HIV Flashcards
what is the definition of HIV?
HIV infection is caused by a retrovirus that infects and replicates in human lymphocytes and macrophages, eroding the integrity of the human immune system over a number of years, culminating in immune deficiency and a susceptibility to a series of opportunistic and other infections as well as the development of certain malignancies.
what is the epidemiology of HIV?
Majority of transmission is undiagnosed people
Transmission rate is zero for people on antiretroviral therapy
what is the aetiology of HIV?
HIV is a retrovirus that infects and replicates primarily in human CD4+ T cells and macrophages. HIV can be transmitted via blood, blood products, sexual fluids, other fluids containing blood, and breast milk. Most individuals are infected with HIV through sexual contact, before birth or during delivery, during breastfeeding, or when sharing contaminated needles and syringes (intravenous drug users).
what are the risk factors of HIV?
Needle sharing with IV drug use Unprotected receptive anal intercourse Unprotected receptive penile-vaginal intercourse Percutaneous needle stick injury High maternal viral loads
what is the pathophysiology of HIV?
The virus gains entry to the cells by attaching to the CD4 receptor and a co-receptor (CCR5 or CXCR4) via its envelope glycoproteins. It is called a retrovirus because it encodes the enzyme reverse transcriptase, allowing a DNA copy to be made from viral RNA. The reverse transcriptase enzyme is inherently error-prone, resulting in a high rate of HIV mutation, which can rapidly lead to viral resistance in those on treatment.
Once integrated into the cellular DNA the provirus resides in the nucleus of infected cells and can remain quiescent for extended periods of time. Alternatively it can become transcriptionally active (especially where immune activity is occurring) and can use the human host cell machinery to replicate itself. Viral RNA is then spliced singly or multiply to make a variety of structural and regulatory and accessory proteins. Viral proteases further process proteins and mature viral particles are formed when the virus buds through the host cell membrane.
what are the key presentations of HIV?
Presence of risk factors Fevers and night sweats Weight loss Skin rashes Oral ulcers Diarrhoea TB Mental state changed Sexual activity Kapsoi’s sarcoma Genital STIs shingles Headaches Periodontal disease Retinal lesions on fundoscopy
what are the signs of HIV?
Periodontal disease Retinal lesions on fundoscopy TB Mental state changed Sexual activity Kapsoi’s sarcoma Genital STIs shingles Presence of risk factors
what are the symptoms of HIV?
Fevers and night sweats Weight loss Skin rashes Oral ulcers Diarrhoea headaches
what are the first line and gold standard investigations for HIV?
Serum HIV enzyme-linked immunosorbent assay - pos Serum HIV rapid test - pos HIV non-invasive test - pos Serum Western blot - pos Serum p24 antigen - pos Serum HIV DNA PCR - pos CD4 count - <200 = AIDS Serum viral load - level in the millions Drug resistance testing Pregnancy tests Hep B and C serology Serum venereal disease research laboratory tests Treponema pallidum haemagglutination test Rapid plasma reagin Tuberculin skin test FBC w differential - anaemia, thrombocytopenia Serum electrolytes - deranged Serum creatinine - elevated Urinalysis
what are the differential diagnoses for HIV?
Infectious mononucleosis
CMV
Influenza
Common cold
how is HIV managed?
Acute - antiretroviral, supportive care
Ongoing - reassessment of antiretroviral
how is HIV monitored?
A patient with early HIV disease should be monitored every 3-6 months, whereas a patient with late HIV disease should be monitored every 2-3 months.
At each visit patients should be assessed for opportunistic infection and their clinical stage updated.
HIV RNA (viral load) should be measured at entry into care and immediately prior to commencing antiretroviral therapy (ART). While on ART, HIV RNA should be checked at 2-8 weeks after commencing therapy, every 3-4 months during the first 2 years of therapy, and every 6 months after 2 years of therapy with consistently suppressed viral load.
A CD4 count should be done at entry into care and prior to initiation of ART. While on ART, the CD4 count should be checked 3 months after the initiation of therapy, then every 3-6 months for the first 2 years of therapy or if viraemia develops or the CD4 count drops to <300 cells/microlitre. After 2 years, patients with a consistently suppressed HIV RNA (viral load) can have their CD4 count checked every 12 months if their CD4 count is 300-500 cells/microlitre. Monitoring the CD4 count is optional in patients with a count of >500 cells/microlitre
what are the complications of HIV?
Acute seroconversion
Severe acute syndrome
Rapid progressors
AIDS
what is the prognosis of HIV?
The majority of HIV-infected individuals are able to regulate viral replication for many years because of an effective immune response; however, in the current era of potent combination antiretroviral therapy (ART), the recommendation is to initiate ART in all HIV-infected people and not to monitor with serial blood testing and clinical assessments in patients who are off therapy
