Disease emergence Flashcards
(14 cards)
What are EIDs? (emerging infectious diseases)
Infections that have recently appeared in a population
Or ones that have previously existed but are now rapidly increasing in incidence, geographic range or severity
Examples include new pathogens like SARS-CoV-2, known diseases in new regions like West Nile virus transmitted via mosquitoes or re-emerging diseases like tuberculosis
Why study EIDs?
Threats to global health
Economical impact
Social disruption
Forecast future pandemics
Enable rapid response and prevention
What are zoonotic diseases?
Any infectious disease or infection that’s naturally transmissible from vertebrate animals to humans (around 60% of all EIDs)
Can be caused by bacteria, viruses, parasites, fungi or prions
Spread through direct contact or indirectly via food, water or the environment
Spillovers
Transmission of a pathogen from its original reservoir population (animals) into a new host species (humans) that wasn’t previously infected
Examples of zoonotic disease
Ebola and rabies - both severe and lethal
Human to human transmission is a predominant feature of epidemics
What are the two emergence processes?
Introduction of pathogen in a new host population
Establishment and dissemination within a new host population
Factors contributing to disease emergence - ecological changes
Deforestation increases human-wildlife contact, altered vector habitats, biodiversity loss and habitat fragmentation
Example - zika virus pandemic is linked to deforestation as increased spread of mosquito
Agricultural development and land use also increased human-wildlife contact, habitat alteration, changes in vector ecology, intensified animal farming, water and food-borne diseases
Rice fields filled with still water are a good habitat for mosquitoes (malaria)
Factors contributing to disease emergence - pathogen and vector distribution
Increased survival and reproduction, expand geographical range, lengthen transmission season and susceptibility of hosts due to climate-induced stress
Lyme disease expansion through ticks, bacterium is called Borrelia burgdoferi
Canada has had recent severe heat waves leading to 144 cases in 2009 to 3000 in 2022
Factors contributing to disease emergence - climate change
Displacement and crowding, changes in recreational and social activities
Changes in agricultural practices like deforestation and land use
Examples include airborne disease transmission
Human demographics
Urbanisation and population growth
High population density, half global population lives in urban centres
Rapid spread due to global connectivity
Environmental infrastructure challenges
Migration and susceptibility
Mixed effects of urbanisation
Examples include Chikungunya pandemic in Bangladesh (2017) - spread really fast due to population density
Globalisation, international travel and trade
Microbial adaptation and change - Antibiotic resistance in S.aureus
The challenge
No one agency or organisation can do it alone
Resources are limited
No one is discipline trained to engage in such complex problems
Wildlife conservation society approaches
Hot spots
Sampling strategy
Testing strategy
Risk characterisation
Advantages of WCS
Better understanding of disease ecology
Improves environmental risk assessment
Provides stronger evidence of zoonotic transmission risk
Maximises resources
Surveillance and control - the importance of early detection and public health infrastructure
Role of biomedical innovations
Vaccine development - rVSV-ZEBOV vaccine for Ebola in 2014
Or covid mRNA vaccine
Drug-resistant malaria in South-east asia
AMR could cause 10 million deaths yearly by 2050
