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

26. Mycobacterium bovis
26.1. HAZARD IDENTIFICATION
26.1.1. Aetiological agent
Mycobacterium bovis, an intracellular bacterium that causes bovine tuberculosis in several
species of mammal, including humans.
26.1.2. OIE list
Listed.
26.1.3. New Zealand status
Mycobacterium bovis, is an endemic organism that is subject to an official control
programme in New Zealand, in the form of a National Pest Management Strategy (NPMS)
under the Biosecurity Act, 1993.
26.1.4. Epidemiology
Tuberculosis in camelids has been reviewed by Wernery & Kaaden (2002). It is primarily
caused by M. bovis (Thoen et al 1977; Barlow et al 1999; Wernery & Kaaden 2002; Ryan
et al 2008), and there are rare reports of M. tuberculosis (Wernery & Kaaden 2002) and
very rare reports of M. microti (Oevermann et al 2004; Emmanuel et al 2007; Lyashchenko
et al 2007; Zanolari et al 2009).
Camelids generally become infected with M. bovis by contact with other infected animal
species (Twomey et al 2007). While there has been anecdotal evidence suggesting that
camelids are not very susceptible to tuberculois and that transmission between camelids or
to other animals from camelids is limited (Fowler 1992), in recent years tuberculosis in
camelids has been recognised as a problem in a number of herds of farmed camelids in the
UK, where there has been an increase in vector-related M. bovis infection in cattle herds
(Defra 2008).
Tests available for international trade purposes are described in the Manual. The
prescribed test is the delayed hypersensitivity (tuberculin) skin test. There are a number of
blood-based tests, including interferon-gamma and ELISA. Isolation of organisms or
demonstration of DNA by PCR are reliable diagnostic tests but are not generally suitable
for use in live animals for export testing. Several reports indicate that the tuberculin test is
unreliable, with problems associated with both specificity and sensitivity (Fowler 1992;
Stevens et al 1998; Everett et al 1999; Wernery & Kaaden 2002; Lyashchenko et al 2007;
Twomey et al 2007; Connolly et al 2008; Ryan et al 2008). Although serological tests
show some promise (Stevens et al 1998; Lyashchenko et al 2007), only limited information
is available on their use. The best approach seems to be to use a combination of tuberculin
testing and serological testing.
26.1.5. Hazard identification conclusion
M. bovis can infect camelids. It is an endemic organism that is the subject of an official
eradication programme (a National Pest Management Strategy under the Biosecurity Act
MAF Biosecurity New Zealand Import risk analysis: Llamas and alpacas from specified countries ● 95