Table 2.

Risk factors for GLOBAL viruses

Factor	Variables	Description	Variable associated with GLOBAL viruses	p value†
Biological characteristics	genome envelope evolutionary rate	RNA or DNA absent or present mutation rate (nucleotide substitutions per nucleotide per year)	RNA absent high	0.289 0.721 0.149
Manners or routes of transmission	contact	virus transmits commonly from human to human via daily life activities or not (rare)	common	0.113
	respiratory	virus transmits commonly via respiratory route or not (rare)	no (rare)	1
	fecal-oral	virus transmits commonly via fecal-oral route or not (rare)	common	0.062
	sexual	virus transmits commonly via sexual contacts or not (rare)	no (rare)	0.412
	blood	virus transmits commonly via blood (e.g. contaminated blood transfusion or syringe) or not (rare)	no (rare)	0.044
	vertical*	virus transmits commonly from mother to child or not (rare)	no (rare)	1
Host responses	incubation period	length of incubation period	short	0.001
	infectious period	length of infectious period	short	0.036
	asymptomatic infection	rate of asymptomatic infection	high	0.401
	persistent	virus persists commonly in host cell or not (rare)	no (rare)	0.087
	re-infection	frequent re-infection with virus (of same serotype) occurs or not (rare)	frequent	0.004
Epidemiological factors	the basic reproductive number (R0) annual incidence seroprevalence seasonality	mean number of secondary cases from single infected case	small	0.008
		occurrence of the disease	high	0.002
		proportion of people with antibody to the virus	high	0.068
		infection has seasonality (in temperate zone) or not	existence of seasonality 0.722

Bold characters indicate significant results.

^*Virus that can be transmitted from mother to child, but the child is not infectious (e.g. rubella) was inferred as 'no (rare) vertical transmission'.

^†Comparisons were made by the Mann-Whitney U test or Fisher's exact test, as appropriate.