Final Risk Analysis - Biosecurity New Zealand

2000). However, in the vast majority of cases there are no or only mild clinical signs
(Vermunt and Parkinson 2000).
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 they are stressed (Babuik et al 2004; van Oirschot 2004). Semen may be
infected with virus and insemination with such semen causes infection in recipient females
(Parsonson and Snowdon 1975; Schlafer et al 1990; van Oirschot 1995b).
BHV-5 associated with encephalitis (Wentink et al 1993) has been described in Australia
(Brake and Studdert 1985), USA (Barenfus et al 1963; Delhon et al 2003), Canada (Gough
and James 1975), and Europe (Bartha et al 1969; Moretti et al 1964) but not in New Zealand.
10.1.5. Hazard identification conclusion
Abortifacient strains of IBR/IPV virus are exotic notifiable organisms and they are commonly
present in chronic carrier animals. These organisms are therefore classified as potential
hazards. However, since practical tests are not available to identify abortifacient strains in the
laboratory it is necessary to regard all BHV 1.1 and BHV 1.2a strains as potential hazards.
BHV-5 is also exotic and is regarded as a potential hazard.
10.2. RISK ASSESSMENT
10.2.1. Entry assessment
Recently infected cattle may excrete the virus in nasal secretions and aerosols for up to 14
days after infection (Babuik et al 2004). Carriers of the virus may periodically excrete virus
particularly during periods of stress (Babuik et al 2004; van Oirschot 2004). The likelihood of
entry of virus in the commodity is therefore considered to be non-negligible.
10.2.2. Exposure assessment
Imported animals are likely to be kept in herds with indigenous New Zealand cattle and the
likelihood of exposure of naïve indigenous cattle is high. Infection could be spread by contact
(Babuik et al 2004) or by insemination or natural mating using infected bulls (Parsonson and
Snowdon 1975; Schlafer et al 1990;van Oirschot 1995b).
10.2.3. Consequence assessment
Introduction of abortifacient strains of BHV1.1 or 1.2a or strains of BHV 5 is likely to result
in outbreaks of abortion or encephalitis. This would have a negative effect on the economy of
the cattle industry and individual farmers.
The virus does not infect humans and therefore the consequences for people are negligible.
Other ruminants can possibly be infected with BHVs since they have been found to have
antibody to the virus. However, the antibody that has been detected may be cross-reacting
antibody as in the case of deer infected with cervine herpesvirus (Motha and Jenner 2001;
MAF Biosecurity New Zealand Import Risk Analysis: Cattle from Australia, Canada, the EU & the USA ● 33