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

17. Vesicular stomatitis virus
17.1. HAZARD IDENTIFICATION
17.1.1. Aetiological agent
Family: Rhabdoviridae; Genus: Vesiculovirus; Species: Vesicular stomatitis virus (Tordo
et al 2005). There are two main types; Indiana and New Jersey. Indiana has three sub-types
and New Jersey contains only a single sub-type.
17.1.2. OIE list
Listed as a disease of multiple species.
17.1.3. New Zealand status
An exotic, notifiable disease.
17.1.4. Epidemiology
The disease occurs in horses, cattle and pigs and, more rarely, in sheep and goats (Swenson
2008; CFSPH 2009). Naturally occurring infections in South American camelids are rare
(APHIS 2007; Bridges et al 1995; Schmidtmann et al 1999). Gomez (1964) infected
camelids by injection into the dorsum of the tongue (Fowler 1992).
In addition to being a virus of vertebrates, the virus has also been shown to multiply in
insects such as blackflies (Simulium spp.), sandflies (Lutzomyia spp.), mosquitoes (Aedes
aegypti) and leafhoppers (Peregrinus maidis) (Mare & Mead 2004).
Vesicular stomatitis (VS) is important mainly because it is clinically indistinguishable
from foot and mouth disease (Sellers & Daggupaty 1990; Rodriguez 2002; Mare & Mead
2004). Therefore, initial diagnosis of the disease before laboratory confirmation of the viral
aetiology may trigger the massive initial response usually reserved for foot and mouth
disease. Alternatively, if an outbreak of foot and mouth disease is incorrectly assumed to
be VS, as occurred in Saskatchewan in 1951, the response to the foot and mouth disease
outbreak can be delayed (Sellers & Daggupaty 1990).
The disease is endemic in Central and South America and thousands of outbreaks occur
each year from southern Mexico to northern South America (Rodriguez 2002). In the USA
the disease occurs sporadically in some southern states but is endemic in at least one
location in Georgia (Stallknecht 2000). During 2009, 5 outbreaks occurred affecting horses
resident in New Mexico and Texas (OIE 2009). In some seasons the disease spreads
northward along riverbeds into northern locations in the USA (Schmidtmann et al 1999)
and even as far as Canada (Wilks 1994).
Despite the large numbers of livestock exported from North America, the disease has only
been reported outside the Americas on one occasion and this was in a large consignment of
horses exported from North America to France during the First World War. The disease
failed to establish in Europe (Mare & Mead 2004).
The most commonly held view is that the virus is transmitted by an insect vector. Virus has
been isolated from the sand fly Lutzomyia shannoni, which is the most likely vector
(Braverman 1994; Comer et al 1994; Rodriguez et al 1996; Schmidtmann et al 1999;
MAF Biosecurity New Zealand Import risk analysis: Llamas and alpacas from specified countries ● 57