Import Risk Analysis - Biosecurity New Zealand

Cats are much more susceptible to plague than dogs, generally developing high temperatures
with head and neck buboes. Since infection in cats is acute with obvious and dramatic clinical
signs (within 1-3 days) including a mortality rate of 50 % (within 4-9 days); it is unlikely that
a clinically healthy imported cat would be incubating the disease. Therefore, there is a very
low likelihood of entry when a cat is clinically healthy.
Cats and dogs may however pose a risk of introducing Y. pestis through the importation of
infected fleas. Therefore, the likelihood of entry is considered to be low, but non-negligible
for fleas associated with imported animals.
13.2.2. Exposure assessment
The most common mode of plague transmission to humans is through flea bites. If infected
fleas are present on the animal, particularly rat flea species, then human or animal exposure
might occur.
Establishment might occur if a susceptible reservoir host here (e.g. rodents, rabbits, and their
fleas) were exposed to infected fleas in a suitable ecological niche. Elimination of the disease,
if it established, would be difficult and expensive.
13.2.3. Consequence assessment
Plague is notifiable to the World Health Organization in accordance with international health
regulations and is one of four internationally quarantinable human diseases (Gray et al 2006).
Humans that come into contact with an infected animal would require prophylactic
antimicrobial therapy. Plague is fatal in 50 % of infected humans if untreated. Secondary
spread of plague from person to person, person to animal and animal to person is also possible
(Macey 2006). All contacts may require identifying, tracing, treating and possibly quarantine.
In the worst case scenario where an animal was not identified as afflicted with plague, it could
have contact with multiple humans and animals. The severity of the consequences would
depend on the speed of diagnosis. Introduction of Y. pestis could result in the establishment of
infected populations of rats and other rodents.
There would probably be significant public concern if even a single case of plague occurred in
an imported animal or in an in-contact person.
The introduction of plague is likely to cause significant direct and indirect negative
consequences. The consequences are therefore assessed to be moderate to potentially high.
13.2.4. Risk estimation
The risk of introducing Y. pestis by importing healthy cats and dogs is remote. The risks are
considered low for transported fleas that may be associated with the commodity. Therefore,
the risk estimate for the introduction of Y. pestis is non-negligible and it is classified as a
hazard in the commodity. Therefore risk management measures can be justified.
40 • Import risk analysis: Cats, dogs and canine semen MAF Biosecurity New Zealand