Detection of
Echinococcus granulosus and Echinococcus equinus in dogs and epidemiology of canine echinococcosis in the UK

Lett, W S

Abstract

Echinococcus granulosus is a canid cestode species that causes hydatid disease or cystic
echinococcosis (CE) in domestic animals or humans. Echinococcus equinus formerly
recognised as the ‘horse strain’ (E.granulosus genotype G4) is not known to be zoonotic
and predominantly involves equines as its intermediate host. The domestic dog is the
main definitive host for both species, which are also both endemic in the UK but data is
lacking especially for E.equinus. An E.equinus-specific PCR assay was designed to
amplify a 299bp product within the ND2 gene and expressed 100% specificity against a
panel of 14 other cestode species and showed detection sensitivity up to 48.8pg (approx.
6 eggs). Horse hydatid cyst isolates (n = 54) were obtained from 14 infected horse livers
collected from an abattoir in Nantwich, Cheshire and hydatid cyst tissue was amplified
using the ND2 PCR primers to confirm the presence of E.equinus and used to
experimentally infect dogs in Tunisia from which serial post-infection faecal samples
were collected for coproanalysis, and indicated Echinococcus coproantigen and
E.equinus DNA was present in faeces by 7 and 10 days post infection, respectively.
Canine echinococcosis due to E.granulosus appears to have re-emerged in South Powys
(Wales) and in order to determine the prevalence of canine echinococcosis a coproantigen
survey was undertaken. The Welsh Assembly Government also funded a 2 year hydatid
disease eradication campaign (2008-10) as a preventative public health measure and
faecal samples were tested from farm dogs in the control area. In addition 8 foxhound
packs (5 from Wales and 3 from England) were sampled and screened for echinococcosis
infection using an Echinococcus genus-specific coproantigen ELISA that was optimised
against a panel of known Echinococcus and control faecal samples. Farm dogs and
foxhounds were also screened using two coproPCR assays (predominantly E.granulosus
G1 or E.equinus G4 specific). In the Welsh farm dog study, 609 dog faecal samples were
collected at baseline (pre-treatment) of which 10.8% (66/609) were found to be
coproantigen positive, 5.1% (31/609) were G1 E.granulosus coproPCR positive, and
1.8% (12/609) were E.equinus ND2 coproPCR positive. A total of 742 farm dog samples
were tested after 3 quarterly deworming treatments and showed a coproantigen decrease
to 0.7% (5/742). One year after the last dosing round 4.2% (45/1076) of farm dogs were
found to be coproantigen positive; of these only 123 were tested with the G1 primers of
which 15.4% (19/123) were positive for E.granulosus DNA. Of 8 foxhound packs
screened by the Echinococcus genus specific coproantigen ELISA and by the two
coproPCR tests (E.granulosus, E.equinus) 3 of the 4 Welsh hunts had copropositive dogs
(hunt prevalence 30.9%, 9.7%, 61.2%) and 2 of the 3 English hunts (hunt prevalence
17.5%, 44.5%). Hounds in 6 of the 8 hunts were coproPCR positive for E.granulosus
DNA and 2 of the 8 hunts were positive for E.equinus coproDNA. Additional foxhound
data was collected in the form of a survey questionnaire to hunt staff which suggested
that there may be a link between increased Echinococcus coproantigen prevalence and
inadequate worming protocols and unsafe feeding practices. The study showed that
canine echinococcosis due to E.granulosus and E.equinus occurred in farm dogs and
foxhounds in Wales and England and that an intervention programme in mid-Wales
reduced canine echinococcosis in farm dogs after four dosing rounds, but coproprevalence
increased by 12 months after cessation of dosing. The data are discussed with
reference to potential human infection, risk factors and optimal intervention approaches.
The study showed that the distribution of canine echinococcosis in farm dogs and
foxhounds was not homogenous and also confirms the continued presence of both
E.granulosus and E.equinus in foxhounds in England and Wales.

Citation

Echinococcus granulosus and Echinococcus equinus in dogs and epidemiology of canine echinococcosis in the UK. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Oct 9, 2013
• Publicly Available Date: Apr 5, 2016