Blood Bourne Viruses Flashcards
Name 3 key BBV agents and resultant diseases
- HBV - Hepatitis
- HCV - Hepatitis
- HIV - AIDS and HIV seroconversion illness
Describe the taxonomic status of HBV
Hepadnavirus with dsDNA genetic core
Describe the taxonomic status of HCV
Flavivirus with single-stranded RNA genetic core
Describe the taxonomic status of HIV
Lentivirus with RNA genetic core
What are the 2 similarities between the 3 key BBVs?
- Share routes of transmission
2. Have a lipid envelope
What are 3 routes of transmission of BBVs?
- Penetrative sexual intercourse
- Contaminated blood
- Vertical
What BBV is mainly transmitted by penetrative sexual intercourse?
HIV
What BBV is mainly transmitted by contaminated blood?
HCV
What BBV is mainly transmitted by vertical means?
HBV
Describe the pathogenesis of HBV
HBV does not directly kill liver cells and pathology is largely immune mediated (virus specific cytotoxic T cells)
What is the lab test for HBV?
Surface antigen test “HBsAg”
What 2 factors increase risk of chronic HBV infection?
- Immunosuppression
2. Being male
What is the age-related effect on carrying HBV?
Likelihood of become a carrier decreases as a person grows older
What are 2 consequences of chronic hepatitis?
- Cirrhosis
2. Hepatocellular carinoma
What is cirrhosis?
Irreversible form of liver injury where liver is replaced by scar tissue which is fibrous so cannot carry out normal liver function
Give 3 examples of the vertical manner in which HBV can be transmitted
- Intrauterine
- Perinatal infection
- Postnatal infection
What are 4 ways BBVs can be transferred via blood?
- Contaminated needles or equipment shared by injecting drug users
- Tattooing or body piercing
- Healthcare settings
- Hepatitis carrier HCWs to patients while carrying out procedures
Give an overview of HBV epidemiology
- 350 million infected
- Prevalent in southeast Asia, sub-Saharan Africa and China
What are the 4 components of HBV diagnosis?
- HBs Ag
- HBe Ag
- HB core IgM
- Anti-HBs Ag
What is the function of HBe Ag test?
Measure the amount of HBV DNA present to grae infection
What would a positive test of HB core IgM indicate?
Recent infection
What would a patient’s result be if there was HBsAg only present in their blood?
Infected with HBV
What would a patient’s result be if there was HBsAg and high levels of HBe present in their blood?
High grade infection
What would a patient’s result be if there was HBsAg and anti-HBe IgG present in their blood?
Low grade infection (les likely to suffer and transmit)
What would a patient’s result be if there was anti-HBsAg only present in their blood?
Immune (vaccinated or virus has been cleared)
How is HBV treated?
Suppression therapy using oral antiviral tenofovir
How is the HBV vaccine engineered?
Genetically engineered HBsAg produced in yeast
What 4 groups of people would HBV immunization be recommended for?
- Dialysis patients
- HCWs
- Sexual contacts of individuals with HBV
- Injecting drug users
Why do E antigen positive mothers need to be aware of HBV?
There is 95% chance of transmission to baby which can be prevented by vaccine and immunoglobulin
Describe 4 characteristics of the clinical course of HCV
- Incubation period of 2-4 moths
- Subclinical infection in acute phase is normal
- 75% of HCV-infected patients develop chronic HCV
- 15% progress to cirrhosis within 20 years and 1% per year risk of liver cancer in those with established cirrhosis
Give an overview of HCV epidemiology
- 170 million infected
- 3% blood donors in world have HCV
- 0.24% population in NI have HCV
- Long gap between infection and significant disease
What are 3 diagnostic methods which identify HCV?
- Serological assays to detect HCV antibody
- Qualitative and quantitative HCV RNA detection
- Genotype analysis
Name 2 serological assays which detect HCV antibody
- EIA
2. RIBA
What 2 ways was HCV treated in the past?
- Ribavirin
2. PEGylated interferon
What 2 reasons are oral direct acting agents used to treat HCV now?
- Few side effects
2. Much higher efficacy
What 2 types of cells does HIV infect?
- CD4 lymphocytes
2. Macrophages
Describe HIV pathogenesis
- CD4 molecule acts as receptor
- Gradual immune destruction
- Opportunistic infections
What is CD4 count used as?
Measure of disease progression in HIV
Name 5 types of opportunistic infections and an example of each which attack the body as a cause of HIV
- Viruses (CMV)
- Bacteria (salmonella)
- Protozoa (toxoplasma gondii)
- Fungi (Histoplasmosis)
- Tumours (Kaposi’s sarcoma B cell lymphoma)
Describe HIV epidemiology
- More than 40 million people infected
- Around 30 million infected in sub-Saharan Africa
- Rural communities in Africa have 40% positivity
- TB big killer in rural African communities as reactivates due to immunosuppression
What are the 4 steps in HIV diagnosis?
- Screening assays (antigen and antibody)
- Confirmatory assays (check specificity)
- Second sample as check
- Avidity testing (how recent was infection)
Name 3 lab tests used for patients with HIV but are not to diagnose the virus
- HIV viral load (response to treatment)
- CD4 count (stage of illness)
- Mutational analysis (resistance to treatment)
Name 3 main HIV antiretroviral therapies
- NRTIs (nucleoside reverse transcriptase inhibitors)
- NNRTIS (non-nucleoside reverse transcriptase inhibitors)
- RIs (protease inhibitors)
What does PrEP stand for?
Pre-exposure prophylaxis
What is the function of PrEP?
Drugs which prevent a negative patient from becoming infected with HIV
Describe the risk of HIV in pregnancy
20% risk of mother to baby transmission
What 3 ways can reduce the chance of HIV transmission during pregnancy?
- Elective caesarean
- Antiretroviral drugs given prophylactically
- No breast feeding
Name 5 places a HIV test is offered
- GUM or sexual health clinics
- Antenatal services
- Pregnancy services
- Drug dependency programmes
- Healthcare services
What 4 patients may be at risk of HIV?
- Patients diagnosed with STI
- Sexual partners of patients known to be HIV positive
- Men with disclosed sexual contact with other men
- Patients with history of injecting drug use
What are 5 oral manifestations of HIV?
- Candidiasis
- Linear gingival erythema
- Hairy leuokplakia
- Kaposi’s sarcoma
- Gingivitis
What is Kaposi’s sarcoma?
Tumour with systemic distribution with erythematous to violaceous cutaneous and oral lesions
What is oral hairy leukoplakia?
Presents with white corrugated lesions on the tongue caused by Epstein-Barr virus