Humans and other animals: Zoonoses and Public health Flashcards
(105 cards)
1
Q
What are zoonoses?
A
Diseases that are naturally transmitted between vertebrate animals and humans
A diverse group of diseases caused by different types of agents (bacteria, parasites, viruses…)
Their transmission pathways are also very diverse
2
Q
How are zoonotic diseases transmitted?
A
Airborne
- E.g. Transfer of viruses
Vectors
- Transmitting infected agents from animals
Direct contact with animals
- E.g. bites from an infected animal
Food-borne
- Consuming infected meat or milk
Close proximity to animals
- Faecal/oral transfer/animal body fluid in cuts
3
Q
Give an example of a zoonosis that can be transmitted by direct contact:
A
Transmission of rabies by bite (saliva) from a rabid animals
4
Q
Give an example of a zoonosis that can be transmitted by faecal-oral route:
A
Transmission of salmonella to humans from different animal species
5
Q
Give an example of a zoonosis that can be transmitted by food products:
A
Brucellosis from cheese made from contaminated unpasteurised milk
6
Q
Give an example of a zoonosis that can be transmitted by dust:
A
Q fever
7
Q
Give an example of a zoonosis that can be transmitted by insects:
A
Rift valley fever (mosquitoes)
Lyme disease (ticks)
8
Q
Do zoonoses always have only one transmission pathway?
A
NO!
Many zoonotic pathogens will have overlapping transmission pathways
9
Q
Some pathogens which are typically foodborne can also be transmitted by direct contact or through the environment via the faecal-oral transmission pathway. Can you name some of these?
A
Salmonella
Campylobacter
E Coli O157
Cryptosporidium
Giardia
10
Q
Who might be at high risk of infection by zoonoses which can be transmitted via food or contact with the environment through the faecal-oral transmission pathway?
A
Young children
11
Q
What do we know about notifiable zoonoses?
A
Statutory requirement to report a suspicion of a clinical case of disease
Notifiable diseases are diseases named in section 88 of the animal health act 1981 or an order made under that act…
12
Q
Can you name any notifiable zoonotic diseases?
A
Brucella Spp.
Bovine TB
Avian Influenza
13
Q
What do we know about reportable zoonoses?
A
The report is to be made by the laboratory which isolated the organism from an animal derived sample
Based on laboratory diagnosis and not clinical suspicion
14
Q
Can you name any reportable zoonotic diseases?
A
Q-fever
Avian chlamydiosis
15
Q
Can you name any zoonotic disease examples in cats?
A
Cat scratch disease
Pasteurellosis
Ringworm
16
Q
Can you name any zoonotic disease examples in Dogs?
A
Campylobacter infection
Salmonellosis
E coli infection
Rabies
Toxocara spp
Ringworm
17
Q
Can you name any zoonotic disease examples in Rabbits?
A
Tularaemia
Salmonellosis
Cheyletiellosis
Cryptosporidium
Ringworm
18
Q
Can you name any zoonotic disease examples in Parrots?
A
Psittacosis
Salmonellosis
Newcastle disease
19
Q
Can you name any zoonotic disease examples in Turtles?
A
Salmonellosis
Campylobacter infection
Pentastomid parasites
20
Q
What percentage of human pathogens are zoonotic? (according to WHO)
A
At least 61%
21
Q
What percentage of emerging diseases in humans are zoonotic? (According to WHO)
A
75%
22
Q
What are emerging zoonoses?
A
New agents, or previously known agents appearing in places or species in which they were known
23
Q
What are re-emerging zoonoses?
A
Previously known and controlled or of a low incidence, and has returned or is resurging
24
Q
Can you name some re-emerging infectious diseases?
A
2022 - Dengue
2021 - Avian influenza A
2007 - Chikungunya
2016 - Crimean-Congo Haemorrhagic fever
2014 - Ebola
etc.
25
What are the evolution stages of animal pathogens to cause infection in humans?
Stage 1: Agent only in animals
No transmission
Stage 2: Primary infection
Transmission only from animals
Stage 3: Limited outbreak
Transmission from animals or (few cycles) humans
Stage 4: Long outbreak
Transmission from animals or. (many cycles) humans
Stage 5: Exclusive human agent
Transmission only from humans
26
Which evolution stages of animal pathogens to cause infection in humans are reached by Rabies?
Stage 1 and 2
27
Which evolution stages of animal pathogens to cause infection in humans are reached by Ebola?
Stages 1, 2, and 3
28
Which evolution stages of animal pathogens to cause infection in humans are reached by Dengue?
Stages 1, 2, 3, and 4
29
Which evolution stages of animal pathogens to cause infection in humans are reached by HIV-1 M?
Stages 1 to 5
30
What are some factors (drivers) associated with emergence of emerging zoonotic diseases?
Environmental, climatic changes
Habitat destruction
Human and animal demography (living in close contact with animals)
Changes in farming practices/land use
Pathogen changes
Global travel
Social and cultural factors
- Food habits
- Religious beliefs
- Cultural practices
31
What are the factors associated with emergence of emerging zoonotic infections from a one health perspective?
All interconnected
Environment
- Translocation
- Encroachment introduction
- Human encroachment
- Ex-situ contact
- Ecological manipulation
Human:
- Global travel
- Urbanisation
- Biomedical manipulation
- Technology and industry
- Human encroachment
- Ex-situ contact
- Ecological manipulation
Animal:
- Technology and industry
- Encroachment introduction
- Agricultural intensification
32
What is the ecosystems perspective on disease emergence?
Landscape:
Population growth, technology, and consumption
leads to regional environmental change
Natural community:
Urbanisation, forest habitat alteration, agricultural intensification
leads to species ecological-evolutionary dynamics
Population:
Host pathogen dynamics
leads to DISEASE EMERGENCE
33
What do you know about the example of disease spread to new geographical areas - Ebola 2014?
Ebola virus outbreak in West Africa, 2014.
2-year-old child who died in a remote village (Meliandou) in forested area of Guinea on December 6, 2013
Single introduction into the population, thought to be through contact with wildlife (bats)
34
Can you think of another example of disease spread to new geographical areas?
Zika virus
Has spread to 14 countries
35
Can you give an example of when zoonotic diseases spread to new species?
Bovine TB spread from Alpaca to humans
Bovine TB spread from pet cats to humans
36
Where can zoonotic diseases spread?
To new geographical areas
To a new species
37
What are some ways that zoonotic diseases can spread?
Global travel
Global agricultural markets
Bush meats
Live markets
Indirect animal exposure
38
How can global travel spread zoonotic diseases? An example?
Global travel significantly contributes to the spread of zoonotic diseases by facilitating the rapid movement of infected individuals and animals across geographical boundaries. Increased human mobility, including air travel, allows infectious diseases to be introduced to new regions quickly, potentially initiating or exacerbating epidemics.
H1N1 global invasion by air travel (March - Mid May)
39
How can global agricultural markets spread zoonotic diseases? An example?
Animals exported as meat or their products can facilitate the spread of disease.
E.g. lamb from New Zealand
Carrots from South Africa
pears from Argentina
pineapples from Ghana
40
How can bush meat spread zoonotic diseases?
Bushmeat can spread zoonotic diseases through several pathways, primarily during hunting, butchering, and consumption. These activities involve contact with animal blood, bodily fluids, and tissues, increasing the risk of pathogen transmission to humans
41
How can live markets lead to zoonotic spread?
Animal crowding in wet markets can cause zoonosis by forcing interaction among different taxa that would not encounter each other in nature
Could also infect humans via close contact
42
Can you describe the example of indirect animal exposure in MERS-CoV?
Insects
- Attract bats
Bats
- Excreta
- Saliva
- Parturition
Palms
- Dates
- Sap/drinks
- Shade
- Contact (climbing)
Dust/dirt
- Contaminated
Wind
- Stirs up dust
Structures/caves
- Bat roosts
- Baboon/cat contact
Baboons
- Fresh excreta
Camels
- Fresh excreta
- Meat prep
- Milking
- Close contact
Cats
- Fresh excreta
- Pets
- Close contact
Humans
- Aerosol
- Inhalation
- Ingestion?
- Self-inoculation
- Eye rubbing
- Nose picking
43
What are vector-borne diseases?
Transmitted through an intermediate arthropod including ticks and insects (mosquitos, sandflies)
Vector is essential for the life-cycle of the pathogen
Can be zoonotic (reservoir: animal)
44
What is the primary transmssion cycle of a vector borne disease?
Natural host
Vector
Natural host
Vector
Incidental host
Vector
Natural host
etc
45
Can you give some examples of vectors?
Mosquitos (dengue)
Sand flies (leishmania)
Ticks (TBE, Lyme disease)
Fleas (plague)
46
Can you give some examples of animal reservoirs?
Bats
Rodents
Pets
Livestock
Primates....
47
What do map distributions of vectors depend on?
Geographical factors
Meterological factors (climate change)
ECDC monitors occurrence of disease vectors in the EU
48
What is Nipah Virus, where was it first detected?
Paramyxovirus
First detected in Kampung Sungai Nipah, Malaysia
49
What is the animal reservoir for Nipah?
Pteropus bats and pigs (intermediate host)
50
What happens with Nipah virus?
Causes acute respiratory syndrome and fatal encephalitis (in humans)
High fatality rate (up to 100% in some outbreaks)
51
When would you consider a zoonosis to be 'endemic'?
When it is constantly present in a certain population
52
What do you know about endemic zoonotic disease? What factors may cause endemicity?
It is constantly present in a certain population
Common in developing countries
People living in close contact with animals
Often affects both animal and human health
High impact on livelihoods
53
What are the impacts of animal diseases in low-income countries?
Animal disease
- Production losses
- Costs of interventions
- Reduced market access
Zoonoses
Nutrition
Human disease
- Morbidity and mortality
- Costs of interventions
- Income losses
All lead to poverty
54
What are neglected zoonotic diseases?
Massively under-reported
Cause significant human morbidity and mortality
Cause dual burden in human and animal health
Often eliminated in affluent countries
Control is cost-effective if feasible
Usually no potential for global spread
Affect poor and marginalised communities
55
What is WHO's comment on neglected zoonotic diseases?
"The vast majority are not prioritised by health systems at national and international levels and therefore labelled as neglected"
56
Can you give some examples of neglected zoonotic diseases?
Anthrax
Brucellosis
Bovine TB
Cysticercosis and neurocysticercosis
Hydatid disease
Rabies
Human African Trypanosomiasis
57
What is the causative agent of anthrax?
Bacillus anthracis
58
What are the sources of anthrax infection?
Infected animals
Infected animal products (meat, hides)
59
What are the types of Anthrax infection?
Cutaneous anthrax
Inhalation anthrax
Gastrointestinal anthrax
Injection anthrax
60
What are the causative agents of Brucellosis?
Brucella abortus
B. melitensis
B. suis
61
What does Brucellosis cause?
Abortion and orchitis in affected animals
Up to 268.8 human cases per 100,000 person-years (Iraq)
High morbidity - children and elderly
Pathways for human exposure mainly occupational or foodborne
62
What do you know about Neurocysticercosis (Taenia solium)?
1. Eggs of gravid proglottids in faeces and passed into the environment
2. Embryonated eggs and/or gravid proglottids ingested by pigs or humans
3. Oncospheres hatch, penetrate intestinal wall, and circulate to musculature in pigs or humans
Infective stage!
Oncospheres develop into cysticerci in muscles of pigs or humans. Cistercerci may develop in any organ, being more common in subcutaneous tissues as well as the brain and eyes
4. Humans acquire the infection by ingesting raw or undercooked meat from infected animal host
5. Scolex attaches to the intestine
6. Adults in the small intestine
63
What do you know about a Hydatid Cyst (Echinococcus granulosus)?
1. Adult in small intestine
2. Embryonated egg in faeces (faecal-oral route)
3. Oncosphere hatches: penetrates intestinal wall
4. Hydatid cyst in liver, lungs etc
5. Protoscolex from cyst
6. Scolex attaches to intestine
64
What are some factors affecting bovine tuberculosis?
Fomites in soil
Latrines
Water
Mineral licks
Feed troughs
Concurrent disease
history of bTB
Numbers in herd
Herd type
Production cycle in cow
From market
Other disease problems e.g liver fluke, paratuberculosis
65
What is the food chain?
Animal --> Raw material --> Product --> Consumer
or
Animal --> Raw material --> Consumer
66
What are supplies needed pre-harvest?
Feed
Housing
Hygiene
Treatments
Etc.
67
What happens at harvest?
Collecting
Milking
Slaughter
Cutting, cold store
Etc.
68
What happens post harvest?
Processing
Transport
Storage
Handling
etc.
69
What is the definition of risk?
Requires the existence of a hazard
Several possible outcomes, one or more unwanted
Uncertainty about which outcome will occur and the frequency and magnitude of that outcome
Risk is the combination of FREQUENCY and MAGNITUDE of an unwanted outcome existence of a HAZARD
70
What are the parts of risk?
Probability of occurrence and impact
E.g. probability of being infected with a pathogen originating from an animal or food of animal origin
71
What does risk depend on?
Occurrence of the pathogen in animals
Transmission pathways
72
What is risk analysis?
Structured, transparent approach to deal with undesired events that might happen in the future
Based on scientific knowledge
73
What are the objectives of risk analysis?
Priority setting
Selection of prevention strategies
74
What are the steps of risk analysis?
Hazard identification --> Risk assessment --> Risk management
All part of Risk Communication
75
How is risk of infection with a pathogen originating from an animal assessed?
Evidence on the prevalence of the hazard in the target populations
- Different animal species
- Different regions/countries/areas
- Production systems
Probability of infection
76
What information about the biology of the hazard is required for risk?
Transmission pathways
Survival in the environment
Infective dose
Consequences of exposure in humans (disease, severity, duration, cost)
77
How can zoonoses be prevented and controlled at farm level? (Health of animals)
Healthy animals = reduced risk of infection
Vaccination and worming programmes
Avoid contamination of animal drinking water
Routine veterinary health checks
Implementation of Herd health plans
Good animal husbandry and management practices
Implementation of biosecurity measures
78
How can zoonoses be prevented and controlled at farm level?
Control pests and vermin
Educated/make aware farmers and visitors
Detection and reporting of human and animal diseases
- Surveillance programmes
- Awareness
- Communication
79
What are the objectives of surveillance of emerging zoonotic diseases?
Detect geographical expansion of known pathogens
Detect virulent strains of known pathogens (e.g. AMR, MDR-TB)
Detect new pathogens (unknown causative agent, reservoirs, vectors)
80
What are some types of surveillance?
Syndromic or rapid response surveillance
Information surveillance
Sentinel surveillance
Laboratory surveillance
81
What is syndromic or rapid response surveillance?
Broad case definition --> High sensitivity
Focus on a set of symptoms
Not clinical or lab-based
82
What are the strengths of syndromic or rapid surveillance?
Timelines
Completeness of data
Ability to detect emerging diseases
Ability to assess the true absence of local outbreaks
83
What is a weakness of Syndromic or rapid response surveillance?
Low specificity --> High number of false positives
84
What is information surveillance?
Scanning process - use of email or internet-based data gathering
ProMed, HealthMap, e-journals, discussion forums, Google...
85
What are the strengths of information surveillance?
No governmental bureaucracy - no censorship
Disregards jurisdictional boundaries
86
What are the weaknesses of information surveillance?
Not 'peer-reviewed' - use of informal sources
False positives observed
87
What is sentinel surveillance?
Use groups of animals or locations representative of the general population of interest
Surveillance of bovine, pig and poultry diseases
Use of animals to assess risk to humans
Most effective if combined with targeted surveillance
88
What is a strength of sentinel surveillance?
Allocation of resources when these are limited
89
What are some weaknesses of sentinel surveillance?
Can be expensive - lab testing required for asymptomatic reservoirs
Cost-effective? Prevention of human cases
90
What is laboratory surveillance?
Systematic collection, analysis and interpretation of laboratory data to monitor and track disease in a population
Data from laboratory networks
Standardised lab testing methods - can be adapted for new pathogens (e.g. PCR)
91
What are the strengths of laboratory surveillance?
Differential diagnosis possible (various pathogens can be differentiated by standardised lab testing methods)
92
What is a weakness of laboratory surveillance?
Needs well-defined case definitions to be diagnosed/recorded as a case, which can be a challenge in newly emerging diseases
93
What are the challenges of emerging zoonoses surveillance?
May require collaboration between multiple agencies
- Multi-species transmission (production animals, companion animals, wildlife...)
Absence of regulations for sharing of data across sectors and countries
Underreporting of zoonotic diseases
- Fear of economic losses, negative press by farmers
- No economic incentive for reporting by labs
Limited understanding of disease at the time of emergence
Lack of case definition
94
What is anti-microbial resistance (AMR)?
Antimicrobial resistance (AMR) occurs when microorganisms, like bacteria, viruses, fungi, and parasites, develop the ability to withstand the effects of antimicrobial medicines that are normally used to treat them
95
What are some mechanisms of resistance?
Natural or intrinsic resistance
Mutational resistance
Extrachromosomal or acquired resistance
Horizontal transfer
96
What are the steps of horizontal gene transfer?
a. Bacterial transformation
Release of DNA
Antibiotic-resistance
b. Bacterial transduction
Phage infected donor cell
Release of phage
c. Bacterial conjugation
Transposon donor cell
97
What do we know about Methicillin-Resistant Staphylococcus Aureus (MRSA) in companion animals?
Animals act as reservoirs (colonisation) or develop disease
Pet owners, healthcare workers, history of hospitalisation
Small animal hospitals: nosocomial transmission
98
What do we know about Methicillin-Resistant Staphylococcus Aureus (MRSA) in livestock?
LA-MRSA-DT 398
Pigs and Calves
Colonisation but can also cause disease
Occupational risk? Farmers and veterinarians
Meat of colonised/infected animals deemed safe for human consumption
99
What is Colistin resistance (mcr-1 gene)?
Colistin is critical for the treatment of infections caused by carbapenem-resistant bacteria in humans (in combination with tigecycline)
Colistin has been widely used in livestock (poultry and pigs) for mass treatment of gastrointestinal infections and prophylaxis
HGT of colistin resistance first described in china and now widespread globally
100
What are ESBLs (extended spectrum beta-lactamases)?
Gram-negative bacteria (Enterobacteriaceae)
Beta-lactamases that hydrolyse extended-spectrum cephalosporins with an oxyimino side chain
Plasmid-mediated
- Occurred by mutation (TEM-1, TEM-2, or SHV-1) or by transfer from Kluyvera spp (CTX-M)
- Community and healthcare-associated infections
- Isolated in pigs, poultry, cattle, but also in companion animals
101
Why no new antimicrobials?
Issues for the pharmaceutical industry
Regulatory requirements increase
- Marked increase of costs of R&D
Patents expire soon after market introduction
Treatment times are short
- Decreased revenues or higher prices
- No economical incentive for pharmaceutical companies!!
New drugs reserved as a last resort
102
How is AMR prevented and controlled?
In the absence of new antimicrobials down the pipeline...
Stewardship of antimicrobials in human and veterinary medicine
- Guidelines and recommendations
- Auditing of use at practice, farm level
- Education and training of antibiotic users
- Compliance from animal owners
Develop alternatives to antimicrobial therapy?
Better preventative medicine!
Improve animal husbandry and management practices
103
How can zoonoses transmission occur?
Through contact with animals, vectors or a contaminated environment
104
Why is risk analysis important?
Important to identify potential hazards and to develop prevention and control measures
105
Why is surveillance data essential?
Essential for early detection of new emerging zoonoses, to monitor endemic zoonotic diseases and assess effectiveness of intervention measures
