This article was downloaded by: [141.214.17.222] On: 07 November 2014, At: 09:28 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Veterinary Quarterly Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tveq20
An epidemiological study of Fasciola hepatica in the Netherlands a
a
a
C.P.H. Gaasenbeek , H.J. Over , N. Noorman & WA. de Leeuw
a
a
Central Veterinary Institute (CDI‐DLO) , PO Box 65, Lelystad, 8200 AB, The Netherlands Published online: 01 Nov 2011.
To cite this article: C.P.H. Gaasenbeek , H.J. Over , N. Noorman & WA. de Leeuw (1992) An epidemiological study of Fasciola hepatica in the Netherlands, Veterinary Quarterly, 14:4, 140-144, DOI: 10.1080/01652176.1992.9694351 To link to this article: http://dx.doi.org/10.1080/01652176.1992.9694351
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
7. Conners JL, and Belluci MJ. Natural selection resisting inbreeding
16. Muller J, Kirk S. and Scott DW. Small Animal Dermatology (3rd ed).
depression in captured wild house mice. Evolution 1979; 33: 929-40. 8. Dorn CP, and Schneider R. Inbreeding and canine mammary cancer, a retrospective study. J Nat Canc Inst 1976; 57: 545-8. 9. Ettinger SJ. Textbook of Veterinary Internal Medicine - Diseases of the dog and cat (3rd ed). Philadelphia: Saunders, 1989. 10. Falconer DS. Patterns of response in selection experiments with mice. Cold Spr Harb Symp Quant Biol 1955; 20: 178-96.
Philadelphia: Saunders, 1983. 17. Nicholas FW. Veterinary Genetics. Oxford: Clarendon Press, 1987. 18. Patterson DF. Is this a genetic disease? J Small Anim Pract 1989; 30: 127-
11. Falconer DS. Introduction to quantitative genetics (3rd ed). Harlow: Longman Group, 1989. 12. Fleiss JL. Statistical methods for rates and proportions. New York: Wiley & Sons, 1981. 13. Hutt FB. Animal Genetics. New York: Ronald Press, 1964. 14. Kostense PJ, Eriksson AW, and Pronk JC. In JC Pronk, JPM Geraeds et al (Eds), Medische Genetica. Utrecht: Wetenschappelijke Uitgeverij Bunge, 1989.
Downloaded by [141.214.17.222] at 09:28 07 November 2014
15. Lynch CB. Inbreeding effects upon animals derived from a wild population of Mus Musculus. Evolution 1977; 31: 526-37.
39.
19. Pirchner F. Populations Genetik in der Tierzucht (2er ed). Hamburg: Paul Parey, 1979. 20. Rails K, and Ballou J. Effect of inbreeding on juvenile mortality in some small animal species. Lab Anim 1981; 16: 159-66. 21. Rasmusen BA. Animal Genetics. Hull: FB, 1982 22. Stansfield WD. Theory and Problems of Genetics. Hull: FB, 1982. 23. Venker-van Haagen AJ. Investigations on the pathogenesis of hereditary laryngeal paralysis in the Bouvier. Thesis University of Utrecht, 1980. 24. Willis MB. Genetics of the dog. London: Witherby, 1989. 25. Wright S. Coefficients of inbreeding and relationship. Am Natur 1922; 56: 330-9. 26. Wright S. An approximate method of calculating inbreeding and relationships from livestock pedigrees. J Agr Res 1925; 31: 376-7. .
AN EPIDEMIOLOGICAL STUDY OF FASCIOLA HEPATICA IN THE NETHERLANDS C.P.H. Gaasenbeek, H.J. Over, N. Noorman and WA. de Leeuwl Veterinary Quarterly 1992; 14: 140 - 4
SUMMARY Transmission of F.hepatica under natural conditions was analy-
sed in a three year programme. The variables used were the indirect haemagglutination (IHA) technique, worm establishment in tracer lambs and the population dynamics, infection rate and shedding pattern of Lymnaea truncatula. It is concluded that fluke eggs, infected snails and metacercariae on herbage can survive the winter in the Netherlands. Metacer-
carial availability was positively correlated to the amount of rainfall in the grazing period The role of developed eggs that survive the winter is important, because this results in earlier infections in the herd The use of the serological diagnosis method IHA is important to detect F. hepatica infection in an early stage. Use of cellophane paper on floats is a useful method for determining the shedding
stages and grazing periods should be related to meteorological
data. In simulated field experiments, Over and Dijkstra (6) found that fluke eggs, infected snails and metacercariae can survive the winter in the Netherlands. Shaka and Nansen (8) confirmed these results under Danish field conditions.
The indirect haemagglutination (IHA) technique is used to detect early and low infections of Ehepatica, as antibodies against this parasite can be detected 2-3 weeks after infection (11,12). This article describes the transmission of all stages of Ehepatica and its serology in cattle and sheep. The results are based on a
three-year study (1987-1989) under natural conditions on a commercial farm in the Netherlands.
pattern of cercariae from L. truncatula. It is concluded that
MATERIALS AND METHODS
collection of metacercariae on cellophane floats, inventarization
Meteorological observations Average daily temperature 1.5 m above ground level and the amount of rainfall were measured at nearby weather stations and were related to normal values for the region.
of L. truncatula and its infection level are useful tools for the prediction of liverfluke infections. INTRODUCTION
To predict the infection risk of fasciolosis and for effective
The experimental farm
control of the disease, it is essential to understand its epidemiology. This knowledge will also be important to reduce the use of drugs. Epidemiological descriptions based only on liver condemnation
The total area of the farm is approximately 45 hectares divided
figures from slaughterhouse statistics (4) are not sufficient. Although the mutual influence of moisture and temperature on the development of the parasitic stages of the snail has been described (1,3,7), it is only in relation to the dynamics of the snail population that these meteorological data are ultimately reflected in the infection risk of grazing herds. Therefore, the dynamics of the snail population, the survival of E hepatica 1
Central Veterinary Institute (CDI-DLO), PO Box 65, 8200 AB Lelystad The Netherlands.
140
T
II
EVETER
I
in 22 pastures. The soil is peaty, with the groundwater level being between 0-80 cm below the surface (10). The drainage furrows in approximately 30 hectare are potential L.truncatula habitats. These drainage furrows are fraised out every autumn. As the farmer was re-stocking during the experimental period, year categories of cattle were not normally distributed. Hence the farmer's herd comprised about 70 dairy cows, 30 heifers and
15-20 female calves. The farmer bought seven sheep in the winter of 1986.
Cattle were occasionally treated with a flukicide (Fasinex®, Ciba-Geigy or Acedist®, ACF), depending on the extent of the infection. Treatment was given as indicated in Figure 3.
NARYQUARTERLY. Vol. .
..
1
4.
No
.
4
DECEMBER
,
1
992
0.5
20
Overwintered stages off".hepatica
Table 2a
autumn 1986 F.hepatica eggs 0.4 15
0.3
spring 1987
autumn 1987
spring 1988
d-
-I-
inf. L.truncatula
d-
metacercariae
d-
ir -F
4 CO
Table 2a. Overwintered stages o F. hepatica
,110 -
c (t)
0,2 c
(B) were selected because of their soil and hydrological
0, 1
1 I I
O
V° 01"
11
10
EL 2PZ
I
_,
t1
0
(total 40 lambs/year). Prior to grazing they were kept under fluke-free conditions. The first group was turned out at the beginning of May, four lambs on field A and four on field B.
'
0 mean inf. snails/m2 (old inf. )
mean snails/m2
conditions and were grazed by tracer lambs. Five groups of eight 3- to 6-month-old lambs of the Texel breed were used each year
'i"e 11
1116 011 e NOS
# 25)1
These were attached to a post in the drainage furrow with a 8-m long rope. Each lamb grazed a surface of approx. 200 m2 and was moved weekly to another place over a 5-week period. After the grazing period, they were again maintained under fluke- free conditions for 12 weeks and then slaughtered, when their livers were examined and the flukes counted. Thus Ehepatica burdens
0.3
20
0.25 15
Downloaded by [141.214.17.222] at 09:28 07 November 2014
0, 2 tn
r
In
..
...,
to
0.0 2
m10
c Sn
.._
c 0, 1
5
0,05
O
Experimental pastures Two experimental pastures of 1.2 hectares (A) and 1.8 hectares
5
1
1 I Ir te
sc3f) 111 ,t01% 019
11 1
'+1
2. ()IV
1
10'
61k R.
1 11 1 I 00".$. M I 1 I
;2,11
0%
were between 12 and 17 weeks of age. Blood was sampled weekly during the grazing period (except in 1987) and
fortnightly when the animals were housed. The indirect haemagglutination (IHA) technique was used to detect antibodies against Ehepatica. Faecal samples were taken from each group 0,11,13,15 and 17 weeks after exposure. This sampling timing was chosen to optimize the analysis of the occurrence of infections. The number of Ehepatica eggs per gram faeces (epg) was counted by the Dorsman technique (2). Metacercariae were
0
.09
collected from the drainage furrows in each pasture by
291
introducing floats wrapped in cellophane paper. The cellophane was changed every fortnight and examined under a microscope
mean snails/m2 0 mean inf. . snails/m2 (young inf . Fig. 1. Density and infection of L. truncatula
1600
1600 1987
800
...... ---
an
0
1988
. --------
800
..... ....-.'
, ------, ............... //
4,
200
I
I
..,
.
200
.....
.
....
/
.,*
t'
..
.,.. ...,.*1--
/
50
..
......... ........
50
7ss,
4
III...,
001 ,
0
0 9
7
11
wks
13
15
0
17
2
1
3
.
.
4
I
1
1
5
7
9
11
13
17
15
wks 1600 1989
BOO
0
grazing period 1987
1988
1989
1
19/5-23/6
10/5-14/6
9/5-13/6
2
23/6-28/7
14/6-19/7
13/6-10/7
3
28/7-16/9
19/7-23/8
18/7-22/8
4
16/9-6/10
23/8-27/9
22/8-26/9
5
6/10-10/11
27/9-1/11
26/9-31/10
group
symbol
wk 0-5 = grazing period
m 200
50
...............
0 0
2
3.
4
5
7
9
13
11
15
17
wks Fig. 2. Mean IHA titres of tracer lambs in weeks after exposure
141
TIIlVI-.rrRIN1\kY QUARTERLY. Voi
1
4 .
N o
.
4 .
Di:
CI-N1
11
1
It.
1
9 .9
2
for the presence of metacercariae. Approximately 2000 cm2
Table 3. Mean Fasciola egg output (ep3gr.)
cellophane floats were used in each period. Cages prevented the floats from being damaged by grazing stock. The grazing system used by the farmer and slurry application was also registered. The cumulated egg input by grazing animals in risk areas was
1206 M/8 1087
1
18/3
1
16
1
14
1
2
a
0
20/10
2
a
0
4/12
2
10
9/2
2
0
7/4
3
0
23/8
3
1
27/9
3
3
6/12
3
22
1969 17/1
3
33
21/2
3 4
42
8/4 18/7
4
0
31/10
4
1
milking cows
yearlings
14
30/8
1908
Snail sampling On this farm L.truncatula only exists in the drainage furrows. There are two or more drainage furrows in each pasture. Snails were collected from all pastures in 20 randomly chosen plots of 20 x 50 cm. Snails were measured and dissected to investigate the infection rate. Snail density was determined approximately
calves
1
4/11
calculated by an approximation based upon the length of the grazing period, the amount of faeces and the e.p.g..
1
I
2
a 0 0
0
3
2 3
treatment was carried out on the following dates:
every 6 weeks throughout the year. During severe winter
28/4-87 calves and yearlings 15/12-87 calves 1/4-89 calves
periods, data could not be obtained because of ice cover.
Downloaded by [141.214.17.222] at 09:28 07 November 2014
year group
date
Cattle Cattle on the farm were examined for the presence of fluke infections, by taking blood samples every 5 weeks from 10 calves, 10 heifers and 10 dairy cows. These had grazed for 0, 1 and more than 2 grazing seasons, respectively. Every year new calves were involved and the other groups graduated to older
n.b. year group is indicated for calves and yearlings
estimate of total egg output of 7,200,000 over the grazing period. The fluke burdens of the tracer lambs grazing on A and B were different (Table 2). During the first grazing period (19/5-23/6), no lambs became infected. In the second grazing period (23/628/7), the first tracer lambs became infected on pasture A with a total fluke burden of 199. In the third grazing period (28/7-16/ 9), the fluke burden of the tracer lambs increased to 928. In the
age groups.
The indirect haemagglutination (IHA) technique was used to
detect antibodies against Ehepatica. Faecal samples were collected five times a year when infections were expected. The number of Ehepatica eggs per 3 gram faeces was established using the Dorsman technique (2).
fourth and fifth grazing period (16/9-6/10 and 6/10-10/11, respectively), fluke burdens of 467 and 699 were calculated, respectively.
The first tracer lambs on pasture B were infected in the third period (28/7-16/9) and they had a total fluke burden of 175. In
RESULTS Table 1 gives the meteorological data, table 2 the transmission of -
the fourth and fifth groups the fluke burden increased considerably, to 1068 and 1954, respectively. Faecal examination showed
Ehepatica and table 3 the number of Ehepatica eggs in the commercial herd. Figure 1 shows the density and infection rate of L.truncatula, figure 2 the IHA titres of tracer lambs, figure 3 the IHA titres of selected animals of the commercial herd and figure 4 the percentage deviation of the rainfall from the norm
that tracer lambs in pasture A became patent mid-September and in mid-November in pasture B. Many metacercariae encysted on the cellophane paper from September until December (Table 2). The snail density and infection rate of snails increased from July (Figure 1). Young and old infections were observed. In tracer lambs IHA titres
calculated for the grazing period (5 weeks). There was a relationship between rainfall and fluke burden in tracer lambs.
(Figure 2) were positively correlated (P
Veterinary Quarterly Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tveq20
An epidemiological study of Fasciola hepatica in the Netherlands a
a
a
C.P.H. Gaasenbeek , H.J. Over , N. Noorman & WA. de Leeuw
a
a
Central Veterinary Institute (CDI‐DLO) , PO Box 65, Lelystad, 8200 AB, The Netherlands Published online: 01 Nov 2011.
To cite this article: C.P.H. Gaasenbeek , H.J. Over , N. Noorman & WA. de Leeuw (1992) An epidemiological study of Fasciola hepatica in the Netherlands, Veterinary Quarterly, 14:4, 140-144, DOI: 10.1080/01652176.1992.9694351 To link to this article: http://dx.doi.org/10.1080/01652176.1992.9694351
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
7. Conners JL, and Belluci MJ. Natural selection resisting inbreeding
16. Muller J, Kirk S. and Scott DW. Small Animal Dermatology (3rd ed).
depression in captured wild house mice. Evolution 1979; 33: 929-40. 8. Dorn CP, and Schneider R. Inbreeding and canine mammary cancer, a retrospective study. J Nat Canc Inst 1976; 57: 545-8. 9. Ettinger SJ. Textbook of Veterinary Internal Medicine - Diseases of the dog and cat (3rd ed). Philadelphia: Saunders, 1989. 10. Falconer DS. Patterns of response in selection experiments with mice. Cold Spr Harb Symp Quant Biol 1955; 20: 178-96.
Philadelphia: Saunders, 1983. 17. Nicholas FW. Veterinary Genetics. Oxford: Clarendon Press, 1987. 18. Patterson DF. Is this a genetic disease? J Small Anim Pract 1989; 30: 127-
11. Falconer DS. Introduction to quantitative genetics (3rd ed). Harlow: Longman Group, 1989. 12. Fleiss JL. Statistical methods for rates and proportions. New York: Wiley & Sons, 1981. 13. Hutt FB. Animal Genetics. New York: Ronald Press, 1964. 14. Kostense PJ, Eriksson AW, and Pronk JC. In JC Pronk, JPM Geraeds et al (Eds), Medische Genetica. Utrecht: Wetenschappelijke Uitgeverij Bunge, 1989.
Downloaded by [141.214.17.222] at 09:28 07 November 2014
15. Lynch CB. Inbreeding effects upon animals derived from a wild population of Mus Musculus. Evolution 1977; 31: 526-37.
39.
19. Pirchner F. Populations Genetik in der Tierzucht (2er ed). Hamburg: Paul Parey, 1979. 20. Rails K, and Ballou J. Effect of inbreeding on juvenile mortality in some small animal species. Lab Anim 1981; 16: 159-66. 21. Rasmusen BA. Animal Genetics. Hull: FB, 1982 22. Stansfield WD. Theory and Problems of Genetics. Hull: FB, 1982. 23. Venker-van Haagen AJ. Investigations on the pathogenesis of hereditary laryngeal paralysis in the Bouvier. Thesis University of Utrecht, 1980. 24. Willis MB. Genetics of the dog. London: Witherby, 1989. 25. Wright S. Coefficients of inbreeding and relationship. Am Natur 1922; 56: 330-9. 26. Wright S. An approximate method of calculating inbreeding and relationships from livestock pedigrees. J Agr Res 1925; 31: 376-7. .
AN EPIDEMIOLOGICAL STUDY OF FASCIOLA HEPATICA IN THE NETHERLANDS C.P.H. Gaasenbeek, H.J. Over, N. Noorman and WA. de Leeuwl Veterinary Quarterly 1992; 14: 140 - 4
SUMMARY Transmission of F.hepatica under natural conditions was analy-
sed in a three year programme. The variables used were the indirect haemagglutination (IHA) technique, worm establishment in tracer lambs and the population dynamics, infection rate and shedding pattern of Lymnaea truncatula. It is concluded that fluke eggs, infected snails and metacercariae on herbage can survive the winter in the Netherlands. Metacer-
carial availability was positively correlated to the amount of rainfall in the grazing period The role of developed eggs that survive the winter is important, because this results in earlier infections in the herd The use of the serological diagnosis method IHA is important to detect F. hepatica infection in an early stage. Use of cellophane paper on floats is a useful method for determining the shedding
stages and grazing periods should be related to meteorological
data. In simulated field experiments, Over and Dijkstra (6) found that fluke eggs, infected snails and metacercariae can survive the winter in the Netherlands. Shaka and Nansen (8) confirmed these results under Danish field conditions.
The indirect haemagglutination (IHA) technique is used to detect early and low infections of Ehepatica, as antibodies against this parasite can be detected 2-3 weeks after infection (11,12). This article describes the transmission of all stages of Ehepatica and its serology in cattle and sheep. The results are based on a
three-year study (1987-1989) under natural conditions on a commercial farm in the Netherlands.
pattern of cercariae from L. truncatula. It is concluded that
MATERIALS AND METHODS
collection of metacercariae on cellophane floats, inventarization
Meteorological observations Average daily temperature 1.5 m above ground level and the amount of rainfall were measured at nearby weather stations and were related to normal values for the region.
of L. truncatula and its infection level are useful tools for the prediction of liverfluke infections. INTRODUCTION
To predict the infection risk of fasciolosis and for effective
The experimental farm
control of the disease, it is essential to understand its epidemiology. This knowledge will also be important to reduce the use of drugs. Epidemiological descriptions based only on liver condemnation
The total area of the farm is approximately 45 hectares divided
figures from slaughterhouse statistics (4) are not sufficient. Although the mutual influence of moisture and temperature on the development of the parasitic stages of the snail has been described (1,3,7), it is only in relation to the dynamics of the snail population that these meteorological data are ultimately reflected in the infection risk of grazing herds. Therefore, the dynamics of the snail population, the survival of E hepatica 1
Central Veterinary Institute (CDI-DLO), PO Box 65, 8200 AB Lelystad The Netherlands.
140
T
II
EVETER
I
in 22 pastures. The soil is peaty, with the groundwater level being between 0-80 cm below the surface (10). The drainage furrows in approximately 30 hectare are potential L.truncatula habitats. These drainage furrows are fraised out every autumn. As the farmer was re-stocking during the experimental period, year categories of cattle were not normally distributed. Hence the farmer's herd comprised about 70 dairy cows, 30 heifers and
15-20 female calves. The farmer bought seven sheep in the winter of 1986.
Cattle were occasionally treated with a flukicide (Fasinex®, Ciba-Geigy or Acedist®, ACF), depending on the extent of the infection. Treatment was given as indicated in Figure 3.
NARYQUARTERLY. Vol. .
..
1
4.
No
.
4
DECEMBER
,
1
992
0.5
20
Overwintered stages off".hepatica
Table 2a
autumn 1986 F.hepatica eggs 0.4 15
0.3
spring 1987
autumn 1987
spring 1988
d-
-I-
inf. L.truncatula
d-
metacercariae
d-
ir -F
4 CO
Table 2a. Overwintered stages o F. hepatica
,110 -
c (t)
0,2 c
(B) were selected because of their soil and hydrological
0, 1
1 I I
O
V° 01"
11
10
EL 2PZ
I
_,
t1
0
(total 40 lambs/year). Prior to grazing they were kept under fluke-free conditions. The first group was turned out at the beginning of May, four lambs on field A and four on field B.
'
0 mean inf. snails/m2 (old inf. )
mean snails/m2
conditions and were grazed by tracer lambs. Five groups of eight 3- to 6-month-old lambs of the Texel breed were used each year
'i"e 11
1116 011 e NOS
# 25)1
These were attached to a post in the drainage furrow with a 8-m long rope. Each lamb grazed a surface of approx. 200 m2 and was moved weekly to another place over a 5-week period. After the grazing period, they were again maintained under fluke- free conditions for 12 weeks and then slaughtered, when their livers were examined and the flukes counted. Thus Ehepatica burdens
0.3
20
0.25 15
Downloaded by [141.214.17.222] at 09:28 07 November 2014
0, 2 tn
r
In
..
...,
to
0.0 2
m10
c Sn
.._
c 0, 1
5
0,05
O
Experimental pastures Two experimental pastures of 1.2 hectares (A) and 1.8 hectares
5
1
1 I Ir te
sc3f) 111 ,t01% 019
11 1
'+1
2. ()IV
1
10'
61k R.
1 11 1 I 00".$. M I 1 I
;2,11
0%
were between 12 and 17 weeks of age. Blood was sampled weekly during the grazing period (except in 1987) and
fortnightly when the animals were housed. The indirect haemagglutination (IHA) technique was used to detect antibodies against Ehepatica. Faecal samples were taken from each group 0,11,13,15 and 17 weeks after exposure. This sampling timing was chosen to optimize the analysis of the occurrence of infections. The number of Ehepatica eggs per gram faeces (epg) was counted by the Dorsman technique (2). Metacercariae were
0
.09
collected from the drainage furrows in each pasture by
291
introducing floats wrapped in cellophane paper. The cellophane was changed every fortnight and examined under a microscope
mean snails/m2 0 mean inf. . snails/m2 (young inf . Fig. 1. Density and infection of L. truncatula
1600
1600 1987
800
...... ---
an
0
1988
. --------
800
..... ....-.'
, ------, ............... //
4,
200
I
I
..,
.
200
.....
.
....
/
.,*
t'
..
.,.. ...,.*1--
/
50
..
......... ........
50
7ss,
4
III...,
001 ,
0
0 9
7
11
wks
13
15
0
17
2
1
3
.
.
4
I
1
1
5
7
9
11
13
17
15
wks 1600 1989
BOO
0
grazing period 1987
1988
1989
1
19/5-23/6
10/5-14/6
9/5-13/6
2
23/6-28/7
14/6-19/7
13/6-10/7
3
28/7-16/9
19/7-23/8
18/7-22/8
4
16/9-6/10
23/8-27/9
22/8-26/9
5
6/10-10/11
27/9-1/11
26/9-31/10
group
symbol
wk 0-5 = grazing period
m 200
50
...............
0 0
2
3.
4
5
7
9
13
11
15
17
wks Fig. 2. Mean IHA titres of tracer lambs in weeks after exposure
141
TIIlVI-.rrRIN1\kY QUARTERLY. Voi
1
4 .
N o
.
4 .
Di:
CI-N1
11
1
It.
1
9 .9
2
for the presence of metacercariae. Approximately 2000 cm2
Table 3. Mean Fasciola egg output (ep3gr.)
cellophane floats were used in each period. Cages prevented the floats from being damaged by grazing stock. The grazing system used by the farmer and slurry application was also registered. The cumulated egg input by grazing animals in risk areas was
1206 M/8 1087
1
18/3
1
16
1
14
1
2
a
0
20/10
2
a
0
4/12
2
10
9/2
2
0
7/4
3
0
23/8
3
1
27/9
3
3
6/12
3
22
1969 17/1
3
33
21/2
3 4
42
8/4 18/7
4
0
31/10
4
1
milking cows
yearlings
14
30/8
1908
Snail sampling On this farm L.truncatula only exists in the drainage furrows. There are two or more drainage furrows in each pasture. Snails were collected from all pastures in 20 randomly chosen plots of 20 x 50 cm. Snails were measured and dissected to investigate the infection rate. Snail density was determined approximately
calves
1
4/11
calculated by an approximation based upon the length of the grazing period, the amount of faeces and the e.p.g..
1
I
2
a 0 0
0
3
2 3
treatment was carried out on the following dates:
every 6 weeks throughout the year. During severe winter
28/4-87 calves and yearlings 15/12-87 calves 1/4-89 calves
periods, data could not be obtained because of ice cover.
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year group
date
Cattle Cattle on the farm were examined for the presence of fluke infections, by taking blood samples every 5 weeks from 10 calves, 10 heifers and 10 dairy cows. These had grazed for 0, 1 and more than 2 grazing seasons, respectively. Every year new calves were involved and the other groups graduated to older
n.b. year group is indicated for calves and yearlings
estimate of total egg output of 7,200,000 over the grazing period. The fluke burdens of the tracer lambs grazing on A and B were different (Table 2). During the first grazing period (19/5-23/6), no lambs became infected. In the second grazing period (23/628/7), the first tracer lambs became infected on pasture A with a total fluke burden of 199. In the third grazing period (28/7-16/ 9), the fluke burden of the tracer lambs increased to 928. In the
age groups.
The indirect haemagglutination (IHA) technique was used to
detect antibodies against Ehepatica. Faecal samples were collected five times a year when infections were expected. The number of Ehepatica eggs per 3 gram faeces was established using the Dorsman technique (2).
fourth and fifth grazing period (16/9-6/10 and 6/10-10/11, respectively), fluke burdens of 467 and 699 were calculated, respectively.
The first tracer lambs on pasture B were infected in the third period (28/7-16/9) and they had a total fluke burden of 175. In
RESULTS Table 1 gives the meteorological data, table 2 the transmission of -
the fourth and fifth groups the fluke burden increased considerably, to 1068 and 1954, respectively. Faecal examination showed
Ehepatica and table 3 the number of Ehepatica eggs in the commercial herd. Figure 1 shows the density and infection rate of L.truncatula, figure 2 the IHA titres of tracer lambs, figure 3 the IHA titres of selected animals of the commercial herd and figure 4 the percentage deviation of the rainfall from the norm
that tracer lambs in pasture A became patent mid-September and in mid-November in pasture B. Many metacercariae encysted on the cellophane paper from September until December (Table 2). The snail density and infection rate of snails increased from July (Figure 1). Young and old infections were observed. In tracer lambs IHA titres
calculated for the grazing period (5 weeks). There was a relationship between rainfall and fluke burden in tracer lambs.
(Figure 2) were positively correlated (P
