HIV
Pathophysiology / transmission
Heterosexual, MSM (inc. sex work), mother-to-child, MSM, IVDU
Prevention
Pre-exposure prophylaxis (PrEP): HIV-negative partner takes ART (e.g. Tenofovir [TDF]/Emtricitabine[FTC]) before sexual contact (reduced HIV infections: PROUD trial, 2016)
Post-exposure prophylaxis (PEP): e.g. Truvada + Raltegravir, 28/7
Microbicides for women, treatment as prevention, male circumcision, STI treatment, condoms, HIV testing, behavioural measures (ABC..)
Epidemiology
37 million PLHIV, 70% live in Africa. 1.8 million infections. 1 million deaths (2018)
Highest rates: Swaziland (27.4%), Botswana (22.8%), Lesotho (23.8%), South Africa (19%), Zimbabwe (13.3%). Note in-country variation
Absolute numbers: South Africa (7 million), Nigeria (3.4 million), India (2.1 million), Japan (28,000 PLHIV, 1,500 new infections/year)
90% know their status, 90% on treatment, 90% viral load suppressed (90:90:90 UNAIDS goal)
Natural course
Acute (0-12 weeks): HIV RNA peak and decrease, CD4 blood and GIT start to decrease
Asymptomatic (1-7 years): slow increase in RNA and decrease in CD4
AIDS (7+ years): increase in RNA, decrease in CD4
Clinical features by stage
Acute HIV infection
Rash, lymphadenopathy
WHO stage 1
Persistent lymphadenopathy
WHO stage 2 (wt loss, URTI, various skin, nails...)
Moderate unexplained weight loss >10%,
Recurrent URTI (sinusitis, tonsillitis, otitis media, pharyngitis)
Papular pruritic eruptions (immune dysregulation: prolonged allergic reaction to insect bites)
Fungal nail infections
WHO stage 3 (oral, pulmonary TB...)
Severe weight loss >10%
Chronic diarrhoea >1 month
Persistent fever (intermittent or constant >1 month)
Severe bacterial infections
Unexplained anaemia (<8 g.dl) and/or chronic thrombocytopenia (<50)
Oral candidiasis
Oral hairy leukoplakia (EBV-associated)
Pulmonary TB
WHO stage 4 (oesophageal, malignancy, neuro)
Kaposi's sarcoma
Fungal
Oesophageal candidiasis
Pneumocystis jirovecii pneumonia
Cryptococcal meningitis / cryptococcosis
Talaromycosis (penicilliosis), endemic in Asia only
Coccidioidomycosis (America only)
Neuro (toxo, PML, CMV, lymphoma)
Opportunistic infections by system
Respiratory
Pneumocystis jiroveci pneumonia, herpes zoster, candidiasis
TB
GI
Cryptosporidium diarrhoea
Skin: umbilicated papules
Molluscum contagiosum (Poxvirus)
Cryptococcal disease
Disseminated mycobacterial infection
Bacillary angiomatosis (B. henselae, B. quintana)
Histoplasmosis
Talaromycosis (penicilliosis)
Neuro big 3
TB, crypto, toxo
Cytomegalovirus retinitis: (cheese & tomato pizza), gangcliclovir
Cryptococcal meningitis (e.g. chronic headache, 6th nerve palsy)
Cerebral SOL in HIV
Toxoplasmosis
Bacterial abscess
Cryptococcoma
Tuberculoma
Neoplasm: primary CNS lymphoma
Other: Progressive Multifocal Leukoencephalopathy (PML), stroke, neurosyphlis, (cerebral) malaria
Rx: treat the treatable....
Diagnosis
Antibody tests: HIV-1 and 2 antibodies (3 months) e.g .ELISA, Western Blot, qualitative immunoassays/RDTs (highly specific but false positives can occur, therefore needs further confirmation)
Antigen tests: detects the presence of the p24 antigen/protein (capsid protein) of the virus (1 month: window period approx. 16 days)
Combined antigen/antibody tests: 4th generation ‘combined’ antibody/antigen test -
Nucleic acid detection: (window period approx. 12 days)
A negative result on a 4th generation test performed at 4 weeks post-exposure is highly likely to exclude HIV infection. A further test at 8 weeks post-exposure need only be considered following an event assessed as carrying a high risk of infection
Sequence of testing
HIC: ELISA + p24 antigen testing. If positive: Western blot. If positive, take blood again: ELISA + p24 antigen/Western blot/PCR
LIC: POC tests: ELISA and p24. If positive: repeat.
EMTCT
Vaccines for HIV positive adults: annual influenza, pneumococcal, Hepatitis B, hepatitits A (for MSM). Live vaccines should not be given BCG, cholera, oral typhoid, oral polio [Sabin]. All inactivated immunisations are safe (pertussis, diphtheria, tetanus, polio [salk], typhoid, meningitis C)
Follow up: women: annual cervical smears as at more risk from HPV-related disease, including cervical cancer and warts
Prognosis
Late diagnosis of HIV (CD4,350) is associated with tenfold increased risk of dying within a year in the UK.