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

eports were found in which T. evansi was positively identified in natural cases in camelids
or transmitted experimentally to camelids. However, it is a major disease in camels and
since a wide variety of animal species are susceptible to the disease it is likely that
camelids could also be susceptible.
In camels, surra has an incubation period of 5-60 days (DAFF 2007). Acute cases may
occur but the disease is more often chronic and although most cases end fatally infected
animals may live for several years (DAFF 2007; Uilenberg 1998). The disease is
characterised by recurrent bouts of fever and parasitaemia, loss of condition, oedema and
anaemia. It can be diagnosed by the demonstration of parasites in the blood by a number of
microscopic techniques, by inoculation of laboratory rodents or by PCR. However PCR
has not proven to be any more sensitive than mouse inoculation (Luckins 2008).
Serological tests are available. The ELISA is probably the most reliable test and a card
agglutination test can be used to confirm equivocal test results (Luckins 2008). Generally,
the diagnosis of surra is based on the demonstration of parasites in the blood,
supplemented by serological tests.
T. cruzi
T. cruzi is the aetiological agent of Chagas disease a common and serious disease of
humans. The disease is restricted to South and Central America and occurs more rarely in
the southern parts of the USA. Closely related trypanosome species such as T. rangeli also
occur in these regions. The organisms can infect large numbers of animal species.
The agent is transmitted by kissing bugs (Family: Reduviidae, Sub-family: Triatomatinae).
Kissing bugs do not stay on the host but hide in cracks in walls and other places and attack
humans or animals for brief periods, usually at night, during which time they take blood
meals from their hosts (Krinsky 2009). Infected animals are not contagious.
T. vivax
T. vivax is an African trypanosome that is transmitted by tsetse flies. However, it can also
be transmitted mechanically by biting flies and has become established in Central and
South America, Mauritius and some Carribean islands (Silva & Davila 1996; Silva &
Davila 2001; Connor & Van den Bossche 2004).
Trypanosoma vivax can infect camels but the position with regard to camelids remains
uncertain and no specific descriptions of the disease in camelids were found. However,
since the parasite infects a wide variety of animals including camels it is assumed that it
could infect camelids. A diagnosis can be made by a variety of techniques for the
microscopic examination of blood but these tests lack sensitivity in cases with low
parasitaemia. PCR methods are available but species-specific primers are required for each
Trypanosoma spp. By using a primer specific for T. vivax PCR should be highly sensitive.
Antibody tests are also available and ELISAs for T. vivax have high sensitivity and genus
specificity but species specificity is generally low (Desquesnes 2008).
32.1.5. Hazard identification conclusion
Since the vectors necessary for transmission of T. cruzi are not carried on animals, and do
not occur in New Zealand, the likelihood that the parasite could be introduced by camelids
and become established in New Zealand is negligible.
116 ● Import risk analysis: Llamas and alpacas from specified countries MAF Biosecurity New Zealand