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

33. Echinococcus granulosus
33.1. HAZARD IDENTIFICATION
33.1.1. Aetiological agent
Echinococcus granulosus is a tapeworm (cestode) parasite.
33.1.2. OIE list
Echinococcosis/hydatidosis is a listed disease of multiple species.
33.1.3. New Zealand status
New Zealand was declared provisionally free from Echinococcus granulosus in 2002
(Pharo 2002) with no cases having been found since. Echinococcus spp. are listed on the
Unwanted Organisms Register as notifiable organisms and hydatid disease is notifiable to
the Medical Officer of Health (MoH 2009).
33.1.4. Epidemiology
The adult parasite is a small tapeworm found in the intestines of dogs that have eaten offal
from sheep infested with hydatid cysts. Hydatid cysts, the cystic form of Echinococcus
granulosus, occur particularly in the lungs, liver and occasionally in other organs of sheep,
goats and other susceptible host animals that have ingested tapeworm eggs that have been
voided with dog faeces. Humans are accidental hosts infested by ingesting tapeworm eggs
that rarely go on to develop into hydatid cysts. Echinococcus granulosus can cause a
severe (potentially fatal) disease in humans when the cyst stage develops in vital organs.
Humans are considered to be dead-end hosts. Dogs are infested by eating hydatid cyst
infested offal from sheep or other intermediate hosts.
Hydatidosis has been described in camelids and camels. The advent of molecular typing
techniques has resulted in the identification of at least 10 genotypes of Echinococcus
granulosus. Type G1 is the common sheep type, G2 is the Tasmanian sheep variant, G4 is
the horse type, G5 is the cattle type, G6 is the camel type, G7 is the pig type, G8 is a cervid
type and G10 a reindeer type (Lavikainen et al 2006). It has been suggested that types G6-
10 may represent a separate species (Lavikainen et al 2006). Most human infestations are
caused by the G1 type.
There is little information about hydatidosis in camelids. However, a large number of
human infestations in Argentina are caused by G6 (the camel type) and therefore it seems
probable that camelids are infected with this type (Guarnera et al 2004). Evidence from
several papers suggests that sheep type G1 and the camel type G6 exist in
epidemiologically distinct sheep/carnivore and camels/carnivore cycles respectively
(Ahmadi & Dalimi 2006; Oudni-M'rad et al 2006).
New Zealand is free from the parasite but it could be re-introduced through the importation
of animals. These could be dogs, the definitive host, or any imported intermediate host
animal that is infested with hydatid cysts and subsequently fed to dogs.
Diagnosis of hydatids in live animals is difficult since they show no signs of infestation.
Serological diagnosis in intermediate hosts has proved to be specific but insensitive
120 ● Import risk analysis: Llamas and alpacas from specified countries MAF Biosecurity New Zealand