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The Journal of Ecology, Photon 109 (2014), 408-413
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Original Research Article. ISJN: 6853-3275 Impact Index: 5.12
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The Journal of Ecology
Studies on prevalence of infection of trematode cercarial parasitism
in fresh water Gastropods, Barabanki, U.P state, India
Dr. Priyanka Tripathi*, Shailendra Ray, Nirupama Agrawal
Department of Zoology, University Of Lucknow, Lucknow, 226007 India
Dr. Priyanka Tripathi*, Shailendra Ray, Nirupama Agrawal
receive Photon Young Scientist Award-2014 in Ecology by
Photon Foundation
Article history:
Received: 21 January, 2014
Accepted: 26 January, 2014
Available online: 08 November, 2014
Keywords:
Cercarial parasitism, Prevalence, Gastropods, Bellamya
bengalensis
Abbreviations:
EC: Echinostome cercariae,
FC: Fercocercous cercariae,
XC: Xiphidiocercariae,
GM: Gymnocephalous cercariae
Corresponding Author:
Priyanka Tripathi*
Research worker
Email: Priyankatripathi24@gmail.com
Shailendra Ray
Research worker
Nirupama Agrawal
Professor
Abstract
Prevalence of infection of snails L. acuminata, I. exustus
and B. bengalensis have been observed for a year. Four
cercariae EC (5.6%), FC (9.2%), XC (6.2%) and GC
(3.1%), were encountered during study. Present study
reveals that long summer season is associated with more
probable chances of transmitting infection.
Citation:
Tripathi P., Ray S., Agrawal N., 2014. Studies on
prevalence of infection of trematode cercarial parasitism in
fresh water Gastropods, Barabanki, U.P state, India. The
Journal of Ecology. Photon 109, 408-413
All Rights Reserved with Photon.
Photon Ignitor: ISJN68533275D650908112014
1. Introduction
The number of parasite individuals per host,
determines the importance of parasitism
(Poulin & Mario, 2007) and it is the major
selective force in evolution and a key
structuring force in ecosystem (Combes, 2001,
& Thomas et al., 2005). Study on prevalence
of trematode larval infection is more common
in Lucknow but this type of study has never
been explored from district Barabanki. The
present study has evaluated the prevalence of
trematode cercarial parasitism with three
populations of snails belonging to three
families including Lymnaeidae, Planorbidae &
Viviparidae, including three genera viz.
Lymnea
acuminata
(Lamark,
1882),
Indoplanorbis exustus (Deshayes, 1834) and
Bellamya bengalensis (Lamarck, 1822). For
this purpose two sampling areas for collecting
the snails were selected and both sites were
connected from river. One site named “Kakrai
Lake” extending in 6 acre area was connected
with Sharda River in Barabanki. Second sites
named “Naya Tal” near river named “Kalyani”
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it was covering 3 acre area, 40 km for away
from first site. Attempts were made to collect
samples at these stations over a period of 12
months during Jan 2010- Dec 2011.
2. Objective of Research
To observe the rate of seasonal infection in
snails belonging to three families of
gastropods, Lymnaeidae, Planorbidae &
Viviparidae.
3. Experimental
Prevalence of infection in snails is a major
threat for socio-economic development of the
country because of their use as a food and
medicinal significance. Two collection sites
were selected for sampling to know the rate of
infection of larval trematodes in gastropods.
Two natural lakes located in Barabanki were
surveyed for occurrence of three different
populations of snails during Jan, 2010-Dec
408
2011. This region has a subtropical &
mansonic climate located at 26º30
and
27º19
north latitudes and 80º55
east
latitudes. Since the prevalence of cercarial
infection increases with snail size (Karvonen
et. al. 2006), only older snails (shell length >
3cm for B. bengalensis, > 2.5 cm for L.
acuminata, > 2cm for I. extustus) were
collected. The trematode larval infection was
detected by examining the tissue & visceral
organs microscopically by crushing the snails
or by inducing the cercarial emergence at a
comparatively high temperature rising to 24 ±
3ºC.
For observing their emergence; snails were
kept in beakers containing 100 ml
dechlorinated water. Snails were also
maintained in small water tanks in our
laboratory at room temperature fed with
Vellisnaria and Pistia leaves. During night all
beakers were covered by muslin cloth to avoid
slide over beaker. Water changed regularly to
clean excessive fecal matter. Suspension of
emerged cercariae was counted with the aid of
stereomicroscope. Cercariae were studied
alive with and without stains. Neutral Red was
principal vital stain used for staining of flame
cells and gonads. Figures were drawn with the
help of drawing tube attached to Phase
Contrast microscope (Olympus CX-41) in
phase-2.
4. Justification of Research
Several diseases like cercarial dermatitis,
schistosomiasis and fascioliasis are common
caused by larval trematodes. So there was a
need to minimize their exposure to understand
their emergence and rate of seasonal
infection.
5. Results and Discussion
Variability among snail population has been
noticed from two different sample collecting
sites, though they are located at a distance of
only 40 kms. Second site was found to be
infected with one species of snail B.
bengalensis only. The density of snails may
vary locally rather geographical isolation. It
was also pointed out that population of snails
is basically determined by abiotic factors, such
as environmental and landscape variables
(Heino & Mutko 2005). Specific group of snails
have been found to carry distinct group of
cercariae. It is more likely that trematode show
a high degree of specificity for their gastropod
hosts (Sapp & Loker, 2000). This host
specificity is basically functioning of physiology
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and evolution (Nobel, 1960). Such marked
variations in the prevalence of infection in
snails are probably due to the different
ecological niches in which they exist (Hunter
and Wigington, 1972).
Representive of two different cercarial groups
st
were found from 1 sampling site. A total 1464
specimens of L. acuminata were collected
from site and 83, or 5.6%, were positive for
emerging of echinostome cercariae (Fig. 1).
Echinostome cercariae were encountered five
times during collection. Their rate of infection
peaked in October, 2011 with air temperature
24ºC and water temperature 22ºC with 7.1 pH
of water and low during August when air
temperature 27ºC (Fig. 2a) and water
temperature 22ºC with 7.4 pH of water.
Present study shows the peak of infection of
these cercariae in October 9.8%, in rest
(August 3.4%, September 4.7%, November
8.1% and in December, 7.2 %.) were
comparatively low. These results were
different from Hunter and Birkenhotz (1961),
who reported that their increased 15% peak in
mid June to over 50% in mid August.
913 specimens of I. exustus have been
observed from same site and 26 out of 913, or
9.2% were positive for emergence of
fercocercous cercariae (Fig. 1). Prevalence of
these cercariae found to be peak in November
12.7% and low during October, 5.3%. The
infection of these cercariae encountered four
times from snail I. exustus. They peaked in
month of November with air temperature 23ºC
and water temperature 21ºC, & low in October
(Fig. 2b), with 7.1 pH of water. After this month
these snails (I. exustus) have not been found
during collection. This high rate of prevalence
seems to be directly correlated with the
maturation & age of these snails in this month.
These snails acquire large shell length and
suppose to be accumulating heavier infection.
Larger hosts also have greater external
surface areas and are older, making them
more vulnerable to ectoparasites, therefore,
they carry more parasites than smaller ones
(Poulin, 2013).
1567 specimens of B. bengalensis were
examined, double infection recorded, 98 or
5.8%
were
found
infected
with
xiphidiocercariae and 18 out of 570 or 3.1%
were found infected with gymnocephalous
cercariae. However, mostly xiphidiocercariae
have been noticed in months of March (9.5%),
April (6.6%), May (9.2%), June (7.6%),
September (2.8%), October (3.5%), November
(3.6%) & December (5.8%). These cercariae
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were encountered eight times, while
gymnocephalous found only two times during
study. High peak of their prevalence of
xiphidiocercariae cercariae were recorded in
month of March when temperature air
temperature 31ºC and water temperature 25ºC
(Fig. 2d) with 7.2 pH of water. While low peak
of emergence was recorded in September
when air temperature 28ºC and water
temperature 23ºC with 7.5 pH of water.
Infection of gymnocephalous cercariae during
months of October and November only
(Fig.2c), and high peak in November when
temperature air temperature 23ºC and water
temperature 21ºC with 7.2 pH of water.
Table 1: Summary of air and water temperature and pH at site1 on Kakrai lake (NF-Not found, EC- Echinostome
cercariae, FC- Fercocercous cercariae, XC- Xiphidio cercariae, GM- Gymnocephalous cercariae)
Months
Aug
Sep
Oct
Nov
Dec
No. of host
collected
Host
1
347
461
268
143
242
Host 2
No.
of
host
found
infected
Host1
Host 2
EC
FC
224
213
318
158
NA
12
23
16
13
19
3.4
4.9
5.9
9.09
7.8
12.5
7.04
5.6
14.5
NF
28
15
18
23
NA
%
infection
of
Temp of Air
(ºC)
Temp
of
water (ºC)
pH of
water
27
28
24
23
22
22
23
21
19
20
7.3
7.4
7.2
7.3
7.3
Temp of water
(ºC)
25
27
24
28
23
22
23
22
21
19
pH
of
water
7.2
7.3
7.4
7.1
7.5
7.4
7.5
7.1
7.2
7.3
Table 2: Summary of air and water temperature and pH at site 2 on Naya Tal
Months No.
of
host No. of host
% of infection Temp of Air
collected
found infected XC
(ºC)
GM
March
76
8
10.5 NF
31
April
126
9
7.1
NF
32
May
177
18
10.1 NF
34
June
156
13
8.3
NF
33
July
NF
NF
NF
NF
28
Aug
NF
NF
NA
NF
27
Sep
268
8
2.9
4.1
28
Oct
374
14
3.7
2.5
24
Nov
184
7
3.8
NF
23
Dec
206
21
10.1 NF
22
Shell
length
L.acuminata
S.L
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
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Length
2.1
1.8
1.6
1.9
2
1.8
1.7
1.8
1.9
2.1
1.8
1.7
1.5
1.8
2
1.7
1.5
1.8
2
1.7
1.8
1.9
1.7
Width
1.1
0.9
1.8
0.8
1.3
1
0.9
1.1
1
1.4
1.3
1.2
0.9
1.1
1.3
1.1
0.8
0.9
1.2
0.9
0.8
1
1.1
of
Shell length of
exustus
Length
1.8
1.7
2
1.6
1.9
1.7
2
1.7
1.8
1.7
1.8
2
1.8
2.1
1.8
1.7
1.9
2.1
1.6
2.1
1.8
1.7
1.6
Width
1.9
1.8
2.1
1.8
1.7
1.8
2.1
1.9
1.6
1.8
1.7
2.1
1.9
2
1.9
1.8
1.7
2.2
1.8
1.9
1.7
1.9
1.5
I.
Shell length
bengalensis
Length
3.5
3.6
3.4
3.1
3.2
3.4
3.3
3.2
3.3
3.2
3.6
3.2
3.3
3.2
3.5
3.2
3.1
3.3
3.3
3.4
3.2
3.3
3.2
of
B.
Width
2.4
2.8
2.4
2.8
2.1
2.9
2.8
2.6
2.7
2.2
2.5
2.3
2.7
2.4
2.7
2.4
2.6
2.7
2.5
2.7
2.4
2.5
2.4
410
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
1.9
2.1
1.9
1.7
1.6
2
1.8
1.7
1.9
2.2
1.8
2.1
1.7
1.8
1.9
1.2
1.3
0.9
0.8
0.9
1.3
0.8
0.9
1
1.4
1.1
1.2
0.9
0.8
0.7
2.1
2
1.8
1.9
1.7
1.8
2.1
1.9
1.8
1.7
2
1.6
1.7
1.9
1.7
1.9
1.9
1.6
2
1.6
2
2
2
1.9
1.9
1.8
1.8
1.9
1.8
1.9
3.3
3.2
3.1
3.4
3.3
3.2
3.5
3.2
3.1
3.2
3.2
3
3.2
3.3
3.4
2.7
2.8
2.4
2.9
2.6
2.7
2.8
2.4
2.3
2.5
2.4
2.5
2.3
2.5
2.6
39
40
2.1
1.6
1.1
0.9
2
1.8
2.2
1.9
3.2
3.1
2.4
2.4
Figure 1: shows total percentage of cercarial group
from two different sites (Site 1.Kakrai lake, Site 2.
Naya ta)
(b) Shows prevalence of Fercocercous cercariae
with snail Indoplanorbis exustus
Figure 2: shows monthly prevalence of trematode
cercarial infection
(a) Shows prevalence of Echinostome cercariae
(c) Shows
cercariae
Infection in these snails has been found over a
period of 8 months except in January,
February, July and August. However these
peaks were different from infection of
xiphidiocercariae noted during April, May, Nov
& Dec, from Goniobasis floridensis on the
Wekia River (Hunter & Wigington, 1972).
It appears that peak of the prevalence may
vary from place to place and it may be
associated with varied geographical variations.
Infection of gymnocephalous cercariae has
also been reported only in months of October
(2.5%) & November (4.1%).
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%
infection
of
Gymnocephalous
411
(d) Shows prevalence of Xiphidio cercariae from
snail Bellamya bengalensis
Authors’ Contribution and Competing Interests
Collections of snails have been done regularly
to observe the rate of cercarial infection. This
problem needed more attention because high
human populations are at risk.
Acknowledgement
It would be interesting to note that their peak
of prevalence were different from high
altitudinal area in Crested Buttle and Gothic
areas of Colorado, where elevation ranged
between 9000, and 9,500 ft, prevalence 32.5%
for 2,379 snails reported by Hunter
&Birkenholz,1961. It is clearly indicated that
long summer season having less rate of
prevalence may be associated with more
probable chances of transmitting infection.
August, September, October and November
have only been found to be highly risky
months of cercarial infection by major group of
cercariae. However, B. bengalensis carries
high infection rate, because of the availability
of these snails in almost eight months of a
year.
Financial assistance to S. Ray under Rajeev
Gandhi National Fellowship of UGC: F-117.1/2011-12/ RGNF-SC-UTT-2050/ (SA-III),
is
gratefully
acknowledged.
Facilities
developed under UGC-SAP (DRS-1) of the
Department of Zoology, University of Lucknow,
Lucknow, India is also acknowledged.
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