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-borne viral disease

– Primarily human-mosquito-human transmission

– Mainly Aedes aegypti and Aedes albopictus

 Clinically characterized by acute onset of fever and 

often 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

0

200000

400000

600000

800000

1000000

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 

widespread

 Often rapid increase in size

 30%–60% population 

infected within few months

 Huge outbreaks, like 2014–

2016 in Americas, unlikely in 

future

 Continued reporting of large 

outbreaks likely

 Many commence during 

tropical rainy season

 Can occur in dry season

 Period of intense 

transmission 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