Posted by Vector and Vector-borne Disease Committee
July 25, 2022
Camila Lorenz,* and Francisco Chiaravalloti-Neto
Department of Epidemiology, School of Public Health, University of S~ao Paulo, S~ao Paulo, Brazil
The Lancet Regional Health – Americas 2022;12: 100276;
Published online: https://doi.org/10.1016/j.lana.2022.100276
Note: Historically the North American encephalitis viruses have more or less ‘disappeared’ into the Neotropics, with sporadic detection during enhanced surveillance and small outbreaks documented in Argentina. The current Comment piece proposes the following hypotheses. 1) Under-reporting. Diagnosis of WNV fever cases may be lost among the frequent occurrence of other arboviruses such as DENV, ZIKV and Mayaro. 2) Co-circulation. Other viruses such as Rocio and SLEV may provide cross protection and limit amplification. However, this would seem poorly supported given the recent resurgence of SLEV in the SW USA where WNV remains endemic. 3) Evolution of attenuated strains. Several isolates from the Neotropics have been attenuated and may not produce neuroinvasive disease and therefore are not detected.