Hydatids, something my dad used to go on about! Is it still around?

Hydatids, something my dad used
to go on about! Is it still around?
David Jenkins
School of Animal and Veterinary Sciences, Charles Sturt University
Locked Bag 588, Wagga Wagga, NSW 2678
[email protected]
What is hydatids?
• It is infection with the cystic (intermediate) stage of a tapeworm that
infects dogs
• Cysts contain fluid and protoscoleces (the next generation of
tapeworms)
• Hydatid cysts occur mainly in the liver and lungs of a range of animal
species
What does a hydatid cyst look like?
Why is hydatids important?
• Humans can also act as a host for the cystic stage. Infection can lead
to major health impacts and in some cases death
• Infection in domestic livestock may not be evident but leads to
production losses
• In native wildlife (macropods) infection leads to severe health impacts
and death
Hydatids in humans (Turkana, NW Kenya)
Hydatids in humans
Human hydatid cysts
Hydatids in livestock – ovine liver
Where does hydatid disease occur in Australia?
Thompson and Jenkins International Journal for
Parasitology 44 (2014)
865–877
Between 30-50 cases of human hydatidosis diagnosed,
nationally, each year.
Jenkins & Power (1996) Aust Med J 164; 18-21.
How are hydatids transmitted?
• Dogs eat cysts in offal
• Protoscoleces activate, attach to the inside of the dog’s gut and
develop
• They are mature at about 42 days post infection and begin releasing
eggs
Tapeworm in definitive host - dog.
PPP=42 d
Cysts in internal organs of intermediate
host, eaten by definitive host.
Protoscoleces
Eggs in faeces/environment.
6-hooked
onchosphere
Eggs ingested by intermediate host – sheep.
The Australian hydatid transmission pattern
has changed
• Hydatid disease in sheep now uncommon
• Hydatid tapeworm infection in rural domestic digs also uncommon
• Probably due to
- the development of palatable, inexpensive, dry dog food
- the inclusion of praziquantel in all widely available generic allwormers for dogs
• Today hydatid disease is mainly perpetuated in a wildlife cycle
between wild dogs (dingoes and their hybrids) and macropod
marsupials, particularly wallabies
Tapeworms in definitive hosts - dingoes/& hybrids, (foxes)
Cysts in internal organs of intermediate
host, eaten by definitive host.
Eggs in faeces/environment.
Eggs ingested by intermediate hosts – macropod marsupials/wombats, (feral pigs)
Predator/prey interaction
Dingoes (Canis lupus dingo)
Dingo/domestic dog hybrids
B. Purcell
B. Purcell
B. Purcell
E. granulosus
segments
Hydatids in wildlife
Eastern Grey
Kangaroo
Wombat
Swamp wallaby
Exotic parasites and naïve host
populations.
Cysts 9 months post experimental infection (infected with same batch of eggs)….
Tamar wallaby (fertile)
Sheep (not fertile, usually 2.5-6 years pi)
Barnes et al (2011) J Comp Path 144; 113-122
Study site
Collection areas
Maroochydore Shire
“Urban” dingoes in and around
Maroochy Shire….
Images by M Goullet
….a few more!
Images by M Goullet
Maroochy Shire “urban“ dingo E. granulosus
prevalence data.
-108 intestines examined (June 2003- August
2006).
-E. granulosus found in 50 (46.3%).
-Worm burdens ranged between 30 and
104,000.
Jenkins et al (2008) Aust Vet J 86; 294-300
Urban dingo, potential spreader of E.
granulosus eggs
Images by M Goullet
Transmission importance of flies?
E granulosus
segment
Tasmania
• “Provisional
eradication” of E granulosus in
Tasmania announced in 1996, following almost
30 years of intense control
• About 8000 dogs enter Tasmania annually
• Owners must treat their dogs with
praziquantel within 14 days of arrival into
Tasmania (must also sign a statutory declaration
to say they have done so)
Locations of
Echinococcus
granulosus-infected
cattle (stars) and sheep
(triangles), E.
granulosus
coproantigenpositive
ELISA and coproPCRpositive dogs
(dots).
Bovine hydatidosis financial impact study
Although hydatid disease in sheep is
now uncommon in many areas of
eastern Australia hydatid disease in
cattle is common
Image: Phil Kemsley
Google images
Data collected……
• from one abattoir in north-eastern NSW
• between 1st of July 2013 - 30th of June 2015
• n = 781,873
• 43,002 (5.5%) infected with hydatid disease
• Financial impact analysis
• linear regression model to determine the impact of hydatid infection on carcass
and hide weights
• value models of monthly and yearly financial impact
• 5.5% beasts infected with hydatid cysts
• organs condemned
for hydatid infection:
•
•
•
•
51% livers
48% lungs
1%
spleen
< 1% heart
• 93% of infected cattle had both liver and lung
infection
•
Mean weight loss in cattle infected with hydatid cysts
• hide
= 1.24 kg
• carcass
= 16.8 kg
•
Financial loss per annum
•
•
•
•
•
•
Hide
Carcass
Liver
Lung
Heart
Spleen
=
$32,155
= $1,255,574
= $283,126
= $166,767
=
$1,687
=
$588
• Financial value model
•
Financial loss = Total loss due to carcass weight loss + total
loss due to hide weight loss + cost due to organ
condemnation/ downgrading
• Total lost over the two year period $3,479,738.05
• Total lost per year = $1,739,869.03
•Potential confounders:
• Not all data were available that might influence
prevalence and financial impact of hydatid disease
were included. For example:
•
•
•
Breed of cattle
Travel time of cattle to abattoir
Pasture raised vs. grain-fed (feed lot)
• This is a case study based on an individual abattoir,
therefore results cannot be extrapolated to fit other
abattoirs
Controlling hydatid transmission
• Do not allow dogs access to offal (domestic & wild
animals). Confine dogs; offal pits.
• Treat dogs with de-worming products.
• Feed dry/tinned/cooked food.
• Public education.
• Vaccination of livestock.
Despite a major change in transmission pattern, hydatids
is still around and should not be written off!