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Pathogenesis Flashcards

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1
Q

What is a pathogen

A

Any agent that can cause disease
Similar to parasites

One organism using resources of another in a way which is not beneficial to the host.

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2
Q

Differences between parasites and pathogens

A

Cant see virus with naked eye

Can see parasites

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3
Q

What are prions

A

Infectious proteins that make correctly folded proteins folded incorrectly

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4
Q

What makes a successful pathogen

A

Gains access to the host

Locate nutritionally compatible niches

Avoid, subvert, or circumvent the host innate and adaptive immune response

Access host and resources

Exit and spread to new host (transmission)

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5
Q

When does infection occur

A

Access host resources and replicate

Not all exposure to pathogens result in disease

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6
Q

What is the innate immune system

A

Non-specific

Rapid

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7
Q

What is the adaptive immune system

A

Highly specific

Slower

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8
Q

What is virulence

A

Measure of disease severity

Mortality - number of deaths

Morbidity - number of cases

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9
Q

How do you measure pathogen success

A

“is it still around”

Infectious dose - number of individual particles required for infection

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10
Q

What is the mortality rate of ebola, plague, rabies and vCJD

A

ebola - 90%

Others - 100%

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11
Q

What are virulence factors

A

Adhesins - Find a niche and colonise host

Capsules (S-layer) - immune evasion/survival in host

Digestive enzymes - Finding a niche, colonizing and finding host resource

Toxins - Reprogram host biology to benefit the pathogen - make you sick

Stealth mode - Absence of outer-surface structures (immune evasion)

NOT for causing disease

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12
Q

What number of lower respitory infections are deaths worldwide

A

3.2 million

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13
Q

How many diarrhoeal deaths

A

1.4 million

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14
Q

How many TB deaths

A

1.4 million deaths

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15
Q

How many HIV deaths

A

1.1 million

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16
Q

What percentage of deaths world wide are from pathogens

A

54%

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17
Q

Who proved germ theory

A

Robert Koch

Established a scientific basis linking microbes and diseases

Pioneered the use of pure cultures to understand infectious diseases

States many diseases are caused by microbes

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18
Q

What did Robert Koch demonstrate germ theory with

A

bacterium Bacillus anthracis (anthrax)

Invented petri dish (hi Adam and Meg and Aidan)

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19
Q

What are Koch’s postulates

A

To prove a specific pathogen causes a specific disease

Host + pathogen = disease

Healthy rabbit never contains anthrax

Unhealthy rabbit always has anthrax

Microbe is isolated from the diseased host and grown

Inject healthy rabbit with anthrax and it becomes unhealthy

Same strain is obtained from the new host

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20
Q

What are the main advances in combating disease in the last 200 years

A

Clean water and better diet

Improved sanitation

Less overcrowding in urban areas with better living conditions also
contribute.

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21
Q

What are vaccines

A

Chemical agents which prime the adaptive immune system to repel a pathogen

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22
Q

What is immunity through vaccination

A

After vaccination, if the subject can be exposed to the pathogen
and does NOT develop the disease, they are said to be immune.

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23
Q

What is IgG

A

Default antibody

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24
Q

What is IgM

A

5 IgG molecules

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25
What does attenuated mean
Damaged particles
26
What is inactivated
Wont replicate
27
Who invented vaccination
Lady Montagu Directly added pus from smallpox into open vein of patient
28
What did Edward Jenner discover
Cross protection - inoculated a person with cowpox and they were then protected from smallpox Can vaccinate someone from a disease without using the disease
29
What is the last therapeutic option
Antibiotics
30
What are antibiotics
Chemicals produced by bacteria and fungi that inhibit or kill other microbes
31
Who invented penicillium
Alexander Fleming
32
Who did the first use of penicillin
Dr Cecil Paine
33
What did Florey and Chain discover
successfully manufactured the drug from the liquid broth in which penicillin grows.
34
How many lives has penicillin saved
between 80 and 200 million
35
What is the family of penicillins
Different types of penicillin for different usage Injection only, orally, narrow spectrum, broad spectrum, extended spectrum and resistant to B-lactamase enzymes
36
What does penicillin target
Cell wall synthesis
37
What do antibiotics target
Cell wall synthesis Protein synthesis Cell membrane integrity Nucleic acid function Intermediary metabolism
38
What is a symptom
A change in body function that is felt by a patient because of a disease "I feel a bit tired"
39
What is a sign
A change in the body that can be measured or observed because of disease  "temperature is high"
40
What is a syndrome
A specific group of signs and symptoms that accompany a disease High temperature, Feeling tired, Cough, Confusion
41
What diseases can streptococcus pneumoniae cause
Pneumonia, sepsis, Meningitis
42
How many ways can pneumonia be caused
Bacterial, Viral and Fungal Symptoms and signs are identical
43
What is the most abundant life form on the planet
Bacteria
44
What does the microbiota do
Help with digestion Metabolism Immune function Mood
45
What is commensalism
One organism benefits and the other is unaffected
46
What is mutalism
Both organisms benefit
47
What is parasitism
One organism benefits at the expense of the other
48
What is Clostridium Difficle
Pathogen - Clostridium difficile Disease - CDI Classification - Spore forming, Gram-positive bacteria Symptoms - Diarrhoea, Colonisation and inflammation of the colon Virulence - Mortality rate of 9%
49
What is an opportunistic pathogen
Microbes which are not normally pathogenic but can cause infection or disease if the host is compromised
50
What are hospital acquired infections
These infections are acquired because of a hospital stay Usually, patients are the cause of their own illness not the hospital
51
How does urbanization effect pathogenesis
More than 50% of the world live in urban areas Higher population densities drive many potential routes of transmission
52
What is Vibrio cholerae
Pathogen - Vibrio cholerae Classification - Gram - negative Disease - Cholera Symptoms - Large amounts of watery diarrhoea (rice water stool) Virulence - Death through severe dehydration - Can be 1% mortality if treated quick Transmission - Faecal-Oral route MVF - Cholera toxin Treatment - Oral REHYDRATION`
53
What was the first historical cause of epidemiology
Broad street water pumb for Vibrio cholerae
54
What is epidemiology
Study of where and when diseases occur to control | spread of disease
55
What are the principles of epidemiology
Identify first person to have the disease ‘Patient zero’ • Identify anyone who had contact with that person • Identify the reservoir for the pathogen • Blocking or contain it
56
What are the struggles of epidemiology
Difficult for new pathogens • Disease must first be recognised • Many already infected by then
57
What is an epidemic disease
disease acquired by many hosts in a given area in a short time
58
What is an endemic disease
Disease constantly present in a population
59
What is a pandemic disease
Worldwide epidemic
60
What is - Salmonella ‘typhi’
Pathogen - Salmonella enterica serovar Typhi Class - Gram-negative bacterium Disease - Typhoid Fever Symptoms - Rash (Rose Spots) - Symptoms are non-specific and extremely variable Reservoir - Human carriers (colonised gall bladder), 1-3% of people will permanently carry the disease Transmission - Faecal-Oral route Virulence - Mortality rate is about 30% without treatment.
61
What is Polio Virus
Pathogen - Polio Virus Class - + strand RNA virus Disease - Polio Symptoms - Irreversible paralysis (1/200), muscle weakness, atrophy, deformities, twisted feet or legs Reservoir - Faecal - Oral route, usually via a contaminated water source Treatment - Vaccine - Attenuated (weakened) virus
62
Why is polio virus vaccine an imperfect solution
In very rare cases, the virus can revert into a form capable of causing disease and infecting others (OPV paradox) In extremely rare cases some immunocompromised individuals appear to become ‘healthy carriers’ - Excreting large amounts of active Polio virus for long periods of time Polio vaccine is extremely safe to the person receiving the vaccine – but what about everyone else
63
What are famous examples of healthy carrierr
Typhoid Mary - thyphoid Birmingham man - Polio
64
What is Yersinia Pestis
Pathogen - Yersinia pestis Disease - Bubonic plague, Pneumonic plague Symptoms - Buboes (swollen lymph nodes), Pneumonia Virulence - extremely high mortality if untreated, bubonic - 50%, pneumonic - 90-100%. Treatable if less than 24hrs since symptoms Reservoir - Rodents, Priarie dogs - Rodent fleas, Human respiratory aerosol (pneuomonic)
65
What type of pathogen is Yersinia pestis
Zoonotic
66
What is Epizootics
Animal equivalent of an epidemic
67
What can pathogens infect
Any organism apart from viruses
68
What is Phytophthora infestans
Pathogen - Phytophthora infestans Disease - ‘Potato Blight’, Late blight Virulence - Approaching 100% of crops Treatment - Fungicides and copper sulphate Blight makes soil full of spores so the field is no longer usable
69
Where do potatoes originate
South America
70
Why is blight not a problem in South America
Wide variety of genetically different potatoes. Europe has a genetic bottleneck
71
What is influenza virus
Pathogen - Influenza virus Disease - Influenza 'flu' Virulence - Very varied 0.01% - 50%‘newer’ strains have higher case fatality rates. H1N1 (Hemagglutinin 1 and Neuraminidase 1) Flu weakens the immune system so that secondary infections are common
72
How are new influenza viruses made
Re-assortment of genetic material generates ‘new’ influenza virus particles Bird virus + human virus --> Swine cell --> new reassortant virus
73
What is Zika Virus
Pathogen - Zika Disease - Zika virus disease Virulence - Extremely low, most people have no symptoms Transmission - Mosquito (aedes)
74
How are new diseases identified
A disease is first identified as a geographically clustered pattern of symptoms and signs
75
What was the factor that identified zika
Microcephaly in babies (small skull --> small brain)
76
What is the Aedes mosquito a vector for
Dengue virus Zika virus
77
What is epidemiological surveillance
Epidemiological surveillance is the collection, analysis and dissemination of public health data Takes time, can be inaccurate Correlation based data falls very short of ‘cause and effect'
78
What is the updated Zika pathogen information
Sexually transmitted (men - 6 month and women - 8 weeks) Associated with birth defects microcephaly, Guillain–Barré syndrome
79
Where is Zika found
It is not limited to areas where the mosquito is found
80
What did epidemiological surveillance discover in the Zika virus
Set up the Zika Birth Defects Surveillance, Zika-associated birth defect rate in the US ≈ 5% Chances of any pregnancy having a birth defect ≈ 3%
81
What is Ebola
Pathogen - Ebola virus Disease - Ebola virus disease, Ebola hemorrhagic fever Symptoms - bleeding Virulence - Highly virulent, 40-90% mortality Reservoir - Unknown thought to be zoonotic Treatment - Currently untreatable Named after the ebola river in DRC
82
What is the biggest challenge to modern medicine
Antimicrobial resistance
83
Why is AMR such a big deal
The problem is the rate of drug discovery has sharply declined The continued use of antibiotics has driven selection for resistant strains Without antibiotics • Relatively minor infections would become life threatening • Surgery • Child birth • Chemotherapy (for cancer treatment) - ‘anyone who is immunocompromised’ • Infectious diseases would claim many more lives - particularly the elderly and the very young
84
Why is AMR so complex
Each antibiotic has a different target, each bacterial pathogen has a different virulence, characteristic and survival strategies and the resistance mechanisms are varied and poorly understood
85
What are antibiotics
chemicals produced by bacteria and fungi that | inhibit or kill other microbes
86
An infectious disease state is…
when a biological conflict occurs between host and pathogen

University - Microbiology (8 decks)

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