Import risk analysis: Llamas (Lama glama) and alpacas (Vicugna ...

12. Eastern equine encephalitis virus
12.1. HAZARD IDENTIFICATION
12.1.1. Aetiological agent
Family: Togaviridae; Genus: Alphaviridae; Species: Eastern equine encephalitis virus
(EEEV) (Weaver et al 2005).
12.1.2. OIE list
Listed as a disease of equidae.
12.1.3. New Zealand status
It is listed as notifiable on the Unwanted Organisms Register.
12.1.4. Epidemiology
Eastern equine encephalitis virus is an arthropod-borne virus transmitted by mosquitoes.
The disease has remained confined to the southern United States, central and northern
South America where the virus is maintained in a mosquito/bird cycle. Virus titres build up
in birds during the summer with the ornithophilic mosquito Culiseta melanura acting as
the primary vector. When high levels of virus are present, so called ‘bridge vectors’ that
feed on both birds and mammals transmit the virus to mammals. Virus has been isolated
from at least 20 species of mosquitoes from six genera (Gibbs 2004). Birds that are
indigenous to infected areas are not susceptible to the disease but may act as carriers of the
virus. Introduced species of birds and mammals including man, horses and South
American camelids (Nolen-Watson et al 2007) are susceptible and may develop a usually
fatal disease when infected. The overwintering mechanism in temperate parts of America
remains obscure as transovarial transmission is not considered to be important. In tropical
and subtropical areas the mosquito/bird cycle may be continuous (Gibbs 2004). As with
horses and humans, infected camelids are considered to be non-contagious dead-end hosts.
The disease has not established anywhere in the world outside of the known endemic
regions, indicating that conditions required for the maintenance of the virus are specific to
these geographic areas.
12.1.5. Hazard identification conclusion
Culisetia melanura is not present in New Zealand and the likelihood that other critical
elements for the maintenance of the virus to be able to establish in New Zealand is
considered to be negligible. Since infected camelids are not contagious and vectors are not
present, the virus could not be transmitted from introduced camelids or establish here.
Therefore, EEEV is not considered to be a hazard in the commodity.
MAF Biosecurity New Zealand Import risk analysis: Llamas and alpacas from specified countries ● 39