Yellow Fever in Senegal: Strategies for Control Nicholas Eriksson, Heather Lynch, Brendan O’Fallon, Katharine Preedy Advisor: Simon Levin

World Health Organization: Communicable Diseases Epidemiological Report (2003)

Three patch model: Urban, Village, and Forest U V F ~ 1,000 individuals with constant rate of infection from forest (monkey) reservoir ~ 10,000 individuals with infection coming from contact with infected individuals from the forest patch ~ 100,000 individuals with infection coming from contact with infected individuals from the village patch

Urban Village Forest infection from the reservoir

Number of Infected Individuals Time (days) ~ 2.3 years rate of infection from reservoir = /day transmission-rate = 0.12/infected individual/day recovery rate = 0.10/day contact probability between forest-village = 0.01/infected individual/day contact probability between village-urban = 0.01/infected individual/day birth rate = death rate = /day

Vaccination = vaccination rate = 2.5e-4 vaccinations/person/day Fraction of Days Sampled Number of Infected Individuals +

Quarantine 50% Quarantine 75% Mean Urban Infected Individuals Vaccination Rate A Comparison of Vaccination Strategies

Further Work: pulsed vaccinations seasonal fluctuations mosquito population mosquito-based control - spraying - mosquito nets less parameter-sensitive models Summary: in this model, the most effective vaccination strategy is in the urban patch quarantine can be as effective as vaccination if infected individuals can be properly identified vaccination is most effective at the ‘tails’ of the infected distribution, i.e. it eliminates the worst outbreaks

Eigenvalues of Equilibrium Point of Homogeneous System Real part of eigenvaluesImaginary part of eigenvalues

Dominant Eigenvalue

Vaccination vs. Immigration