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

25.3. RISK MANAGEMENT
25.3.1. Options
The following points were considered when drafting measures for the effective
management of exotic Leptospira serovars in the commodity:
� There are a very large number of pathogenic Leptospira serovars and the species in
each country vary.
� Vaccines that protect against all serovars are not available. There is little
information on the efficacy of vaccines in camelids, and none are registered for use
in this species. Vaccination is generally unreliable; to be effective it must take place
before exposure and immunity must be maintained by repeated vaccination.
Vaccination is effective only against those serovars included in the particular
vaccine.
� Leptospirosis is a rare disease of camelids, but subclinical infections may occur.
� The length of time that camelids may remain carriers is not known, but
extrapolation from other species suggests that it may be a protracted period should
they be maintenance hosts for a particular serovar(s).
� Isolation of organisms is a difficult and lengthy process taking up to 6 months and
not suitable as a diagnostic method for international trade of animals.
� There are problems with the use of serological tests as a screening test particularly
relating to serovar specificity. The MAT screening test for the importation of
animals has limitations due to its poor sensitivity in both early and chronic
infections, particularly if the relevant antigens are not represented and testing is
carried out on a single sample. Serological screening for leptospirosis is of limited
value because animals may be carriers without evidence of antibody production and
the detection of antibody does not indicate carrier status.
� Antibiotic treatment has been used for many years as the sole method for
management of the introduction of the organisms when importing animals.
Antibiotic treatment is generally effective but cannot be guaranteed to clear
leptospires from the kidneys in all cases.
� Recently, at the OIE General Session in May 2009, the International Committee
accepted the recommendation of the Terrestrial Animal Health Standards
Commission that the empty Code chapter on leptospirosis should be deleted from
the Code. Leptospirosis still remains an OIE listed disease.
� The rationale for deletion was cited in the March 2009 report of the Terrestrial
Animal Health Standards Commission:
“Leptospirosis is distributed globally; it is improbable that any country can,
with any credibility, claim to be free from the disease. Further, it is unlikely
that any country has an official control programme for leptospirosis. Current
serological tests and culture techniques are not able, with any degree of
confidence, to demonstrate that an animal is free from leptospirosis. Antibiotic
treatment to clear renal carriage of leptospires is not consistently successful
and has not been validated in all the species subject to international trade.
92 ● Import risk analysis: Llamas and alpacas from specified countries MAF Biosecurity New Zealand