Zoonotic Bacteria

Question 1

Define Zoonotic disease

Answer 1

Disease that is transmitted from animals and humans

Question 2

What is reverse zoonosis?

Answer 2

Humand to animals

Question 3

What is a disease reservoirs?

Answer 3

Environment or a population that maintains a pathogen

Question 4

What are the reservoir of:
Botulism
Brucellosis
Thphoid fever

Answer 4

Botulism: Soil, but the source of most motulism infection is improperly canned contailing C. botulinum spores

Brucellosis: Domesticated and wild animals, but the source of infection is unpasteurised food derived from these reservoirs

Thphoid fever: Can exist in asymptomatic individuals

Question 5

What is Campylobacter? WhO is effected Etc.

Answer 5

Diarrhoea caused by campylobacter spp.
Mild but can be fatal
Very young children, Elderly, immunosuppressed individuals
1 in 10 people fall ill and 33 mil of healthy life years are lost

Question 6

Provide some key virulence factors of Gram -ve food borne zonnotic bacteria

Answer 6

Flagella- prevent flushing out by peristalsis
Several adhesins that allow initial colonisation of the gut epithelium
Polysaccharide caspsule- immune evasion
Toxins: Cytolethal distending toxin CDT, AB-type toxin (a is a Dnase (damages the cell), for cell attachment.
Interferes with cell division
Only produced by some strains

Question 7

What is Verocytotoxin/Shiga toxin- producing Escherichia coli O157 (VTEC O157)?

Answer 7

Can cause severe stomach pain, bloody diarrhoea and kidney failure
E.coli O157 is found in the gut and faeces of many animals, particularly cattle

Question 8

Describe the mechanism of action of shiga toxin? (5)

Answer 8

Binding of GB3 receptor

Endocytosis and transport

Retrograde transport to the golgi and ER: toxins moves to golgi then to ER by passing lysosomall degradation

Inhibition of protein synthesis: The A subunit of the toxin is released into the cytoplasm, where it cleaves a specific adenine residue from the 28S rRNA of the ribosome. This modification prevents ribosomal function, effectively blocking protein synthesis.

Cell death: inhibition of protein synthesis leads to cell death—> leads to tissue damage particuatly in the intestine and kidneys

Question 9

Why are cattle a tolerant reservoir for Ecoli O157:H7?

Answer 9

They lack vascular receptor for Stx

Question 10

Give 2 Vector borne bacterial zoonoses?

Answer 10

Yesinia pestis- causitive agent of plague
Borrelia burgdorferi- causitive agent of lyme disease Gram -ve

Question 11

What does the salivary proteins help with in lyme disease?

Answer 11

Help in dissemination of Borrelia spp. by inhibiting macrophages and dedritic cells’ inhibition

Question 12

Describe the role of biodiversity in disease control?

Answer 12

Loss of biodiversity reduces host diversity
oNLY SPECIES THAT ARE MORE EFFICIENT AT HABOURING AND TRANSMISTTINF TE BACTRIUM STAY

Overabundance of reservoir hosts, White footed mice pop increase as bio div decreases (foxes and other predetors), Greater proportion of ticks become infected and more easily transmit lyme disease to humans

Increase Human-tick interactions: Higher transmission rates of Lyme disease to people as deforestation and habitata gramentation happens oftern bring humans, ticks and reservoir hosts into closer contact