Influence of Parasitism on Trace Element Contents in Tissuesof Red Fox (Vulpes vulpes) and Its Parasites Mesocestoides spp.(Cestoda) and Toxascaris leonina (Nematoda)

Ivana Jankovska Æ Daniela Miholova ÆVladimır Bejcek Æ Jaroslav Vadlejch ÆMiloslav Sulc Æ Jirina Szakova Æ Iva Langrova

Received: 20 November 2008 / Accepted: 15 June 2009 / Published online: 5 July 2009

� Springer Science+Business Media, LLC 2009

Abstract Bioaccumulation of cadmium, chromium,

copper, manganese, nickel, lead, and zinc in 56 foxes

(Vulpes vulpes) and their parasites Mesocestoides spp.

(Cestoda) and Toxascaris leonina (Nematoda) was studied.

The levels of heavy metals were determined in the livers

and kidneys of the animals depending on parasitism in the

following ranges: Pb, 0.029–3.556; Cd, 0.055–9.967; Cr,

0.001–0.304; Cu, 4.15–41.15; Mn, 1.81–19.94; Ni: 0.037–

0.831; Zn, 52.0–212.9 lg/g dry weight (dw). Cd in para-

sites (0.038–3.678 lg/g dw) were comparable with those

in the livers of the host and lower than in the kidneys

(0.095–6.032 lg/g dw). Contents of Pb, Cr, Cu, Mn, Ni,

and Zn in cestodes were predominantly higher than those in

the kidney and liver of the host. Median lead levels in

Mesocestoides spp. (45.6 lg/g dw) were 52-fold higher

than in the kidney and liver of the red fox (Vulpes vulpes)

infected by both parasites and median Pb values in

T. leonina (8.98 lg/g dw) were 8-fold higher than in the

tissues of the parasitized red fox. Bioaccumulation factors

of copper, zinc, nickel, and manganese are lower than those

of lead and mostly range from 1.9 to 24 for Mesocestoides

spp. and from 1.5 to 6 for nematode T. leonina depending

on the tissue of host and element. A significant decrease in

the content of Pb was found in the kidney of animals

infected by T. leonina (0.260 lg/g dw) as well as those

infected by Mesocestoides spp. (0.457 lg/g dw) in com-

parison with the lead content (0.878 lg/g dw) in the kid-

neys of the nonparasitized red fox. Regardless of a

bioaccumulation of copper and manganese in the parasites,

a significant increase of the concentrations of Mn and Cu

was observed in the host’s livers infected predominantly by

Mesocestoides spp.

Wild animals are naturally exposed to basal levels of heavy

metals in their natural habitats. Field studies have shown

that high levels of heavy metals in the environment can be

monitored appropriately by the assessment of their con-

centrations in the internal organs of free-living mammals.

The red fox (Vulpes vulpes) is a representative of the canid

family. It is widely distributed in the northern hemisphere

and the most abundant wild carnivore living in the territory

of the Czech Republic. Annual captures in the Czech

Republic currently range between 60,000 and 90,000 foxes,

and red fox populations are still growing (Cerveny et al.

2004). The increase in the distribution and density of red

foxes (V. vulpes) in most European countries could be

explained by a reduction in the mortality rate due to an

intensive campaign of vaccination against rabies (oral

baits), the opportunist behavior of the red foxes, and nature

I. Jankovska (&) � J. Vadlejch � I. Langrova

Department of Zoology and Fisheries, Faculty of Agrobiology,

Food and Natural Resources, Czech University of Life Sciences,

165 21 Prague 6–Suchdol, Czech Republic

e-mail: jankovska@af.czu.cz

D. Miholova � M. Sulc

Department of Chemistry, Faculty of Agrobiology, Food and

Natural Resources, Czech University of Life Sciences,

165 21 Prague 6–Suchdol, Czech Republic

V. Bejcek

Department of Ecology, Faculty of Environmental Science,

Czech University of Life Sciences,

165 21 Prague 6–Suchdol, Czech Republic

J. Szakova

Department of Agroenviromental Chemistry and Plant Nutrition,

Faculty of Agrobiology, Food and Natural Resources,

Czech University of Life Sciences, 165 21 Prague 6–Suchdol,

Czech Republic

123

Arch Environ Contam Toxicol (2010) 58:469–477

DOI 10.1007/s00244-009-9355-2

conservation measures (Cerveny et al. 2004; Hanosset et al.

2008). The colonization of urban and suburban habitats by

red foxes provides a novel sentinel species to monitor the

spread of anthropogenic pollutants. The red fox is the first

example of an urban wildlife species that faithfully reflects

the dynamic distribution of toxic contaminants in the cor-

responding human population. Red foxes are relatively

long-lived and readily available for sampling, can be easily

aged and sexed, have a limited home range, and, therefore,

meet several important requirements to serve as a surrogate

species for the assessment of toxic health hazards.

The increasing utilization of urbanized habitats by red

foxes prompted us to test whether this species might be

used for monitoring the presence of anthropogenic pollu-

tants in the environment. Dip et al. (2001) monitored heavy

metals in the tissues of the red fox from adjacent urban,

suburban, and rural areas. They found that animals from

separate environmental compartments contain different

patterns of tissue residues, implying that red foxes might

serve as a bioindicator species to detect certain toxic haz-

ards in urbanized as well as forest habitats.

Because the red foxes are frequently infected by para-

sites (e.g., Willingham et al. 1996) it is necessary to follow

their possible influence on heavy metal levels in the tissues

of red foxes, which are used in the monitoring of envi-

ronmental pollution. Yet it is known that some endo-

helminths of the terrestrial hosts do accumulate toxic

elements above values detected in the tissues of their hosts.

This is particularly true for acantocephalans and cestodes

that dwell in the intestine of their definitive host and are

able to effectively accumulate heavy metals (Sures et al.

2002; Torres et al. 2004, 2006). There is need for sentinel

organisms reflecting small-scale changes in heavy metal

pollution of different habitats and the role of terrestrial

mammalian parasites is an important field of research

aimed at the potential use of parasitic models as bioindi-

cators. Information on endohelminths of vertebrates living

in terrestrial ecosystems as sentinels for heavy metal

environmental pollution is limited mostly to parasites of

rodents.

The aim of the present study was to assess the role of the

red fox (V. vulpes), a representative of the canid family,

and their helminths as biomonitors for intake of heavy

metals from the environment in natural field conditions.

Simultaneously, the impact of the parasite burden on bio-

accumulation of heavy metals in some tissues of red foxes

was studied. This information can be important for the use

of red fox tissues in the monitoring of environmental pol-

lution, if no information about the possible infection of red

foxes by parasites is available.

Materials and Methods

Study Area

Field research was conducted in the industrial emission

affected area of the Krusne hory Mts (Natura 2000

CZ0421005) (approximately 30�420N 13�360E), in the

Northwestern Bohemia Sumny Dul area (Fig. 1), where

pollutants from petrochemical industries and brown coal

power plants are common. Heavy metals, which are part of

industrial contaminants, negatively affect individuals in

this area. In addition to directly affecting organisms in an

unfavorable way, sulfur dioxide causes considerable acid-

ification of soil. The pollutants also negatively affect the

chemical conditions in the pedosphere (Table 1).

Sampling

Experimental material was obtained from a total of 56 red

foxes (24 females and 32 males) collected between

December 2006 and January 2007. The majority of animals

were shot in the course of population control programs.

The carcasses were wrapped in plastic bags and stored at -

20�C until further examination. During the necropsy, the

animals were sexed and their age was evaluated. The ani-

mals were adult foxes over 2 years old. The entire gut was

collected and kept for at least 3 weeks at -80�C in order to

inactivate the infective material. The animals were dis-

sected in the laboratory and particularly analyzed for

intestinal endohelminths; 39 animals (i.e., 69.4% from a

total of 56 red foxes) were helminthologically positive.

Five animals were infected by Mesocestoides spp. (5–25

specimens in 1 red fox), 9 animals by Toxascaris leonina

(1–10 specimens in 1 red fox), and 25 red foxes by both

Mesocestoides spp. (1–71 specimens) and T. leonina (1–10

specimens). Seventeen red foxes [i.e., 30.4% (10 males and

7 females)] were without endohelminths. It is known that

the red fox (V. vulpes) can be infected by Echinococcus

multilocularis. This parasite is the causative agent of

alveolar echinococcosis, a zoonotic parasitic disease that

causes a severe hepatic disorder in humans. However, no

E. multilocularis was found in the small intestine of the

foxes from this experimental area. Endohelminth specimens

were preserved in glass vials filled with ethanol. Tissues

were carefully examined for postmortem degradation and

for the presence of gunshot wounds; such samples were

eliminated from further analysis. Samples of the kidneys,

the livers as the targent organs, and the endohelminths were

deep-frozen until posterior processing for chemical analy-

sis. Muscle samples were not used in the study.

470 Arch Environ Contam Toxicol (2010) 58:469–477

123

Determination of Trace Elements in Animal Tissues

and Parasites

The contents of cadmium, chromium, copper, lead, man-

ganese, nickel, and zinc were determined in digested

samples of the kidneys and livers of red foxes and parasites

by inductively coupled plasma optic emission spectrometry

(ICP-OES) or electrothermal atomic absorption spectrom-

etry (ET-AAS). Frozen samples of tissues (4–5 g of wet

material) were dried by lyophilization using the LYOVAC

GT 2 (LEYBOLD-HERAEUS, GmbH, FRG). Because

parasites were stored in the minimum volume of ethanol

(96%), the first step of analysis was mild evaporation of the

solution to a wet sample followed by freezing at -20�C

and lyophilization. Parasite samples were small. There was

a risk of a loss of frozen material during transport from the

original vials to the analytical vessels. It was the reason for

the use of ethanol in parasite preservation. Ethanol was

tested on heavy metal contents before use. Analytical

blanks prepared in parasite analysis contained of ethanol

evaporation under the same conditions as the samples. All

samples were decomposed by the dry ashing procedure in

the Dry Mineralizer Apion (Tessek, Ltd., CZ) in the

atmosphere of oxygen, ozone and nitrogen oxides. The

decomposition proceeded for 18 h at temperatures ranging

between 120�C and 400�C as described by Miholova et al.

(1993). The white ash obtained was leached with 1.5%

nitric acid prepared from HNO3 65%, p.a. ISO (Merck) and

Fig. 1 Monitoring area: Sumny dul, Krusne hory Mts., Czech Republic

Table 1 Chemical properties of mineral horizons in the Krusne hory Mts. monitoring area

pH pH Al Cu Fe Mn Pb Zn

(KCl) (H2O) (lg/g) (lg/g) (lg/g) (lg/g) (lg/g) (lg/g)

Surface horizon 3 3.8 3,052 5 5,364 42 75 10

Subsurface horizon 3.4 4.2 4,097 3 8,032 105 36 9

Note: Concentration of elements determined in 2 M HNO3 extract of soil

Source: Data from Slodicak et al. (2008)

Arch Environ Contam Toxicol (2010) 58:469–477 471

123

deionized water (Barnstead). The concentrations of ana-

lytes in the digests of parasites were measured by the ET-

AAS technique using a Varian AA 280Z (Varian, Austra-

lia) with the graphite tube atomizer GTA 120 (Cd, Cr, Cu,

Ni, and Pb) and by the ICP-OES technique using a Varian

Vista (Mn and Zn). The ICP-OES method was used in the

measurement of the concentration of the all determined

elements in the tissue digests. Standard solutions ASTA-

SOL (Analytika, CR) of elements were used in the prepa-

ration of a calibration curve for the measurement. Samples

of the animal tissues were analyzed in two replicates; the

number of replicates in the case of parasites depended on

the sample quantity. If the overall mass of a sample was

less than 5 mg dry weight, the sample was analyzed only

once. To prevent inaccuracies in the determination of wet

weight of both the parasites and the tissues, the concen-

trations of heavy metals were applied to dry weight. For the

comparison of our data with data reported (Bukovjan 1997;

Dip et al. 2001), the heavy metal contents were recalcu-

lated using an average dryness value of 0.32 for the liver

tissue and 0.25 for the kidney tissue.

The quality of analytical data was assessed by simulta-

neous analysis of certified reference material CRM 12-02-01

(Bovine liver) (4% of all the samples). The background of the

trace element laboratory was monitored by analysis of 17.5%

of the blanks prepared under the same conditions, but with-

out samples, and experimental data were corrected by a mean

concentration of analyte in blanks and later compared with

detection limits. The detection limits (mean ± 3 SD of

blanks) as well as analytical data obtained for Cd, Cu, Mn,

Pb, and Zn contents in CRM 12-02-01 (Bovine liver) along

with certified values are given in Table 2. Values for chro-

mium and nickel contents are not certified in this CRM.

Bioaccumulation factors (BFs) of heavy metals in par-

asites were calculated as a ratio of metal concentration in

parasites to metal concentrations in various tissues of the

host as proposed by Sures et al. (1999).

Statistical Evaluation

The data were evaluated using the Microsoft Excel pro-

gram and Statistica 7.0 (Mann–Whitney test, Kruskal–

Wallis test). The results are expressed as median, mini-

mum, and maximum from total range within the groups.

Results

Bioaccumulation of Heavy Metals in Parasites

As can be seen in Tables 3, 4, 5, Pb, Mn, Cu, Ni, and Zn

were accumulated more in parasites than in host tissues,

and a significantly higher content of Pb, Cu, Mn, and Ni

(*p \ 0.05, **p \ 0.01) was found in Mesocestoides

spp. when compared with nematode T. leonina using the

Mann–Whitney test. To compare the accumulation ability of

cestodes Mesocestoides spp. and nematode T. leonina with

minimizing the effect of the differences among the animals

(sex, age, health state), the BF was calculated for the cases in

which both cestode and nematode parasites infected the host

simultaneously (n = 25). The highest median value of BF

(52) was found for the Pb level in Mesocestoides spp. BFs of

Cu, Zn, Ni, and Mn are lower than those of Pb and mostly

range from 1.9 to 24 for Mesocestoides spp. and from 1.5 to

6 for nematode T. leonina depending on the tissue of the host

and the element.

Differences in Heavy Metal Contents in Tissues

of Parasitized and Nonparasitized Foxes

The Kruskal–Wallis test was used for the comparison of

element contents in the tissues of three groups of red foxes:

one negative (nonparasitized) group (n = 17) and two

positive (parasitized) groups. One of the positive groups

(designated as T. leonina) is formed from the hosts (n = 9)

infected by nematode T. leonina only. In the second group

(designated as Mesocest.), the hosts infected by Mesoces-

toides spp. (n = 5) and those infected by both Mesoces-

toides spp. and T. leonina (n = 25) were collected. The

reason for the formation of the second group is that there

was an insufficient number of hosts infected by cestodes

only (n = 5) for statistical calculations. Significant differ-

ences found are marked by asterisks (*p \ 0.05,

**p \ 0.01, ***p \ 0.001) in Tables 4 and 5. Along with

Table 2 Detection limits (ng/mL) and results of the quality assessment of analytical data by simultaneous analysis of certified reference material

CRM 12-02-01 (Bovine liver) (lg/g)

Method Cd Cr Cu Mn Ni Pb Zn

Detection limit (mean ± 3 SD of blanks) ET-AAS 0.07 0.17 0.69 0.21 0.21

ICP-OES 0.18 0.71 9.1 3.3 1.21 1.9 11.5

CRM 12-02-01 (Bovine liver) Mean 0.48 – 26.3 7.6 – 0.71 162

Certified CI (95%) 0.03 1.6 0.5 0.08 6

Found Mean 0.47 26.1 7.4 0.69 159

SD 0.04 0.8 0.6 0.09 5

472 Arch Environ Contam Toxicol (2010) 58:469–477

123

the high accumulation of Pb in parasites, a significant

decrease of Pb concentration was found in the hosts’ kid-

neys as the target organ in comparison with the negative

group of the animals (Table 4). No significant difference of

the Pb level was observed in liver tissues of noninfected

and infected animals; however, the concentration of this

element in the livers of hosts infected by T. leonina was

significantly lower than those infected by Mesocestoides

spp. Regardless of the accumulation of Mn predominantly

in cestodes, a significant increase (**p \ 0.01) of Mn

content in the livers of parasitized red foxes (V. vulpes) was

found in comparison to those of nonparasitized foxes.

Similarly, a significant increase (***p \ 0.001) of Cu

concentration in the livers of parasitized animals was

observed (Table 5). Parasitism has no significant influence

on the concentrations of Ni in analyzed tissues. Medians of

Zn contents in hosts’ livers were slightly increased in

comparison to those of nonparasitized animals and those in

the hosts’ kidneys were slightly decreased; however, the

differences were not significant (Tables 4, 5).

Discussion

The results of this study can be discussed using two points

of view. The first one is the use of parasites of carnivora as

Table 3 Concentrations (lg/g dry weight) of selected elements determined in cestodes and nematode from the intestinal tract of red fox (V.vulpes)

Parasite No. Value Pb Cd Cr Cu Mn Ni Zn

Mesocestoides spp. n = 30 Median 45.60** 0.427 0.140 36.03* 87.54** 0.827* 354.0

Minimum 10.40 0.038 0.018 25.47 32.03 0.494 177.2

Maximum 150.8 3.678 0.415 59.20 135.9 1.337 792.5

n = 25 BF/kidney-M 52 0.3 2.5 4.8 23 6.4 24

BF/kidney-R 39–130 0.1–0.6 2.1–4.8 2.9–4.9 7.8–26 2.2–7.1 2.4–45

BF/liver-M 52 0.8 3.1 1.9 11 4.3 18

BF/liver-R 25–141 0.1–2 2.1–6.3 0.3–3 3–15 1–9 1.6–47

T. leonina n = 34 Median 8.98** 0.510 0.216 19.06* 20.48** 0.383* 237.8

Minimum 2.504 0.198 0.012 6.55 5.65 0.309 69.78

Maximum 15.65 3.236 0.361 31.80 79.99 0.687 524.2

n = 25 BF/kidney-M 7.2 0.3 5.1 1.5 6 1.5 3.4

BF/kidney-R 6.7–21 0.2–0.5 3.6–5.6 0.6–2.9 1.4–15 1.1–2.2 2.2–7

BF/liver- M 7.7 1.8 3.9 0.5 4.2 1.2 3.3

BF/liver- R 4.4–24 0.4–3.4 1.1–8.1 0.1–1.8 0.5–8.6 0.05–2.6 1.3–14

Note: Asterisks denote a significant difference between Mesocestoides spp. and T. leonina groups calculated by the Mann-Whitney U-test

(* p \ 0.05, ** p \ 0.01). BF (bioaccumulation factor) = concentration in parasite/concentration in tissue of the identical host infected by both

parasites

M median, R range between minimum and maximum value

Table 4 Concentrations (lg/g dry weight) of selected elements in the kidney of parasitized and nonparasitized red foxes (V. vulpes)

Parasite Group Value Pb Cd Cr Cu Mn Ni Zn

None n = 17 NegativeN Median 0.878T***, M** 2.137T* 0.051 9.424 3.838M* 0.183 79.29

Minimum 0.493 0.706 0.001 8.372 3.245 0.124 58.68

Maximum 3.556 9.967 0.229 14.86 6.753 0.487 113.9

Mesocestoides spp.

and T. leonina n = 30

PositiveM Median 0.457 N**, T* 2.960T*** 0.055 10.48T* 4.850N*, T*** 0.207 71.99

Minimum 0.029 0.310 0.001 8.195 3.376 0.037 52.00

Maximum 2.970 6.032 0.178 20.78 11.83 0.485 95.79

T. leonina n = 9 PositiveT Median 0.260N***, M* 0.985N*, M*** 0.030 9.226M* 3.390M*** 0.196 66.60

Minimum 0.078 0.095 0.013 6.733 1.860 0.157 58.95

Maximum 0.478 1.479 0.054 11.27 4.208 0.388 77.55

Note: Asterisks denote a significant difference between nonparasitized and parasitized groups calculated by the Kruskal–Wallis test (* p \ 0.05,

** p \ 0.01, *** p \ 0.001)

N nonparasitized red foxes, M red foxes infected by either Mesocestoides spp. or both Mesocestoides spp. and Toxascaris leonine, T red foxes

infected by T. leonina only

Arch Environ Contam Toxicol (2010) 58:469–477 473

123

sentinels in the monitoring of environmental pollution. The

second one is the use of red fox tissues as biomonitors as

recommended by Bukovjan (1997) and Dip et al. (2001) in

connection with possible changes in heavy metal contents

in the tissues caused by parasitism.

There is an hypothesis that parasites without a digestive

tract (Cestoda, Acanthocephala) accumulate metals to a

higher degree than the host tissues (Sures and Siddall 1999;

Sures et al. 2003). Studies on endohelminths of fish have

revealed that several helminthes are able to accumulate

considerable concentrations of heavy metals (e.g., Barus

et al. 2007; Landsberg et al. 1998; Sures 2003, 2004; Sures

et al. 1998; Sures and Siddall 1999, 2001; Thielen et al.

2004; Turcekova et al. 2002). Considerably less literature

is available on the use of the mammalian endoparasites in

environmental-impact studies. However, as was described

in recent studies (Barus et al. 2003; Sures et al. 2002, 2003;

Eira et al. 2005; Torres et al. 2004, 2006), some parasites of

the small mammal hosts accumulate toxic elements above

values detected in the tissues of their hosts. It was pointed

out that cestode parasites of rodents could be a promising

biomonitor for Pb due to its great accumulation capacity.

This was confirmed by Jankovska et al. (2007, 2008);

moreover, bioaccumulation of Ni, Mn, and Znc was

observed in cestodes as well. We tested the reliability of

the cestode/red fox (V. vulpes) model as another bioindi-

cator system for heavy metal pollution under field (forest)

conditions. These species were chosen considering that

there are no other models utilizing carnivora and their

parasites in environmental monitoring. However, the ani-

mals are frequently infected both by Mesocestoides spp.

and nematode T. leonina; therefore, it seems appropriate to

compare the bioaccumulation ability in these two different

groups of parasites, as data published are ambiguous. No

accumulation of Pb and Cd in Ascaris suum (nematode)

was found in comparison with tissues (muscle, liver, and

intestine) of porcine and bovine hosts by Sures et al.

(1998). Contrary to that Barus et al. (2003) determined a

higher Pb content in nematode Protospirura muricola in

comparison with cestode Inermicapsifer arvicanthidis and

the muscle and liver of its definitive host, the silvery mole

rat (Heliophobius argenteocinereus: Rodentia).

According to our results, Mesocestoides spp. presented

52 times more Pb than was determined in the kidney and

liver of red foxes (V. vulpes), and nematode T. leonina pre-

sented 7 times more Pb than that detected in the kidney and

liver of the host (Table 3). Although the bioaccumulation of

Zn, Mn, and Ni in parasites is not so high, levels of Mn in

Mesocestoides spp. in comparison with those in the liver

were around 10 times higher and 23 times higher than those

in the kidney. Bioaccumulation coefficients of Mn in nem-

atode T. leonina were lower (four to six times) than those of

Pb, as well. Similarly, as reported by Torres and colleagues

(2004, 2006) and Jankovska et al. (2007, 2008), no accu-

mulation of Cd was observed in cestodes as well as nema-

todes in this study. This means that V. vulpes/Mesocestoides

spp. could be a promising bioindication system serving as a

complement to the rodent models R. norvegicus/H. diminuta

(Sures et al. 2002, 2003), A. sylvaticus/G. arfaai (Torres

et al. 2004), A. sylvaticus/S. lobata (Torres et al. 2006),

and M. agrestris/Paranoplocephala spp. and C. glareolus/

Paranoplocephala spp. (Jankovska et al. 2009).

However, the use of the parasites as biomonitors in the

large-scale monitoring of environmental pollution has its

limits. As described by Sures (2004), ideal biomonitors

must fulfill certain requirements. Several of them are

present in cestodes of the red fox (high accumulation

potential, well-defined home range, widespread), whereas

several are absent. One of them is the unknown correlation

between pollutant concentration in a cestode and in the

environment; other limits include relatively small body

mass for analysis in comparison with the mass of the

Table 5 Concentrations (lg/g dry weight) of selected elements in the liver of parasitized and nonparasitized red foxes (V. vulpes)

Parasite Group Value Pb Cd Cr Cu Mn Ni Zn

None n = 17 NegativeN Median 0.428 0.389 0.049 11.63M*** 6.45M** 0.227 96.17

Minimum 0.175 0.039 0.011 4.15 1.81 0.113 75.69

Maximum 2.856 2.988 0.276 17.58 15.23 0.577 199.4

Mesocestoides spp.

and T. leonina n = 30

PositiveM Median 0.572T* 0.936T*** 0.042 18.62N, T*** 10.18N**, T*** 0.186 108.0

Minimum 0.109 0.079 0.009 10.83 4.98 0.111 60.12

Maximum 2.279 2.558 0.304 41.15 19.94 0.831 212.9

T. leonina n = 9 PositiveT Median 0.264M* 0.306M*** 0.035 15.16M*** 7.08M*** 0.167 104.4

Minimum 0.093 0.055 0.031 9.98 4.95 0.129 93.29

Maximum 0.357 0.377 0.088 16.18 7.94 0.302 123.7

Note: Asterisks denote a significant difference between nonparasitized and parasitized groups calculated by the Kruskal–Wallis test (* p \ 0.05,

** p \ 0.01, *** p \ 0.001)

N non-parasitized red foxes, M red foxes infected by either Mesocestoides spp. or both Mesocestoides spp. and T. leonine, T red foxes infected by

T. leonina only

474 Arch Environ Contam Toxicol (2010) 58:469–477

123

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eys)

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NA

no

tav

aila

ble

Arch Environ Contam Toxicol (2010) 58:469–477 475

123

tissues usually used in pollution monitoring (liver, kidney),

insufficiently studied physiology, including of the effect of

age, size, and reproduction activity on the accumulation of

pollutants, and so forth. To prevent misleading data, the

cestode sampling procedure has to be standardized as

recommended by Sures et al. (2003).

The impact of the parasite burden on bioaccumulation of

heavy metals in the liver and the kidney as the target

organs of red foxes was studied as well. This information is

important for the use of the tissues of these carnivora in the

monitoring of environmental pollution, when no informa-

tion about the possible infection of red foxes by parasites is

available. As can be seen in Table 4, the accumulation of

heavy metals in parasites of the red fox (V. vulpes) is

accompanied by a significant decrease in the kidney Pb

content of the host in comparison with Pb contents in

noninfected animals. The infection of red fox (V. vulpes)

by parasites is reflected in a significant increase of Cu and

Mn in the livers of the hosts in comparison with the non-

parasitized group (Table 5). The increase in cestode

infection is greater than that of nematode infection. The

increase of the Mn content in the livers of small terrestrial

rodents—field voles Microtus agrestris and bank voles

Clethrionomys glareolus—infected by cestode Parano-

plocephala spp. in comparison with the livers of nonpara-

sitized animals was observed by Jankovska et al. (2009) as

well. For these reasons, the livers of red foxes might be less

suitable as an indicator of environmental pollution by Cu

and Mn, as there is a risk of misleading (higher) data

caused by cestode infection. The kidneys of hosts showed a

significant change (decrease) in the concentrations of Pb

that is accumulated in parasites; this means that kidneys

might be less suitable in the monitoring of Pb environ-

mental pollution (data could be underestimated).

The use of red foxes for biomonitoring purposes in the

Czech Republic (Central Bohemia) has been proposed by

Bukovjan (1997). Dip et al. (2001) has compared heavy

metal concentrations in the tissues of red foxes from

adjacent urban, suburban, and rural areas near Zurich

(Switzerland). However, there is no information about

possible parasitism of red foxes used in these studies. As

can be seen in Table 6, there are differences between the

element contents determined in the tissues of red foxes

collected in the area of Krusne hory Mts., Central Bohemia

in Czech Republic and in the Zurich area in Switzerland.

The concentrations of Pb in the liver tissues (regardless

of parasitism) in our study are 2.5- to 3-fold lower than

those found by Bukovjan (1997) and Dip et al. (2001); the

Pb content in the kidneys of red foxes infected by Mes-

ocestoides spp. from Krusne hory Mts. is fivefold lower

than in red foxes within the municipality of Zurich (Dip

et al. 2001). Similar contents of Cd were observed in the

livers of red foxes from all three territories: The differences

in Cd concentrations were higher in the kidneys and the

highest value was found in Zurich area. The differences in

Cu content were found predominantly in liver tissues; the

Cu concentration found in the animals from the Zurich

territory was more than four times higher than in the livers

of the nonparasitized red foxes from Krusne hory Mts. and

roughly 2.5 times higher than in the animals infected by

Mesocestoides spp. A higher content of Cu in the livers and

kidneys in comparison with our data was observed in the

samples from central Bohemia as well. As the parasitism of

red foxes was not investigated in these studies, the possi-

bility that the increase in Cu content was due to the pres-

ence of the parasites in their intestinal tract cannot be

ignored. However, there are no other findings to support

this statement. Zinc contents in the tissues from all three

territories are for livers ranging from 30.9 (noninfected red

foxes from Krusne hory Mts.) to 41.8 lg/g wet weight

within the municipality of Zurich.

The burden of the red foxes by heavy metals can be

compared with the contents of these elements in small

terrestrial rodents, which are part of their food chain. The

concentration of heavy metals in rodents (Microtus

agrestris) infected by Paranoplocephala spp. from the

(area) studied territory (Jankovska et al. 2008), is mostly

lower in rodent livers in comparison with infected red

foxes (Table 6). Cadmium concentration was much higher

in the kidneys of red foxes than in rodent kidneys. The

concentration of the other elements was lower in red foxes

than in rodents.

Acknowledgments This study was supported by project MSM

6046070901 of the Ministry of Education, Youths and Sports, Czech

Republic and by project No. 524/06/0687 of the Grant Agency of the

Czech Republic. The authors declare that the experiments comply

with the current laws of the Czech Republic, in which they were

performed.

References

Barus V, Jarkovsky J, Prokes M (2007) Philometra ovata (Nematoda:

Philometroidae): a potential sentinel species of heavy metal

accumulation. Parasitol Res 100:929–933. doi:10.1007/s00436-

006-0384-8

Barus V, Tenora F, Sumbera R (2003) Relative concentrations of four

heavy metals in the parasites Protospirura muricola (Nematoda)

and Inermicapsifer arvicanthidis (Cestoda) in their definitive

host silvery mole-rat (Heliophobius argenteocinereus: Roden-

tia). Helminthol0gy 40:227–232

Bukovjan K (1997) Concentration of selected foreign substances in

the tissues of red fox (Vulpes vulpes). Folia Venatoria 26–27:

107–112

Cerveny J, Kamler K, Kholova H, Koubek P, Martınkova M (2004)

Encyklopedie myslivosti (Hunting encyclopedy). Ottovo nak-

ladatelstvı-Cesty, Praha, p 591 (in Czech)

Dip R, Stieger C, Deplazes P, Hegglin D, Muller U, Dafflon, Koch H,

Naegeli H (2001) Comparison of heavy metal concentrations in

tissues of red foxes from adjacent urban, suburban, and rural

476 Arch Environ Contam Toxicol (2010) 58:469–477

123

areas. Arch Environ Contam Toxicol 40:551–556. doi:10.1007/

s002440010209

Eira C, Torres J, Vingada J, Miquel J (2005) Concentration of some

toxic elements in Oryctolagus cuniculus and in its intestinal

cestode Mosgovoyia ctenoides, in Dunas de Mira (Portugal). Sci

Total Environ 346:81–86. doi:10.1016/j.scitotenv.2004.11.014

Hanosset R, Saegerman C, Adant S, Massart L, Losson B (2008)

Echinococcus multilocularis in Belgium: prevalence in red foxes

(Vulpes vulpes) and in different species of potential intermediate

hosts. Vet Parasitol 151:212–217. doi:10.1016/j.vetpar.2007.09.

024

Jankovska I, Langrova I, Bejcek V, Miholova D, Vadlejch J (2007)

Bioaccumulation of some heavy metals (Cd, Cr, Cu, Mn, Ni, Pb,

Zn) in parasitized and non-parasitized small mammals. Quim

Clin 26:55

Jankovska I, Langrova I, Bejcek V, Miholova D, Vadlejch J, Petrtyl

M (2008) Heavy metal accumulation in small terrestrial rodents

infected by cestodes or nematodes. Parasite 15:581–588

Jankovska I, Miholova D, Langrova I, Bejcek V, Vadlejch J,

Kolihova D, Sulc J (2009) Influence of parasitism on the use

of small terrestrial rodents in environmental pollution monitor-

ing. Environ Pollut 157:2584–2586

Landsberg JH, Blakesley BA, Reese RO, McRae G, Forstchen PR

(1998) Parasites of fish as indicators of environmental stress.

Environ Monit Assess 51:211–232. doi:10.1023/A:1005991420

265

Miholova D, Mader P, Szakova J, Slamova A, Svatos Z (1993)

Czechoslovakian biological certified reference materials and

their use in the analytical quality assurance system in a trace

element laboratory. Freshuis J Anal Chem 345:256–260. doi:

10.1007/BF00322606

Slodicak M, Balcar V, Novak J, Sramek V et al (2008) Lesnicke

hospodarenı v Krusnych Horach (Management of forestry in

Krusne Hory Mts.). 1. vyd. Hradec Kralove, Strnady : Lesy Ceske

republiky s.p., Grantova sluzba LCR, VULHM v.v.i., Strnady (in

Czech)

Sures B (2003) Accumulation of heavy metals by intestinal helminths

in fish: an overview and perspective. Parasitology 126:S53–S60.

doi:10.1017/S003118200300372X

Sures B (2004) Environmental parasitology: relevancy of parasites in

monitoring environmental pollution. Trends Parasitol 20:170–

177. doi:10.1016/j.pt.2004.01.014

Sures B, Siddall R (1999) Pomphorhynchus laevis: the intestinal

acanthocephalan as a lead sink for its fish host, chub (Leuciscuscephalus). Exp Parasitol 93:66–72. doi:10.1006/expr.1999.4437

Sures B, Siddall R (2001) Comparison between lead accumulation of

Pomphorhynchus laevis (Palaeacanthocephala) in the intestine of

chub (Leuciscus cephalus) and in the body cavity of goldfish

(Carassius auratus auratus). Int J Parasitol 31:669–673. doi:

10.1016/S0020-7519(01)00173-4

Sures B, Jurges G, Taraschewski H (1998) Relative concentrations of

heavy metals in the parasites Ascaris suum (Nematoda) and

Fasciola hepatica (Digenea) and their respective porcine and

bovine definitive hosts. Int J Parasitol 28:1173–1178. doi:

10.1016/S0020-7519(98)00105-2

Sures B, Siddall R, Taraschewski H (1999) Parasites as accumulation

indicators of heavy metal pollution. Parasitol Today 15:16–21

Sures B, Grube K, Taraschewski H (2002) Experimental studies on

the lead accumulation in the cestode Hymenolepis diminuta and

its final host Rattus norvegicus. Ecotoxicol 11:365–368. doi:

10.1023/A:1020561406624

Sures B, Scheible T, Bashtar AR, Taraschewski H (2003) Lead

concentrations in Hymenolepis diminuta adults and Taeniataeniaeformis larvae compared to their rat hosts (Rattus norvegi-cus) sampled from the city of Cairo, Egypt. Parasitol 127:483–487.

doi:10.1017/S0031182003003901

Thielen F, Zimmermann S, Baska F, Taraschewski H, Sures B (2004)

The intestinal parasite Pomphorhynchus laevis (Acanthocephala)

from barbel as a bioindicator for metal pollution in the Danube

river near Budapest, Hungary. Environ Pollut 129:421–429. doi:

10.1016/j.envpol.2003.11.011

Torres J, de Lapuente J, Eira C, Nadal J (2004) Cadmium and lead

concentrations in Gallegoides arfaai (Cestoda Anoplocephali-

dae) and Apodemus sylvaticus (Rodentia: Muridae) from Spain.

Parasitol Res 94:468–470. doi:10.1007/s00436-004-1232-3

Torres J, Peig J, Eira C, Borras M (2006) Cadmium and lead

concentrations in Skrjabinotaenia lobata(Cestoda: Catenotaenii-

dae) and its host, Apodemus sylvaticus (Rodentia: Muridae), in

the urban dumping side of Garraf (Spain). Environ Pollut 143:4–

8. doi:10.1016/j.envpol.2005.11.012

Turcekova L, Hanzelova V, Spakulova M (2002) Concentration of

heavy metals in perch and its endoparasites in the polluted water

reservoir in Eastern Slovakia. Helminthology 39:23–28

Willingham AL, Ockens NW, Kapel CM, Monrad J (1996) A

helminthological survey of wild red foxes (Vulpes vulpes) from

the metropolitan area of Copenhagen. J Helminthol 70:259–263

Arch Environ Contam Toxicol (2010) 58:469–477 477

123