HIV/AIDS Flashcards
What is HIV
Retrovirus which infects and replicates in human lymphocytes (CD4+ cells) Results in: - progressive immune dysfunction - opportunistic infection - malignancy
When does HIV become AIDS?
HIV becomes AIDS when CD4 count drops below 200
What are the risk factors of HIV infection?
- High maternal viral load
- Unprotected sex
- Needle stick injury
- Needle sharing in IV drug users
- Herpes Simplex Virus Type 2 infection
What are the causes of HIV infection?
- Transmitted via bloods, blood products, sexual fluids, breast milk
- Sexual contact
- Before birth or during delivery
- During breastfeeding
- IV drug use
What are the main clinical features of HIV infection?
- Headaches
- Fevers
- Rash
- Myalgia
- Chest infections
- Pharyngitis
- Lymphadenoapthy
What is the pathophysiology of HIV infection?
=> HIV targets CD4+ cells:
- T cells
- Dendritic cells
- Macrophages
- HIV binds to the CD4 receptor and co receptors on the immune cells via its own gp120 glycoprotein
- Once bound, the viral RNA is injected into the immune cells, converted into viral DNA via reverse transcriptase
- Intergrase then integrates the viral DNA into the hosts DNA
- The infected immune cell then travels to the lymphoid organs, where other immune cells become infected
- Once activated, transcription and translation allow multiple viral proteins to be made
How does HIV become resistant to treatment?
- Mutation each time the protein is translated
What is the relationship between disease progression and CD4 count?
- As disease progresses, CD4 count sees a general decline
What are the AIDS defining conditions?
- Recurrent bacterial Pneumoni
- Pneumocystis pneumonia
- Fungal infections
- Tumours - Kaposi sarcoma and Primary lymphoma
What are the investigations in suspected HIV cases?
=> HIV antibody test
- Most common and accurate test
- Most people develop the antibodies against HIV by 4-6 weeks
=> p24 antigen
- Usually positive from 1 week - (3-4 weeks)
=> Viral load
- Quantifies viral load and is used to monitor response to ART
=> CD4 count
- Cannot be used to diagnose HIV
- Used to monitor disease progression
=> Testing for an asymptomatic patient should be done at 4 weeks after initial exposure. If a negative result is found, test is repeated at 12 weeks
How is HIV infection prevented in contraction and spread?
- Protected sex
- Short term use of ART after potential HIV exposure
- Use of ART when at high risk of acquiring HIV
- All pregnant woman with HIV should be taking ART by 24 week gestation to prevent vertical transmission
What are the different classes of ART drugs?
=> CCR5 ANTAGONISTS
- Eg Maraviroc, Enfurvitide
- Block co receptors therefore HIV cannot enter
=> NRTIs
- Eg Zidovudine, Abacavir, Tenofovir
- Prevent conversion of viral RNA to DNA through inhibition of reverse transcriptase
- General side effect: peripheral neuropathy
=> NNRTIs
- Eg Nevirapine, Efavirenz
- Side effects: P450 enzyme interaction, rashes
=> PROTEASE INHIBITORS
- Eg Indinavir, Nelfinavir, Ritonavir, Saquinavir
- Inhibits proteases needed for viral maturation
- Side effects: diabetes, hyperlipideamia, buffalo hump, central obesity
=> INTERGRASE INHIBITORS
- Eg Raltegravir, Elvitegravir, Dolutegravir
- Inhibit Intergrase
=> PHARMACOKINETIC ENHANCERS/BOOSTERS
- Increase effectiveness of ART drugs allowing lower doses to be given
What are the different opportunistic diseases that may occur in those with HIV?
=> Pneumocystitis Jirovecii
- Presents as progressive dyspnoea on exertion, malaise and dry cough
- Investigation CXR
- Treated via Co-Trimoxazole
=> Candidiasis
- Most common cause of oesophagitis
- Investigation endoscopy
- Treated with Fluconazole
=> Cyrptococcus Neoformans
- Commonest fungal infection, presents as meningism, headache, fever
- Investigation with LP, CSF stain, cryptococcal antigen
- Treated Fluconazole and stablise ICP
=> Toxoplasmosis
- Intracranial lesions, presents as focal neurological signs
- Investigation CT: Ring enhanced lesions
- Treated via Pyrimethamine, Sulfadiazine, Folinic acid
=> Primary CNS lymphoma
- Investigation CT: Single lesion
- Treated via steroids, chemotherapy, with or without whole brain irradiation
=> CMV
- Presents as retinitis, encephalitis, GI disease, hepatitis
- Treated via Ganciclovir/valganclicovir
=> Cryptosporidium
- Commonest cause of diarrhoea in HIV
- Investigation stool microscopy
- Treatment ART
=> Kaposi’s sarcoma
- Most common tumour
- Presents as purple papules or plaques on the skin or mucosa
- Treated via radiotherapy + resection
=> CD4 count 200-500
- Oral thrush
- Shingles
- Kaposi’s sarcoma
=> CD4 count 100-200
- Cryptosporiodium
- Toxoplasmosis
- Pneumocystitis Jirovecii
=> CD4 50-100
- Oesophageal Candidiasis
- Lymphoma
=> CD4 < 50
- CMV
