8th International Symposium on Tilapia in Aquaculture 2008
1351
DIGENETIC TREMATODES OF THE LITTLE EGRET, EGRETTA
GARZETTA, AND POSSIBILITY OF TRANSMISSION TO
OREOCHROMIS NILOTICUS
AT EL-ABBASSA FISH FARMS, EGYPT
ABD-AL-AAL, Z.1, O. H. AMER2, A. I. I. BADAWY2 AND A.M.M. EL-ASHRAM3
1. Dept. of Zoology, Fac. of Science.
2. Dept. of Parasitology, Fac. Vet. Med., Zagazig University
3. Fish diseases Dept., Central Lab. for Aquaculture Research (El-Abbassa),
Agricultural Research Center, Egypt.
Abstract
Migratory aquatic birds consider as a potential reservoir hosts
for many parasitic diseases that
may affect seriously both farmed fish and the public health. In
this study, the digenetic trematodes of the migratory fish-eating
bird, Egretta garzetta, and the possibility of transmission to
Oreochromis niloticus at El-Abbassa fish farms, Sharkia province
were investigated. Out of examined 75 E. garzetta, 45 (60%) were
infected with digenetic trematodes. Four mature species were
identified, in which Euclinostomum heterostomum was the most
prevalent (44%), followed by Clinostomum complanatum (12%),
Apharyngostrigea cornu (8%) and Strigea falconis (4%). In one
bird (1.3%), an unidentified encysted metacercaria species was
found on the subcutaneous and underlying muscular fascia for the
first time in this bird species. Investigation of 350 O. niloticus for
digenetic trematodes encystation revealed a total infection rate of
31.14%, represented by five types of encysted metacercariae
including Centrocestus species (11.1%), Prohemistomum species
(10.9%), Posthodiplostomum species (7.7%), C. complanatum
(0.9%) and E. heterostomum (0.6%). It appears that the migratory
E. garzetta could be a source of infection to O. niloticus at ElAbbassa fish farms with the zoonotically important parasite, C.
complanatum, as well as E. heterostomum. The study recommends
investigation of other fish-eating birds for determination of
reservoirs of parasitic diseases at this region.
INTRODUCTION
Migratory fish-eating birds should be considered as a potential reservoir hosts for
many parasitic diseases that affect seriously the birds, fish and the public health
(Torres et al., 1991; Kijewska et al., 2002; Barson and Marshall, 2004 and Mattiucci et
al., 2008). On the other hand, fish-borne zoonotic trematodes represent an important
group of human parasites, which transmitted to man through eating of raw or
insufficiently cooked fish and consider a serious risk factor on the public health (Thu et
al., 2007 and Trung Dung et al., 2007). According to the reports of the world health
organization (WHO), the number of people currently infected with fish-borne
trematodes exceed 18 million and the number of people at risk worldwide estimated at
more than half a billion (Thu et al., 2007). Regarding this point of view, this study was
1352 DIGENETIC TREMATODES OF THE LITTLE EGRET, EGRETTA GARZETTA, AND POSSIBILITY OF
TRANSMISSION TO OREOCHROMIS NILOTICUS AT EL-ABBASSA FISH FARMS, EGYPT
conducted to investigate the digenetic trematodes of the fish-eating bird, E. garzetta,
and possibility of transmission to O. niloticus at fish farms of El-Abbassa, Sharkia
province through investigation of this fish species for digenetic trematodes
encystation.
MATERIALS AND METHODS
Birds
Seventy five little Egret, E. garzetta, were captured at El-Abbassa fish farms, ElAbbassa, Sharkia province during the period extended from October 2007 to April
2008. Birds were submitted to the laboratory at the department of parasitology,
faculty of veterinary Medicine, Zagazig University, identified according to Brown et al.
(1982) and examined for the digenetic trematodes.
Examination
of
birds
for
digenetic
trematodes
and
preparation
of
permanent specimens
Birds were opened longitudinally, the skin was reflected and the underlying
subcutaneous tissues, the body cavity and the viscera were examined by the naked
eyes. The digestive system, beginning from the peak to the cloaca, was opened and
any found parasites were collected. Intestinal mucosal scrap as well as the contents
were washed several times with physiological saline, and after sedimentation, the
sediments were examined under dissecting microscope for parasites. The recovered
adult digenetic trematodes were relaxed in the refrigerator, fixed in formalin 10% and
stained with acetic acid alum carmine stain according to the technique of Kruse and
Pritchard (1982). The encysted metacercaria, recovered from the subcutaneous
tissues of birds, as well as the excysted ones (by gentle pressure between two glass
slides) were directly photographed without staining.
Examination of O. niloticus for encysted metacercariae
Three hundred and fifty O. niloticus were collected from El-Abbassa fish farms
between the period extended from October, 2007 to April, 2008 and examined for
digenetic trematodes encystation. Fish were macroscopically examined, both externally
and
internally, for
presence
of macroscopic encysted
metacercariae. Direct
compression between two glass slides as well as using the standard pepsin digestion
solution (Meyer and Olsen, 1971), as well as, haematoxylin and eosin stained
histopathological sections from the gills (Bancroft et al., 1996) were used for recovery
and isolation of encysted metacercariae. The recovered metacercariae were identified
according to Paperna (1996).
ABD-AL-AAL, Z. et al.
1353
RESULTS
Incidence of digenetic trematodes in the little Egret, E. garzetta
Investigation of 75 E. garzetta collected from El-Abbassa fish farms, Sharkia during
the period extended from October, 2007 – April, 2008 for infection with digenetic
trematodes revealed that 45 birds (60%) were infected (Table, 1). Four mature
digenetic trematodes species were recovered from the digestive tracts of examined
birds. Two species were recovered from the pharynx and oesophagus of infected
birds, in which Euclinostomum heterostomum was the most prevalent (44%), followed
by Clinostomum complanatum (12%). Apharyngostrigea cornu (8%) and Strigea
falconis (4%) were recovered from the small intestine of infected birds. The intensity
of infection of E. garzetta with mature digenetic trematodes worms was particularly
low, where the recovered maximum number of worms per infected bird was 6, 6, 8,
and 2 for E. heterostomum, C. complanatum, A. cornu, and S. falconis, respectively.
In only one case (1.3%), an unidentified macroscopic encysted metacercaria species
was detected in the subcutaneous and underlying muscular fascia of the thigh region
of one bird (Table, 2).
Table 1. Incidence of digenetic trematodes in little Egret, E. garzetta, captured at ElAbbassa fish farms
Bird
E. garzetta
No. examined
Infected
%
75
45
60
Table 2. Incidence of digenetic trematode species in little Egret, E. garzetta, hunted at
El-Abbassa fish farms
E. garzetta
Birds
No. examined
75
Intensity of
Digenetic trematodes
Site
Infected
%
infection
(Max. No/Bird)
E. heterostomum
Pharynx and
33
44
6
C. complanatum
oesophagus
9
12
6
Small intestine
6
8
8
3
4
2
1
1.3
18
A. cornu
S. falconis
unidentified
metacercaria
encysted
Subcutaneous
and underlying
muscular fascia
1354 DIGENETIC TREMATODES OF THE LITTLE EGRET, EGRETTA GARZETTA, AND POSSIBILITY OF
TRANSMISSION TO OREOCHROMIS NILOTICUS AT EL-ABBASSA FISH FARMS, EGYPT
Prevalence of encysted metacercariae of digenetic trematodes in O.
niloticus
Among 350 examined O. niloticus collected from El-Abbassa fish farms between
the period extended from October, 2007 to April, 2008, 109 (31.14%) proved to be
infected with digenean encysted metacercariae. Five species of metacercariae could be
identified. High infection rate with Centrocestus species (11.1%) was recorded,
followed by Prohemistomum species (10.9%), Posthodiplostomum species (7.7%), C.
complanatum (0.9%), and E. heterostomum (0.6%). The highest infection rate of O.
niloticus with the metacercariae (52%) was observed in October, 2007, while the
lowest infection rate (10%) was observed in December, 2007 and January, 2008
(Table 3).
Table 3. Prevalence and monthly fluctuation of encysted metacercariae of digenetic
trematodes in O. niloticus at El-Abbassa fish farms
Metacercariae
Macroscopic
50
26
52
0
0
November
50
22
44
0
December
50
5
10
January
50
5
February
50
March
Prohemistomum
October
No. % No.
sp.
%
Centrocestus sp.
No.
Posthodiplostomum
fishes
sp.
examined Total infected
C. complanatum
Month
E. heterostomum
No. of
Microscopic
%
No.
%
No.
%
0
0
15
30
4
8
7
14
0
0
0
12
24
5
10
5
10
0
0
0
0
0
0
3
6
2
4
10
0
0
0
0
0
0
3
6
2
4
9
18
0
0
0
0
0
0
6
12
3
6
50
20
40
0
0
0
0
0
0
10
20
10 20
April
50
22
44
2
4
3
6
0
0
8
16
9
Total
350
109
31.14
2
0.9
27
7.7
39
0.6 3
No. %
18
11.1 38 10.9
Morphological features of the detected digenetic trematodes
Mature worms recovered from E. garzetta
C. complanatum (Plate 1, A)
The worm was pear shape, with a narrow anterior end which widens greatly at the
level of the ventral sucker. It measured 5.5 mm in length and 3 mm in breadth. The
oral sucker was terminal and measured 234 µm x 450 µm, while the ventral one
ABD-AL-AAL, Z. et al.
1355
measured 1.1 mm x 1.0 mm and apart from the oral sucker by 1.1 mm. The intestinal
caeca were simple and reached the posterior end of the body. The testes were
tandem in position, and lied near the middle of the body and measured 0.8 mm x 1.2
mm and 0.6 mm x 1.4 mm. The ovary was ovoid, between the testis and measured
0.7 mm x 1.0 mm. The ootype located beside the ovary and measured 0.4 mm x 0.3
mm. The vitellaria were present laterally and extended from the level of the ventral
sucker to the end of the body. The eggs were oval, operculated and measured 144 µm
x 72 µm.
E. heterostomum (Plate 1, B)
The body was truncate anteriorly, then widens greatly near beginning of the lateral
branching of the intestinal caeca and broadly rounded posteriorly. It measured 1.9 cm
x 3.5 mm. The oral sucker was subterminal, lied about 0.5 mm from the anterior end
and measured 0.4 mm x 0.48 mm, while the ventral one measured 1.7 mm x 1.6 mm.
The oesophagus leads to an intestinal caecum, which bifurcates anterior to the ventral
sucker into two main intestinal branches, which in turn give rise to 10 – 13 simple
secondary blind diverticula begins behind the ventral sucker to the end of the body.
The testes were lobulated, tandem in position and lied caudally in the last third of the
body. The anterior testis measured 1.8 mm x 2.1 mm, while the posterior one
measured 1.8 mm x 1.6 mm. The ovary was ovoid, between the testis and measured
1.1 mm x 1.5 mm. The ootype was beside the ovary and measured 0.8 mm x 0.6 mm.
The vitellaria were present laterally and extended from the level of the ventral sucker
to the end of the body. The eggs were oval, operculated and measured 130 µm x 76
µm.
S. falconis (Plate 1, C)
The body was divided into fore body, measuring 1.0 x mm 0.98 mm, and an elongated
cylindrical hind body, measuring 4.5 mm x 0.95 mm. The oral sucker was rounded and
measured 144 µm in diameter, while the ventral sucker was larger and measured 252
µm in diameter and lied behind the oral one by about 180 µm. A bilobed tribocytic
organ was located caudally in the fore body. The testes were tandem, in the second
half of the hind body and measured 594 µm x 576 µm and 630 x 576 µm for the
anterior and posterior testis, respectively. The ovary was oval, measured 234 µm x
360 µm and lied anterior to the testes. The uterus had a thin loop, laterally and opens
in a genital cone caudally. The eggs were oval, operculated and measured 108 µm x
90 µm. The vitellarine glands were in form of small follicles, along the whole lateral
side of the hind body and present also caudally in the fore body.
1356 DIGENETIC TREMATODES OF THE LITTLE EGRET, EGRETTA GARZETTA, AND POSSIBILITY OF
TRANSMISSION TO OREOCHROMIS NILOTICUS AT EL-ABBASSA FISH FARMS, EGYPT
A. cornu (Plate 1, D)
The body of the worm consisted of a pear shaped fore body, which measured 1.6 mm
x 1.0 mm, and an elongated cylindrical hind body, measured 3.3 mm x 0.8 mm. The
oral sucker was terminal, rounded in shape and measured 180 µm in diameter. The
ventral sucker measured 306 µm in diameter and lied behind the oral one by about
360 µm. A triangular shaped Tribocytic organ was located caudally in the fore body.
The testes were tandem, in the second half of the hind body and measured 630 µm x
540 µm and 720 x 486 µm for the anterior and posterior testis, respectively. The ovary
measured 180 µm x 360 µm and lied anterior to the testes. The uterus had a small
ascending limb and contained oval, operculated eggs which measured 126 µm x 68
µm. The vitellaria were in form of small follicles, present laterally in the whole hind
body and extended in the fore body reaching the tribocytic organ.
Unidentified encysted metacecaria from E. garzetta (Plate 2)
The encysted metacercaria appeared as macroscopic globoid whitish cysts, measured
about 0.96 mm in diameter. Excysted metacercaria was fragile and ruptured
spontaneously under the glass cover after a short period of examination with the
microscope. The metacercaria showed a somewhat pointed anterior end and a much
rounded posterior one.
Encysted metacercaria from O. niloticus
C. complanatum (Plate 3, A)
The body was convex dorsally and concave ventrally and measured 5.1 mm x 2 mm.
The oral sucker was small and subterminal, while the ventral one was larger and
situated in the anterior third of the body. The intestinal caeca were simple, reaching
the posterior end of the body. The testes were lobulated, tandem in position and
located in the second half of the body, and the ovary between them. Vetillaria
extended from level of the ventral sucker to the end of the body.
E. heterostomum (Plate 3, B)
The body was truncate anteriorly and more rounded posteriorly. It measured 6.6 mm
x 1.1 mm. The oral sucker was small, rounded and subterminal, while the ventral
sucker was larger and located in the first third of the body. Both intestinal caeca
showed about 10 – 13 simple lateral blind diverticula. The testes were lobulated and
located in the second half of the body, and the ovary between them.
Prohemistomum species (Plate 3, C & D)
The cysts were spherical and surrounded with an easily ruptured fragile outer cyst
wall. It measured 0.26 – 0.3 mm (aver. 0.28 mm) in diameter. The excysted
metacercaria appeared oval in shape, with a somewhat pointed anterior end and a
round posterior one.
Posthodiplostomum species (Plate 3, E)
The cysts were transparent and ovoid in shape. It measured 0.98 – 1.0 mm (aver.
0.99 mm) in length and 0.7 – 0.9 mm (aver. 0.8 mm) in breadth. The metacercaria
ABD-AL-AAL, Z. et al.
1357
was enclosed in a double layered cyst wall, in which the outer layer was thick and dark
in colour, while the inner one was thin.
Centrocestus species (Plate 3, F & G)
A double layered oval or elliptical and hyaline transparent cysts. It measured 1.9 - 2.0
mm (aver. 1.95 mm) in length and 0.13 – 0.14 mm (aver. 0.13 mm) in breadth. The
outer cyst wall was thin and fragile, while the inner one was thick and difficult to be
ruptured. The body of the metacercaria was pigmented.
Plate 1. Mature digenetic trematodes recovered from E. garzetta at El-Abbassa fish
farms (Alum carmine stain). A: C. complanatum (Bar= 1.6 mm); B: E.
heterostomum (Bar= 5 mm); C: S. falconis (Bar= 1.2 mm); D: A. cornu
(Bar= 0.8 mm).
1358 DIGENETIC TREMATODES OF THE LITTLE EGRET, EGRETTA GARZETTA, AND POSSIBILITY OF
TRANSMISSION TO OREOCHROMIS NILOTICUS AT EL-ABBASSA FISH FARMS, EGYPT
Plate 2. Unidentified encysted metacercaria recovered from the subcutaneous and
underlying muscular fascia of E. garzetta. A: Photograph of the encysted
metacercaria (Arrows) on the subcutaneous and underlying muscular fascia
(Bar= 10 mm); B: Micrograph of the encysted metacercaria (Bar= 0.5 mm);
C: Metacercaria out from the cyst wall (Bar= 0.6 mm); D: Excysted
metacercaria (Bar= 0.4 mm).
ABD-AL-AAL, Z. et al.
1359
Plate 3. Encysted metacercariae recovered from O. niloticus at El-Abbassa fish farms.
A: C. complanatum (Alum carmine stain) (Bar= 0.8 mm); B: E. heterostomum
(Alum carmine stain) (Bar= 1.1 mm); C & D: Prohemistomum species
(Arrows) (Unstained) (Bar= 0.1 mm); E: Posthodiplostomum species
(Unstained) (Bar= 0.6 mm); F: Centrocestus species encysted metacercaria in
gills (Arrow) (Unstained) (Bar= 1.3 mm); Histopathological section in gills
showing Centrocestus species metacercaria (Arrow) (Haematoxylin and Eosin
stain) (Bar= 2.7 mm).
1360 DIGENETIC TREMATODES OF THE LITTLE EGRET, EGRETTA GARZETTA, AND POSSIBILITY OF
TRANSMISSION TO OREOCHROMIS NILOTICUS AT EL-ABBASSA FISH FARMS, EGYPT
DISCUSSION
This study was conducted to investigate the digenetic trematodes of the
migratory fish-eating bird, little Egret (E. garzetta), and the possibility of their
transmission to O. niloticus fish farms at El-Abbassa region, Sharkia province. Sixty
percent of birds harboured mature worms of four digenetic trematode species. A
similar high prevalence rate of adult digenea in Egrets was also recorded previously
(Ryang et al., 1991 and Aohagi et al., 1992 and Navarro et al., 2005).
Results of this study revealed that the prevalence rates of E. heterostomum
and C. complanatum in E. garzetta were 44% and 12%, respectively. As early stated
(Aohagi et al., 1992), clinostomatids were prevalent in Egrets and other fish eating
birds. The wide geographical distribution and high infection rates of clinostomatids
might be related to the wide range of birds acting as final hosts as well as fish acting
as intermediate hosts for these worms as previously reported (Aohagi et al., 1992 and
Chung et al., 1995).
In the present study, A. cornu was recovered from the small intestine of 8%
of the examined E. garzetta. Similar findings were documented in Ardea cinerea and
E. garzetta in Spain (Navarro et al., 2005).
As described by Ryang et al. (1991), birds of the family ardiedae were proven
to be final hosts for the strigeid digenean, S. falconis, where the authors isolated S.
falconis from 83% of Ardea alba in Korea. In comparison to clinostomatids, the
infection rate of E. garzetta with strigeids was low during this study. This is may be
attributed to the host's diet as well as abundance of the intermediate hosts of the
worms.
In one E. garzetta, an unidentified species of subcutaneous metacercaria was
detected. Although encysted metacercariae of digenetic trematodes were not
previously detected from little egret, E. garzetta, but this finding could be supported
by the findings of Kramer et al. (1996), who recorded a 38-year-old man suffering
from bronchospasms and isolated later a mesocercaria, most likely that of Alaria spp.
or Strigea spp, from the subcutaneous nodule. The authors stated that eating
undercooked wild goose meat during a hunting trip was the most likely source of
infection; and also, with the findings of Krone and Streich (2000), who recovered the
metacercaria of Strigea falconispalumbi from the connective tissue of the neck of 10%
- 58% of the Eurasian buzzards in different localities in Germany.
Except minor differences in the measurements, morphological features of the
detected mature digenetic trematodes in this study were in close agreement with the
preceding descriptions (Yamaguti, 1958; El-Naffar et al., 1980; Amer and Gattas, 1993
and Chung et al., 1995). The difference in measurements of the worms might be
ABD-AL-AAL, Z. et al.
1361
attributed to the birds, from which the parasites were collected and the methods of
preparation of the parasites for examination.
Examination of O. niloticus revealed five types of digenean encysted
metacercariae, with a total infection rate of 31.14%. Similar records of high infection
rate of O. niloticus with digenean metacercariae were also described (El-Ashram, 2003
and Abd El Rahman, 2005).
In the present study, the prevalence rates of C. complanatum and E. heterostomum
encysted metacercariae in O. niloticus were 0.9% and 0.6%. These low infection rates
were unexpected; especially the prevalence rates of adult parasites of both species in
the E. garzetta were high. As well as results of the previous related studies (ElAshram, 2003), who found that 34% and 29% of this fish species were infected with
these types of metacercariae, respectively; and that of Abd El Rahman (2005), who
found that 45% and 11.8% of O. niloticus were infected with Clinostomum species
and Euclinostomum species metacercariae, respectively. This is can be returned to the
difference in sampling periods and the ponds from which the examined fishes were
obtained.
Centrocestus species metacercariae were detected in 11.1% of examined O.
niloticus. Clinostomum species, Euclinostomum species, Posthodiplostomum species
and Centrocestus species proved to be commonly affected tilapias and other fresh
water fishes (El-Nobi, 1998 and Dzikowski et al., 2003). Prohemistomum species and
Posthodiplostomum species metacercariae affected 10.9% and 7.7% of the examined
tilapia species.
Morphological characters of the detected metacercariae in this study were in
agreement with earlier descriptions (Amer et al., 1988; Saad, 1994; Hoole et al., 2001;
El-Ashram, 2003 and Raef and El-Ashram, 2004).
Since infections by metacercariae of Clinostomum species adversely affect
aquaculture fish and are potentially transmissible to humans (Dzikowski et al., 2004),
the results suggest that the little Egret, E. garzetta, is a reservoir for digenetic
trematodes of fish and of public health importance in El-Abbassa region. It is
recommended to investigate the other fish-eating migratory birds in this region for
determination of reservoirs of parasitic diseases.
ACKNOWLEDGEMENTS
The present authors are very grateful to Prof. Dr. Maher El-Domiety, President of
Zagazig University, for his continuous encouragement and supports.
1362 DIGENETIC TREMATODES OF THE LITTLE EGRET, EGRETTA GARZETTA, AND POSSIBILITY OF
TRANSMISSION TO OREOCHROMIS NILOTICUS AT EL-ABBASSA FISH FARMS, EGYPT
REFERENCES
1. Abd El Rahman, A. M. M. 2005. Studies on prevailing parasitic diseases among
some fresh water fishes caused by digenetic trematodes. SCVMJ, 8 (1): 13 – 24.
2. Aohagi, Y., T. Shibahara, N. Machida, Y. Yamaga, K. Kagota, and T. Hayashi.
1992.
Natural
infections
of
Clinostomum
complanatum
(Trematoda:
Clinostomatidae) in wild herons and egrets, Tottori Prefecture, Japan. J. Wildl.
Dis., 28 (3): 470 – 471.
3. Amer, O. H. and M. W. Gattas. 1993. Studies on the role played by fresh water
fish in transmitting of some trematodes to fish eating birds. J. Egypt. Vet. Med.
Ass., 53 (1 & 2): 121 – 127.
4. Amer, O. H., M. S. Nada and E. A. Desoky. 1988. Further study on some digenetic
trematodes from fresh-water fishes. Bull. Fac. Sci., Zagazig Univ., 10 (1): 469 –
483.
5. Bancroft, J. D., A. Stevens and D. R. Turner. 1996. Theory and practice of
histological technique. 4th ed. Churchill, Livingston, London.
6. Barson, M. and B. E. Marshall. 2004. First record of Contracaecum spp.
(Nematoda: Anisakidae) in fish-eating birds from Zimbabwe. J. S. Afr. Vet. Assoc.,
75 (2): 74 – 78.
7. Brown, L. H., E. K. Urban and K. Newman. 1982. The birds of Africa. Vol. 1,
Academic press INC, London: 151 – 159.
8. Chung, D., H. Kong and C. Moon. 1995. Demonstration of the second intermediate
hosts of Clinostomum complanatum in Korea. Korean J. Parasitol., 33 (4): 305 –
312.
9. Dzikowski, R., A. Diamant and I. Paperna. 2003.
Trematode metacercariae of
fishes as sentinels for a changing limnological environment. Dis. Aquat. Organ., 55
(2): 145 – 150.
10. Dzikowski, R., M. G. Levy, M. F. Poore, J. R. Flowers and I. Paperna.
2004.
Clinostomum complanatum and Clinostomum marginatum (Rudolphi, 1819)
(Digenea: Clinostomidae) are separate species based on differences in ribosomal
DNA. J. Parasitol., 90 (2): 413 – 414.
11. El-Ashram, A. M. M. 2003. Studies on some macroscopical larval stages of
helminth parasites in tilapias. Beni-Suef Vet. Med. J., 12 (2): 1 – 13.
12. El-Naffar, M. K., R. M. Khalifa and A. A. Sakla. 1980. Parasitofauna of the Egyptian
aquatic birds. II. Trematode parasites of the giant heron ( Ardea goliath) in Assiut
governorate. J. Egypt. Soc. Parasitol., 10 (1): 107 – 116.
13. El-Nobi, G. 1998. Studies on the main parasitic diseases affecting cultured fish and
their influences by some ecological factors. Ph.D. Thesis, Vet. Med. Sci., Zagazig
University.
14. Hoole, D., D. Bucke, P. Burgess and I. Wellby. 2001. Diseases of carp and other
cyprinid fishes. 1st ed., Blackwell science Ltd., London.
ABD-AL-AAL, Z. et al.
1363
15. Kijewska, A., J. Rokicki, J. Sitko and G. Wegrzyn. 2002. Ascaridoidea: a simple
DNA assay for identification of 11 species infecting marine and freshwater fish,
mammals, and fish-eating birds. Exp. Parasitol., 101(1): 35 – 39.
16. Kramer, M. H., M. L. Eberhard
and T. A. Blankenberg. 1996. Respiratory
symptoms and subcutaneous granuloma caused by mesocercariae: a case report.
Am. J. Trop. Med. Hyg., 55 (4): 447 – 448.
17. Krone, O. and W. J. Streich. 2000. Strigea falconispalumbi in Eurasian buzzards
from Germany. J. Wildl. Dis., 36 (3): 559 – 561.
18. Mattiucci, S., M. Paoletti, J. Olivero-Verbel, R. Baldiris, B. Arroyo-Salgado, L.
Garbin, G. Navone and G. Nascetti. 2008. Contracaecum bioccai n. sp. from the
brown pelican Pelecanus occidentalis (L.) in Colombia (Nematoda: Anisakidae):
morphology, molecular evidence and its genetic relationship with congeners from
fish-eating birds. Syst. Parasitol., 69 (2): 101 – 121.
19. Meyer, C. M. and W. O. Olsen. 1971. Essentials of parasitology. W. M. C. Brown
Co. publishers, USA: P. 288.
20. Navarro, P., J. Lluch and E. Font. 2005. The component helminth community in six
sympatric species of Ardeidae. J. Parasitol., 91 (4): 775 – 779.
21. Paperna, I. 1996. Parasites, infections and diseases of fishes in Africa. CIFA
Technical paper 31, Rome, FAO: 220.
22. Raef, A. M. and A. M. M. El-Ashram. 2004. Observation on the morphological
characters
on
metacercariae
and
adults
of
Posthodiplostomum
cuticula
(Trematoda: Diplostomatidae) in cultured Oreochromis niloticus. Beni-Suef Vet.
Med. J., 14 (1): 39 – 49.
23. Ryang, Y. S., Y. K. Ahn and M. B. Yoon. 1991. Trematode infections in the small
intestine of Egretta alba modesta in Kangwon-do. Kisaengchunghak Chapchi, 29
(3): 227 – 233.
24. Saad, A. I. 1994. The life cycle of Centrocestus unequiorchalis N. sp.
(Heterophyidae: Centrocestiinae). J. Islamic Academy of Science, 7 (3): 193 –
198.
25. Thu, N. D., A. Dalsgaard, L. T. Loan and K. D. Murrell. 2007. Survey for zoonotic
liver and intestinal trematode metacercariae in cultured and wild fish in An Giang
Province, Vietnam. Korean J. Parasitol., 45 (1): 45 – 54.
26. Torres, P., E. Ruiz, W. Gesche and A. Montefusco. 1991. Gastrointestinal
helminths of fish-eating birds from Chiloe Island, Chile. J. Wildl. Dis., 27 (1): 178 –
179.
27. Trung Dung, D., N. Van De, J. Waikagul, A. Dalsgaard, J. Y. Chai, W. M. Sohn
and K. D. Murrell. 2007. Fishborne zoonotic intestinal trematodes, Vietnam.
Emerg. Infec. Dis., 13 (12): 1828 – 1833.
28. Yamaguti, S. 1958. Systema helminthum. Vol. 1, the digenetic trematodes, Part I
& II., Interscience publishers Inc., London.
‫‪1364 DIGENETIC TREMATODES OF THE LITTLE EGRET, EGRETTA GARZETTA, AND POSSIBILITY OF‬‬
‫‪TRANSMISSION TO OREOCHROMIS NILOTICUS AT EL-ABBASSA FISH FARMS, EGYPT‬‬
‫المثقبات ثنائية العائل التى تصيب البلشون الصغير (إجريتا جارزيتا) وامكانية نقلها‬
‫إلى البلطى النيلى بمزارع العباسة بمصر‬
‫زين عبدالعال‪ – 1‬عمر حسن عامر‪ - 2‬أحمد إبراهيم إبراهيم بدوى‪ – 2‬أحمد محمد محمود‬
‫األشرم‪3‬‬
‫‪ .1‬قسم الحيوان (كلية العلوم)‪.‬‬
‫‪ .2‬قسم الطفيليات (كلية الطب البيطرى) بجامعة الزقازيق‪.‬‬
‫‪ .3‬قسم أمراض األسماك – المعمل المركزى لبحوث الثروة السمكية بالعباسة – مركز البحوث‬
‫الزراعية– مصر‬
‫تعتبررر الطيررور المةرراجرة كعا ررل مةررم للعريررر مررن األم رراض الطفيليررة ال ام ررة والت ر تمثررل خط ر ار عل ر‬
‫الثروة السمكية وصحة اإل سان‪ .‬تم إجراء هذا البحث لرراسة المثقبات ث ا يرة العا رل التر تصريب البل رون‬
‫الصررريركدحر الطيررور المةرراجرة األ لررة ل سررماك لوامكا يررة قلةررا إلر أسررماك البلطر ال يلر بمرزار العباسررة‬
‫بمحافظة ال رقية – مصر‪ .‬وأظةرت ال تا ج أن سبة إصابة البل ون الصرير بةذا ال و من الريرران هر‬
‫‪ ٪06‬وتم عزل ‪ 4‬أ وا من الريران البالرة وه إيكلي وستومم هتروستومم (‪ ٬)٪44‬كلي وسرتومم كمبن يرتم‬
‫(‪ ٬)٪12‬أفري جوستريجيا كور و (‪ ٬)٪8‬ستريجيا فال و س (‪ .)٪4‬هذا وقرر ترم عرزل رو مرن الميتاسرركاريا‬
‫المتحوصررلةتحت الجلررر ألول مررة مررن هررذو الطيررور‪ .‬وبفحر‬
‫‪ 356‬سررمكة مررن أسررماك البلطر ال يلر مررن‬
‫مزار العباسة تبين أن سربة إصرابتةا بالميتاسرركاريا المتحوصرلة (الطرور المعررى للمثقبرات ث ا يرة العا رل)‬
‫ه ‪ ٪31‚14‬وت مل ‪ 5‬أ وا وه س تروسيسرتس (‪ ٬)٪11‚1‬بروهيميسرتومم (‪ ٬)٪16‚9‬بوسوريبلوسرتومم‬
‫(‪ ٬)٪7‚7‬كلي وسررتومم كمبن يررتم (‪ ٬)٪6‚9‬إيكلي وسررتومم هيتيرمسررتومم (‪ .)٪6‚0‬وبمقار ررة ال تررا ج تبررين أن‬
‫هذا ال و مرن الطيرور ي ركل خطر ار علر أسرماك البطر ال يلر وكرذالك صرحة اإل سران وئخاصرة إلحتوا ر‬
‫علر ر ري ررران كلي وسر ررتومم كمبن ي ررتم ذات األهمير ررة الم ررتركة ‪ ٬‬ري ررران إيكلي وسر ررتومم‪ .‬وأوص ررت الر ارسر ررة‬
‫بفح‬
‫المزير من أ وا الطيور المةاجرة لةذو الم طق للتعرر علر ماتحتوير مرن الطفيليرات التر ت ركل‬
‫خط ار عل صحة األسماك واإل سان ف مصر‪.‬‬