3: HIV - pathophysiology and presentations Flashcards
What does HIV stand for?
Human immunodeficiency virus
If untreated, what does HIV infection cause?
AIDS
Acquired immunodeficiency syndrome
HIV infection is untreatable - true or false?
False
HIV is treatable and patients can go on to life an “almost-normal” life expectancy
What type of virus is HIV?
Retrovirus
Retroviruses have which type of genetic material?
RNA
How does a retrovirus replicate?
Converts its RNA to DNA using reverse transcriptase
Inserts its DNA into the DNA of the host cell
So when the host cell undergoes transcription and translation, it produces new viral RNA
Virus also takes over host metabolism to produce new coats
> Replication
Which receptor does HIV target?
CD4 receptors
Which immune cells have CD4 receptors?
TH lymphocytes
Macrophages
Dendritic cells
Microglia
Cells which ___ antigen to other immune cells tend to have CD4 receptors.
present
i.e antigen-presenting cells like macrophages and dendritic cells have CD4 receptors
Which molecules, found on CD4+ cells like macrophages and T helper lymphocytes, help these cells to present antigens to other immune cells?
MHC2
What does antigen presentation by CD4 cells cause?
Immune activation
B cells, cytotoxic T cells, cytokines
i.e your adaptive immune response
How does HIV infection reduce the adaptive immune response?
Affects antigen-presenting CD4+ cells, stopping the activation of the immune system in response to pathogens
HIV infection gammies the immune system.
What does this render the patient susceptible to?
Opportunistic infection
AIDS-related cancers
In untreated HIV infection, the count of CD4+ cells (increases / decreases).
CD4 cell count decreases
In untreated HIV infection, the viral load (increases / decreases).
viral load increases
A CD4 count of less than ___ cells / mm3 constitutes a risk of opportunistic infection.
< 200 cells / mm3
What syndromes do you develop in
a) Weeks 2 - 4
b) Years 9+
of HIV infection?
a) Acute HIV syndrome
b) AIDS
Without treatment, how long do
a) adults
b) babies
with HIV survive?
a) 10 years
b) 1 year
So it’s important to identify and diagnose it early
Which system spreads HIV around the body?
Lymphatic system
Around 2 - 4 weeks after HIV infection, what do 80% of patients present with?
Acute HIV syndrome
What is the presentation of acute HIV syndrome?
Fever
Rash - maculopapular, similar to meningococcal rash
Myalgia
Pharyngitis
Headache
Is acute HIV syndrome a chronic condition?
No
Resolves after a week - opportunity to diagnose HIV passes
Are patients with acute HIV syndrome infectious?
Yes
V much so
If untreated, during which time period are HIV patients asymptomatic?
Week 4 - Year 9+
During asymptomatic HIV infection, what happens to a patients
a) CD4 count
b) Viral load
c) infectivity?
a) CD4 count decreases
b) Viral load increases
c) Still infectious - can transmit via bodily fluids
What are two opportunistic respiratory infections which you need to know about re: HIV patients?
Pneumocystis pneumonia
Tuberculosis
What is the presentation of pneumocystis jirovecci infection?
SOB
Dry cough
What is the presentation of pulmonary tuberculosis?
Chronic productive cough +/- haemoptysis
Fever
Night sweats
What are the antibiotic treatments for
a) pneumocystis pneumonia
b) tuberculosis?
a) Co-trimoxazole +/- steroids
b) 2 RIPE 4 RI - 2 months rifampicin, isoniazid, pyrazinamide and ethambutol, then 2 months rifampicin and isoniazid
What infection, related to cervical cancer, are patients with HIV more susceptible?
HPV
Apart from opportunistic infections and AIDS-related cancers, HIV may also cause severe weight loss and chronic diarrhoea.
What is this collection of symptoms called?
Slim’s disease
What are three AIDS-related cancers?
Kaposi’s sarcoma
Non-Hodgkins lymphoma
Cervical cancer
Kaposi’s sarcoma is a ___ tumour which appears as red/purple patches on the skin, mucosa and internal organs.
vascular tumour
Which viruses are associated with
a) Non-Hodgkins lymphoma
b) Cervical cancer?
a) EBV
b) HPV
you’re more likely to be infected with these if you have HIV
HIV is spread by contact with the bodily fluids of an infected individual.
Name some ways in which this can occur.
Sexual transmission
PWID
Infected blood products
Mother-child transmission
Which type of sex is a risk factor for HIV infection?
Anal sex
MSM have a greater prevalence of HIV
Which groups and patients related to these groups, have a greater chance of contracting HIV?
MSM
PWID
People from abroad (where HIV rates are higher)
A large proportion of people with HIV are ___.
undiagnosed
Which group of patients tend to be carrying undiagnosed HIV?
Heterosexual men
What molecules can be detected in a patient’s blood re: HIV?
Virus itself - viral load
p24 viral antigen - Ag
HIV antibodies - Ab
What is the window period of an HIV infection?
Period in which it’s not detectable on tests because levels of viral antibodies / antigen haven’t risen yet
How long is HIV’s window period?
Around 30 days
