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Infection > Session 8 > Flashcards

Session 8 Flashcards

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1
Q

Does the presence of HIV antibody mean a patient has a confirmed HIV infection?

A

Yes

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2
Q

What does the presence of HIV antibody indicate? Why is this a bad thing?

A

That the patient has been exposed to HIV and has mounted an immune response against it

The immune system is not effective at eliminating HIV

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3
Q

HIV establishes a latent infection in ________ T cells

A

CD4+

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4
Q

Why is HIV difficult to eradicate?

A

The virus is integrated into the host chromosome of CD4+ T cells and these cells are maintained indefinitely

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5
Q

Name four opportunistic infections linked to AIDS

A

Tuberculosis
Toxoplasmosis
PCP
Cryptococcal disease

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6
Q

Which organism causes tuberculosis?

A

Bacteria

Mycobacterium tuberculosis

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7
Q

Which organism causes toxoplasmosis?

A

Protozoa

Toxoplasma gondii

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8
Q

Which organism causes PCP?

A

Fungus

Pneumocystis jirovecii

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9
Q

Which organism causes cryptococcal disease?

A

Fungus

Cryptococcus neoformans

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10
Q

Name three conditions associated with HIV (peripheral signs that someone may have HIV)

A

Oral candidiasis
Kaposi’s Sarcoma
PCP

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11
Q

What type of organism causes Kaposi’s sarcoma?

A

Virus - member of the Herpes family

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12
Q

Kaposi’s sarcoma is almost solely linked with uncontrolled HIV. What is it? What parts of the body does it normally affect?

A

Rare type of cancer caused by viral infection

Skin/Internal Organs

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13
Q

Describe what will be seen in a chest X-ray in a patient with PCP (pneumocystis pneumonia)

A

Bilateral widespread consolidation - white patches of fluid/blood seen on the lungs

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14
Q

Describe how a patient with HIV may clinically present

A 
Weight loss
Loose motions 
New skin lesions on legs, sore mouth 
Fever 
Dry cough blood
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15
Q

Any of the usual pathogens can cause infection in HIV. Which type of infections are patients with HIV particularly prone to? (3)

A

Protozoal infections
Fungal infections
Reactivation of latent viral infections

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16
Q

Is HIV more common in men or women in the UK?

A

Men

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17
Q

Is it common for for IV drug users to have HIV in the UK?

A

No

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18
Q

Is the overall rate of new diagnoses of HIV increasing in the UK?

A

No - except in MSM where rate is increasing

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19
Q

Describe the structure of a virus (from inside to outside)

A

Genome
Capsid (Protein Coat)
(Lipid Envelope)

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20
Q

The genome in viruses can be either… (2)

A

RNA or DNA

Single stranded or Double stranded

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21
Q

What is a capsid of a virus? What two forms can it take?

A

The protein shell protecting the genome

Helical or icosahedral

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22
Q

Do all viruses have a lipid envelope?

A

No

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23
Q

In virus with a lipid envelope, where is this envelope derived? What does it contain?

A

Host cell membranes

Virus-specific proteins (antigens)

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24
Q

What does HIV stand for?

A

Human Immunodeficiency Virus

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25
What does AIDS stand for?
Acquired Immunodeficiency Syndrome
26
Describe the genome found in HIV
Single Stranded RNA
27
HIV is a retrovirus. What is meant by this?
Their genome is in the form of RNA, but they contain reverse transcriptase that allows them to transcribe their RNA into DNA after entering a cell. The retroviral DNA can then be integrated into the chromosomal DNA of the host cell.
28
Does HIV have an enveloped?
Yes - ENVELOPED
29
HIV contains a number of enzymes important for the replication of the virus and infects cell that have a _______ surface receptor
CD4
30
Which cells does HIV infect? (3)
Cells with a CD4 surface receptor Helper T cells (especially CD4+) Macrophages Dendritic cells
31
How does HIV cause damage once inside a cell?
Replicates inside cells. Destroys the cell. Causes inflammation. Spreads to more cells.
32
Describe how HIV infects and replicates in a cell
Virus binds to CD4 receptor and another co-receptor (either CCR5 or CXCR4) Virus contents emptied into the cell Genome of HIV converted into DNA form by the action of RT Viral DNA integrated into cell's own DNA by action of integrase Cell divides - long chains of viral proteins are made Viral proteins come together Immature virus pushed out of the cell (with some cell membrane) Protein chains in new virus are cute by proteases to make working virus
33
HIV binds to CD4 receptors and one of which other two receptors before it can enter a cell?
CCR5 | CXCR4
34
What role does reverse transcriptase play in HIV replication?
Converts single stranded RNA to double stranded DNA
35
What role does integrase play in the replication of HIV?
Integrates newly converted viral DNA into cell's own DNA
36
What action do viral proteases have in the replication of HIV?
Cut protein chains in the immature virus particle into individual proteins to produce a working virus
37
How is HIV transmitted?
Contact of infected bodily fluids with mucosal tissue/blood/broken skin
38
Generally, is a large or small quantity of infected bodily fluids required for transmission of HIV?
Large quantity
39
Name three ways HIV can be transmitted by infected bodily fluids
Sexual contact Transfusion Contaminated needles Perinatal transmission
40
Name three ways HIV can be transmitted in perinatal transmission. Which method is the most common?
During delivery (most common) Transplacental Breastfeeding
41
As well as in transfusions, HIV can be transmitted in... (2)
Skin grafts | Organ donation
42
What are the four main stages of HIV?
Primary infection Latent infection Symptomatic infection Severe infection/AIDS
43
Describe the viral load seen in the primary infection stage of HIV
Very high viral load
44
In which stage of HIV is a patient very infectious?
Primary infection - very high viral load
45
What happens to the CD4 cell count in primary infection stage of HIV?
Temporary drop in CD4 cell count
46
The primary infection stage of HIV lasts a few...
Months (~3)
47
How long can the latent infection stage of HIV last?
Months or years
48
In the latent infection stage of HIV, the virus begins at a certain low...
Set-point
49
What is the significance of a low set-point in the latent infection stage of HIV?
The lower the set-point, the better the prognosis
50
What happens in the latent infection stage of HIV? Describe the viral load and CD4 count seen in this stage of HIV.
Virus replicates and evades the immune system Increased viral load Decreased CD4 count ---> symptoms
51
The symptomatic infection stage of HIV is when the CD4 count drops below... What change will you see in the patient at this point?
350 Have symptoms - noticeably unwell
52
The severe infection (AIDS) stage of HIV is when the CD4 count drops below... What implication does this have for the patient?
200 High risk of life-threatening infections/cancer
53
What is myalgia?
Muscle pain
54
State some symptoms of acute HIV
``` Fever Weight loss Malaise Sores in mouth Oral candidiasis Lymphadenopathy Myalgia Liver and spleen enlargement Nausea Vomiting Rash ```
55
How might the liver and spleen be physically affected in acute HIV?
Enlarged
56
State 4 factors affecting HIV transmission
Type of exposure (e.g. Which sexual act, mucous membranes or blood) Condom use Viral level in blood Breaks in skin or mucosa
57
Give an example of when transmission of HIV is unlikely with regards to the viral level in the blood
Transmission is unlikely if undetectable viral load
58
How is life expectancy and quality of life affected by HIV?
Now usually normal life expectancy/quality of life
59
What can lead to a worse prognosis for HIV?
Late detection
60
Name 3 different diagnostic methods of testing for HIV and what each method detects
Serology - detects HIV Antibody + HIV Antigen PCR - detects HIV nucleic acid 'Rapid' Tests - detect HIV antibody
61
Which antigen/antibody is detected for by serology?
HIV antigen - Ag | HIV antibody - Ab
62
When can serology pick up HIV? How long does it take for results?
Any HIV after 4 week of initial infection Same day
63
When can PCR tests pick up HIV? Why is it not used for initial testing?
Detects very early infection (within few weeks) Expensive and slow
64
What do 'rapid' tests for HIV detect? What are some benefits of using these tests? What are they confirmed with?
HIV antibody Cheap, Quick Serology
65
What form may 'rapid' tests for HIV take?
Blood test - finger prick | Oral - saliva
66
Everyone should be tested for HIV if the rate is above... in a population
> 2/1000
67
Name two diseases that particularly should warrant HIV testing
Bacterial pneumonia | Meningitis
68
What are the aims of HIV treatment?
Undetectable HIV viral load (reduced risk of transmission) Reconstitute CD4 count Reduce general inflammation Good lifespan/quality of life
69
What is used to treat HIV?
Anti-retroviral drugs (ARVs)
70
ARVs are particularly focused on... ...to treat HIV
Inhibiting enzymes
71
When should treatment be started for HIV?
ASAP for everyone regardless of CD4 count
72
Name 5 types of antiretroviral drugs that may be given to treat HIV, that target different parts of the cycle of HIV replication
Nucleoside reverse transcriptase inhibitors (NRTI) Non-nucleoside reverse transcriptase inhibitors (NNRTI) Integrase Inhibitors Protease Inhibitors CCR5 Inhibitor
73
How many different ARVs are given to a patient with HIV?
3
74
Which combination of 3 ARVs are given in the treatment of HIV?
2x NRTIs + 1 Other (NNRTI, Protease Inhibitor, Integrase Inhibitor, CCR5 inhibitor)
75
Why are 3 different ARVs given in the treatment of HIV?
Virus mutates - every 2/3 rounds, millions of rounds per day. So resistance to drugs develops in days. With 3 drugs, viral replication is suppressed enough and it is harder for the virus to develop resistance.
76
Can a patient with HIV stop taking their ARVs at any point?
NO - important for the patient to keep taking drugs
77
State some strategies to reduce the prevalence of HIV
``` Increased condom usage Prevention of mother-child transmission AVR treatment as prevention Medical circumcision Pre/post -exposure prophylaxis of non-positive patient ```
78
What is hepatitis?
Inflammation of the liver
79
Many viruses cause 'collateral' liver damage. Give an example of such a virus. How do hepatitis viruses differ from this?
Epstein-Barr Virus (EBV) They replicate specifically in hepatocytes
80
Replication of hepatitis viruses in hepatocytes results in...
The destruction of hepatocytes Fibrosis ---> Cirrhosis ---> Cancer
81
Does hepatitis B result in chronic illness?
Yes
82
Does hepatitis C result in chronic illness?
Yes
83
Compare the incubation period of hepatitis B and hepatitis C
Hep B - 6 weeks - 6 months Hep C - 6 weeks - 12 weeks
84
How is hepatitis C transmitted? (3)
Blood Sex Vertical transmission
85
How is hepatitis C transmitted?
Blood (sex)
86
How are hepatitis A and E transmitted? Do they usually result in chronic illness?
Faeco-oral No
87
Describe the structure of Hepatitis B
DNA Double Stranded Enveloped
88
Describe the structure of hepatitis C
``` RNA Single stranded +ve Strand Enveloped Icosahedral ```
89
Are hepatitis B and hepatitis C enveloped?
Yes - both enveloped
90
Describe how a person with viral hepatitis may present
``` Fatigue Loss of appetite Abdominal pain Nausea Jaundice ```
91
Give examples of molecules that are measured in blood tests looking at liver function
Bilirubin Alanine transaminase (ALT) Alkaline phosphatase (ALP) Haemoglobin
92
What type of jaundice is seen as a result of viral hepatitis?
Intrahepatic jaundice
93
What is located in the centre of liver lobules?
Terminal hepatic venule (central vein)
94
The central vein of a liver lobule is surrounding by...
Sinusoids
95
What three structures are found at the edges of hepatic lobules? What name is given to this group of structures?
Bile duct Portal vein Hepatic artery Portal triad
96
Excess bilirubin leads to...
Jaundice
97
How is bilirubin formed? Where is it formed?
The breakdown product of haem Bone marrow
98
How is bilirubin transported to the liver for excretion?
Attached to albumin
99
What happens to bilirubin once it enters the liver?
Conjugation takes place, bilirubin made water soluble
100
In which two ways is conjugated bilirubin excreted?
In urine Most makes up the bile ---> Bowel ---> Faeces
101
State 3 types of jaundice
Prehepatic Intrahepatic Extrahepatic
102
What is the cause of prehepatic jaundice?
Haemolysis
103
State two causes of intrahepatic jaundice
Viral hepatitis Drugs Alcoholic hepatitis Cirrhosis
104
State two causes of extrahepatic jaundice
Common duct stones Carcinoma of... -bile duct -head of pancreas
105
Name 5 molecules that can be tested for in liver function tests
``` Bilirubin Liver transaminases ALP Albumin Clotting factors ```
106
Give two examples of liver transaminases. How will their levels be affected by hepatocyte damage?
ALT AST Raised in hepatocyte damage
107
Raised ALP in a liver function test indicates...
Biliary tract cell damage/cholestasis
108
What is cholestasis?
Abnormal/reduced/stopped bile flow
109
Where is albumin synthesised?
Liver
110
What effect will liver cirrhosis have on the production of albumin?
Less albumin will be produced
111
Where are clotting factors synthesised? A high INR indicates an increased or decreased risk of bleeding?
In the liver Increased risk of bleeding
112
What is the most common method of transmitting Hep B?
Vertical transmission
113
Apart from vertical transmission, how else can Hep B be transmitted?
Sexual contact IV drug use Needle-stick injury (healthcare) Close household contacts
114
Is it particularly common for Hep B to be spread to close household contacts?
Not particularly - significant blood exposure would be required
115
State some symptoms of acute Hep B
``` Jaundice Fatigue Abdominal pain Anorexia Nausea Vomiting ```
116
What is the incubation period of Hep B?
6 weeks - 6 months
117
AST/ALT will be seen at what levels in acute Hep B?
In the 1000s
118
In the majority of patients with acute Hep B infection what is the outcome?
Clearing of the infection in 6 months and life-long protection
119
In ~___% of adults Hep B can become chronic once infected How does this percentage change with infants?
10% Much higher risk with infants - ~90%
120
What is serology?
Blood tests helping to detect antibodies/antigens
121
How many detectable antigens/antibodies are seen in hepatitis B?
3 (of each)
122
What three antigens can be detected in hepatitis B serology?
HBsAg (surface antigen) HBeAg (e-antigen) HBcAg (core antigen)
123
Which antibody detects each of the following... I) HBsAg II) HBeAg III) HBcAg
HBsAb HBeAb IgM + IgG
124
What is the first antigen to become detectable in Hepatitis B? What is significant of the antibody for this antigen?
Surface antigen (HBsAg) HBsAb is the last antibody to appear
125
Which antigen is next to be detected after HBsAg? What is significant of the antibody for this antigen?
HBeAg (e-antigen) HBeAb is the first antibody to appear (after IgM)
126
On detection of which antigen, is Hepatitis B most infectious?
e-antigen (HBeAg)
127
Which antibodies detect core antigen (HBcAg)? Describe each of their roles.
IgM and IgG IgM - early infection IgG - once infection persists, will persist for life
128
Is core antigen detectable in the blood?
No - found ON liver tissue
129
What is the significance of IgM in serology for hepatitis B?
Can indicate whether Hep B has been acquired recently or not
130
How can levels of HBV in the blood be measured?
By carrying out PCR of the viral DNA
131
What is the definition of chronic Hep B infection?
Persistence of HBsAg after 6 months
132
The presence of the last Hep B antibody to be detected (HBsAb) indicates...
Clearance of the virus/recovery
133
Chronic Hep B infection can result in... (2)
Cirrhosis Hepatocellular carcinoma
134
Is there a cure for Hepatitis B?
No cure
135
Why is there no cure for Hepatitis B?
It integrates into the host genome
136
What is there treatment for individuals with Hep B?
Life-long antivirals to suppress viral replication
137
Why do some individuals infected with Hep B not require antiviral treatment?
Some people are inactive carriers and show a low viral load, normal LFTs and no liver damage
138
What does the HepB vaccine consist of?
Genetically engineered surface antigen producing a surface antibody response
139
How do transmission routes of Hep B compare with Hep C?
Same transmission routes ``` Vertical transmission Sexual contact Vertical transmission IV drug use Needle-stick injuries ```
140
The vast majority of people with Hep C in the UK are...
IV drug users
141
Are patients that contract Hep C likely to become chronically infected?
Yes - ~80% become chronically infected
142
Describe the symptoms seen by the majority of patients with Hep C
No symptoms - asymptomatic
143
In many cases individuals with Hep C (and Hep B) will have no symptoms. What vague symptoms may someone with Hep C experience?
Fatigue Anorexia Nausea Abdominal pain
144
How can Hep C be tested for?
Looking for the anti-Hep C antibody
145
What does a positive result for the anti-Hep C antibody indicate? (2)
Currently infected | Cleared in past (antibody remains life-long after infection)
146
What investigation is carried out if a positive anti-Hep C antibody result is taken?
Viral PCR to check viral load and confirm ongoing/chronic infection
147
Can Hep C be cured?
YES
148
What is the cure for hepatitis C?
Directly acting antiviral drug combo
149
How long are the antiviral drugs for the treatment of Hep C taken for? How effective is the cure?
8-12 weeks > 90% cure
150
State two disadvantages of the antiviral drug combo used in the treatment of Hep C
Expensive Patient can become re-infected
151
Is there a vaccine for Hep C?
NO
152
What precaution is taken in the case of needle-stick injuries in healthcare workers?
Post-exposure prophylaxis
153
State the risk of transmission from needle-stick injuries for the following conditions... I) HIV II) Hep C III) Hep B
1/300 (much lower if patient on ARVs) 1/30 1/3 (much lower if recipient is vaccinated)
154
Rate the following in order of their risk of transmission from needle-stink injury... HIV, Hep B, Hep C
Highest Risk ---> Lowest Risk Hep B Hep C HIV
155
Describe the immediate measures that would be taken in case of needle-stick injury in a healthcare worker
``` First aid - bleed and wash wound Collect blood from both parties Inform occupational health Check Hep B vaccination status Assess risk and need for HIV PEP ```
156
What does HIV PEP involve?
Early initiation of ARVs reducing the spread and replication of HIV
157
When must the ARVs in HIV PEP be given to a healthcare worker to be effective? How long are they given for? When are HIV tests taken to see whether PEP has been effective?
Within the first few hours 3x ARVs for 28 days Baseline, 1 Month, 3 Months
158
Describe the symptoms usually seen in acute infection from... I) HIV II) Hep B III) Hep C
Flu-like symptoms (sometimes no symptoms) Jaundice, nausea, abdominal pain, anorexia Usually none
159
How can the following be prevented... I) HIV II) Hep B III) Hep C
PEP, Condoms Vaccination Risk avoidance
160
What is the outcome of the following if untreated... I) HIV II) Hep B III) Hep C
AIDS Cure (majority), Chronic Infection (~10%) Chronic Infection (majority)
161
What is the treatment for the following... I) HIV II) Hep B III) Hep C
Life long ARVs None (if cleared), Lifelong anti-viral drugs (otherwise) 8-12 weeks of antiviral drugs

Infection (10 decks)

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