trichinella in italy and in the european union...trichinella larvae survive for long period in...
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Trichinella in Italy and in the
European Union
Edoardo PozioEuropean 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)
Total 3,607 38.5% 59.5% 2.0%
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 incidencex 100.000
inhabitantsBulgaria 1990-06 4108 2.4. 2.9
Czech Rep. 1986-09 31 0.01Estonia 1986-09 91 0.0-2.9France 1986-89 1261* 0.005-0.006
Germany 1986-09 185 0.005Greece 2009 1 0.008Hungary 1986-09 158 0.18-0.027Ireland 2007 2** 0.04
Italy 1986-09 1181* 0.0-0.9Latvia 1986-09 636 0.07-0.38
Lithuania 1990-04 3979 0.4–21.8Poland 1986-07 3084 0.05-1.5
Romania 1986-07 28564 1.7-16.1Slovakia 1986-08 440 0.0-6.2Slovenia 1989-06 203 0.00-10.5
Spain 1986-09 1684 0.0-0.4UK 1999 7** 0.01
TOTAL 45.615
*most from
imported
horse meat
** from
imported pork
Trichinellosis in humans in the EU
2010-2015Country N. of cases Average incidence
x 100.000 inhabitantsAustria 6 (imported) 0.07Belgium 18 (imported meat) 0.14Bulgaria 234 2.9Croatia 6 0.07Estonia 3 0.07Finland 1 (imported)
Germany 31 0.02Greece 4 0.03
Italy 80 0.07Latvia 150 7.3
Lithuania 219 6.2Poland 93 0.17
Romania 1083 (2 deaths) 4.97Spain 69 (1 death) 0.14
Sweden 2 (imported) 0.01
TOTAL EU 2,005 0.070.7 cases per million inhabitants
mortality rate 0.15%
Trichinella spp. in Italy
• From 1985 to 2016, 354 Trichinella sp. isolatesfrom 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
800 m asl
500 m asl
200 m asl
T. britovi
+++
+++
+++
+
-- -
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 pigsSource of infection hunted
wild boar ( ), foxes ( )
Source of infection
imported horse meat
Trichinellosis in Italy from 1948 to 2015
by source Source No. of
foci
No. of infected
persons (%)
Domestic swine 13 180 (11.9)
Hunted wild boar 11 288 (19.0)
Hunted foxes 2 11 (0.7)
Imported horses 7 1038 (68.4)
Total 33 1517
1
10
100
1000
19
75
19
77
19
79
19
81
19
83
19
85
19
87
19
89
19
91
19
93
19
95
19
97
19
99
20
01
20
03
20
05
20
07
20
09
20
11
20
13
20
15
Horse
Pig
Wild boar
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