Blood Bourne Viruses Flashcards
What are viruses?
Obligate intracellular parasites without cellular structure
What do viruses consist of?
Molecule(s) of either DNA or RNA (but not both) surrounded by a protein coat
Do viruses have an envelope?
They may or may not
Where is the envelope of a virus derived from?
The plasma membrane of the host cell from which it is released
How do viruses reproduce?
They hijack the host’s mechanism for creating mRNA and production of proteins
What happens once viruses have reproduced in the host cells?
They can be released from the cell to infect other cells
How can new viruses be released from the original cell?
Can often occur by death of the infected cell
How can viruses be classified?
In a variety of ways, based on their structure
Give 7 examples of key viral classifications
Single-stranded, non-enveloped DNA viruses
Double-stranded, non-enveloped DNA viruses
Double-stranded, enveloped DNA viruses
Single-stranded, positive stand, icosahedral, non-enveloped RNA viruses
Single-stranded, positive strand, icosahedral or helical, enveloped RNA viruses
Single-stranded, negative strand, helical, enveloped RNA viruses
Double-stranded, icosahedral, non-enveloped RNA viruses
How many people does HIV infect per year around the world?
~2 million
How many new cases of HIV are there per year in the UK?
~6,000
How many people in the world have HIV?
37million
What happens if HIV is left untreated?
Most cases of HIV will progress to AIDS
How many deaths worldwide did HIV cause in 2014?
1.2million deaths
How many deaths did HIV cause in the UK in 2014?
320
How many people with HIV are there in the UK?
103,000
What % of those infected with HIV in the UK are men?
67%
What is the HIV prevalence in Leicester, compared to the UK?
3.8/1,000 in Leicester, compared to 1.9/1000 in the UK
What % of those infected with HIV are heterosexuals?
57%
What has happened regarding new diagnoses of HIV in heterosexuals since 2005?
It has decreased by 50%
How does the stage of diagnosis of HIV differ between heterosexuals and homosexuals?
> 50% of heterosexuals are diagnosed at a later stage
What is the result of heterosexuals being diagnosed with HIV at a later stage?
Worse outcome
What % of those with HIV in the UK are black African?
50-60%
What is the prevalence of HIV in IVDUs in the UK?
2/1000
What % of sexual transmissions of HIV in the UK do MSM account for?
57%
What is happening to the rate of sexual transmission of HIV by MSM?
It is increasing, whilst a decrease has been seen in every other group
What % of people living with HIV in the UK don’t know they have it?
17%
What is HIV?
A retrovirus
What does HIV do?
Infects and replicates within cells of the immune system, particularly CD4+ cells
How does HIV gain access to CD4 cells?
It binds to the receptors on the CD4 cells, and fuses with them to deposit their contents into them
What happens once HIV has deposited it’s contents into CD4 cells?
Single strands of viral RNA are then converted to double stranded DNA by reverse transcriptase
What happens once double stranded DNA has been produced from HIV RNA?
The viral DNA is combine with the cell’s down DNA by the integrase enzyme
What is the result of the combination of HIV DNA and the cells own DNA?
When the infected cell divides, the viral DNA is read and long chains of proteins are made
What happens to the proteins produced as a result of HIV DNA integration?
Sets of these viral proteins come together and push out of the cell, taking some membrane with it to form an immature virus
What happens to the immature HIV virus?
It breaks free of the cell and matures to form a working virus that can infect more cells
What is the result of the use of CD4 cells as a host by HIV?
Causes death of CD4 cells and damages the immune system
What is the result of the damage to the immune system caused by HIV?
Patients present with opportunistic infections
Give 3 examples of opportunistic infections a patient with HIV might present with
Oral candidiasis
Kaposis’s sarcoma
PCP (pneumocystis pneumonia)
What infections are HIV patients prone to in particular?
Infections from yeast, moulds, and protozoa
What happens to the levels of CD4 cells present when infected with HIV?
It alters the levels present, and this changes over time
What is the result of the altered levels of CD4 found in HIV?
Leads to altered states of health
What are the stages in a HIV infection?
Stage 1 - acute infection/seroconversion
Stage 2 - Latent infection
Stage 3 - Symptomatic infection
Stage 4 - Severe infection/AIDS
What happens in the acute infection/seroconversion state of HIV?
The body mounts an unsuccessful immune response and causes a brief fall in CD4 count
When does phase 1 of HIV infection occur?
2-3 months after exposure
What happens in the latent infection stage of HIV?
CD4 count remains high and the viral load is now
How long does the latent infection stage of HIV last?
Can last from 2 to 10 years, with some individuals never progressing from this stage
When do symptoms start to show in HIV?
If the CD4 count falls below viral load
What is the CD4 count in stage I HIV?
> 500
What is the CD4 count in stage II HIV?
<500
What is the CD4 count in stage III HIV?
<350
What is the CD4 count in stage IV HIV?
<200
Where do the symptoms of an acute HIV infection affect?
Systemic Central Mouth and throat Nose Muscles Liver and spleen Lymph nodes Skin Gastric
What are the systemic symptoms of an acute HIV infection?
Fever
Weight loss
What are the mouth and throat symptoms of an acute HIV infection?
Pharyngitis
Sores
Thrush
What are the oesophageal symptoms of an acute HIV infection?
Sores
What are the muscular symptoms of an acute HIV infection?
Myalgia
What are the liver and spleen symptoms of an acute HIV infection?
Enlargement
What are the central symptoms of an acute HIV infection?
Malaise
Headache
Neuropathy
What are the lymph node symptoms of acute HIV infection?
Lymphadenopathy
What are the skin symptoms of an acute HIV infection?
Rash
What are the gastric symptoms of an acute HIV infection?
Nausea
Vomiting
Where do the symptoms of later HIV/AIDS affect?
Brain Eyes Mouth and throat Blood Lungs Bone Heart Liver Stomach Reproductive system Body
What are the brain symptoms of later HIV/AIDS?
Cryptococcal meningitis
Toxo (toxoplasmosis)
AIDS dementia complex
What are the eye symptoms for later HIV/AIDS?
CMV (cytomegalovirus)
What are the mouth and throat symptoms for later HIV/AIDS?
Cold sores and ulcers
Thrush (oral candidiasis)
What are the blood symptoms for later HIV/AIDS?
Hyperglycaemia
Dyslipidaemia
What is dyslipidaemia?
Abnormal amount of fat in blood
What are the lung symptoms of later HIV/AIDS?
Histoplasmosis
PCP
TB
What are the bone symptoms of later HIV/AIDS?
Osteoporosis
What are the heart symptoms of later HIV/AIDS?
Heart disease
Stroke
What are the liver symptoms of later HIV/AIDS?
HCV (Hep C virus)
What are the stomach symptoms of later HIV/AIDS?
CMV
Crypto (cryptosporidiosis)
MAC (mycobacterium avium complex)
What are the reproductive system symptoms of later HIV/AIDS?
Genital ulcers HPV (human papillomavirus) and cervical cancer Menstrual problems PID (Pelvic inflammatory disease) Vaginal yeast infections
What are the body symptoms of later HIV/AIDS?
HIV wasting syndrome
What is the cure for HIV?
There is none
What is the prognosis of HIV?
Can be treated, and leads to a life of chronic infection
How do the life expectancy and quality of life of someone with HIV differ from person without?
Very good- if detected early, is treated adherently and with a healthy lifestyle, life expectancy can be equal to those without disease
What is the result of a late detection of HIV?
Worse prognosis
How is HIV transmitted?
Sexual transmission
Sharing of injecting equipment
Vertical transmission
Medical procedures
What are the methods of sexual transmission of HIV?
Vaginal
Anal
Oral
How can HIV be transmitted vertically?
In utero
During childbirth
Breastfeeding
What medical procedures can lead to HIV infection?
Using blood/blood-products
Skin grafts
Organ donation
What is transmission of HIV affected by?
Type of exposure Viral level Other STIs Condom use Breaks in skin or mucosa
What is the risk of HIV transmission if the source is HIV positive with a one unit blood transfusion?
90-100%
What is the risk of HIV transmission if the source is HIV positive with receptive anal intercourse?
1/90 (1.11%)
What is the risk of HIV transmission if the source is HIV positive with sharing injecting equipment?
1/149 (0.67%)
What is the risk of HIV transmission if the source is HIV positive with mucous membrane exposure?
1/159
What is the risk of HIV transmission if the source is HIV positive with needlestick injury?
1/333
What is the risk of HIV transmission if the source is HIV positive with receptive vaginal intercourse?
1/1000
What is the risk of HIV transmission if the source is HIV positive with insertive vaginal intercourse?
1/1220
What is the risk of HIV transmission if the source is HIV positive with insertive anal intercourse?
1/1667
What are the diagnostic tests for HIV?
Blood tests
‘Rapid’ tests
What is looked for in blood tests for HIV?
HIV antigen
HIV antibody
Is the HIV antigen or antibody used in the current standard test for HIV?
Both
How long after infection will blood tests be positive for HIV?
4-6 weeks
How long does it take to get a result of a HIV blood test?
Same day
Can you get a false negative result with HIV blood tests?
Yes
What is the advantage of rapid HIV tests?
Low cost
<1 hr
What are the types of rapid HIV tests?
Blood test (finger-prick) Oral (saliva)
How can rapid HIV tests be administered?
In-home tests
Postal testing
How accurate are ‘rapid’ HIV blood tests?
If negative, very accurate
May get false positives
Who should be tested for HIV?
Everyone, but some groups have additional need
What respiratory conditions would indicate a need for HIV testing?
Bacterial pneumonia
TB
What neurological conditions would indicate a need for HIV testing?
Aseptic meningitis
Dementia
Neuropathy
What dermatological conditions would indicate a need for HIV testing?
Severe psorasis
Seborrhoeic dematitis
Recurrent/multi-dermal shingles
What GI conditions would indicate a need for HIV testing?
Chronic diarrhoea Weight loss with unknown cause Salmonella Shigella Campylobacter
What haemotological conditions would indicate a need for HIV testing?
Any unexplained blood dyscrasia
LN
What oncological conditions would indicate a need for HIV testing?
Lymphoma
Anal cancer
Head and neck
What gynaecological conditions would indicate a need for HIV testing?
CIN2+
VIN
Any STI/Hep B/ Hep C
What is the treatment for HIV?
Anti-retroviral treatment
When should antiretroviral treatment be started in HIV patients?
As soon as possible, regardless of CD4
Why should antiretroviral treatment be started ASAP in HIV patients?
To increase outlook on morbidity and mortality
What is the aim of anti-retroviral treatment?
Prevent viral replication
How does anti-retroviral treatment prevent viral replication?
Inhibits reverse transcriptase
Inhibits integrase
Inhibits protease
How many drugs are used in combination to treat HIV?
3
Why are 3 drugs used in combination to treat HIV?
To combat resistance
Why must resistance be combated in HIV?
Over a million viruses are made each day, so it mutates quickly
What is the result of the treatment of HIV involving 3 viruses used in combination?
Makes it difficult for the virus to develop resistance to all of them
What does HIV treatment aim to do?
Create an undue table viral load
Reconstitute the immune system
Normalise lifespan
Reduce risk of infection
How many people does HBV infect around the world each year?
4 million
How many new cases of HBV are reported in the UK per year?
500
How many people in the world have the HBV virus?
400million (5-8% of population)
How many deaths did HBV cause worldwide in 2014?
~1 million
What is the prevalence of HBV in the UK?
1/1,000
What can HBV lead to if untreated?
Liver cirrhosis and hepatocellular carcinoma
What % of HBV cases lead to liver cirrhosis?
10%
How is hepatitis B transmitted
Blood
Sexual transmission
Vertically
Long term household contacts
How can HBV be transmitted in blood?
IVDU
HCW with needle stick injury
What is the risk of a HCW contracting HBV if they get a needlestick injury with a contaminated needle?
1:3
How can HBV be transmitted vertically?
Mother to child
Perinatal transmission in patients from high endemic areas
What is the incubation period of HBV?
6 weeks to 6 months
What can HBV progress too?
Chronic infection
What are the symptoms of acute hepatitis B?
Jaundice Fatigue Abdominal pain Anorexia Nausea Vomiting Arthralgia
What is athralgia?
Pain in joints
At what level is AST/ALTs in acute hepatitis B?
1000s
What % of hepatitis B patients present with no/vague symptoms?
50%
How long does it take for some people to clear the infection?
Within 6 months
What may result from acute hepatitis B?
Fulminant hepatic failure
Becomes chronic
In what % of acute hepatitis B cases result in fulminant hepatic failure?
1%
What % of acute hepatitis B cases become chronic?
6-10% of adults (more if from infancy)
What is classified as chronic hepatitis B?
Persistence of HBsAg after 6 months
What may result from chronic hepatitis B?
Cirrhosis
Hepatocellular carcinoma
What % of chronic hepatitis B infections lead to cirrhosis?
25%
What % of chronic hepatitis B infections lead to hepatocellular carcinoma?
~5%
How is hepatitis B diagnosed?
Serology
What is detected for in serology diagnosing hepatitis B?
Antigens and antibodies
When will surface antigen (HbsAg) be found in hepatitis B?
Acute infection
Chronic infection
When will surface antigen not be found in hepatitis B infection?
Past (cleared) infection
Never infected, vaccinated
When will core antibody (HbcAb) be found in hepatitis B infection?
Acute infection
Past (cleared) infection
Chronic infection
What core antibody will be found in acute hepatitis B infection?
IgM
What core antibody will be found in past (cleared) hepatitis B infection?
IgG
What core antibody will be found in chronic hepatitis B infection?
IgG
When will core antibody not be found in hepatitis B infection?
Never infected, vaccinated
When will surface antigen (HbsAb) be found in hepatitis B infection?
May or may not be in acute infection
Past (cleared) infection
Never infected, vaccinated
When will surface antibody (HbsAb) not be found in hepatitis B infection?
Chronic infection
What is the cure for hepatitis B?
None
What is the treatment for hepatitis B?
Life-long anti-virals to suppress viral replication
Are life-long antivirals required for everyone with hepatitis B?
No
Who will not require life-long antiviral treatment for hepatitis B?
‘Inactive’ carrier
How is someone determined to be an inactive carrier of hepatitis B?
Low viral load
Normal LFTs
Mild fibrosis
What is the vaccine for hepatitis B?
Genetically engineered surface antigen
How is the hepatitis B vaccine given? /
3 doses + boosters if required
How effective is the hepatitis B vaccination?
Effective in most people
How does the hepatitis B vaccine convey protection?
Produces surface antibody response
What surface antibody response is adequate to provide protecting in hepatitis B?
> 10
What surface antibody response provides long-term protection in hepatitis B?
> 100
How many people are infected with HCV per year around the world?
Unknown
Why is the number of people infected with HCV around the world unknown?
Many are not tested
How many people in the world have the HCV virus?
Around 200 million (3% of the population)
What is the prevalence of HCV in the UK population?
1 in 200 (most of them untested)
How many deaths from HCV were there in the UK in 2014?
424
What can HCV lead to if untreated?
Liver cirrhosis and hepatocellular carcinoma
In what % of untreated HCV infections does liver cirrhosis result?
80% of cases
Who is at risk of HCV infection?
IVDU/crack or heroin smokers Blood transfusion patients prior to 1991 Infants born to HCV positive mothers Sexual contact Needle stick injuries to HCW
How is the risk of getting HCV from sexual contact increased?
If HIV infected
What is the risk of healthcare workers getting HCV from a needlestick injury with a contaminated needle?
1:30
What % of patients with HCV become chronically infected?
80%
What does chronic liver disease and cirrhosis in patients who develop it as a result of HCV result in?
Decompensated liver disease
Hepatoma
Transplant
Death
What % of people with HCV have no symptoms?
80%
What are the symptoms of HCV?
Fatigue Anorexia Dark urine Nausea Abdominal pain
Can hepatitis C be cured?
Yes
What is the cure for hepatitis C?
Directly acting antiviral drug combination
How long is the course of treatment for hepatitis C?
8-12 weeks
What is the chance of cure for hepatitis C?
> 90%
How much does a course of hepatitis B treatment cost?
£50,000-£80,000
Can someone treated and cured of hepatitis C get reinfected?
Yes
Is there a vaccine for hepatitis C?
No
