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