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. 2021 Jul 19;105(3):807-812.
doi: 10.4269/ajtmh.21-0294.

La Crosse Virus Disease in the United States, 2003-2019

Grace M Vahey  1   2 , Nicole P Lindsey  1 , J Erin Staples  1 , Susan L Hills  1
Affiliations

La Crosse Virus Disease in the United States, 2003-2019

Grace M Vahey et al. Am J Trop Med Hyg. .

Abstract

La Crosse virus (LACV) is an arthropod-borne virus that can cause a nonspecific febrile illness, meningitis, or encephalitis. We reviewed U.S. LACV surveillance data for 2003-2019, including human disease cases and nonhuman infections. Overall, 318 counties in 27 states, principally in the Great Lakes, mid-Atlantic, and southeastern regions, reported LACV activity. A total of 1,281 human LACV disease cases were reported, including 1,183 (92%) neuroinvasive disease cases. The median age of cases was 8 years (range: 1 month-95 years); 1,130 (88%) were aged < 18 years, and 754 (59%) were male. The most common clinical syndromes were encephalitis (N = 960; 75%) and meningitis (N = 219, 17%). The case fatality rate was 1% (N = 15). A median of 74 cases (range: 35-130) was reported per year. The average annual national incidence of neuroinvasive disease cases was 0.02 per 100,000 persons. West Virginia, North Carolina, Tennessee, and Ohio had the highest average annual state incidences (0.16-0.61 per 100,000), accounting for 80% (N = 1,030) of cases. No animal LACV infections were reported. Nine states reported LACV-positive mosquito pools, including three states with no reported human disease cases. La Crosse virus is the most common cause of pediatric neuroinvasive arboviral disease in the United States. However, surveillance data likely underestimate LACV disease incidence. Healthcare providers should consider LACV disease in patients, especially children, with febrile illness, meningitis, or encephalitis in areas where the virus circulates and advise their patients on ways to prevent mosquito bites.

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Figures

Figure 1.
Figure 1.
Counties reporting human La Crosse virus disease cases, United States, 2003–2019. Cases are reported by county of residence. No cases were reported from Hawaii or Alaska.
Figure 2.
Figure 2.
La Crosse virus disease cases by year of onset and clinical presentation, United States, 2003–2019.
Figure 3.
Figure 3.
La Crosse virus disease cases by month of illness onset, United States, 2003–2019.
Figure 4.
Figure 4.
Average annual incidence of neuroinvasive La Crosse virus disease by state, United States, 2003–2019. Calculations are based on cases’ states of residence. No cases were reported from Hawaii or Alaska.
See this image and copyright information in PMC

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