Lecture 6- emerging diseases Flashcards
what is an emergent virus?
a causative agent of a new or previously unrecognized infection in a given population
what is the difference between zoonotic and enzootic?
zoonotic is animals to humans but enzootic is animals to animals
Viruses can ‘emerge’ from one population of hosts to infect a new population of hosts.
what is disease X?
the name given by scientists and the World Health Organization to an unknown pathogen that could emerge in the future and cause a serious international epidemic or pandemic.
how big is the virosphere?
Viruses are present in all kingdoms of life.
1031 virus particles on the planet (1023 stars in the observable universe).
10,000,000 virus particles/ml of seawater
what are the basics for a virus to be successful?
To be successful, viruses must replicate and transmit
These processes are driven by molecular interactions/processes that are by their very nature specific
Many viruses are ‘trapped’ in an evolutionary competition with their hosts – they become specialists in a given species.
what is the red queen hypothesis?
Many viruses are ‘trapped’ in an evolutionary competition with their hosts – they become specialists in a given species.
“It takes all the running you can do to keep in the same place”
what are viruses that are emerging right now?
Clade IIb Mpox – 2022 Global Outbreak with >93,000 cases and 177 deaths
Clade Ib Mpox – Democratic Republic of the Congo 2023-ongoing. in 2024 >30,000 cases and 800 deaths
H5N1 2.3.4.4b Avian Influenza in Cattle: AKA Moo Flu. 976 dairy herds affected as of feb 2025
is measles reemerging??
what are drivers of virus emergence?
climate change, animal husbandry, politics and society and deforestation
specialist vs generalist
specialist infects one host and general is multiple
what are notable emergent viruses?
Flaviviruses, West Nile Virus-
1937 - Uganda
Until 1999, never isolated in Western hemisphere
Culex pipiens
62 cases of encephalitis and 7 deaths
In infected humans ~25% experience flu like symptoms, <1% have serious neurological disease
Flaviviruses, Zika virus-
Originally isolated in the Zika Forest of Uganda in 1947 (and it likely circulates sporadically/low levels in humans in Africa)
Congenital Zika syndrome
Seroprevelance from Nicuragua
Originally isolated in the Zika Forest of Uganda in 1947.
filoviruses-
Cucumber mosaic virus
Ebola Virus
DRC and Ivory Coast
Coronaviruses
what are zoonotic viruses that became truly human viruses?
HIV and SARS-CoV-2
SARS-CoV-2 has optimized for efficient transmission in humans
what is Human Immunodeficiency Virus-1?
a retrovirus
A specialist virus that established in humans
These viruses are well adapted to their respective hosts – red queen and natural divergence of host genes.
Note due to specialist nature of SIVs there is only opportunity for spillover between closely related species.
is specifically adapted to human hosts
