?
& explain what the illness is
HIV seroconversion illness = ‘flu like’ illness for first few weeks following infection can be mild or severe
7 stages of viral replication
- Binding
2.Fusion
3.Reverse transcription
HIV reverse transcriptase copies viral RNA as proviral DNA
4.Integration
HIV integrase facilitates the proviral DNA’s integration into the host’s DNA.
- Replication
the host cell then produces HIV RNA and HIV proteins.
6.Assembly
HIV proteins are assembled into HIV virions and budded from the cell surface.
- Budding
HIV protease cleaves viral proteins, converting the immature virion to a mature, infectious virus.
Which cells does HIV primarily infect ?
CD+4 T cells (T helper cells), monocytes/ macrophages and dendritic cells
3 functions of CD4+ T helper cells:
- help B cells generate stronger longer-lived antibody responses
- maximise CD8+ T cytotoxic cell expansion, and facilitate generation of memory CD8+ T cells
- secrete cytokines and attract macrophages to the site of infection
Name 2 cells that are important reservoir for viral replication, persistence and disease progression
DCs and macrophages
Cell-mediated immunity = activation of…
cytotoxic T cells that induce apoptosis of infected cells (intracellular bacteria/ fungi, viruses, tumour cells)
How do macrophages and NK cells destroy pathogens ?
phagocytosis or cytotoxic granules
Where is cell-mediated immunity directed at ?
pathogens that either survive against phagocytosis (& opsonisation) or pathogens that infect cells directly
which cytokine response does cell-mediated immunity involve ?
pro-inflammatory (IFN-gamma, TNF)
Difference between development of asymptomatic stage once symptoms resove to AIDS in people ?
- some people progress rapidly to advanced HIV infection or AIDS within 1-2 years, while others may remain imunocompetent more than 10 years later
When does advanced HIV infection / AIDS occur ?
- number of CD4 cells < 200 cells per microlitre
- certain opportunistic infections (‘AIDS defining illness’)
- malignancies develop
what is an indicator condition ?
any medical condition associated with an undiagnosed HIV seroprevalence ≥1 per 1000
2 categories of indicator conditions ?
- Conditions that would be AIDS defining in an individual living with
HIV. - Non-AIDS-defining conditions associated with an undiagnosed HIV seroprevalence >1 per 1000
what are AIDS defining illnesses ?
serious and life threatening conditions that occur in HIV positive patients
List 4 AIDS defining illnesses
note. these are examples from ppt there are lots more examples online
- pneumocystis pneumonia
- kaposi’s sarcoma
- histoplasmosis
- cryptococcosis
Cause of pneumocystis pneumonia (PCP) ?
fungus - Pneumocytstis jirovecii (formerly P. carinii)
PCP is extremely rare in …
non-immunocompromised patients
presentation of PCP ?
non specific : dyspnoea (SOB) , non-productive cough (dry, no phlegm)
Kaposi’s sarcoma :
1. tumour ?
2. associated with … ?
3. presentation ? (can form lesions on …)
- mesenchymal
- human herpes virus type 8 (HHV8)
- skin, mouth, lymph nodes and other organs
Histoplasmosis caused by ?
histoplasma capsulatum
histoplasmosis affects ?
primarily the lungs but when disseminated can affect other organs
what can histoplasmosis start with ?
non-specific respiratory infection
Histoplasmosis :
1. often have normal …
2. more common in the …
3. skin involvement in up to … % of those with AIDS and PDH
- CXR
- US
- 25
CNS cyrptococcosis results from infection of CNS with what pathogenic microorganism ?
yeast-like fungus Cryptococcus neoformans
signs & symptoms of cryptococcosis ?
Are of meningitis e.g. headache, seizure, blurred vision (raised ICP)
CD4+ count of cryptococcosis ?
< 100 cells per microlitre
Possibility of HIV infection should be considered whenever a person presents with one or more of the alerting features which are what ?
- Common symptoms or infections that are unusually severe, prolonged, recurrent, or unexplained.
- Persistent enlarged lymph nodes other than in the inguinal area.
- Conditions related to immunosuppression.
- Glandular fever-like illness.
- Lifestyle and social risk factors for contracting HIV, such as high prevalence area, MSM and IVDU
- Weight loss of more than 10 kg
Infants with HIV often present with what ?
- Failure to thrive, and/or
- Pneumocystis pneumonia, or
- Cytomegalovirus disease, or
- HIV encephalopathy.
After first year of lige, consider HIV infection in children presenting with what ?
- Recurrent infections such as URTI, LRTI
- Parotid gland swelling
- Severe presentations of common
childhood infections. - Chronic diarrhoea.
- Herpes zoster.
- Severe pneumonia.
- Tuberculosis.
- Lymphadenopathy.
- Any AIDS-defining condition.
Situations when HIV testing should be offered in primary care?
- As part of routine antenatal care
- If person requests a test, has HIV risk factor, has another STI
- people newly registering at a practice or having a blood test
- people presenting with symptoms of PHI or longstanding HIV infection
HIV testing should be offered in primary care to people newly registered at a practice or having a blood test in what 2 situations ?
- not had an HIV test in past 12 months
- areas where prevalence of diagnosed HIV is greater than 2 in 1000
Some HIV-related conditions such as ..1… or ..2.. can be life threatening and require ..3… to …4… care
- pneumocystis pneumonia
- cryptococcal meningitis
- urgent admission or referral
- secondary
what are the 2 methods for routine HIV testing ?
- laboratory-based tests performed on samples obtained through venepuncture
- self-sampling, self-testing and rapid POCTs which can be performed in the clinic, in the community setting or as a home test
Steps for blood test for HIV testing ?
- small sample of blood is taken from arm in clinic
- sample sent to lab
- results available within several days
Steps for POCT (rapid point of care) test for HIV testing ?
- small spot of blood is taken from finger
- no need to send to lab
- results available within minutes
Steps for home sampling kit for HIV testing ?
- collect a small sample of blood yourself
- send sample to lab
- results available within several days
Steps for home testing kit for HIV testing ?
- you collect a small sample of blood and test it at home
- no need to send to the lab
- results available within minutes
1st generation HIV test ?
based on …. to detect ….
based on viral lysate antigens to detect HIV antibodies e.g. western blot
2nd generation HIV test ?
(antigens, with or without…, detect… )
- utilise synthetic peptide or recombinant protein antigens
- with / without viral lysates
- detect HIV immunoglobulin (Ig) G antibodies
3rd generation HIV test:
1. ….. based tests
2. detect …. antibodies
3. increased sensitivity during …
- synthetic peptide or recombinant protein antigen
- IgM or IgG
- early seroconversion
4th generation HIV test is what ?
combination 3rd generation assays to detect IgM and IgG antibodies, and monoclonal antibodies to detect p24 antigen
What do the consensus guidelines recommend for HIV testing ?
4th generation HIV lab tests with venous sampling as 1st line choice, with POCTs also available (which are largely 3rd gen tests)
According to who and which testing should be undertaken with HIV testing ?
- according to locally determined pathways in liaison with local virology teams
- confirmatory testing
what’s the window period of a test ?
time interval between exposure to infection and accurate detection of that infection
- What may occur if a HIV test is taken in the ‘window period’ after infection ?
- which days can this happen on depending on the test used ?
- false negatives
- 45 days to 90 days
Why should patients be aware of the likelihood of a negative test ?
They may be asked to return to test again, if HIV test taken in window period after infeciton false negative may occur (can be 45 days to 90 days) depending on the test used
What is used for early detection of HIV ?
P24 antigen
What can blunt the HIV antibody response, yielding atypical HIV serology ? [this means what change Q]
post-exposure prophylaxis, PrEP
Diagnosis of AIDS vs HIV difference in what is present ?
HIV = HIV antibodies
AIDS = HIV positive, CD4+ count below 200 cells/microlitre (or CD4+ % of lymphocytes < 14%) or AIDS defining illness
7 barriers to testing & some ideas why
- access to services - geographical distance, waiting time
- testing environment - lack of cultural sensitivity, trans patients
- service capacity - insufficient time, staff and training
- cost - lack of funding
- lack of knowledge by clinicians - may be unaware of who to test
- lack of awareness by the individual - perception of being low risk, assumption of on-going negative status
- fear of a positive result - immigration, dying, lack of knowledge
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