Blood Borne Infections Flashcards
How do you calculate the risk of BBI transmission
Risk of BBI transmission = Risk that source is positive x risk per exposure.
If a source is positive what is the chance of a needle stick injury causing an infection for Hep B, C and HIV?
If source positive
Hep B – 1 in 3
Hep C – 1 in 30
HIV – 1 in 300
How should a needle-stick injury be managed at the time of injury>
Immediate action
Encourage bleeding and wash
Risk assessment by Occupational health
Assess risk of source being positive – risk factors, known, viral load, HBV vaccine?
Nature of exposure – hollow vs solid needles, gloves, skin puncture etc.
What post exposure prophylaxis should be offered to those who have a needle-stick injury where a patient was positive for a BBI?
Post exposure prophylaxis
• HIV – Triple anti-retroviral drugs for 28 days starting within 72 hours
• Hepatitis B – may need booster immunisation or immunoglobulins (if incompletely vaccinated or patient is HBsAg positive)
• Hepatitis C – no prophylaxis available
Who should be tested after a needlestick injury and what precautions should be taken by the recipient in the mean time?
Source patient – consent for HIV, HBsAg and HCV
Recipient – original blood sample stored – test at 4, 6, 12 and 24 weeks
Whilst waiting – safe sex, good infection control and avoid blood donations
What is HIV?
Virus that replicates and kills CD4 lymphocytes causing damage to the immune system over time if not controlled.
How is HIV transmitted?
Sexual
Blood and bodily fluids – IVDU, needlestick and transplant/transfusion
Vertical – during birth or breast feeding (rare due to HAART – both maternal and neonatal)
Increased risk of transmission if: high viral load, STI causing anogenital inflammation or breaks in skin or mucosa
Describe the presentation of seroconversion illness of HIV
Seroconversion = change from seronegative to seropositive i.e. production of antibodies
Fever and rash – very common Malaise Arthralgia and muscle aches Sore Throat Lymphadenopathy
How does symptomatic HIV present?
Weight loss
High temperature
Diarrhoea
Frequent opportunistic infections e.g. herpes zoster or candidiasis
What is AIDS?
Aids is defined as a CD4 count of less than 200 and or opportunistic infections
How should suspected HIV be investigated?
Combo assay (ELISA) detecting HIV antibodies and the p24 antigen
Confirmatory tests in lab if positive – immunoblot
RNA detection in the blood for viral load
Contact tracing very important
What are the AIDS defining conditions
TB Pneumocystis Cerebral toxoplasmosis Primary cerebral lymphoma Cryptococcal meningitis Progressive multifocal leucoencephalopathy Kaposi’s sarcoma* Persistent cryptosporidiosis Non-Hodgkin’s lymphoma* Cervical cancer* Cytomegalovirus retinitis
- = AIDS defining cancers
Wasting syndrome = loss of 10% body weight with fever over 30 days and chronic diarrhoea
How is HIV managed and what drugs does this involve?
HAART – highly active antiretroviral therapy – not a cure but viral load is undetectable
Excellent prognosis and risk of onward transmission is very small
HAART involves a number of classes of drugs:
• Nucleoside reverse transcriptase (NRTIs)
• Protease inhibitors (PIs)
• Non-nucleoside reverse transcriptase inhibitors (NRTIs)
• Integrase strand transfer inhibitors (InSTIs)
These are usually combined into one tablet taken daily. Compliance is very important and non-adherence can lead to resistance mutations.
What is hepatitis C?
RNA virus causing Hepatitis. No vaccine but treatable
Describe how Hep C presents?
Usually asymptomatic Jaundice Fatigue Nausea Fever Muscle aches
Incubation period of 6 weeks
20% clear the infection 80% progress to chronic infection – cirrhosis and hepatocellular carcinoma (1-5%)
