Raillietina echinobothrida
Encyclopedia
Raillietina echinobothrida is a parasitic tapeworm belonging to the class
Cestoda
. It is the most prevalent and pathogenic helminth parasite in birds, particularly in domestic fowl
, Gallus domesticus Linnaeus, 1758. It requires two hosts, birds and ants, for completion of its life cycle
. It is a hermaphrodite
worm having both the male and female reproductive organs in its body. The parasite is responsible for 'nodular tapeworm disease' in poultry
.
. The body can be as long as 25 cm, and generally 1-1.5 cm broad. The body is divisible into the head region called 'scolex', followed by an unsegmented 'neck', and then by highly segmented body proper called 'strobila'. The scolex bears four suckers and a rostellum, which are the organs of attachment to the host. Individual segments in the strobila are called 'proglottids' and are entirely covered with hair-like 'microtriches'. These microtriches are the absorptive structures for feeding, and there are no digestive organs. A number of testes and a pair ovaries are present in each proglottid.
of fowl
, which is the definitive host, and juvenile
period is in ant
, particularly the species
of Tetramorium
, which is the intermediate host. Gravid proglottids containing a large number of egg capsules are passed out to the exterior with the feces
of infested chicken
. Each egg capsule in turn contains 3 to 8 eggs. The larva
e called onchospheres are ingested by ants, and enters the alimentary canal, from where they migrates into the abdominal cavity of the insect
and develops into mature cysticercoid
s.
of adult and decreased egg production of hen. In general the tapeworm does not cause gross pathological damages on well nourished chicken, but do compete for food when they grow to excessive number. In such situation, severe lesion
s on the intestinal walls and diarrhoea could arise, which ostensibly resulted in ill health. Under heavy infestation, R. echinobothrida is listed as one of the most pathogenic tapeworms, causing conspicuous intestinal nodules
in chicken, with characteristic hyperplastic enteritis
associated with the formation of granuloma
. The symptom is termed “nodular tapeworm disease” in poultry. Intestinal nodules often result in degeneration and necrosis
of intestinal villi, accompanied by anaemia with a significant increase of total leukocyte counts and decrease of total serum
protein
.
was shown to be highly effective and is advocated as the drug of choice.
Class (biology)
In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...
Cestoda
Cestoda
This article describes the flatworm. For the medical condition, see Tapeworm infection.Cestoda is the name given to a class of parasitic flatworms, commonly called tapeworms, of the phylum Platyhelminthes. Its members live in the digestive tract of vertebrates as adults, and often in the bodies...
. It is the most prevalent and pathogenic helminth parasite in birds, particularly in domestic fowl
Fowl
Fowl is a word for birds in general but usually refers to birds belonging to one of two biological orders, namely the gamefowl or landfowl and the waterfowl...
, Gallus domesticus Linnaeus, 1758. It requires two hosts, birds and ants, for completion of its life cycle
Biological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
. It is a hermaphrodite
Hermaphrodite
In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...
worm having both the male and female reproductive organs in its body. The parasite is responsible for 'nodular tapeworm disease' in poultry
Poultry
Poultry are domesticated birds kept by humans for the purpose of producing eggs, meat, and/or feathers. These most typically are members of the superorder Galloanserae , especially the order Galliformes and the family Anatidae , commonly known as "waterfowl"...
.
Description
The body of an adult R. echinobothrida is a characteristic tapeworm structure, composed of a series of ribbon-like body segments, gradually enlarging from the anterior end towards the posterior. It is whitish in colour, highly elongated, dorso-ventrally flattened, and entirely covered with a tegumentTegument
Tegument may refer to:* Integumentary system* Tegument * Viral tegument...
. The body can be as long as 25 cm, and generally 1-1.5 cm broad. The body is divisible into the head region called 'scolex', followed by an unsegmented 'neck', and then by highly segmented body proper called 'strobila'. The scolex bears four suckers and a rostellum, which are the organs of attachment to the host. Individual segments in the strobila are called 'proglottids' and are entirely covered with hair-like 'microtriches'. These microtriches are the absorptive structures for feeding, and there are no digestive organs. A number of testes and a pair ovaries are present in each proglottid.
Life cycle
It completes its life cycle in two different hosts. The adult life is spent in the intestineIntestine
In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...
of fowl
Fowl
Fowl is a word for birds in general but usually refers to birds belonging to one of two biological orders, namely the gamefowl or landfowl and the waterfowl...
, which is the definitive host, and juvenile
Juvenile (organism)
A juvenile is an individual organism that has not yet reached its adult form, sexual maturity or size. Juveniles sometimes look very different from the adult form, particularly in terms of their colour...
period is in ant
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
, particularly the species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of Tetramorium
Tetramorium
Tetramorium is a genus of insect in family Formicidae.Tetramorium was first described in the same publication as Monomorium.-Distribution:...
, which is the intermediate host. Gravid proglottids containing a large number of egg capsules are passed out to the exterior with the feces
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
of infested chicken
Chicken
The chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...
. Each egg capsule in turn contains 3 to 8 eggs. The larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e called onchospheres are ingested by ants, and enters the alimentary canal, from where they migrates into the abdominal cavity of the insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
and develops into mature cysticercoid
Cysticercoid
A cysticercoid is the larval stage of certain tapeworms, similar in appearance to a cysticercus, but having the scolex filling completely the enclosing cyst. In tapeworm infestations, cysticercoids can be seen in free form as well as enclosed by cysts in biological tissues such as the intestinal...
s.
Pathogenicity
The adult parasite is infects the small intestine of fowl, from where it obtains nutrition from the digested food of the host. The tapeworm is responsible for stunted growth of young chicken, emaciationEmaciation
Emaciation occurs when an organism loses substantial amounts of much needed fat and often muscle tissue, making that organism look extremely thin. The cause of emaciation is a lack of nutrients, starvation, or disease....
of adult and decreased egg production of hen. In general the tapeworm does not cause gross pathological damages on well nourished chicken, but do compete for food when they grow to excessive number. In such situation, severe lesion
Lesion
A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...
s on the intestinal walls and diarrhoea could arise, which ostensibly resulted in ill health. Under heavy infestation, R. echinobothrida is listed as one of the most pathogenic tapeworms, causing conspicuous intestinal nodules
Nodule (medicine)
For use of the term nodule in dermatology, see Nodule In medicine, a nodule refers to a relatively hard, roughly spherical abnormal structure....
in chicken, with characteristic hyperplastic enteritis
Enteritis
In medicine, enteritis, from Greek words enteron and suffix -itis , refers to inflammation of the small intestine. It is most commonly caused by the ingestion of substances contaminated with pathogenic microorganisms. Symptoms include abdominal pain, cramping, diarrhea, dehydration and fever...
associated with the formation of granuloma
Granuloma
Granuloma is a medical term for a tiny collection of immune cells known as macrophages. Granulomas form when the immune system attempts to wall off substances that it perceives as foreign but is unable to eliminate. Such substances include infectious organisms such as bacteria and fungi as well as...
. The symptom is termed “nodular tapeworm disease” in poultry. Intestinal nodules often result in degeneration and necrosis
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...
of intestinal villi, accompanied by anaemia with a significant increase of total leukocyte counts and decrease of total serum
Blood serum
In blood, the serum is the component that is neither a blood cell nor a clotting factor; it is the blood plasma with the fibrinogens removed...
protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
.
Treatment
There is no prescription drug for the parasite. AlbendazoleAlbendazole
Albendazole, marketed as Albenza, Eskazole, Zentel and Andazol, is a member of the benzimidazole compounds used as a drug indicated for the treatment of a variety of worm infestations. Although this use is widespread in the United States, the U.S. Food and Drug Administration has not approved...
was shown to be highly effective and is advocated as the drug of choice.