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

In cattle, the acute infections are of short duration and virus is excreted in nasal secretions
for up to 14 days after infection. Viraemia is hard to detect (Babuik et al 2004) but can
occasionally occur (van Oirschot 2004). Virus spreads to the conjunctiva and trigeminal
ganglion by neuronal axonal transport (van Oirschot 2004). Many animals become
chronically infected latent carriers of the virus in their trigeminal or sacral ganglia, and
may excrete the virus periodically when stressed (Babuik et al 2004; van Oirschot 2004).
Camelids have been found to have antibody to BHV. Rarely BHV-1 has been isolated from
diseased and dead llamas (Williams et al 1991; Wernery & Kaaden 2002). In Peruvian
llamas and alpacas a seroprevalence of about 16% was found in herds grazed on the same
pastures as cattle, sheep and goats. Alpacas that were managed separately from other
ruminants were found to have a 5% seroconversion rate. In Oregon, a very low rate of
0.7% was found in 270 alpacas surveyed (Wernery & Kaaden 2002). In another serosurvey
of 390 llamas in Argentina an antibody prevalence of 0.77% was reported. The positive
samples were from a herd where the seroprevalence in the cohabitating cattle was found to
be 60% (Puntel et al 1999).
Although camelids are susceptible to infection with BHV-1, disease is rare. It is not known
whether natural transmission occurs in camelids and infection in camelids may be a spillover
from cattle (Puntel et al 1999). Indeed, the prevalences in camelids would be expected
to be higher if natural transmission was occurring within infected flocks. The studies with
very low prevalences are likely to reflect false positive or non-specific reactions. Although
BHV-1 is considered non-pathogenic in camelids (Wernery & Kaaden 2002), the
possibility that they could be infectious cannot be excluded. In other species such as goats,
clinical signs of infection are mild but natural transmission can occur (Straub 1990).
The OIE ad hoc group lists BHV-1 as a significant disease of camelids and recommends
investigation of their susceptibility to BHV-1 (OIE 2008). In view of the uncertainty
around the epidemiology of this virus in camelids and in light of the evidence for
transmission from infected goats, this risk analysis assumes that transmission from infected
camelids can occur.
10.1.5. Hazard identification conclusion
Abortifacient strains of IBR/IPV virus are exotic, notifiable organisms that can be
associated with camelids. Under the assumption that transmission to other susceptible
animals may occur, these organisms are classified as potential hazards.
Since tests suitable for export/import certification are not available to identify abortifacient
strains in the laboratory, it is necessary to regard all BHV-1 strains as potential hazards.
10.2. RISK ASSESSMENT
10.2.1. Entry assessment
In latently infected cattle, the virus remains in the neurons of the ganglia and can be
periodically re-activated. It is assumed that this also occurs in camelids.
Camelids that have become infected without showing clinical signs and are still shedding
virus or are latently infected could be imported from endemic areas. Therefore the
likelihood of entry of BHV-1 in the commodity is assessed to be non-negligible.
32 ● Import risk analysis: Llamas and alpacas from specified countries MAF Biosecurity New Zealand