Examining La Crosse virus research

La Crosse virus: a scoping review of the global evidence. Harding S*, Greig J*, Mascarenhas M*, Young I, Waddell LA*. Epidemiology and Infection. 2018 Dec 5:1–13. doi: https://doi.org/10.1017/S0950268818003096

This science story is based on the collaborative work resulting in a scoping review on the California serogroup La Crosse virus (LACV). LACV is a virus of growing public health concern transmitted by mosquitoes and whose distribution range may expand due to the effects of climate change. The findings in this review can help identify knowledge gaps around LACV, guide further research, and inform evidence-based decision-making for the prevention and control of LACV.

What was known about this area prior to your work, and why was the research done?

LACV, the most pathogenic member of the California encephalitis serogroup viruses, has been found in the Midwest of the United States of America (USA) for decades and in the USA Mid-Atlantic region for the last twenty-five years. To date, no published cases of LACV have been reported in Canada. However, the mosquito that carries the virus (Ae. triseriatus) has been found in Ontario, Quebec and New Brunswick, provinces that border affected US states. Climate change has the potential to expand the range of the virus and vector of LACV, which could result in the emergence of this virus in Canada. We performed a scoping review to summarize currently available evidence on LACV in order to help prepare and anticipate for potential emergence in Canada.

What are your most significant findings from this work?

Our scoping review identified 481 relevant articles that were published from 1969 to 2016. The majority of these articles were from the USA and focused on the epidemiology, transmission, and pathogenesis of LACV in vectors and hosts. The number of reported human LACV cases in the USA varies from 30-130 per year. We identified several knowledge gaps including information on the spectrum of human illness that results from LACV, risk of exposure across various settings, accuracy of diagnostic tests, effective treatments or prevention and control strategies, and estimates of the current or future economic and social burden of infection.

What are the implications or impact of the research?

The findings of our work suggest that while there is a lot of research on LACV and the current epidemiology of the virus in the USA, more research is needed on the landscape and climate factors that determine the distribution, emergence potential and establishment of LACV in new areas. Our scoping review has established a repository of all published LACV research up to the end of 2016. It can also be queried for subsets of research as needed. Our findings may guide research on the potential emergence of LACV in Canada and inform evidence based prevention and control efforts to mitigate the potential emerging public health impact of LACV.

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