MUSALO BRIAN, UNZA , ZAMBIA

1. The University of Zambia
School of veterinary medicine
Department of paraclinical studies
Name: Musalo Brian
Computer #: 10008047
Course code: VMP-4400 (parasitology)
Lab: Practical One-Identification of Trematodes
Attention: Mr. A Chota
Copyright|Musalo Brian Chisanga|Parasitology Lab report|2013
19/11/13

2. Title: Identification of Trematodes
Aim: To see and identify various structures of a given trematode species: fasciola gigantica,
paramphistomum, gastrodiscus aegypticus and schistosoma bovis using a light microscope.
Copyright|Musalo Brian Chisanga|Parasitology Lab report|2013
Introduction:
Trematoda is a class within the phylum Platyhelminthes. It includes two groups of parasitic
flatworms, known as "flukes". They are internal parasites of molluscs and vertebrates. Most
trematodes have a complex life cycle with at least two hosts. These Platyhelminthes are among the
oldest parasite known (cheng, 1973).
Taxonomy and biodiversity of trematodes or flukes are 18,000_24,000 species,
divided into two subclasses. Nearly all trematodes are parasites of mollusks and vertebrates. The
smaller Aspidogastrea, comprising about 100 species, are obligate parasites of mollusks and may
also infect turtles and fish, including cartilaginous fish. The Digenea, the majority of trematodes,
are obligate parasites of both mollusks and vertebrates, but rarely occur in cartilaginous fish.
Formerly the Monogenea were included in Trematoda on the basis that they are also vermiform
parasites, but modern phylogenetic studies have raised this group to the status of a sister class in
the Platyhelminthes, with the Cestoda.
Anatomically, Trematodes are flattened oval or worm-like animals, usually no more than
a few centimeters in length, although species as small as 1 millimeter (Monogenea) and as large
as 7 centimeters (Fasciolopsis) are known. Their most distinctive external feature is the presence
of two suckers, one close to the mouth, and the other on the underside of the animal. The body
surface of trematodes comprises a tough syncytial tegument, which helps protect against digestive
enzymes in those species that inhabit the gut of larger animals. It is also the surface of gas
exchange; there are no respiratory organs. The mouth is located at the forward end of the animal,
and opens into a muscular, pumping pharynx. The pharynx connects, via a short esophagus, to one
or two blind-ending caeca, which occupy most of the length of the body. In some species, the caeca
are themselves branched. As in other flatworms, there is no anus, and waste material must be
egested through the mouth.
Their reproductive system of most trematodes are simultaneous hermaphrodites, having
both male and female organs. There are usually two testes, with sperm ducts that join together on the
underside of the front half of the animal. This final part of the male system varies considerably in structure
between species, but may include sperm storage sacs and accessory glands, in addition to the copulatory
organ, which is either eversible, and termed a cirrus, or non-eversible, and termed a penis.

3. Copyright|Musalo Brian Chisanga|Parasitology Lab report|2013
Materials:
 Light microscope
 Prepared slides
 Specimens: fasciola gigantica, paramphistomum, gastrodiscus aegypticus & schistosoma
bovis
Procedures:
 A light microscope was switched on and the given slides were mounted onto the
microscope for viewing at x10 resolution and what was seen under the light microscope
was drawn.
 Other specimens were provided in preservative chemical solutions in bottles and others
were provided in a petri dish for examination
Results:

4. Discussion:
Fasciola gigantica, the famous liver fluke is a tropical/subtropical trematode: The definitive hosts
of fasciola are a variety of mammals, especially ruminants. Their Site of infection are mainly the
bile ducts and gall bladder. The Typical size is approximately 15-30 mm in length and their
distribution is worldwide. The Intermediate host includes several species of lymnaeid snails :
Lymnaeidae is a taxonomic family of small to large air-breathing freshwater snails, aquatic
pulmonate gastropod mollusks, that belong to the clade Hygrophila. Lymnaeidae is the only family
within the superfamily Lymnaeoidea. The liver flukes have one sporocyst and two redial
generations occur. The Metacercariae undergo encystment on a variety of aquatic vegetation. The
adults are lodged in the gall bladder and bile ducts and they give unembryonated eggs out with
feces, they develop in 9-10 days and hatch, miricidia penetrate several species of snails sporocyst;
two redial generations cercariae emerge 5-7 week post-infection and encyst as metacercariae on
underwater vegetation which are ingested; cross gut and penetrate liver. They feed in the liver for
2 weeks, then enter bile ducts. After another month, mature and produce eggs
Paramphistomum is the genus name in the Paramphistomatidae family, these are Rumen fluke,
conical fluke and pear-shaped fluke. They measure 5 to 13 mm long and 2 to 5 mm wide, light red
or pinkish in color. The definitive host is in the Ruminants, and other herbivores while its
Intermediate host: multiple genera of snails. Their Predilection site are in the Adult flukes in the
rumen and the immature flukes are in small intestines. The paramphistomum are Cosmopolitan in
distribution. Adults are present in rumen of domestic animals and they are pinkish in color. The
Life-cycle starts with adults in rumen that gives eggs out with feces that mature in water into a
miracidium that hatches and penetrates multiple genera (plural form of genus) of snail hosts. They
have one sporocyst and two redial generations and cercariae encyst on aquatic vegetation which is
later eaten by herbivore, then excyst in duodenum; penetrate gut; migrate through tissues to
abomasum enter lumen and migrate anteriorly to rumen and finally mature in 2-4 months.
Gastrodiscus aegypticus genus is in the family of paramphistomatidae. These trematode occurs in
the small and large intestines of equines, pigs, warthogs in Africa and India. It is pink in color
when fresh. It has an anterior part which is more or less cylindrical, while the rest of the body is
saucer-shaped with margins curved inwards. The ventral surface is covered by a number of regular
arranged papillae. The posterior sucker is small and subterminal, the oral sucker has two
posteriolateral pouches. The tests are lobed and slightly diagonal and lie behind the middle with
the ovary posterior to them. The life cycle is similar to that of the rumen fluke.
Schistosomes are blood trematodes belonging to the Phylum Platyhelminthes, class Trematoda,
subclass Digenea. They differ from other trematodes in that they have separate sexes, The male
worms resemble a rolled leaf where they bear the longer and more slender female in a ventral canal
(the gynaecophoric canal).They require definitive and intermediate hosts to complete their life
cycle. Their characteristics include elongated bodies, in general have no pharynx and they are
Dioecious (separate male and female organs) Male carries female in gynaecopholic canal. Their
eggs non-operculate and thin shelled with lateral or terminal spine. Their life cycle have no second
intermediate host. They live in blood vessels, especially mesenteric blood vessels of birds and
mammals.
Copyright|Musalo Brian Chisanga|Parasitology Lab report|2013

5. Conclusion:
The provided specimens of fasciola gigantica, paramphistomum, gastrodiscus aegypticus and
schistosoma bovis were viewed and identified under a light microscope at x10 power.
Copyright|Musalo Brian Chisanga|Parasitology Lab report|2013
References:
 Cheng C.T, 1973, General parasitology, academic press incorporation. Orlando, Florida,
USA. Page 416.
 Stewart C.S Schell, 1990, How to know the trematodes, WM.C.Brown company
publishers, USA.
 Soulsby E.J.L, 1965, Textbook of veterinary parasitology, Blackwell scientific
publications, oxford, UK.