Trichinella in Italy and in the
European Union
Edoardo Pozio
European Union Reference Laboratory for Parasites
Istituto Superiore di Sanità
Rome, Italy
The Trichinella genus in Europe
• At present, 12 taxa are recognized in the
genus Trichinella worldwide
• Of them, 4 species are circulating in Europe
– T. spiralis
– T. nativa
– T. britovi
– T. pseudospiralis
The Trichinella genus in Europe
• At present, 12 taxa are recognized in the
genus Trichinella worldwide
• Of them, 4 species are circulating in Europe
– T. spiralis
– T. nativa
– T. britovi
– T. pseudospiralis
Europeran Trichinella species and their
hosts
•
•
•
•
T. spiralis
T. nativa
T. britovi
T. pseudospiralis
Trichinella spp. circulating in the EU
and their hosts
Trichinella spp.
Tested isolates
Carnivores
Suidae
Other hosts
T. britovi
1,741 (48.3%)
64%
35.4%
0.6% (horses, rodents)
T. spiralis
1,699 (47.1%)
8.6%
87.9%
3.5% (horses, rodents)
T. nativa
124 (3.4%)
98.5%
1.5%
never detected
T. pseudospiralis
43 (1.2%)
20.9%
69.7%
9.3% (rodents, birds)
3,607
38.5%
59.5%
2.0%
Total
Trichinella sp. epidemiology
Sylvatic cycle
Domestic cycle
The sylvatic cycle- 1
• Wild animals susceptible to Trichinella infection (carnivores and
omnivores) are the Trichinella reservoirs
• The Trichinella biomass is higher in wild than in domestic
animals
• The poor management of wild and domestic animals favours the
Trichinella sp. transmission from the wild to the domestic
habitat and viceversa
Trichinella larvae survive for long period in
animal carcasses
• Trichinella larvae of some species can survive for months up to several years in
frozen muscles
– The survival time is higher between 0°C and -18°C
• Encapsulated larvae of Trichinella survive for months in decaying flesh of their
hosts:
– High humidity
– Low temperature
• Larvae can survive in the collagen capsule even when the muscle tissues are
completely liquefied
The subnivium
• The habitat “below snow” provides environmental stability
linked to snow duration, density, and depth
Minimum daily temperatures
- under deep snow (black line)
- shallow snow (dashed line)
- ambient temperature (grey line)
The subnivium climate is characterized
by a stable temperature near freezing
because heat released from the soil is
trapped by the low thermal
conductivity of snow
Rearing practices involved in transmission
of Trichinella spp. to domestic pigs - 1
• Feed on wild animal carcasses
• Hunters who leave animal carcasses in the field after skinning, or
remove and discard the entrails, or dispose of in dumps
• Hunters who feed pigs with animal carcasses
• Road-killed wild animals
• Introduction of new pigs on a farm without any information on the
farm of origin and previous farming conditions
Rearing practices involved in transmission
of Trichinella spp. to domestic pigs - 2
•
•
•
•
•
Cannibalism due to a high mortality rate
Feed on garbage containing pork or wild animal scraps
Feed on pork scraps from pigs slaughtered at the farm
Feed on carcasses or scraps from farmed fur animals
Feed on rats, which can play the role of Trichinella spp. ‘vector’
from one farm to another
• Feed origin and correct daily feed intake not always controlled
Pigs at risk for Trichinella transmission
Trichinella sp. in domestic pigs and
wildlife
Trichinellosis in humans in the EU
1986-2009
Country
Period
N. of cases
Average incidence
x 100.000
inhabitants
Bulgaria
Czech Rep.
Estonia
France
Germany
Greece
Hungary
Ireland
Italy
Latvia
Lithuania
Poland
Romania
Slovakia
Slovenia
Spain
UK
1990-06
1986-09
1986-09
1986-89
1986-09
2009
1986-09
2007
1986-09
1986-09
1990-04
1986-07
1986-07
1986-08
1989-06
1986-09
1999
4108
31
91
1261*
185
1
158
2**
1181*
636
3979
3084
28564
440
203
1684
7**
2.4. 2.9
0.01
0.0-2.9
0.005-0.006
0.005
0.008
0.18-0.027
0.04
0.0-0.9
0.07-0.38
0.4–21.8
0.05-1.5
1.7-16.1
0.0-6.2
0.00-10.5
0.0-0.4
0.01
TOTAL
45.615
*most from
imported
horse meat
** from
imported pork
Trichinellosis in humans in the EU
2010-2015
Country
N. of cases
Average incidence
x 100.000 inhabitants
Austria
Belgium
Bulgaria
Croatia
Estonia
Finland
Germany
Greece
Italy
Latvia
Lithuania
Poland
Romania
Spain
Sweden
6 (imported)
18 (imported meat)
234
6
3
1 (imported)
31
4
80
150
219
93
1083 (2 deaths)
69 (1 death)
2 (imported)
0.07
0.14
2.9
0.07
0.07
0.02
0.03
0.07
7.3
6.2
0.17
4.97
0.14
0.01
TOTAL EU
2,005
0.07
0.7 cases per million inhabitants
mortality rate 0.15%
Trichinella spp. in Italy
• From 1985 to 2016, 354 Trichinella sp. isolates
from animals (both domestic and wild) living in
Italy, have been identified at the species level:
• 342 T. britovi (97.5%)
– 4 cats, 5 dogs, 5 brown rats, 1 black rat, 163 red foxes,
106 wolves, 1 brown bear, 30 wild boars, 18 pigs, 8
stone martens, and 2 badgers;
• 8 T. pseudospiralis (2.2%)
– 1 tawny owl, 1 little owl, 1 red fox, and 5 wild boars;
• 2 T. spiralis (0.3%) (1991, 2016)
– red foxes
Foci of
Trichinella
species in Italy
T. pseudospiralis
T. spiralis
T. britovi
T. britovi
+++
+++
800 m asl
+++
+
500 m asl
-
-
200 m asl
Indirect versus direct detection methods of
Trichinella spp. infection in wild boar
Tested wild boar: 1,462
Seroprevalence of 2.2% in muscle juices
(95% C.I 1.55-3.07; 32/1,462)
Prevalence by digestion: 0.07%
(95%C.I. 0.01-0.39; 1/1,462)
Trichinella britovi larvae
From 2006 to 2012, a prevalence
of 0.017% was detected
by muscle digestion in wild boar
hunted in the whole Italian territory
Hunting dogs as sentinel animals for monitoring
infections with Trichinella spp. in wildlife
Out of 384 tested hunting dogs,
56 tested positive by serology.
All positive dogs hunt in mountain areas
Trichinellosis outbreaks in Italy
from 1948 to 2016
Source of infection free
ranging or backyard pigs
Source of infection hunted
wild boar ( ), foxes ( )
Source of infection
imported horse meat
Trichinellosis in Italy from 1948 to 2015
by source
Domestic swine
Hunted wild boar
Hunted foxes
Imported horses
Total
No. of
foci
13
11
No. of infected
persons (%)
180 (11.9)
288 (19.0)
2
11 (0.7)
7
33
1000
1038 (68.4)
1517
Horse
Pig
Wild boar
100
10
1
1975
1977
1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
Source
Conclusions
• Nematodes of the genus Trichinella are parasites of wild
animals
• These parasites are transmitted from wildlife to domestic
animals when humans do not properly manage
–
–
–
–
game offal and scraps
backyard and free-ranging pigs
fur animals
horses
• Pigs reared under controlled housing conditions are
exempted from these parasites
• Public health and veterinary services should invest funds
into the education of consumers, farmers, and hunters
Thank you for your attention