Increased Human Incidence of West Nile Virus Disease near Rice Fields in California but Not in Southern United States

Abstract

Anthropogenic land use change, including agriculture, can alter mosquito larval habitat quality, increase mosquito abundance, and increase incidence of vector-borne disease. Rice is a staple food crop for more than half of the world's population, with ∼1% of global production occurring within the United States (US). Flooded rice fields provide enormous areas of larval habitat for mosquito species and may be hotspots for mosquito-borne pathogens, including West Nile virus (WNV). West Nile virus was introduced into the Americas in 1999 and causes yearly epidemics in the US with an average of approximately 1,400 neuroinvasive cases and 130 deaths per year. We examined correlations between rice cultivation and WNV disease incidence in rice-growing regions within the US. Incidence of WNV disease increased with the fraction of each county under rice cultivation in California but not in the southern US. We show that this is likely due to regional variation in the mosquitoes transmitting WNV. was an important vector of WNV in California, and its abundance increased with rice cultivation, whereas in rice-growing areas of the southern US, the dominant WNV vector was, which rarely breeds in rice fields. These results illustrate how cultivation of particular crops can increase disease risk and how spatial variation in vector ecology can alter the relationship between land cover and disease.

Spatiotemporal Modeling of Zoonotic Arbovirus Transmission in Northeastern Florida Using Sentinel Chicken Surveillance and Earth Observation Data

“…Although we expected to find some correlation with the landscape variables included in our analyses, this result was not altogether surprising given often contradictory results from previous WNV landscape studies in other regions of the U.S. [53,54]. For example, correlations between WNV and urban and semi-urban environments have been found in multiple U.S. states [17,[55][56][57], while simultaneously agricultural landscapes have also been indicated [17,53,[58][59][60][61]. Although landscape correlations with WNV are less studied in Florida, the presence of multiple vector species inhabiting a broad range of landscape habitats may be reflected in our model results [12].…”

Integrating social and ecological data to model metapopulation dynamics in coupled human and natural systems

“…WNV risk was not retained in Virginia rail occupancy models during model selection (Appendix S1: Table S18), but was detrimental to both colonization and extinction rates of black rails (Appendix S2: Table S11). Wetlands near rice fields in the Central Valley had an order-of-magnitude higher WNV risk compared to wetlands upslope and away from rice agriculture (~1.5 vs.~0.15 infected Culex per trap/ night), similar to elsewhere in California (Kovach and Kilpatrick 2018). Wetlands with more wetland land cover within 2.5 km also had higher WNV risk (Appendix S3: Table S19).…”

Effect of Agroecosystems on Seroprevalence of St. Louis Encephalitis and West Nile Viruses in Birds, La Pampa, Argentina, 2017–2019

“…quinquefasciatus mosquitoes, urbanization positively affects the incidence of WNV disease in humans ( 35 ), whereas on the west coast of the United States, where the most efficient vectors are Cx. tarsalis mosquitoes, the main land cover types associated with increased WNV activity are agricultural irrigated areas, such as rice fields and orchards ( 40 ).…”