Blood Borne Viruses Flashcards
Define blood borne virus
It is a disease that can be spread through contamination by blood and other body fluids
Name the the most common examples of blood borne viruses
- HIV
- Hepatitis B
- Viral haemorrhagic fever
Which classification do we use to classify viruses?
The Baltimore Classification
What is viral hepatitis?
It is liver inflammation du to a viral infection
Name the different Baltimore Classification
Hep A, B ,C, D, E
They are all unrelated
Name some viruses the can cause hepatitis
- hepatitis viruses
- Cytomegalovirus,
- Epstein-Barr virus
- Flavivirus [Yellow fever ].
If a patient comes in with hepatitis what must you ask and establish?
Which type of hepatitis they have and what was the cause of their hepatitis
How is hepatitis A passed?
Passed via food and drink usually infected with faeces
How many cases of hepatitis A have been recorded?
1.4 million cases every year
How can hepatitis A be prevented?
With good hygiene, water systems and vaccine
How is hepatitis A diagnosed?
Diagnosis through IgM antibodies in blood
How many deaths are caused by hepatitis A?
102,000 deaths per year
How is hepatitis A treated?
Treatment is usually rest and fluid
How is hepatitis B passed on?
Through anything contaminated with blood, semen and vaginal fluid
Can also be transmitted vertically from mother to child
How many people globally have been infected with hepatitis b?
Approx 1/3 of the global population has been infected at some point
Is hepatitis B fatal?
It can be fatal
How can hepatitis B be replicated?
It replicates in liver cells
How does hepatitis B cause damage?
Hepatitis B replicates in the liver cells
Host immune reposes then causes damage to hepatocytes
Talk through the stages of viral replication of hepatitis B
- Entry via endocytosis
- Viral capsid is shed and viral DNA is transferred to the cell nucleus
- viral polymerase transforms the DNA into a double stranded circular top (cccDNA)
- The circular DNA contains transcripts for 4 viral mRNAs translated by host RNA polymerase
- The mRNAs make new copies of the viral genome and capsid which are processed to form new irons
- New virons are released from the cell
What type of virus is hepatitis b?
A pararetroviruses
What is a pararetroviruses?
It is a non retrovirus that still use reverse transcription in their replication process
How does viral hepatitis B gain access into the cell?
Gain access by binding to NTCP on the surface and being endocytose
Once inside a cell what does. virus need to do?
As viruses multiply via RNA the viral genomic DNA has to be transferred into the cells nucleus so that the virus can use the cells resources to multiply
This process is aided by proteins called chaperones
Describe what happens to viral DNA in the nucleus
It is made into a closed Circular DNA by viral polymerase
What is cccDNA?
Closed circular DNA
What is the role of ccDNA (Closed circular DNA)?
It serves as a template for transcription of 4 viral mRNAs by host RNA polymerase
What do the 4 mRNAs transcribed by ccDNA do?
The largest mRNA of the 4 is used to make copies of the gene,sme and to make the capsid core protein and the viral polymerase
The 4 mRNAs undergo additional processing to for progeny visions that are related from the cell or are returned to the nucleus
Name the different antigens found on hepatitis B
- HBsAg
- HBeAg
- HBcAg
When you take a blood test to check if you have hep B what are the doctors looking at?
They are looking for HBeAG
Why does the virus replicate in your cells?
As it is a safe place replicate as it is away from your immune cells
What does HBeAg stand for?
Hepatitis b e- antigen
Where is HBeAg found?
Found circulating in infected blood when the virus is actively replicating
If a persons blood tests show they have HBeAg what does that mean?
It suggests the the person is infection and is Able to spread the virus to other people
What does HBsAg stand for?
Hepatitis B surface antigen
If a persons sblood tests show they have HBsAg what does that mean?
It means that they have the hepatitis B surface antigen and so they are infected with hep B
Does everyone who with HBsAG in their blood have hep b?
Noe sometimes it is present in acute cases and in carriers who will have the antigen in their blood for more than 6 months
What does HBcAG stand for?
Hepatitis core antigen
Who will have HBcAG in their blood?
This antigen is present in anyone who has been previously exposed to or is currently infected with Hep b
Blood test results of:
HBsAG -, antiHBc-
means what?
Person is not currently infected and has never been infected with hep b
Blood test results of:
HBsAG+-,
means what?
The person is currently infected with Hep B
Blood test results of:
HBaAG–, anti HBc +
means what?
The person is not currently infected with hep B but has been previously
In chronically infected patients what does a blood test result of :
HBeAG +, anti HBe-
mean?
That there’s active viral replication occurring
In chronically infected patients what does a blood test result of :
HBeAG -, anti HBe+
mean?
That viral replication is under immune control
In vaccinated patients what does a blood count of anti hep
less than 100mlU/ml mean?
The person has not been vaccinated or the vaccine is ineffective
In vaccinated patients what does a blood count of anti Has 10-100mlU/ml mean?
There’s a partial vaccine response but repeating the vaccine should be considered
In vaccinated patients what does a blood count of anti Has more than 100mlU/ml mean?
Full vaccine repose and the patient is fully immunised
Worldwide how many people suffer from chronic hep B?
350 MILLION
In Europe how many people have been infected with hep B?
In Europe, 1 million infected every year
In the UK what is the most common way hep B is spread?
- Unprotected sex
- Needle sharing
- Occupation exposure
- Travelling to areas of high seroprevalence
Give some symptoms of acute hep B
- Loss of apetite
- Nausea
- Vomiting
- Body aches
- Mild fever
- Dark urine
- pruritis which leads to jaundice
8 Liver failure may result causing death
How long do the symptoms of hep B last?
Lasts a few weeks and then generally improvesBut patient nay be asymptomatic
Give some symptoms of chronic hep b
Possible development of hepatocellular carcinoma or cirrhosis
How is hep b treated?
- Most people recover spontaneously
- Some people clear the infection but some become carriers
- Immunocompromisedor chronic infection may need antivirals or immune system modulators
How are antivirals and immune system modulators used to treat hep b?
They are used to treat Immunocompromised or chronic infections
They font clear the infection but can stop it from replicating
What happens if a mother is positive for hep b?
If mother is positive new born is given antibodies (Hep B specific immunoglobins),
First dose of vaccine divine with in 12 hours
Follow up vaccines at 1,2 and 12 months
How can hep B be prevented?
Can be prevented by:
- Immunisation
- Safer sex
- Infecio control measures eg PPE, screening blood products, sterilisation
When was the first hep B vaccine developed?
Developed in 1981
How do current hep B vaccines work?
Currently in a recombinant form is used by inserting HBV coding area for surface protein into yeast allowing the yeast to produce the non-infectious surface protein
What is hepatitis C?
It is a single stranded RNA virus which replicated in hepatocytes
Where does hep C replicate
In hepatocytes
How is hep C spread
Through blood and body fluids
Which classification does Hep c fall under (According to Baltimore Classification )
Classification IV (ssRNA(+)Ta
Talk through the stages of hepatitis C replication
- Hep c attaches to a cell via proteins E on the virus and gets endocytosed
- Hep c is incorporated into cellular DNA, transcription and translation occur
- The virus shuts down other cell function to push viral replication
- Capsid production occurs and viral assembly
- virons are released
How does Hep C enter cell?
Hep c attaches to a cell via proteins E on the virus and gets endocytosed
What increases hep C risk?
- Blood trasfusion (prior to 1991)
- Unprotected sexual intercourse (considered low risk)
- Vertically from mother to baby (considered low risk 6%)
What percentage of the global population is infected with hep c?
3% of the worlds population
How many people worldwide are chronically infected with hep C?
Over 170 milloin
How may people are estimated to be infected with Hep c?
200,000- 400,000 PEOPLE
Give some symptoms of hep C?
Few symptoms at or around the time contract the Hepatitis C virus.
What happens to people infected with hep C?
20% of those infected with hep C clear the virus within the first 6 moths
80% of cases infection persists and this is called chronic infection
Give some symptoms of chronic hep C
Many people with chronic infection do not experience ill health, others are affected by vague symptoms, particularly fatigue.
How is the liver affected with hep C?
- About 20% of cases with develop scarring in the liver as ever cells die off (Cirrhosis)
- Some people may develop Liver cancer to liver failure
What is cirrhosis?
Liver scaring due to heath of liver cells
How quickly is the liver affected by hep c?
Can take 20-30 years for liver to be affected
Is there a vaccine for hep c? why?
No as it has a rapid mutation rate and has a highly variable structure
Describe the structure of hep c
Theres 6 viral genomes
How many people world wide are affected with hep B and hep D?
15 million
What is hep D frequently associated with in developed countries?
With iV drug use
What is hep D?
It is a sub viral satellite as it only replicated in the presence of hep B
What does Hep D need to be able to replicate?
Needs hep B
How does hep D recognise and enter liver cells
Hep D gains entry to the liver cells by recognising the presence of HepB surface antigens
How does Hep D replicate?
RNA polymerases are made by the viral genome to replicate the virus.
How does hep D affect hep b?
It worsens the progression of hep b as it increases cirrhosis, liver failure and caner risk
Which combination of hepatitis viruses has the highest mortality rate?
Hep B in combination with Hep d
How is hep E transmitted?
Via fecal oral route
What is the mortality rate of Hep E?
Low mortality 2%
Describe the effect of hep E in healthy patients
Often acute and self limiting
Describe the effect of hep E in immunocompromised patients
Hep E may become chronic leading to fibrosis and cirrhosis
What acts as a reservoir for hep E?
Domestic animals
What type of virus is HIV?
Retrovirus
what does HIV. stand for?
Human Immunodeficiency Virus
How does HIV work?
It uses RNA to store genetic information then uses reverse transcription to produce DNA which is incorporated into the host cell genome
Talk through the stages of HIV replication
- HIV binds and releases its capsid into the cell
- HIV releases reverse transcriptase to transform viral RNA to DNA
- The viral DNA then enters the cell nucleus and combines with the cells DNA
- HIV then replicates, gets re-assembled with viral protein present ‘immature HIV’)
- As the viral buds from the cell vital down the proteins making a ‘mature’ HIV.
Where is HIV present?
It is a blood borne virus present in blood, semen, vaginal fluid and breast milk
Name the main transmission routes of HIV
- Blood to blood contact
- Sexual transmission
- Vertically from mother to baby
How can we prevent the spread of HIV?
- Practice safer sex by using condoms
- Safer injecting, don’t share needles
- Antenatal treatment (vertical transmission)
- Sterile body piercing
- No sharing personal items like razors
- Infection control measures (PPE)
- Conception (insemination methods & sperm washing)
What does HIV target?
It targets and depletes CD4+ T cells
What does HIV progress into and how?
If enough CD4+ cells are delpleted then HIV progresses into AIDs
How is AIDs dangerous?
It leads to opportunistic infections and increases risk of certain cancers
When diagnosing HIV what do we look for?
We carry out routine HIV blood tests that test for:
CD4 and viral load
How are CD4 levels used to diagnose HIV?
Uninfected adults have adult 500-1600 cells/mm3,
The lower the number of CD4 cells the poorer the prognosis
What is considered a very low CD4 level?
Less than 200 cells/mm3
What does a CD4 level of Less than 200 cells/mm3 mean?
Means the patient has a very low level of CD4 and their condition may have progressed to AIDs
How is viral used to diagnose HIV?
By measuring the amount of HIV in the blood per ml
When is viral load undetectable?
Viral load is undetectable if there is less than 40-75 copies within 1ml of blood, depending upon the lab
How does the level of CD4 in the blood vary day to day?
lack of sleep, exercise
with exposure to transient infections
Other than diagnosing HIV what else is viral load used for?
Demonstrates how well the patient is responding to treatment
Give some of the symptoms of acute HIV
- Fever
- Head ache
- Rash
- Sore throat
- lymphadenopathy
- Fatigue
Give some of the symptoms of chronic HIV
- Fever
- lymphadenopathy
- Fatigue
- Weight loss
- diarrhoea
- Opportunistic infections
Give some of the symptoms of AIDs
- Weight loss
- lymphadenopathy
- Depression/ neurological changes,
- RAS
- Kaposi’s sarcoma
- opportunistic infections
What is common in HIV and Hepatitis?
Co infection is common due to shared routes of transmission
Which hepatitis does HIV accelerate?
accelerates Hep C progressions
What is a major cause of AIDs related death?
Hepatitis liver disease
What is a prion?
Infectious agent made entirely of protein
What do all non prion diseases in animals usually affect/
Affects the brain and neural tissue
What happens when a prion enters a healthy organism?
It induces existing portly folded proteins to convert into the misfiled prion form
The prion acts as a template to guide the misfiling of more proteins into the prion form
How do prions cause damage?
They aggregate and accumulate in infected tissue causing tissue damage and ultimately cell death
What are prions resist to and how?
Die to their structural stability prions are resistant to denaturation by chemical and physical agents making disposal and decontamination
What problems arise due to the fact that prions can’t be dentured?
Makes disposal and decontamination difficult
Are prions destroyed by autoclaveS?
NO if an instrument is suspected to have prions disease then that instrument is destroyed by incineration
describe how tissues infected with prions disease look under a microscope?
Microscopic holes occur in the affected tissue, giving a sponge-like appearance
What is CJD?
Creutzfeldt–Jakob disease
What does CJD (Creutzfeldt–Jakob disease) lead to?
Dementia
Personality changes
Hallucinations
Psychoses
How many people are believed to be carries of CJD (Creutzfeldt–Jakob disease)
1/2000 people due to infected beef products
Name the 4 different types of CJD
- Sporadic (sCJD)
- Familial (fCJD)
- Variant (vCJD)
- Iatrogenic
Which of the 4 different types of the CJD is the most common?
Sporadic (sCJD) account for 85% of CJD cases
What is the cause of Sporadic (sCJD)?
No cause identified
Familial (FCJD) accounts for how many cases of CJD?
15%
What is variant (vCJD) caused by?
Though to be caused by the consumption of food contamination with prions which also cause mad cow disease (BSE)
What causes iatrogenic CJD?
Arises from contamination with tissues from an infected person usually as a result of medical procedure
Name some medical procedures that are associated with the spread of CJD?
- Blood transfusion from infected person
- Use of human derived pituitary growth hormones
- gonadotropin hormone therapy
- corneal and meningeal transplants
What os HTLV?
Human T-lymphocytic virus
How many types of HTLV (Human T-lymphocytic virus) exist and which is the most important?
There are 4 types
Type 1 is the most important
What type of virus is HTLV (Human T-lymphocytic virus)
It is a retrovirus
What is HTLV 1 linked to?
myelopathy and leukaemia
What is HTLV 2 linked to?
milder neurological conditions and infections
What can people infected with HTLV develop?
Can develop cancer
1 in 20 - 1 in 25
How many people worldwide are infected with HTLV?
15-20 MILLION
What are Oncoviruses?
Viruses that can lead to cancer
Which cancer is associated with Hep B?
Heptocellular carcinoma
Which cancer is associated with Hep C
Heptocellular carcinoma
Which cancer is associated with HTLV (Human T-lymphocytic virus)
Adult T-cell leukemia
Which cancer is associated with HPV (Human papillomavirus)
Types 16and 18 are associated with cancers of the curved, anus, penis, vulva, vagina
Which cancer is associated with Kaposi’s sarcoma associated herpesvirus (HIV8)
Kapsoi’s sarcoma
Multicentric castlemasn disease
Primary effusion lymphoma
Which cancer is associated with Merkel cell polyomavirus (MCV)
Merkel cell carcinoma
Which cancer is associated with Epstein bar virus (EBV)
- Burkitt’s lymphoma
- Hodgkin lymphoma
- Post-transplant lymphoproliferative disease
- Nasopharyngeal carcinoma
Name the universal precaution to protect against HBV, HCV and HIV
- Personal hygiene – wash hands
- Protective wear – gloves, apron
- Cleaning up spillages
- Skin care
- Reported numbers of people who do not know they have HIV/hepatitis
- Stigma socially/culturally
By what percentage does a needle stick injury risk your chances of getting HIV?
low 0.3%
By what percentage does a needle stick injury risk your chances of getting HCV?
medium 3% - 10%
By what percentage does a needle stick injury risk your chances of getting HBV?
High 20%
What do you need to do if you have a needle stick/ sharps injury ?
- Bleed it
- Wash it h
- Cover it
- Report it
What is PEP?
Post Exposure Prophylaxis
It is a drug treatment to prevent infection under exposure
How effective is PEp against HIV?
up to 99% effective when taken correctly (within 72 hours)
HCV – no vaccine available, monitor for
How are we promoting the transition away from injecting drug use?
- By helping injectors switch
- By encouraging oral substitution drugs
- By preventing initiation into injecting
How are we preventing initiation into injecting by?
- By helping non injectors resist IV use
- By reducing influence of injectors on non injectors
- By offering alternatives to injecting eg smoking. snorting, swallowing , rectal
What is the probe with sharing injections?
Sharing needles and syringes can spread blood borne viruses
Who do people usually share needles with?
With sexual partners and friends
Name some commonly injected drugs
- Heroin
- Speed
- Cocaine
- Temazepam
- Dicinol
- Cyclizine
- Steroids
What is unsterile/ unsafe injecting also associated with?
Other infections like:
- Abscesses
- Cellulitis
- Ulcers
- Vein collapse
- septicaemia
- Endocarditis
What should safer injecting advice include?
- Use of sterile equipment
- Where to get sterile supplies
- How to prepare dugs fro injection
- Where and how to inject
- Dealing with problems associated with injecting
- Information about cross infection
- Cleaning injecting equipment
