Posted by Vector and Vector-borne Disease Committee
June 6, 2022
Mary E. Danforth1, Robert E. Snyder1, Emma T. N. Lonstrup2, Christopher M. Barker2, Vicki L. Kramer1ID
1 Vector-Borne Disease Section, California Department of Public Health, Sacramento, CA,
2 Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, Davis, CA
PLoS Negl Trop Dis 16(5): e0010375. https://doi.org/10.1371/journal.pntd.0010375
Abstract [partial]. … We built models to determine the association between risk level and the number of reported symptomatic human West Nile disease cases with onset in the following three weeks to identify the essential components of the risk level and to compare California’s risk estimates to vector index. Risk level calculations based on Culex tarsalis and/or Cx. pipiens complex levels were significantly associated with increased human risk, particularly when accounting for vector control area
and population, and were better predictors than using the vector index. Including all potential
environmental components created an effective tool to estimate the risk of WNV transmission
to humans in California.
Note. There has been a trend among MVCAC agencies to reduce the number of surveillance components used to monitor WNV transmission risk. Currently fewer agencies report and test dead birds, and deploy chicken flocks each year. These components have been replaced by increased mosquito trapping and testing, and the calculation of the Vector Index. The current analyses show that the inclusion of avian host as well as mosquito infection data enhances estimates of human disease risk.