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AASCIT Journal of Health
2015; 2(4): 26-31
Published online July 20, 2015 (http://www.aascit.org/journal/health)
Keywords Intestinal Parasites,
Nematodes,
Trematodes,
Cestodes,
Protozoans,
Acanthocephalans,
Schilbe mystus
Received: June 30, 2015
Revised: July 10, 2015
Accepted: July 11, 2015
Isolation of Intestinal Parasites of Schilbe mystus from the Mid Cross River Flood System Southeastern Nigeria
Uneke Bilikis Iyabo, Egboruche Joy
Dept of Applied Biology, Faculty of Biological Sciences, Ebonyi State University, Abakaliki,
Ebonyi State, Nigeria
Email address [email protected] (U. B. Iyabo), [email protected] (U. B. Iyabo)
Citation Uneke Bilikis Iyabo, Egboruche Joy. Isolation of Intestinal Parasites of Schilbe mystus from the
Mid Cross River Flood System Southeastern Nigeria. AASCIT Journal of Health.
Vol. 2, No. 4, 2015, pp. 26-31.
Abstract A survey of Schilbe mystus of the mid Cross River flood system was conducted between
August and October, 2014 to determine the presence of parasitic infection in S. mystus.
The fish were collected with gill nets, hook and line. Seventy five out of the one hundred
fish examined were infected (75.0%) with parasites. The end oparasites recovered were
mostly nematodes, trematodes, cestodes, protozoa and acanthocephalans. Numerical
abundance of parasites showed that a total of 128 species of end oparasites occurred in
the fish examined. Nematodes had 33.6% (43/128), trematodes 11.7% (15/128),
cestodes 24.2% (31/128), protozoa 12.5% (16/128) and acanthocephalan 18.0%
(23/128). The prevalence of end oparasites of the fish showed that parasites were most
prevalent in fishes with length Class 14.1-16 cm TL with 67.2% while class 21.1-22cm
had the least prevalence (1.60%). This weight graph showed that those within the range
of 11-15(g) had the highest prevalence rate (30.6%) while those within the range of
36-40(g) had the least of prevalence (2.76%). Sex wise distribution of parasites amongst
the study population showed that female fish were more infected than male fishes.
Fishes from the river system should be properly cooked or smoked before consumption
to avoid health risk due to ingestion of the parasites.
1. Introduction
Most fish carry pathogens and parasites. Usually this is at some cost to the fish. If the
cost is sufficiently high, then the impacts can be characterized as a disease (Idodo-Umeh,
2003). All of the major groups of animal parasites are found in fish, and apparently healthy
wild fish often carry heavy parasite burdens. Parasites with direct life cycles can be
important pathogens of cultured fish; parasites with indirect life cycles frequently use fish
as intermediate hosts. Knowledge of specific fish hosts greatly facilitates identification of
parasites with marked host and tissue specificity, while others are recognized because of
their common occurrence and lack of host specificity. Examination of fresh smears that
contain living parasites is often diagnostic. Like humans and other animals, fish suffer
from diseases and parasites. Fish defenses against disease are specific and non-specific.
Non-specific defenses include skin and scales, as well as the mucus layer secreted by the
epidermis that traps microorganisms and inhibits their growth. If pathogens breach these
defenses, fish can develop inflammatory responses that increase the flow of blood to
infected areas and deliver white blood cells that attempt to destroy the pathogens. Specific
defenses are specialized responses to particular pathogens recognized by the fish's body,
27 Uneke Bilikis Iyabo and Egboruche Joy: Isolation of Intestinal Parasites of Schilbe mystus from the Mid Cross River
Flood System Southeastern Nigeria
which is adaptative immune responses (Okaka, 1991). In
recent years, vaccines have become widely used in
aquaculture and ornamental fish, for example vaccines for
furunculosis in farmed salmon and koi herpes virus in koi
(Okaka, 1991). The most common parasites of fish are
protozoa. These include species found on external surfaces
and species found in specific organs. Most protozoa have
direct life cycles, but the myxosporidia require an
invertebrate intermediate host. Parasites in fish are a natural
occurrence and common. Parasites can provide information
about host population ecology. In fisheries biology, for
example, parasite communities can be used to distinguish
distinct populations of the same fish species co-inhabiting a
region. Additionally, parasites possess a variety of
specialized traits and life-history strategies that enable them
to colonize hosts. Understanding these aspects of parasite
ecology, of interest in their own right, can illuminate
parasite-avoidance strategies employed by hosts (Okaka,
1998). Usually parasites (and pathogens) need to avoid
killing their hosts, since extinct hosts can mean extinct
parasites. Evolutionary constraints may operate so parasites
avoid killing their hosts, or the natural variability in host
defensive strategies may suffice to keep host populations
viable. Parasite infections can impair the courtship dance of
male three spine sticklebacks. When that happens, the
females reject them, suggesting a strong mechanism for the
selection of parasite resistance (Okaka and Akhigbe, 1999).
However not all parasites want to keep their hosts alive, and
there are parasites with multistage life cycles who go to some
trouble to kill their host. For example, some tapeworms make
some fish behave in such a way that a predatory bird can
catch it. The predatory bird is the next host for the parasite in
the next stage of its life cycle Specifically, the tapeworm
Schistocephalus solidus turns infected three spine
stickleback white, and then makes them more buoyant so that
they splash along at the surface of the water, becoming easy
to see and easy to catch for a passing bird. Other parasitic
disorders includes; Gyrodactylus salaris, Ichthyophthirius
multifiliis, cryptocaryon, velvet disease, Brooklynella
hostilis, Hole in the head, Glugea, Ceratomyxashasta,
Kudoathyrsites, Tetracapsuloides bryosalmonae,
Cymothoaexigua, leeches, nematode, flukes, carp lice and
salmon lice. Some internal fish parasites are spectacular,
such as the philometrid nematode Philometra fasciati which
is parasitic in the ovary of female Blacktip grouper the adult
female parasite is a red worm which can reach up to 40
centimetres in length, for a diameter of only 1.6 millimetre;
the males are tiny. Schilbe mystus and Schilbe intermedius
belongs to family Schilbeidae and is a siluroid catfish of
commercial importance. The schilbeid catfish are salient
components of the ichthyofauna of many freshwater bodies
(Ekanemet al., 2011) and like other catfishes are heavily
exploited. Past work on biology of members of family
Schilbeidae in Nigeria aquatic ecosystems were mainly on
their food and feeding habits and reproduction (Oniyeet al.,
2004; Imam and Dewu, 2010; Awharitowa and Ehigiator,
2012). Thus, this paper seeks to identify the possible
intestinal parasites of Schilbe mystus, determine the various
classes of the parasites observed in the fishes, determine the
frequency distribution of the parasites isolated and access the
parasitic load in relation to sex and fish length of the fish
sample from the mid Cross River flood system, Southeastern
Nigeria.
2. Materials and Methods
2.1. Study Area
The study area is the middle course of the Cross River
system located at Ndibe in Afikpo North local government
Area of Ebonyi state. It is about 5km east eastwards away
from Afikpo main town. This part of Cross River system
forms the basic border between Ebonyi state and Cross River
state. Cross River is a major component of the inland waters of
South Eastern Nigeria and its role to the fishery of the area is
quite significant (Okoh et al., 2007). Cross River originates
from Cameroon and flows through Ebonyi State and Cross
River State into the Atlantic Ocean. The river (Fig. 1) (Okoh et
al., 2007) lies in the area between 5057” latitude
5030’20”North and 7
058” longitude 5
030’20” East. The
approximate surface area of the Cross River is 3,900,000 ha
(Ita et al., 1985). The rainy seasonand the dry season are the
two main seasons of the area. The vegetation around the river
is predominately grasses, tall and thin palm trees, and bamboo
plants and elephant grasses unevenly distributed. Hence, the
vegetation and the ecological built of the area attract some
activities such as recreation (escortion, picnic), fishing,
lumbering farming activities as well as sand mining due to the
presence of sand banks. A mini market is located beside the
river where fishes are marketed immediately they are caught.
However, in most cases, fishes are transported to other areas
of Ebonyi state and Cross River state. There is also water
fluctuation in the Cross River system with season which goes
a long way to determine the agricultural activities of the
occupants during each period. During the dry season,
(between November and March), some areas of the river floor
is seen and covered with sand hence fishing activities is
usually hampered and most fishermen would abandon their
fishing activities and change over to sand mining. During the
raining season (April- September), water levels will increase
and reverse the activities of the people.
AASCIT Journal of Health 2015; 2(4): 26-31 28
Fig. 1. Map of Afikpo North Local Government Area showing the sampling locations in the Cross River basin (Okoh et al., 2007).
2.2. Sample Collection
A total of 100 fish specimen were collected from local
fishermen at the beach site for a period of three months
(August-October, 2014).The fishes used for this study were
caught by local fishermen at Ndibe River of the Cross River
basin using locally available crafts and fishing gears which
include canoes, cast nets, gill nets, hook and lines. The
experimental Africa Butter Catfish species caught were
collected and transported in ice chests to Applied Biology
laboratory of Ebonyi state University, Abakaliki, Southeastern
Nigeria where they were preserved in 10% formalin, to avoid
decay before examination for parasites.
2.3. Laboratory Analysis
In the laboratory, the fishes were sorted out and identified to
species level using key provided by Olaosebikan and Raji
(1998). The standard length (from the snout to the tip of
caudal fin) were measured to 0.1cm and recorded accordingly.
The weight of each fish was measured to the nearest 0.1g on a
top electronic weighing balance. Each fish sample was
assigned a reference. The sexes of the fish were determined
only after dissecting the fishes and noting the presence of
testes or ovaries. The intestines of individual fish were
carefully slit open and were placed in the glass petri dish.
Physiological saline floatation method and microscopy were
employed according to Cheesbrough (2000). The parasites
were identified using guides provided by Paperna (1980).
2.4. Data Analysis
For statistical analysis the student t- test was used to compare
the monthly prevalence of parasites of the African Butter catfish
29 Uneke Bilikis Iyabo and Egboruche Joy: Isolation of Intestinal Parasites of Schilbe mystus from the Mid Cross River
Flood System Southeastern Nigeria
and the relationship between parasites density-body
weight/body length was determined using chi-square analysis.
3. Results
Seventy five out of the one hundred fish examined from the
mid Cross River system were infected with parasites. The
endoparasites (75.0%) recovered were mostly nematodes,
trematodes, cestodes, protozoa and acanthocephalas.
Numerical abundance of parasites showed that a total of 128
species of endoparasites occurred in the landed fish examined.
Nematodes had 33.6% (43/128), trematodes 11.7% (15/128),
cestodes 24.2% (31/128), protozoa 12.5% (16/128) and
acanthocephalan 18.0% (23/128) (Table 1). Nematodes
43(33.6%) had highest number of abundance while Trematode
15(11.7%) had the least (Table 1). The prevalence of intestinal
parasites in S. mystusin relation to size (standard length)
showed that the length range 14-16cm SL were most infected
(67.2%) while the length range 20-22cm SL were the least
infected (1.6%). the length range 12-14(cm) and 16-18(cm)
had zero occurrence (Table 2). Prevalence rate (30.6%) in
relation to size (weight) revealed that the weight range 11-15g
had the highest prevalence rate while the weight range 35-40g
had the lowest prevalence (2.8) (Table 3). Table 4 shows the
pattern of parasites distribution in relations to sex of S. mystus.
Female samples were 54 in number while male samples were
46. The prevalence percentage of parasites in female fish
was 67.7% while that of male fish was 37.3%.
Table 1. Numerical abundance of endoparasites of S. mystus.
Parasite No. of parasites isolated Percentage (%)
Nematode:
Capillaria sp 8 18.6
Cucullanus barbi 2 4.7
Spinitectus allaeri 6 14.0
Cammallanus sp 10 23.4
Eustrongyloides sp 1 2.3
Dujardinascaris sp 3 7.1
Procamillanus laeviochus 2 4.7
Contracaecium micropapillatum 9 20.9
Anguillicola papernai 1 2.3
Total 43 33.6
Trematode:
Sporocyst of diplomatids 6 4.7
Pygidopsis metacercariae 4 3.1
Furcocercariae of diplomatids 5 3.9
Total 15 11.7
Cestode
Ligula intestinalis 6 4.7
Lystocestos marcusseni 4 3.1
Bothriocephalus acheilognathi 9 7.0
Caryophyllideran cystercoids 3 2.3
Protocephalus cargoproglotis 3 2.3
Monobothroides woodlandi 2 1.5
Amphillina sp 6 4.7
Total 31 24.2
Protozoa
Hexamita sp 9 7.0
Spironucleus sp 1 0.7
Trypasomes sp 6 4.7
Total 16 12.5
Acanthocephalan
Pallentis tetraodontis 8 6.3
Acanthella 6 4.7
Neochinorhynchus cylindratus 7 5.4
Paragorhynchus chariensis 2 1.6
Total 23 18.0
Overall total 128 100
AASCIT Journal of Health 2015; 2(4): 26-31 30
Table 2. Prevalence of intestinal parasites in relation to size (standard length) of S. mystus.
Standard length (cm) No. of fish examined No. of parasites recovered (%) Prevalence
10-12 19 18 14.1
12-14 0 0 0
14-16 65 86 67.2
16-18 0 0 0
18-20 14 12 9.4
20-22 2 2 1.6
Total 100 128 100
Table 3. Prevalence of intestinal parasites in relation to size (weight) of S. mystus.
Weight (g) No. of fish examined No. of fish infected (%) Prevalence
5-10 3 3 4.0
10-15 25 23 30.7
15-20 20 16 21.3
20-25 18 17 22.7
25-30 9 4 5.3
30-35 11 3 4.00
35- 40 6 2 2.7
41-45 8 7 9.3
Total 100 75 100
Table 4. Prevalence of intestinal parasites in relation to sex of S. mystus.
Months No. sampled No. of male sampled No. (%) of male infected No. of female sampled No. (%) of female infected
August 53 22 11(14.7) 31 28(37.3)
September 20 8 7(9.3) 12 9(12.0)
October 27 16 10(13.3) 11 10(13.3)
Total 100 46 28(37.3) 54 47(67.7)
4. Discussion
This preliminary investigation of the parasitofauna of S.
mystus presents 75.0% infection rate. This is a bit high as
compared to other similar work such as those of Awharitoma
and Okaka (1999) that recorded 60.8% infection rate for
cichlid fishes from Okhuaihe River in Edo State. Others are
Onwuliri and Mgbemena (1987), Umuoeren et al., (1988) who
recorded 60.4% and 53.8% respectively. However Ugwuzor
(1987) obtained a very low prevalence figure (7.7%) in the
fishes examined from Imo River. This shows that parasitic
infection rates vary greatly from one area to another and this
depends on a number of factors which include among other
things, the nature of the water which is reflected in the human
use and the endemicity of infection in the area. A water body
that is being used as a source of drinking water is likely to be a
clean water, while that which serves a collecting basin for all
kinds of waste (mainly organic waste) are usually unclean and
thus capable of harbouring different kinds of organisms
including parasites. Endoparasites recovered include
nematode, cestode, protozoa, trematode and acanthocephala
which was similar to Ekanem et al., (2011) who also reported
that the low infection rate in these fishes could be attributed to
the sanitary condition of the study areas, the location of the
river from living place, number and classes of people visiting
the river and their purposes. In the study nine species of
nematodes were recorded. Nematode parasites have been
reported as having common incidence among freshwater
fishes. Okaka and Omoigberale (2002) recorded nematodes as
the most common parasite, infecting 18.6% of the fish
population: trematodes infecting 13.7%; anthocephalans
infecting 8.8%, and cestodes infecting 17.6% of the total fish
population. Okaka (1998) also reported that nematode
parasites were found to infect most fish species studies at the
Ikpoba River. The number of nematodes (43) isolated in this
study was higher than acanthocephalan (23), trematode (15),
protozoa (16) and cestodes (31). This observation is similar to
Ekanemet al., (2011) and Onyedineke et al., (2010) who
reported higher number of nematodes than other parasites.
According to Ekanem et al., (2011), nematodes are known to
occur in body cavities and subcutaneous tissues. Host
specificity of nematodes agrees with the findings of
Akinsanyaet al., (2007) and Onyedinekeet al., (2010). In the
present study, acanthocephalans were found in the intestine of
fish examined which agrees with the findings of Onyedineke,
et al., (2010); Olurin and Somorin (2006) in fishes from Kainji
Lake and Owa stream respectively. This finding also support
the work of Rosas-Valdez. and de Leon (2011) who reported
that parasites show some level of preference for the host they
31 Uneke Bilikis Iyabo and Egboruche Joy: Isolation of Intestinal Parasites of Schilbe mystus from the Mid Cross River
Flood System Southeastern Nigeria
parasitize. According to Kabata (1985), Clinostomum
(Acanthocephalans) when ingested with poorly cooked fish is
capable of producing laryngopharyngitis which is an
unpleasant inflammatory condition in man. Comparing the
prevalence of parasites in relation to length classes for all the
species, 14-16cm SL recorded the hightest number of parasites
which disagrees with Ekanem et al., (2011) who reported
highest prevalence for all the species in length class
30-39.9cm SL. This might be attributed to large amount of
food intake by the animals. Sex wise distribution of parasites
amongst the study population showed that female fish were
more infected than male fishes. In conclusion, endoparasites
were recovered in seventy-five fish samples of S. mystus.
Endoparasites recovered include nematode, cestode,
trematode and acanthocephalan. It could be concluded that
fishes of the mid Cross River flood system are infected with
stomach and intestinal parasites that could pose public health
concern to fish consumers who consumes raw or improperly
cooked or smoked fish as popularly consumed. Therefore it is
recommended that fishes from the river system should be
properly cooked or smoked before consumption to avoid
health risk due to some parasites.
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