Bloodborne Pathogens Flashcards
transmission methods of blood borne pathogens
- direct contact with infected blood/fluids
- infection via contaminated needles, syringes, or other unsterilised equipment
- direct infection into the blood stream by arthropod vectors
three routes of HIV transmission
- via blood/blood products or contaminated needles
- sexually (virus is present in semen and vaginal secretions)
- perinatally (transplacentally during delivery, ingestion of breast milk)
viral features of HIV
retrovirus - uses reverse transcriptase to make DNA copy from viral RNA
Has surface proteins
where do drugs relating to the treatment of HIV target
- reverse transcriptase inhibitors
- lack of editing allows resistant mutants to emerge rapidly so target this by using Non-ucleoside Reverse Transcriptase Inhibitors
- protease inhibitors
how does HIV progress to AIDS
- exposure to HIV
- seroconversion
- asymptomatic
- persistant generalised lymphadenopathy
- AIDS related clinical features
- AIDS
What do you need to be diagnosed with AIDS
HIV + and CD4 less then 200
HIV+ and a certain condition
what is the main therapy used in treating HIV
Anti-retrovrial therapy ART this treatment includes – 1 NRTI + 1 PI or – 2 NRTIs + 1 NNRTI
Diagnosis of HIV Infection
• Diagnosis of HIV-specific antibodies
– ELISA
– Western blotting
• NAAT used to detect viral RNA in serum
• Quantitative NAAT used to measure viral load
• Individual testing must be preceded by counselling
• An initial negative result should always be followed up
Prevention of HIV Infection
- Screening of blood products
- Needle exchange programmes
- Anti-retroviral prophylaxis for needlestick injuries
surface antigen
HBsAg
– Indicates infectivity
– Anti-HBsAg provides immunity & appears late
core antigen
HBcAg
– Appears early in infection
pre-core antigen
HBeAg
– Indicates high transmissibility
HBV - Stages of Infection
• Long incubation period - up to 6 months
• Development of acute hepatitis
• Fulminant disease carries 1-2% mortality rate
• 50% patients develop chronic active hepatitis
– Cirrhosis
– Hepatocellular carcinoma
HBV - Clinical Features
• Pre-icteric Stage – Malaise – Anorexia – Nausea – Pain in right upper quadrant (tender liver)
• Icteric Stage
– Jaundice
– Dark urine (bilirubin)
Jaundice
• Yellowish pigmentation – Skin
– Sclerae
– Other mucous membranes
• Caused by hyperbilirubemia
HBV - Treatment
• Pegylated interferon (peginterferon) sustaining suppression of viral replication
Antiviral activity of nucleoside analogues
HBV - Prevention
HBsAg vaccine • HBV immunoglobulin • Blood screening • Needle exchange programmes • Sexual health education
HCV - Viral Features
- Destroys liver cells
* Virus cannot be cultured
HCV - Clinical Features
- Usually asymptomatic
- Fatigue
- Nausea
- Weight loss
- May rarely progresses to cirrhosis
- Small proportion may develop hepatocellular carcinoma
HCV - Treatment
- alpha-Interferon reduces liver transaminases in 80% of patients
- Ribavirin works well in combination with pegylated α-interferon
- Combination therapy
- Monitor viral load by NAAT
- No vaccine available yet
HCV - Screening
- NAAT performed on blood samples
* Therefore current incidence of transfusion- associated HCV is low
Malaria - Cause
– P. falciparumFemale Anopheles mosquito injects sporozoa into the bloodstream
• Zoonotic disease
Malaria – Clinical Features
• Fever • Flu-like symptoms • P. falciparum infection can rapidly progress to death • P. falciparum affects every organ – wide range of complications e.g. – Cerebral malaria – Circulatory shock – Hepatitis
Malaria - Diagnosis
- At least 3 blood films (both thick and thin) obtained from different times for microscopy
- NAAT – useful for detecting drug resistance
Malaria - Treatment
- Chemotherapy kills blood stages of parasite
- Resistance means treatment advice should be changed regularly
- Combination therapy is the norm
Malaria - Prevention
- Sleep under bed nets
- Cover exposed skin between dusk and dawn
- Use of mosquito repellants
- Prophylaxis
- Vaccines currently being developed
