Impact of prior and projected climate change on US Lyme disease incidence

Abstract

Lyme disease is the most common vector‐borne disease in temperate zones and a growing public health threat in the United States (US). The life cycles of the tick vectors and spirochete pathogen are highly sensitive to climate, but determining the impact of climate change on Lyme disease burden has been challenging due to the complex ecology of the disease and the presence of multiple, interacting drivers of transmission. Here we incorporated 18 years of annual, county‐level Lyme disease case data in a panel data statistical model to investigate prior effects of climate variation on disease incidence while controlling for other putative drivers. We then used these climate–disease relationships to project Lyme disease cases using CMIP5 global climate models and two potential climate scenarios (RCP4.5 and RCP8.5). We find that interannual variation in Lyme disease incidence is associated with climate variation in all US regions encompassing the range of the primary vector species. In all regions, the climate predictors explained less of the variation in Lyme disease incidence than unobserved county‐level heterogeneity, but the strongest climate–disease association detected was between warming annual temperatures and increasing incidence in the Northeast. Lyme disease projections indicate that cases in the Northeast will increase significantly by 2050 (23,619 ± 21,607 additional cases), but only under RCP8.5, and with large uncertainty around this projected increase. Significant case changes are not projected for any other region under either climate scenario. The results demonstrate a regionally variable and nuanced relationship between climate change and Lyme disease, indicating possible nonlinear responses of vector ticks and transmission dynamics to projected climate change. Moreover, our results highlight the need for improved preparedness and public health interventions in endemic regions to minimize the impact of further climate change‐induced increases in Lyme disease burden.

Infectious disease in an era of global change

“…Many transmission-related life cycle traits of the mosquito (biting rate, adult lifespan, population size and distribution) and the pathogen (extrinsic incubation rate) are temperature sensitive, and oviposition patterns depend on water availability 55 . Consequently, the geographical range for dengue, malaria and other vector-borne diseases 56 – 58 is affected by the local climate, and there is substantial effort to understand how these ranges may change with climate change 59 – 61 . For certain vector-borne diseases such as Zika virus disease, climate change may lead to an expanded range 62 .…”

Models of spatial analysis for vector-borne diseases studies: A systematic review

“…We have observed that many studies show that short-term temperature variations may affect the emergence, dissemination, persistence, and resurgence of VBD outbreaks and directly affect the survival rates of pathogenic agents outside their host Available at www.veterinaryworld.org/Vol.15/August-2022/10.pdf as well as their dissemination [111]. Climate variations driven by El Niño-Southern Oscillation have been correlated with increases in VBD transmission cycles, as in the cases of dengue fever [112], malaria [113], hemorrhagic fever with renal syndrome [114], leishmaniasis [115], Lyme disease [116], and rickettsiosis [117], among others. Climate variations may also indirectly affect disease transmission probabilities as they change the distribution behavior of host or vector populations [118].…”

“…The complexity of the interactions between climate, biotic/abiotic variables, and non-climate factors vary considerably depending on the type of disease and the particular location. VBDs are among the most studied illnesses in relation to climate and environmental aspects due to their high disease burden, their extended presence in tropical and subtropical areas, and their high sensitivity to variations in the climate and environment [12,119,125], in contrast with other risks, such as high-temperature stress, or exposure to storms and floods [116]. The closest association observed involves temperature, which affects vector biting and stinging rates, their survival and growth, and the survival and development of the pathogens they bear [132].…”

“…Climate conditions exert a wide range of indirect effects on the environment and human systems that favor the transmission of VBDs. Droughts may influence water storage, land use, irrigation practices, population movements, and vector ecology, driving changes in vector geographical distribution and human exposure to infection [116,134]. According to the World Health Organization, the geographical distribution of VBDs has remained relatively stable; however, this has currently been changing due to different factors, such as global warming, intensive farming, dam building, irrigation, deforestation, population movements, non-planned urbanization, and the dramatic increase in travel and international commerce (globalization) [135].…”

Projecting the Potential Distribution Areas of Ixodes scapularis (Acari: Ixodidae) Driven by Climate Change

“…Since Lyme disease was first described in the 1970s in the United States, its geographical range has gradually expanded from northeastern to western and southern, and even to Eurasia and other regions [ 5 , 6 ]. Evidence is mounting that climate change affects the spread of Lyme disease [ 7 ]. As the main vector of Lyme disease, I. scapularis is also affected by climate change.…”