Table 4 Variable assignments of multivariate unconditioned logistic regression

Educational background (X₁)

1 = High school degree or above, 2 = below high school degree

Working countries (X₂)

Countries were divided into three groups according the incidence, 3 = >20% (high-affected courtiers), 2 = 10–20% (middle-affected countries), 1 = 5–10% (low-affected countries)

Type of the local ecological environment (X₃)

According the infection rate, types separated into two groups, 2 = mountainous regions and others, 1 = city, plain and island

Working duration (X₄)

Figured on a monthly basis

Intensity of mosquito bite prevention (X₅)

Cases without any protective measure are defined as a set of “0”; cases using one measure are defined as a set of “1”; cases using two measures are defined as a set of “2”, and so on