Emergence of zoonotic arboviruses by animal trade and migration

Parasites & Vectors

Table 1 Qualitative estimation of the impact of zoonotic arboviral diseases with a non-zero likelihood of evolving in response to animal trade, animal migration and climate change.

Arbovirus	Chances for dispersal	Major mode of dispersal	Chances for establishing new endemic foci (c)	Chances to be eliminated again (d)	Impact on public health (e)	Impact on veterinary public health (e)	Occurrence and distribution influenced by climate (f)
WEEV	Moderate	Long distance (viremic birds)	Moderate to high	Low to moderate	Low	Low	Yes
EEEV	Moderate	Long distance (viremic birds)	Moderate to high	Low to moderate	Low	Low	Yes
VEEV	Moderate to high (a)	Short distance (mosquitoes, rodents)	Moderate	Low to moderate	Low	Low to moderate (a)	Yes
WNV	Moderate to high	Long distance (viremic birds)	Moderate to high	Zero to low	Moderate to high	Low	Yes
JEV	Moderate	Long distance(viremic birds)	Moderate	Low to moderate	Moderate to high	Low to moderate	Yes
RVFV	Moderate to high	Short to long distance (livestock animals)	Moderate to high	Low to moderate	Moderate	Moderate to high	Yes
USUV	Moderate to high	Long distance (viremic birds)	Moderate to high	Zero to low	Negligible	Low	Yes
TBEV	Low to moderate	Short distance (ticks, rodents) (b)	Moderate to high	Zero to low	Low	Negligible	Yes
POWV	Low to moderate	Short distance (ticks, rodents) (b)	Moderate to high	Zero to low	Low	Negligible	Yes

(a) = Depending on the VEEV subtype involved.
(b) = When ticks are attached to birds, the respective viruses can as well be carried over long distances.
(c) = Because the mechanisms allowing a successful establishing of new endemic foci are poorly understood, the estimates provided are speculative despite for the viruses where this happened in recent history, e.g. WNV in America. Expansion of the geographic range of tick-borne TBEV and POWV mainly occurs on a different scale than with mosquito-borne arboviruses.
(d) = The general rule "the earlier the detection of the alien virus, the better the chance to successfully terminate it" applies for both mosquito- and tick-borne viruses, but due to the life cycle of mosquitoes and the availability of efficient larvicides and adulticides, their abundance can be better addressed with an integrated pest management and mosquito control program than fighting ticks in a tick habitat.
(e) = TBEV and JEV cause diseases in humans that can be prevented by applying safe and efficient vaccines. There is an inactivated vaccine available for the three equine encephalitis viruses and WNV.
(f) = The distribution of all arboviruses depends to a major part of the abundance of suitable vector species. Since their life cycle is strongly influenced by the weather, climate is an important issue in the occurrence and spread of arboviruses.

ISSN: 1756-3305