All 5 viruses have high reported seroprevalence rates in endemic regions: [approximately equal to] 1%-27% for LACV
, JCV, and SSHV; [approximately equal to] 24%-51% for INKV; and up to 80% for TAHV (1,2,10-12).
In August 2017, the North Carolina Department of Public Health (NCDPH) was notified of a suspected LACV
encephalitis case in a boy aged 2 years from western North Carolina.
Previously, most LACV
disease cases were associated with forested areas in the midwestern United States (10), where LACV
was maintained through a cycle involving the eastern tree-hole mosquito (Ochlerotatus triseriatus), hereafter called the tree-hole mosquito, and mammals of 3 species: eastern chipmunks (Tamias striatus), gray squirrels (Sciurus carolinensis), and fox squirrels (Sciurus niger) (10, 11).
In 2013, CDC received reports of 2,605 cases of nationally notifiable arboviral diseases, including those caused by WNV (2,469 cases), LACV
(85), JCV (22), POWV (15), EEEV (eight), unspecified California serogroup virus (five), and St.
strains are known to cause different symptoms (34), but neither INKV nor CHATV have been isolated from a human sample.
In 2012, CDC received reports of 5,780 cases of nationally notifiable arboviral diseases, including those caused by WNV (5,674 cases), LACV
(78), EEEV (15), POWV (seven), SLEV (three), JCV (two), and an unspecified California serogroup virus (one).
However, given the lack of widespread testing availability and the few reported cases, the actual clinical spectrum of JCV infection, unlike that of LACV
, remains unclear.
In 2011, CDC received reports of 871 cases of nationally notifiable arboviral diseases (excluding dengue), including those caused by WNV (712 cases), LACV
(130), POWV (16), SLEV (six), EEEV (four), and JCV (three) (Table 1).
In recent years, LACV
reportedly has increased above endemic levels in regions of the southeastern United States, including areas of eastern Tennessee (6).
In comparison with clinical illness caused by LACV
, JCV has been described as affecting adults and is more likely to cause meningitis (6,7).
La Crosse virus (LACV
), a California serogroup bunyavirus, is a leading cause of pediatric arboviral encephalitis in the United States and is transmitted primarily by the eastern treehole mosquito (Aedes triseriatus) (1).
Serologic tests (IgM capture ELISA and IgG ELISA) on serum for Eastern equine encephalitis virus, LACV
, POWV, SLEV, and WNV were all negative.