HIV Flashcards
What type of virus is HIV?What cells does it destroy?
An RNA retrovirus
The virus enters and destroys the CD4 T-helper cells
Which HIV strain is most common?
HIV-1
HIV-2 is mainly found in West Africa
What does seroconversion mean?
Seroconversion isthe transition from the point of viral infection to when antibodies of the virus become present in the blood.
It is the period during which HIV antibodies first become detectable
When do you usually get symptoms if you are infected with HIV?
An initial seroconversion flu-like illness occurs withing a few weeks of infection. The infection is then asymptomatic until the condition progresses to immunodeficiency.Disease progression may only occur years after the initial infection.
How is HIV spread?
It is spread through:
mother to child at any stage of pregnancy,birth or breastfeeding (called vertical transmission)
Unprotected sex
Open wound exposure/mucous membrane to infected blood/bodily fluids (e.g. sharing needles or blood splash in eyes)
What does AIDS-defining illnesses mean?What are some examples?
Certain serious and life-threatening diseases that occur in HIV-positive people are called “AIDS-defining” illnesses.It is associated with end-stage HIV infection and occurs when the CD4 level is low enough ofr oppurtunistic infections and malignancies to occur.
This includes:
Kaposi’s sarcoma
PCP (pneumocystis pneumonia)
Cytomegalovirus infection
Candidiasis
Lymphomas
TB
PCP (pneumocystis jiroveci pneumonia) is the MOST common oppurtunistic infection in AIDS. How does it usually present and what is a common complications of it? What would be typically seen on a chest X-ray?
Features
dyspnoea
dry cough
fever
very few chest signs
PNEUMOTHORAX is a common complication of PCP
Bilateral intersititial pulmonary infiltrates but this can be present on other X-ray findings e.g. lobar consolidation.
Exercise-induced desaturation
What is PCP caused by?
Caused by the fungus Pneumocystis jirovecii.
What is first-line treatment for PCP?
Co-trimoxazole
Kaposi’s sarcoma is another example of AIDS-defining illness. What is it and how does it usually present?
It is a disease in which cancer cells are found in the skin or mucous membranes that line the gastrointestinal (GI) tract, from mouth to anus, including the stomach and intestines.
Caused by HHV-8
Presents as purple papules or plaques on the skin or much
Resp involvement —> may cause massive HAEMOPTYSIS and pleural EFFUSION
What doe the guidelines state for HIV testing when a patient comes into the emergency department?
BHIVA (2023) have draft guidelines for assumed consent (unless the patient voluntarily chooses to opt-out) to HIV screening on blood tests taken in emergency departments (provided posters and leaflets are available)
How many weeks should you wait before testing for HIV in asymptomatic patients after a possible exposure?
Testing for HIV in asymptomatic patients should be done at 4 weeks after possible exposure
What are is the standard screening test to diagnose HIV?
The combined (HIV p24 antigen and HIV antibody test).
If this test is positive, REPEAT it again to confirm the diagnosis
What is the HIV p24 antigen test? How is it different to the HIV antibody test?
This antigen is the most abundant HIV protein and is essential for forming the capsid that encases the HIV genetic material.
Detection of this antigen is used to clinically diagnose early HIV infection.
It is different to the HIV antibody test as HIV-specific antibodies are not yet detectable early in HIV exposure (compared to p24 antigens which are)
What is the window period for HIV antibody test and p24 antigen? Is it reliable?
45 day window (this means it can take up to 45 days after the exposure to the virus for the test to turn positive).
It is only unreliable if it shows a negative result within the 45 days of exposure (must be more than 45 days).More than 45 days, a negative result is reliable.
