wk 12- emerging infectious diseases Flashcards
what are emerging infectious diseases?
those that appear or re-appear in a population without warning
emergence and reemergence is associated with geographical location y/n?
yes
reasons for increased disease with developing compared to developed countries?
-poor sanitation
-increased population and housing density
-malnutrition
-reduced accèss to public health
list the risk factors for the emergence of infectious diseases 10
antimicrobial resistance
viral mutation
host resistance or susceptibility
economic development
technological changes
environmental change
international travel
inadequate/ reduced public health measures
wars and natural disasters
lifestyle factors
how can antimicrobial resistance contribute to emergence of infectious disease
antimicrobial overuse, underuse and misuse contributes to resistance through selection for infectious agents that can survive and or reproduce in the presence of the antimicrobial agent.
how does viral mutation contribute to emergence of infectious diseases
changes in viral replication are called antigenic drift. This causes newly emerging viruses to become unresponsive to vaccines and antiviral meds due to the immunity being naive of the strand
mutations occur quicker in single stand viruses
host susceptibility contributes to emerging diseases how
predisposing factors such as environment, climate and sanitation as well as biological and health factors increase the susceptibility to emerging infections
how does economic development contribute?`
Economic development and land use leads to changes in the exposure of human hosts to native environments, animals, and insects. Changes made by humans during industrial development often select for infectious agents, by enhancing the food supply or breeding environment for the animal or insect host, and arthropod vectors.
Areas in which close contact occurs between humans and animal reservoirs facilitates transmission of zoonotic diseases.
how do technological changes contribute?
Technological changes such as air-conditioning are associated with the distribution of infectious agents around internal building spaces.
Food production, processing, and preservation methods combined with cold chains mean that infectious agents in food can now be transported around the globe.
how does climate change contribute to infectious diseases emerging
Climate change now sees vectors (mosquitoes, ticks, and sand flies) more widely distributed, spreading beyond previous geographical regions.
how does international travel contribute
short transit times facilitate transmission of infectious agents during incubation and prodromal stages of disease
reduced public health measures contribute how?
breakdown in controls by the government to prevent disease such as vaccinations (objection, lack of access, poverty, etc)
how do wars and natural disasters contribute?
lead to a breakdown in infrastructure, displacement of large numbers of individuals, and subsequent poor sanitation and over-crowding. Collectively, these events result in the production of large volumes of untreated waste material, which acts as a reservoir for infectious agents and vectors
how do lifestyle factors contribute ?
behaviors such as multiple sexual partners, recreational drug use support increase in infectious disease rates
do vaccines needs to be revised and updated?
yes because of error-prone replication and transfer of virulence factors
which means viruses commonly have errors in its replication because there is no proof reading machinery
what challenges does antigenic variation in influenza cause? 2
accumulation of subtle differences in surface antigens over time (antigenic drift - A), which lead to failure of host antibodies to recognise and bind viral antigens
rapid and major recombination events (antigenic shift - B), which result in significant changes in viral surface antigens to which human hosts are completely immunologically naïve.
differences between antigenic drift and shift
change in surface antigens:
drift- minor point mutations (single nucleotides), shift- major mutations (gene reassortment)
differences between antigenic drift and shift
change in surface antigens:
drift- minor point mutations (single nucleotides), shift- major mutations (gene reassortment)
classification: drift- new strain. shift- new subtype
time frame- drift- random/spontaneous. shift- large, sudden
partial immunity: drift- yes. shift- no
vaccines and serogroups
vaccines are based on the most predominant serogroups for specific bacterial pathogens. Serogroups can differ between population groups
can serogroup predominance change ?
yes it can, therefore surveillance is required to track circulating serogroups
types of hosts for zoonotic diseases
primary (natural) host - asymptomatic carrier (bats)
secondary (transmission) host - moderate-severe illness (chickens)
Tertiary (spillover) host - severe illness (humans)
how do zoonotic diseases come about?
Where animals and humans co-habitate or interact frequently, viruses have the potential to jump the host barrier. The outcome of this interaction is generally detrimental to the immune naïve human host.
roles of healthcare worker with emerging diseases
comply with infection prevention and control policies and procedures
remain vigilant
remain up-to-date with controls
educate the public
these will all work to interrupt the chain of infection
