Accepted Manuscript Title: Environmental determinants of the spatial distribution of Trichinella britovi and T. spiralis in Hungary Author: Z. Tolnai Z. Sz´ell G. Marucci E. Pozio T. Sr´eter PII: DOI: Reference:
S0304-4017(14)00233-7 http://dx.doi.org/doi:10.1016/j.vetpar.2014.04.024 VETPAR 7231
To appear in:
Veterinary Parasitology
Received date: Revised date: Accepted date:
15-11-2013 2-4-2014 21-4-2014
Please cite this article as: Tolnai, Z., Sz´ell, Z., Marucci, G., Pozio, E., Sr´eter, T.,Environmental determinants of the spatial distribution of Trichinella britovi and T. spiralis in Hungary, Veterinary Parasitology (2014), http://dx.doi.org/10.1016/j.vetpar.2014.04.024 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1
SHORT COMMUNICATION
2 3
ip t
4
cr
5
Environmental determinants of the spatial distribution of Trichinella britovi
7
and T. spiralis in Hungary
us
6
an
8
Z. Tolnaia, Z. Szélla, G. Maruccib, E. Poziob, T. Srétera,*
9
11
a
M
10
Laboratories of Parasitology, Fish and Bee Diseases, Veterinary Diagnostic Directorate, National Food Chain Safety Office, Tábornok utca 2, H−1143 Budapest, Hungary
b
te
13
d
12
Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di
14
16 17 18 19
Ac ce p
15
Sanitá, viale Regina Elena 299, 00161 Rome, Italy
20 21 22
* Corresponding author: E-mail: [email protected]; Fax +36 1 252 5177; Tel. +36 1 460
23
6322
24 1 Page 1 of 13
Abstract
25
Trichinella spiralis and T. britovi are the two most common species of the genus Trichinella
26
persisting in the European wildlife. To investigate the spatial distribution of these Trichinella
27
spp. and the factors influencing their circulation in Hungary, 3,304 red foxes (Vulpes vulpes)
28
and 0.29 million wild boars (Sus scrofa) were tested for Trichinella sp. infection in Hungary
29
from 2006 to 2013. Trichinella spp. larvae from 68 (2.0%) foxes and 44 (0.015%) wild boars
30
were identified by a multiplex PCR as T. britovi or T. spiralis. The locality of origin of foxes
31
and wild boars were recorded in a geographic information system database. There was no
32
correlation between environmental parameters in the home range of foxes and wild boars and
33
the T. spiralis larval counts, but there was a positive correlation between the boundary zone of
34
Hungary and T. spiralis infection (P < 0.0001; odds ratio: 24.1). These results indicate that the
35
distribution of T. spiralis in the Hungarian wildlife is determined by the transborder
36
transmission of the parasite from the surrounding endemic countries. Multiple regression
37
analysis was performed with environmental parameter values and T. britovi larval counts.
38
Based on the statistical analysis, non-agricultural areas (forests, scrubs, herbaceous vegetation
39
and pastures) and the mean annual temperature (P < 0.0001; odds ratios: 9.53 and 0.61) were
40
the major determinants of the spatial distribution of T. britovi in Hungary. The positive
41
relationship with non-agricultural areas can be explained by the generalist feeding behaviour
42
including scavenging of foxes in these areas. The negative relationship with the mean annual
43
temperature can be attributed to the slower decomposition of wildlife carcasses favouring a
44
longer survival of T. britovi larvae in the host carrion and to the increase of scavenging of
45
foxes.
Ac ce p
te
d
M
an
us
cr
ip t
24
46
2 Page 2 of 13
46
1.
47
Introduction Nematode parasites of the genus Trichinella are among the most widespread zoonotic
pathogens in the world (Pozio and Murrel, 2006). In Hungary, T. britovi is the most common
49
species circulating among carnivore and omnivore wild animals (Széll et al., 2008, 2012). To
50
assess the consumer risk for T. britovi and T. spiralis infections, it is important to know the
51
spatial distribution pattern of these parasites and environmental factors (e.g., temperature, land
52
cover) influencing this pattern. Geographical information systems (GIS) represent new tools
53
for studying the spatial distribution of parasites (Rinaldi et al., 2006). To investigate
54
environmental factors which can play a role in Trichinella spp. transmission in wildlife, red
55
foxes and wild boars, the most important indicator species of these parasites in the European
56
wildlife, were sampled and examined for Trichinella spp. infection in Hungary. The pattern of
57
infection in foxes and wild boars, and the relationship of these patterns with landscape and
58
climate was analysed by GIS.
62 63
te
61
2.
Materials and methods
Ac ce p
60
d
59
M
an
us
cr
ip t
48
2.1. Sample collection, parasite isolation and identification From November 2008 to February 2013, carcasses of red foxes killed by hunters in
64
Hungary were sent in individual plastic bags to the National Food Chain Safety Office of
65
Budapest. Carcasses were labelled by the hunters with an identification number reporting the
66
information on the nearest place to killing on the topographic map. Red fox carcasses,
67
representing more than 4% of the total fox population of each county, were randomly selected
68
out of all the foxes from 19 counties and from the Budapest municipality (Fig. 1). Muscle
69
samples were collected and examined as previously described (Széll et al., 2008).
70 71
Between June 2006 and September 2013, a total of 0.29 million hunted wild boars were tested at official control laboratories for Trichinella sp. larvae during routine meat inspection. 3 Page 3 of 13
When a Trichinella spp. positive animal was detected, a 100 g sample was collected from the
73
predilection muscles and sent to the National Food Chain Safety Office, Budapest, Hungary,
74
for the confirmatory diagnosis, evaluation of the worm burden (number of larvae/g, LPG) and
75
parasite isolation (Széll et al., 2012). As the place of killing of uninfected wild boars is not
76
recorded in Hungary, these data could not be included in the analysis.
Trichinella spp. larvae were washed, counted, and forwarded to the Istituto Superiore di
cr
77
ip t
72
Sanità, Rome, Italy, for the species identification as previously described (Széll et al. 2008,
79
2012).
us
78
81 82
an
80
2.2. Geographic information system database, spatial and statistical analysis The locality of origin of foxes and wild boars and the number of larvae/g were marked on a point layer by the Quantum GIS 1.8.0 softwareQGIS Team, 2012). The vector layers of
84
altitude, land cover, permanent water bodies, protected areas according to the Hungarian Law
85
No. LII/1996 (national parks, landscape protection areas, nature conservation areas), soil water
86
retention and soil permeability, were obtained from VÁTI Hungarian Nonprofit Ltd. for
87
Regional Development and Planning (Budapest, Hungary). The vector layers of the mean
88
annual temperature and annual precipitation were created and vector-based analysis was
89
carried out by the Quantum GIS 1.8.0 software on the basis of the georeferenced digital map of
90
the Hungarian Meteorological Service. The spatial resolution of the vector layers varied from
91
10 m (land cover, country border) to 50–100 m (other layers). The radius around the locality of
92
animal origin was restricted to 2.5 and 3.0 km, which was assumed to represent the average
93
home range of foxes and wild boars, respectively (Staubach et al., 2001; Calenge et al., 2002).
94
Along permanent water bodies, a 100 meter wide buffer zone was created, where the
95
probability of the presence of reservoir hosts was high. Along country border, a 10 km wide
96
buffer zone was created to evaluate the transborder transmission of these parasites from
97
neighbouring countries. The digitized home range and the vector data were used to calculate
Ac ce p
te
d
M
83
4 Page 4 of 13
the altitude, mean annual temperature, annual precipitation, areas of land cover types, and the
99
buffer zones of permanent water bodies and country borders. The associations between
100
environmental factors and the larval burden of T. britovi and T. spiralis infection were
101
analysed by multiple linear regression analysis and logistic regression analysis as previously
102
described (Tolnai et al., 2013).
ip t
98
104
3.
cr
103 Results
T. spiralis larvae were detected in 8 foxes and 12 wild boars (Table 1). T. britovi larvae
106
were identified in 60 foxes and 32 wild boars (Table 1). The spatial distribution of T. britovi
107
and T. spiralis was highly clumped in Hungary (Fig. 1).
an
108
us
105
There was no correlation between environmental parameters and the T. spiralis LPG. The multiple regression analysis and the logistic regression analysis show a positive correlation
110
(95% CI of odds ratios: 3.81–108.3) between the buffer zone of the Hungarian border and T.
111
spiralis LPG in foxes (P < 0.0001). When the data of T. spiralis infected wild boars were
112
included in the analyses, the results were very similar (95% CI of odds ratios: 7.9–73.4).
te
d
M
109
There was no correlation between protected areas, permanent water bodies, soil water
114
retention or soil permeability in the home range of foxes and wild boars and the T. britovi LPG.
115
A positive correlation between the annual precipitation and T. britovi LPG in foxes (P
S0304-4017(14)00233-7 http://dx.doi.org/doi:10.1016/j.vetpar.2014.04.024 VETPAR 7231
To appear in:
Veterinary Parasitology
Received date: Revised date: Accepted date:
15-11-2013 2-4-2014 21-4-2014
Please cite this article as: Tolnai, Z., Sz´ell, Z., Marucci, G., Pozio, E., Sr´eter, T.,Environmental determinants of the spatial distribution of Trichinella britovi and T. spiralis in Hungary, Veterinary Parasitology (2014), http://dx.doi.org/10.1016/j.vetpar.2014.04.024 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1
SHORT COMMUNICATION
2 3
ip t
4
cr
5
Environmental determinants of the spatial distribution of Trichinella britovi
7
and T. spiralis in Hungary
us
6
an
8
Z. Tolnaia, Z. Szélla, G. Maruccib, E. Poziob, T. Srétera,*
9
11
a
M
10
Laboratories of Parasitology, Fish and Bee Diseases, Veterinary Diagnostic Directorate, National Food Chain Safety Office, Tábornok utca 2, H−1143 Budapest, Hungary
b
te
13
d
12
Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di
14
16 17 18 19
Ac ce p
15
Sanitá, viale Regina Elena 299, 00161 Rome, Italy
20 21 22
* Corresponding author: E-mail: [email protected]; Fax +36 1 252 5177; Tel. +36 1 460
23
6322
24 1 Page 1 of 13
Abstract
25
Trichinella spiralis and T. britovi are the two most common species of the genus Trichinella
26
persisting in the European wildlife. To investigate the spatial distribution of these Trichinella
27
spp. and the factors influencing their circulation in Hungary, 3,304 red foxes (Vulpes vulpes)
28
and 0.29 million wild boars (Sus scrofa) were tested for Trichinella sp. infection in Hungary
29
from 2006 to 2013. Trichinella spp. larvae from 68 (2.0%) foxes and 44 (0.015%) wild boars
30
were identified by a multiplex PCR as T. britovi or T. spiralis. The locality of origin of foxes
31
and wild boars were recorded in a geographic information system database. There was no
32
correlation between environmental parameters in the home range of foxes and wild boars and
33
the T. spiralis larval counts, but there was a positive correlation between the boundary zone of
34
Hungary and T. spiralis infection (P < 0.0001; odds ratio: 24.1). These results indicate that the
35
distribution of T. spiralis in the Hungarian wildlife is determined by the transborder
36
transmission of the parasite from the surrounding endemic countries. Multiple regression
37
analysis was performed with environmental parameter values and T. britovi larval counts.
38
Based on the statistical analysis, non-agricultural areas (forests, scrubs, herbaceous vegetation
39
and pastures) and the mean annual temperature (P < 0.0001; odds ratios: 9.53 and 0.61) were
40
the major determinants of the spatial distribution of T. britovi in Hungary. The positive
41
relationship with non-agricultural areas can be explained by the generalist feeding behaviour
42
including scavenging of foxes in these areas. The negative relationship with the mean annual
43
temperature can be attributed to the slower decomposition of wildlife carcasses favouring a
44
longer survival of T. britovi larvae in the host carrion and to the increase of scavenging of
45
foxes.
Ac ce p
te
d
M
an
us
cr
ip t
24
46
2 Page 2 of 13
46
1.
47
Introduction Nematode parasites of the genus Trichinella are among the most widespread zoonotic
pathogens in the world (Pozio and Murrel, 2006). In Hungary, T. britovi is the most common
49
species circulating among carnivore and omnivore wild animals (Széll et al., 2008, 2012). To
50
assess the consumer risk for T. britovi and T. spiralis infections, it is important to know the
51
spatial distribution pattern of these parasites and environmental factors (e.g., temperature, land
52
cover) influencing this pattern. Geographical information systems (GIS) represent new tools
53
for studying the spatial distribution of parasites (Rinaldi et al., 2006). To investigate
54
environmental factors which can play a role in Trichinella spp. transmission in wildlife, red
55
foxes and wild boars, the most important indicator species of these parasites in the European
56
wildlife, were sampled and examined for Trichinella spp. infection in Hungary. The pattern of
57
infection in foxes and wild boars, and the relationship of these patterns with landscape and
58
climate was analysed by GIS.
62 63
te
61
2.
Materials and methods
Ac ce p
60
d
59
M
an
us
cr
ip t
48
2.1. Sample collection, parasite isolation and identification From November 2008 to February 2013, carcasses of red foxes killed by hunters in
64
Hungary were sent in individual plastic bags to the National Food Chain Safety Office of
65
Budapest. Carcasses were labelled by the hunters with an identification number reporting the
66
information on the nearest place to killing on the topographic map. Red fox carcasses,
67
representing more than 4% of the total fox population of each county, were randomly selected
68
out of all the foxes from 19 counties and from the Budapest municipality (Fig. 1). Muscle
69
samples were collected and examined as previously described (Széll et al., 2008).
70 71
Between June 2006 and September 2013, a total of 0.29 million hunted wild boars were tested at official control laboratories for Trichinella sp. larvae during routine meat inspection. 3 Page 3 of 13
When a Trichinella spp. positive animal was detected, a 100 g sample was collected from the
73
predilection muscles and sent to the National Food Chain Safety Office, Budapest, Hungary,
74
for the confirmatory diagnosis, evaluation of the worm burden (number of larvae/g, LPG) and
75
parasite isolation (Széll et al., 2012). As the place of killing of uninfected wild boars is not
76
recorded in Hungary, these data could not be included in the analysis.
Trichinella spp. larvae were washed, counted, and forwarded to the Istituto Superiore di
cr
77
ip t
72
Sanità, Rome, Italy, for the species identification as previously described (Széll et al. 2008,
79
2012).
us
78
81 82
an
80
2.2. Geographic information system database, spatial and statistical analysis The locality of origin of foxes and wild boars and the number of larvae/g were marked on a point layer by the Quantum GIS 1.8.0 softwareQGIS Team, 2012). The vector layers of
84
altitude, land cover, permanent water bodies, protected areas according to the Hungarian Law
85
No. LII/1996 (national parks, landscape protection areas, nature conservation areas), soil water
86
retention and soil permeability, were obtained from VÁTI Hungarian Nonprofit Ltd. for
87
Regional Development and Planning (Budapest, Hungary). The vector layers of the mean
88
annual temperature and annual precipitation were created and vector-based analysis was
89
carried out by the Quantum GIS 1.8.0 software on the basis of the georeferenced digital map of
90
the Hungarian Meteorological Service. The spatial resolution of the vector layers varied from
91
10 m (land cover, country border) to 50–100 m (other layers). The radius around the locality of
92
animal origin was restricted to 2.5 and 3.0 km, which was assumed to represent the average
93
home range of foxes and wild boars, respectively (Staubach et al., 2001; Calenge et al., 2002).
94
Along permanent water bodies, a 100 meter wide buffer zone was created, where the
95
probability of the presence of reservoir hosts was high. Along country border, a 10 km wide
96
buffer zone was created to evaluate the transborder transmission of these parasites from
97
neighbouring countries. The digitized home range and the vector data were used to calculate
Ac ce p
te
d
M
83
4 Page 4 of 13
the altitude, mean annual temperature, annual precipitation, areas of land cover types, and the
99
buffer zones of permanent water bodies and country borders. The associations between
100
environmental factors and the larval burden of T. britovi and T. spiralis infection were
101
analysed by multiple linear regression analysis and logistic regression analysis as previously
102
described (Tolnai et al., 2013).
ip t
98
104
3.
cr
103 Results
T. spiralis larvae were detected in 8 foxes and 12 wild boars (Table 1). T. britovi larvae
106
were identified in 60 foxes and 32 wild boars (Table 1). The spatial distribution of T. britovi
107
and T. spiralis was highly clumped in Hungary (Fig. 1).
an
108
us
105
There was no correlation between environmental parameters and the T. spiralis LPG. The multiple regression analysis and the logistic regression analysis show a positive correlation
110
(95% CI of odds ratios: 3.81–108.3) between the buffer zone of the Hungarian border and T.
111
spiralis LPG in foxes (P < 0.0001). When the data of T. spiralis infected wild boars were
112
included in the analyses, the results were very similar (95% CI of odds ratios: 7.9–73.4).
te
d
M
109
There was no correlation between protected areas, permanent water bodies, soil water
114
retention or soil permeability in the home range of foxes and wild boars and the T. britovi LPG.
115
A positive correlation between the annual precipitation and T. britovi LPG in foxes (P
