HIV (Management of needle stick injury)

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HIV (Management of needle stick injury) by Mind Map: HIV (Management of needle stick injury)

1. The student requires PEP to decrease the risk of HIV infection. This 3 drug-combo again has a tenofovir backbone. Commonly used is Truvada (1 daily tablet TDF + FTC) and Isentress (1 tablet twice daily Raltegravir). PEP for Hep B virus is a combination of vaccine and immunoglobulin. No PEP is available for Hep C Virus.

2. Replication

2.1. HIV virus enters cells by binding to CCR5/CXCR4 receptors on CD4 cells

2.2. RNA is converted to DNA by Reverse transcriptase enzyme

2.3. DNA integrates into host cell genome (integrase)

2.4. Viral DNA is transcribed to RNA by host cell

2.5. New virus particles bud form cell and maturation with aid of protease enzyme

3. Classification

3.1. Family: Retroviridae

3.2. Genus: Lentivirus

4. Window and Incubation Period

4.1. The window period is defined as the time between potential exposure to the HIV infection and the point where the test for HIV will give an accurate result. This window period for a 4th generation antigen or antibody test is 4 weeks.

4.2. The incubation period is the time between infection with the virus and the onset of symptoms of AIDS. An infected person can still spread the virus during this period. Time ranges from a few months to ten years or more.

5. Treatment

5.1. Source

5.1.1. The source, if HIV positive, needs to receive first line HAART treatment. This is a fixed dose combination containing two NRTI's and one NNRTI. The combination of choice is: tenofovir, emtricitabine (or lamuvidine) and efavirenz (TDF + FTC/3TC + EFV) . This combo is also effective in treating Hep B virus infection.

5.2. Injured

6. Pathogenesis

6.1. Virus binds to cells that have a CD4 receptor: T helper cells, monocytes, macrophages, T-cell precursors, dendritic cells and microglial cells

6.2. Cell death results in immunosuppression.

7. Co-infections

7.1. TB, Toxoplasmosis, Hepatitis B and C, Kaposi sarcoma, Chancroid, Lyme disease, Cryptococcal meningitis, PJP, Oesophageal candiasis, HSV 1 & 2

8. Lab tests

8.1. Serological assays

8.1.1. Rapid HIV strips

8.1.1.1. Routinely used. Most detect antibodies only. Gives immediate on-site result. With slightly lower sensitivity and specificity. Confirmed with 4th gen ELISA test.

8.1.2. HIV ELISA

8.1.2.1. 3rd generation: Detects HIV antibodies only

8.1.2.2. 4th generation: Simultaneously detects HIV antibodies and p24 antigen

8.1.3. P24 antigen

8.1.3.1. Indicates HIV infection. Not generally used - rather use combined test.

8.1.4. Western Blot

8.1.4.1. Confirmatory (follow-up) test. Not generally used.

8.2. Molecular assays

8.2.1. HIV PCR

8.2.1.1. Viral load testing not recommended in the setting of PEP

8.3. Diagnostic Markers

8.3.1. The following markers can be used (with dates after exposure):

8.3.2. Plasma RNA ~ 11 days

8.3.3. HIV - DNA PCR ~ 16 days

8.3.4. p24 antigen ~ 16 days

8.3.5. p24 antigen and anitbodies ~ 18 days

8.3.6. Antibodies ~ 21 days

9. Transmission

9.1. Sex

9.1.1. Oral sex with an infected person

9.1.2. Anal/vaginal sex without using a condom

9.2. Contact with fluids on mucosa/open skin: blood, semen, vaginal secretions, peritoneal or pleural fluid, breast milk, amniotic fluid

9.3. Vertical transimission

9.4. Sharing needles

9.5. Human bites if person is infected

9.6. Blood transfusion, blood product or organ infected with HIV

10. Precautions

10.1. Precautions to needle stick injuries

10.1.1. Wear gloves and a gown

10.1.2. Retractable needles

10.1.3. Wear eye protection (goggles)

10.1.4. Don’t stick needles into patient’s mattress

10.1.5. Don’t let sharps bin overflow

10.1.6. Handle sharps safely

10.1.7. Don’t recap needle (with one hand or both)

10.1.8. Take extra care with handling needles when tired

10.1.9. Dispose needles safely in sharps bin

10.2. Precautions to splashes

10.2.1. Close any open wounds with plasters

10.2.2. Wash off blood immediately with soap and water

11. Prevalence

11.1. 38% Hepatitis B and C, 4.5% HIV in health workers due to needle stick injuries

11.2. According to WHO: 2 million needle stick injuries annually

12. Risk of infection

12.1. 0.3% for HIV

12.2. 30% for Hepatitis B virus

12.3. 3% for Hepatitis C virus

12.4. Increased risk if:

12.4.1. Source has advanced AIDS

12.4.2. Source has high viral load

12.5. Other factors:

12.5.1. Size of needle

12.5.2. Extent of injury

12.5.3. What tissue/fluids the needle was exposed to.

13. Structure

13.1. Enveloped, + sense single stranded RNA virus

13.2. Surface glycoproteins: GP 120 - binds to the CD4 receptors (CCR5 and CXCR4)

13.3. p24 core protein

14. Enzymes

14.1. Protease

14.2. Integrase

14.3. Reverse transcriptase

14.3.1. High mutation and recombination rate