Table 2.
The number of articles reporting risk factors for La Crosse virus (LACV) studied in human (N = 36), animal (N = 3) and vector (N = 5) populations
| Risk factor category | Population category | Interpretation of the risk factor in studies that reported statistical significance | N* studies (N studies significant risk)a |
|---|---|---|---|
| Demographics | |||
| Age | Human | Prevalence of LACV antibodies increases with age | 6 (3) |
| Sex | Human | Increased risk for males vs. females | 6 (1) |
| Animal | N/A | 1 | |
| Education | Human | Increased risk if less than high school degree | 1 (1) |
| Pregnant | Human | N/A | 1 |
| Species | Animal | Increased risk for chipmunks vs. squirrels | 1 (1) |
| Geographic | |||
| Geographic location | Human | Increased risk identified in certain counties from Illinois and Minnesota | 8 (3) |
| Southern states at greater risk vs. northern states in USA | |||
| Animal | N/A | 2 | |
| Vector | High-risk clusters in north central/eastern USA | 3 (2) | |
| Rural | Human | Increased risk in rural areas vs. urban | 6 (1) |
| Place of residence | Human | Increased risk on reservation vs. off reservation | 4 (1) |
| Suburban | Human | N/A | 3 |
| Housing density | Human | Increased risk if area with lower housing density | 1 (1) |
| Behaviours | |||
| Woods exposure | Human | Children at increased risk if spent >1 h in woods during the day | 7 (1) |
| Outdoor play/leisure | Human | Increased risk with more hours spent outdoors | 5 (1) |
| Travel | Human | N/A | 4 |
| Repellent | Human | Slight increased risk if child never wore repellent | 2 (1) |
| Clothing | Human | N/A | 1 |
| Window screens | Human | N/A | 1 |
| Air conditioning | Human | Increased risk in children living in homes with no air conditioning | 1 (1) |
| Windows open | Human | N/A | 1 |
| Outdoor work | Human | N/A | 1 |
| Not specified | Human | N/A | 1 |
| Landscape | |||
| Tree holes | Human | Increased risk if tree holes near residence | 9 (2) |
| Vector | N/A | 1 | |
| Proximity to woods | Human | Increased risk the closer residence is to forest edge | 8 (1) |
| Artificial containers | Human | Increased risk if artificial containers near residence | 7 (2) |
| Tires | Human | Children were at increased risk if >10 tires near residence | 5 (1) |
| Standing water | Human | N/A | 3 |
| Habitat quality | Animal | Increased risk in high-quality habitatsb | 1 (1) |
| Vector | N/A | 1 | |
| Proximity to water | Human | N/A | 2 |
| Chipmunk abundance | Human | N/A | 1 |
| Vector | Increased chipmunk density | 1 (1) | |
| Landscape maintenance | Human | N/A | 1 |
| Horse stables | Human | N/A | 1 |
| Small mammals abundant | Human | N/A | 1 |
| Ground cover | Vector | Increased ground cover density | 1 (1) |
| Cemetery | Vector | N/A | 1 |
| Not specified | Human | N/A | 1 |
| Other | |||
| Season | Human | Increased risk in June–August and October vs. March–May, September and November | 5 (2) |
| Increased risk in July– September compared with all other months | |||
| Vector | Increased risk in August vs. July | 1 (1) | |
| Year | Animal | N/A | 1 |
| Symptoms of severe LACV | Human | Increased disease progression if patient presented with vomiting, seizure, coma, fever and low sodium | 1 (1) |
N/A, Not applicable no studies reported statistically significant findings for this risk factor category.
a
Number of studies that report a statistically significant (P < 0.05) association between the risk factor and LACV infection, references available in S4.
b
High-quality habitats defined by defined by rolling terrain, dense coverage by oaks trees and good food and water availability.
*Total may not add to 100% as studies may have reported results for multiple population and risk factor categories.