Chikungunya 02 Hills 508

CDC ACIP — Vaccine Advisory Committee

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National Center for Emerging and Zoonotic Infectious Diseases
GLOBAL EPIDEMIOLOGY OF 
CHIKUNGUNYA
Susan Hills, MBBS, MTH
CDC Lead , Chikungunya Vaccines Work Group
Arboviral Diseases Branch
Division of Vector -Borne Diseases
Fort Collins, Colorado
ACIP meeting, February 23, 2023
Chikungunya
Mosquito -b orne viral disease
–Primarily human -mo squito -human transmission
–Mainly A edes aegypti and Aedes albopictus
Clinically characterized by acute onset of fever and 
oft
en severe polyarthralgia
Risk factors for severe disease
–Age >65 years
–Underlying medical conditions
–Neonate infected through intrapartum transmission 
Source: PAHO, 2011. www.paho.org
Spread of chikungunya virus into new regions, 2004 -2015
Zeller et al, Int J Infect Dis, 2016
Spread of chikungunya virus into new regions, 2004 -2015
Zeller et al, Int J Infect Dis, 2016
Chikungunya cases reported in the Americas, 2013 -2022
02000004000006000008000001000000
2013 2014 2015 2016 2017 2018 2019 2020 2021 2022
Countries and territories with past or current 
transmission of chikungunya virus, 2023
https://www.cdc.gov/chikungunya/geo/index.html

Limited data sources for understanding current 
patterns of chikungunya virus transmission
WHO
websites
Ministry of 
Health websites
Cases among 
travelers
General features of chikungunya virus transmission
Occurs in tropical and subtropical regions
–Rare outbreaks in temperate areas
Often seen in areas with similar vector- borne diseases (e.g., dengue, Zika)
Transmission impacted by several factors including weather, environmental 
factors, pre -existing population immunity, population density, local vectors 
Patterns for chikungunya virus transmission vary
Ongoing low -level transmission with periodic outbreak activity in Africa, 
Asia, Central America, and South America
–Immunologically susceptible individuals continue to acquire infection and 
propagate human -mosquito -human cycles
–Outbreaks are unpredictable in terms of timing and size
Cessation of transmission after outbreaks is common in island nations
–Apparent interruption in Pacific Island and most of Caribbean countries and territories
–Risk for reintroduction will increase over time as population immunity decreases
Features of chikungunya outbreaks
More likely in regions 
with no
 or mild 
outbreaks in recent past
Can be localized or w
idespreadOften rapid increase in size
30%– 6 0% population infected within few months
Huge outbreaks, like 2014 –
2
016 in Americas, unlikely in 
future
Continued reporting of large o
utbreaks likelyMany commence during tr
opical rainy season
Can occur in dry season
Period of intense tr
ansmission typically 
short, often 3 –6 months
Interval between outbreaks
Unpredictable and variable, can be >20 years
Related to factors including pre -existing population immunity, build -up 
of non -immune population, environmental factors
Some countries report outbreaks regularly, but typically in different 
locations
Summary
Mainly tropical and subtropical areas
Currently, most countries with chikungunya virus activity have low -level 
transmission 
Outbreak- prone disease 
Important impact when outbreaks occur as often intense, although 
generally short -lived, transmission