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Yellowfever-Aclimate-drivenviralthreat.pptx
Yellow fever- A climate-driven viral threat
Arlene Taveras
BIO 212-Microbiology
Dr. Ruffin
February 19th, 2026
1
Overview
2
What is yellow fever?
How infection happens inside the body?
The virus behind the disease
How climate change affects spread?
Global impact and future outlook
How we can fight it
SECTION 1: The Pathogen
What is yellow fever?
Source support: (WHO 2023; CDC 2024)
Mosquito-borne viral hemorrhagic fever
Causes fever, jaundice, bleeding
Endemic in Africa & South America
Can be fatal in severe cases
4
The Virus
Family: FLAVIVIRIDAE
GENUS: FLAVIVIRUS
Positive-sense single stranded RNA
Enveloped virus
Unique features: only one serotype
Highly effective vaccine exists
(Scientific foundation from Monath & Vasconcelos, 2015
5
Section 2
Life cycle & transmission
TRANSMISSION CYCLES
Sylvatic (Jungle) cycle
Mosquito--- monkeys
2. Urban CYCLE
Mosquito Humans
Primary vector: Aedes aegypti
(From Monath & Vasconcelos, 2015
7
SECTION 3: INFECTION Process
WHAT CELLS ARE ATTACKED FIRST?
After mosquito bites:
Virus enters bloodstream
Infects: Dendritic cells & Macrophages
Travels to lymph nodes
Spreads to liver
HOW THE VIRUS ENTERS CELLS
Viral envelope binds to host receptors
Enters via receptor-mediated endocytosis
Acidification triggers fusion
RNA leased into cytoplasm
Viral replication (inside the host cell)
RNA translated into one large polyprotein
Viral proteases cut polyprotein
RNA-dependent RNA polymerase makes copies
New virions assemble in er
Released by exocytosis
This damages infected cells
WHY DOES IT CAUSE SYMPTOMS?
Main target: Liver
Infects hepatocytes
Causes apoptosis (cell death)
Liver failure bilirubin buildup jaundice
Decreased clotting factor production - bleeding
Severe cases:
“Black vomit” (internal bleeding)
Multi-organ failure
Mortality in severe cases: 20-50%
ROLE OF THE IMMUNE SYSTEM
Interferon response tries to stop replication
Cytokine release fever
Antibodies neutralize virus
Survivors develop lifelong immunity
Sometimes immune overreaction contributes to damage
This Photo by Unknown Author is licensed under CC BY-NC-ND
WHERE IS YELLOW FEVER FOUND?
Endemic in :
Sub-Saharan Africa
Tropical south America
~200,000 cases annually
~30,000 deaths per year
How climate change impacts yellow fever
Rising temperatures:
Expand mosquito habitats
Increase mosquito breeding rates
Shorten viral incubation time inside mosquitoes
Increased rainfall:
More standing water more mosquitoes
Deforestation:
Brings humans into jungle cycle
Urbanization:
Increases human-mosquito contact
Social and economic factors
Limited healthcare access
Low vaccination coverage
Political instability
Poverty
War and displacement
These factors allow outbreaks to grow
Why this matters now?
Climate warming expanding mosquito zones northward
International travel spreads virus
Outbreaks in Brazil and Africa in recent years
Risk of re-emergence in urban areas
Yellow fever could expand into new regions
How we fight yellow fever
Vaccine
Live-attenuated vaccine
1 dose = lifelong immunity
Highly effective (~99%)
Vector control
Eliminate standing water
Insecticide spraying
Mosquito nets
New technologies
Genetically modified mosquitoes
Wolbachia-infected mosquitoes
Satellite climate tracking
Global vaccination campaigns
Organizations involved:
Who
CDC
GAVI
FUTURE OUTLOOK
Likely to persist
May expand with climate change
Control depends on:
Vaccination
Climate mitigation
Global cooperation
What can students do?
Learn about global health
Support vaccination efforts
Reduce standing water at home
Advocate for climate action
Consider careers in healthcare or science
conclusion
Yellow fever is a viral disease transmitted by mosquitoes
It causes severe liver damage
Climate change is expanding mosquito habitats
Vaccination is highly effective
Understanding infectious diseases help protect our future
REFERENCES
Monath, T. P., & Vasconcelos, P. F. C. (2015). Yellow fever. Journal of Clinical Virology, 64, 160–173. https://doi.org/10.1016/j.jcv.2014.08.030
World Health Organization. (2023). Yellow fever: Fact sheet. https://www.who.int/news-room/fact-sheets/detail/yellow-fever
Centers for Disease Control and Prevention. (2024). Yellow fever: Clinical features and diagnosis. https://www.cdc.gov/yellow-fever/hcp/clinical-features.html
Ryan, S. J., Carlson, C. J., Mordecai, E. A., & Johnson, L. R. (2019). Global expansion and redistribution of Aedes-borne virus transmission risk due to climate change. PLOS Neglected Tropical Diseases, 13(3), e0007213. https://doi.org/10.1371/journal.pntd.0007213
Centers for Disease Control and Prevention. (2024). Yellow fever: Transmission. https://www.cdc.gov/yellow-fever/transmission/index.html
World Health Organization. (2023). Eliminate Yellow Fever Epidemics (EYE) Strategy.
Barrett, A. D. T., & Teuwen, D. E. (2009). Yellow fever vaccine – how does it work? The Lancet, 9(10), 613–621.
Gould, E. A., & Solomon, T. (2008). Pathogenic flaviviruses. The Lancet, 371(9611), 500–509.
