Modeling Dynamic Introduction of Chikungunya Virus in the United States

Abstract

Chikungunya is a mosquito-borne viral infection of humans that previously was confined to regions in central Africa. However, during this century, the virus has shown surprising potential for geographic expansion as it invaded other countries including more temperate regions. With no vaccine and no specific treatment, the main control strategy for Chikungunya remains preventive control of mosquito populations. In consideration for the risk of Chikungunya introduction to the US, we developed a model for disease introduction based on virus introduction by one individual. Our study combines a climate-based mosquito population dynamics stochastic model with an epidemiological model to identify temporal windows that have epidemic risk. We ran this model with temperature data from different locations to study the geographic sensitivity of epidemic potential. We found that in locations with marked seasonal variation in temperature there also was a season of epidemic risk matching the period of the year in which mosquito populations survive and grow. In these locations controlling mosquito population sizes might be an efficient strategy. But, in other locations where the temperature supports mosquito development all year the epidemic risk is high and (practically) constant. In these locations, mosquito population control alone might not be an efficient disease control strategy and other approaches should be implemented to complement it. Our results strongly suggest that, in the event of an introduction and establishment of Chikungunya in the US, endemic and epidemic regions would emerge initially, primarily defined by environmental factors controlling annual mosquito population cycles. These regions should be identified to plan different intervention measures. In addition, reducing vector: human ratios can lower the probability and magnitude of outbreaks for regions with strong seasonal temperature patterns. This is the first model to consider Chikungunya risk in the US and can be applied to other vector borne diseases.

Planning for climate change: The need for mechanistic systems-based approaches to study climate change impacts on diarrheal diseases

“…Theses studies can motivate and inform the design of diarrhea modeling efforts. Researchers have studied the effects of climate or weather on schistosomiasis (Zhou et al, 2008; Perez-Saez et al, 2015), dengue fever (Patz et al, 1998), chikungunya (Ruiz-Moreno et al, 2012), cholera (Rinaldo et al, 2012) and malaria (Van Lieshout et al, 2004; Martens et al, 1995) among others. In these studies, researchers combined empirical data with climate models.…”

“…Similarly, to study malaria, van Lieshout et al (2004) included data about mosquito biting rates, mosquito survival, malaria parasite incubation periods, rainfall and temperature threshold values, mosquito distributions, GCMs, population scenarios and adaptive capacity (Van Lieshout et al, 2004). Another mechanistic systems-based study used a compartment model of both human and mosquito susceptibility, exposure and infection along with mosquito lifecycle information to study the geographic sensitivity of epidemic potential of the chikungunya virus in the United States (Ruiz-Moreno et al, 2012). Rinaldo et al (2012) studied the cholera epidemic in Haiti by incorporating hydrological transport, rainfall and human mobility among other factors to accurately reproduce historic cholera outbreaks (Rinaldo et al, 2012).…”

Assessment of Arbovirus Surveillance 13 Years after Introduction of West Nile Virus, United States1

“…Endemic arboviruses that have caused outbreaks of severe illness and death in densely populated areas continue to pose annual threats, and emerging diseases, such as dengue and chikungunya, pose new ones ( 14 , 15 – 17 , 22 ). Knowledge of local vector mosquito populations and early detection of arbovirus activity in these vectors, animals, and humans are essential to guide public health action ranging from health advisories to mosquito control.…”

“…Concomitantly in 2012, the nation experienced the highest incidence of confirmed WNV neuroinvasive disease since 2003 and the highest number of confirmed deaths (286) for any year thus far ( 13 ). In addition to the continued challenge of WNV to financially stressed arbovirus surveillance systems, there is the growing threat of other arboviral diseases, such as dengue ( 14 ), chikungunya ( 15 – 17 ), and Powassan virus encephalitis ( 18 ). …”

Preventing Zika virus infection during pregnancy by timing conception seasonally

“…No official stance on delaying pregnancy has been 57 taken for unexposed women. Problematically, the public is receiving a mixed message, arboviruses vectored by Aedes aegypti (i.e., chikungunya virus, CHIKV) [22][23][24][25][26].…”