Ascaridia galli
Encyclopedia
Ascaridia galli is a parasitic roundworm belonging to the phylum
Nematoda. Nematodes of the genus
Ascaridia
are essentially intestinal parasites
of birds. A. galli is the most prevalent and pathogenic species
, especially in domestic fowl
, Gallus domesticus Linnaeus, 1758. It causes ascaridiasis, a disease of poultry
due to heavy worm infection, particularly in chicken
and turkeys. It inhabits the small intestine
, and can be occasionally seen in commercial eggs.
in birds. The body is semitransparent, creamy-white and cylindrical. The anterior end is characterized by a prominent mouth, which is surrounded by three large tri-lobed lips. The edges of the lips bear teeth-like denticles. Females are longer than males, and the posterior terminal of the male is curved, while that of the female is straight and blunt. The body is entirely covered with a thick proteinaceous structure called cuticle
. The cuticle
is striated transversely throughout the length of the body and cuticular alae
are poorly developed. Two conspicuous papillae are situated on the dorsal
lip and one on each of the subventral lips. These papillae are the sensory organs of the nematode
. A. galli is diecious with distinct sexual dimorphism
. Females are considerably longer and more robust, with vulva
opening at the middle portion (approximately midway from anterior and posterior ends) of the body and anus
at the posterior end of the body. The tail end of females is characteristically curved. Males are much shorter and smaller, with a distinct blunt and straight tail. There are also ten pairs of caudal papillae towards the tail region of the body, and they are arranged linearly in well-defined groups such as precloacal (3 pairs), cloacal (1 pair), post-cloacal (1 pair) and subterminal (3 pairs) papillae.
of A. galli is direct in a single host
, involving two principal populations, namely the sexually mature
parasite in the gastrointestinal tract
and the infective stage (L3). The eggs are oval in shape and have thick, albuminous shells that are highly resistant to desiccation
and persist for a long time in the environment. Larvae
do not hatch but moult inside the eggs until they reach the L3 stage. This can take about two weeks but the period depends on other factors such as the weather condition. The life cycle
is completed when the infective eggs are ingested by new hosts through contaminated water or feed. The eggs containing the L3-larvae
are mechanically transported to the duodenum
. The infective eggs are ingested by a chicken
where it reaches the proventriculus
and hatches. Temperature, carbon dioxide
levels and pH
are thought to be triggering factors that signal the larva
to hatch from its egg. The larva
then burrows into the mucosal lining of the small intestine
where it undergoes two additional moults. It is this phase of their life cycle
where these worms causes the most damage to their host
. They then re-enter the small intestine
and develop into adults where they live their lives out feeding on gut
content and making a vast amount of eggs that would then be excreted by a host and free to continue their life cycle
. If the animal is able to mount an immune respond to the larvae
, i.e. from pre-exposure, the larvae
do not develop into adults but hide in the mucosa of the small intestine
. This is common for infection of older birds. Transport hosts such as earthworm
s are thought to play a role in transmission of A. galli and hence, free range
birds tend to have a higher risk of infection.
of all ages, but the greatest degree of damage is often found in young birds under 12 weeks of age. Heavy infection is the major cause of weight depression and reduced egg production in poultry husbandry. In severe infections, intestinal blockage can occur. Unthriftiness, drooping of the wings, bleaching of the head and emaciation
. It also causes loss of blood, reduced blood sugar
content, increased urates, shrunken thymus glands, retarded growth and greatly increased mortality. In heavy infections, adult worms may move up the oviduct
and be found in hens' eggs, and sometimes they are also found in the birds' feces
.
is the drug of choice. Continuous medication in feed with hygromycin B
is also widely employed. Piperazine
may be administered to chickens in the feed (0.2-0.4%) or water (0.1-0.2%), or as a single treatment (50–100 mg/bird). However, piperazine
is quite in effective for young chickens, while tetramisole is 89-100% effective for chicken of different ages. More recent drugs such as albendazole
and levamisole
are also highly effective. Fenbendazole
is also very effective, 99.2-100% and 69.0-89.6% effective at administration doses of 60.6 ppm and 30.3 ppm. Ivermectin was also demonstrated to be 90 and 95% effective against immature and adult worms, respectively.
Phylum
In biology, a phylum The term was coined by Georges Cuvier from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank below kingdom and above class. "Phylum" is equivalent to the botanical term division....
Nematoda. Nematodes of the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Ascaridia
Ascaridia
-Introduction:Ascaridia is the name of a genus of parasitic nematodes. Members of the genus are primarily intestinal parasites of birds. There are three well known species, namely, A. galli found mostly in chicken, A. dissimilis in turkeys, and A. columbae in pigeons. Lesser known species such as...
are essentially intestinal parasites
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
of birds. A. galli is the most prevalent and pathogenic 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...
, especially 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 causes ascaridiasis, a disease of 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"...
due to heavy worm infection, particularly in 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...
and turkeys. It inhabits the small intestine
Small intestine
The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to...
, and can be occasionally seen in commercial eggs.
Description
It is the largest nematodeNematode
The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...
in birds. The body is semitransparent, creamy-white and cylindrical. The anterior end is characterized by a prominent mouth, which is surrounded by three large tri-lobed lips. The edges of the lips bear teeth-like denticles. Females are longer than males, and the posterior terminal of the male is curved, while that of the female is straight and blunt. The body is entirely covered with a thick proteinaceous structure called cuticle
Cuticle
A cuticle , or cuticula, is a term used for any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticles" are non-homologous; differing in their origin, structure, function, and chemical composition...
. The cuticle
Cuticle
A cuticle , or cuticula, is a term used for any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticles" are non-homologous; differing in their origin, structure, function, and chemical composition...
is striated transversely throughout the length of the body and cuticular alae
Alae (anatomy)
The alae is a protruding ridge that forms longitudinally on many nematodes.In the Caenorhabditis elegans nematode they are present in the L1, dauer and adult stages. The alae is most pronounced during the dauer larval stage and not present in the L2, and L3 C...
are poorly developed. Two conspicuous papillae are situated on the dorsal
Dorsum (anatomy)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...
lip and one on each of the subventral lips. These papillae are the sensory organs of the nematode
Nematode
The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...
. A. galli is diecious with distinct sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
. Females are considerably longer and more robust, with vulva
Vulva
The vulva consists of the external genital organs of the female mammal. This article deals with the vulva of the human being, although the structures are similar for other mammals....
opening at the middle portion (approximately midway from anterior and posterior ends) of the body and anus
Anus
The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,...
at the posterior end of the body. The tail end of females is characteristically curved. Males are much shorter and smaller, with a distinct blunt and straight tail. There are also ten pairs of caudal papillae towards the tail region of the body, and they are arranged linearly in well-defined groups such as precloacal (3 pairs), cloacal (1 pair), post-cloacal (1 pair) and subterminal (3 pairs) papillae.
Life cycle
The life cycleBiological 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...
of A. galli is direct in a single host
Host (biology)
In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
, involving two principal populations, namely the sexually mature
parasite in the gastrointestinal tract
Gastrointestinal tract
The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
and the infective stage (L3). The eggs are oval in shape and have thick, albuminous shells that are highly resistant to desiccation
Desiccation
Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic substance that induces or sustains such a state in its local vicinity in a moderately sealed container.-Science:...
and persist for a long time in the environment. Larvae
Larvae
In Roman mythology, lemures were shades or spirits of the restless or malignant dead, and are probably cognate with an extended sense of larvae as disturbing or frightening...
do not hatch but moult inside the eggs until they reach the L3 stage. This can take about two weeks but the period depends on other factors such as the weather condition. The 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...
is completed when the infective eggs are ingested by new hosts through contaminated water or feed. The eggs containing the L3-larvae
Larvae
In Roman mythology, lemures were shades or spirits of the restless or malignant dead, and are probably cognate with an extended sense of larvae as disturbing or frightening...
are mechanically transported to the duodenum
Duodenum
The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum...
. The infective eggs are ingested by a 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...
where it reaches the proventriculus
Proventriculus
The proventriculus is part of the digestive system of birds, invertebrates and insects.-Birds:The proventriculus is a standard part of avian anatomy...
and hatches. Temperature, carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
levels and pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
are thought to be triggering factors that signal 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...
to hatch from its egg. 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...
then burrows into the mucosal lining of the small intestine
Small intestine
The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to...
where it undergoes two additional moults. It is this phase of their 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...
where these worms causes the most damage to their host
Host (biology)
In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
. They then re-enter the small intestine
Small intestine
The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to...
and develop into adults where they live their lives out feeding on gut
Gut (zoology)
In zoology, the gut, also known as the alimentary canal or alimentary tract, is a tube by which bilaterian animals transfer food to the digestion organs. In large bilaterians the gut generally also has an exit, the anus, by which the animal disposes of solid wastes...
content and making a vast amount of eggs that would then be excreted by a host and free to continue their 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...
. If the animal is able to mount an immune respond to the larvae
Larvae
In Roman mythology, lemures were shades or spirits of the restless or malignant dead, and are probably cognate with an extended sense of larvae as disturbing or frightening...
, i.e. from pre-exposure, the larvae
Larvae
In Roman mythology, lemures were shades or spirits of the restless or malignant dead, and are probably cognate with an extended sense of larvae as disturbing or frightening...
do not develop into adults but hide in the mucosa of the small intestine
Small intestine
The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to...
. This is common for infection of older birds. Transport hosts such as earthworm
Earthworm
Earthworm is the common name for the largest members of Oligochaeta in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening posterior to the female pores, even though the internal male segments are anterior to the female...
s are thought to play a role in transmission of A. galli and hence, free range
Free range
thumb|250px|Free-range chickens being fed outdoors.Free range is a term which outside of the United States denotes a method of farming husbandry where the animals are allowed to roam freely instead of being contained in any manner. In the United States, USDA regulations apply only to poultry and...
birds tend to have a higher risk of infection.
Pathogenicity
The nematode infects fowlFowl
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...
of all ages, but the greatest degree of damage is often found in young birds under 12 weeks of age. Heavy infection is the major cause of weight depression and reduced egg production in poultry husbandry. In severe infections, intestinal blockage can occur. Unthriftiness, drooping of the wings, bleaching of the head and emaciation
Emaciation
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....
. It also causes loss of blood, reduced blood sugar
Blood sugar
The blood sugar concentration or blood glucose level is the amount of glucose present in the blood of a human or animal. Normally in mammals, the body maintains the blood glucose level at a reference range between about 3.6 and 5.8 mM , or 64.8 and 104.4 mg/dL...
content, increased urates, shrunken thymus glands, retarded growth and greatly increased mortality. In heavy infections, adult worms may move up the oviduct
Oviduct
In non-mammalian vertebrates, the passageway from the ovaries to the outside of the body is known as the oviduct. The eggs travel along the oviduct. These eggs will either be fertilized by sperm to become a zygote, or will degenerate in the body...
and be found in hens' eggs, and sometimes they are also found in the birds' 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:...
.
Treatment
PiperazinePiperazine
Piperazine is an organic compound that consists of a six-membered ring containing two opposing nitrogen atoms. Piperazine exists as small alkaline deliquescent crystals with a saline taste....
is the drug of choice. Continuous medication in feed with hygromycin B
Hygromycin B
Hygromycin B is an antibiotic produced by the bacterium Streptomyces hygroscopicus. It is an aminoglycoside that kills bacteria, fungi and higher eukaryotic cells by inhibiting protein synthesis.- History :...
is also widely employed. Piperazine
Piperazine
Piperazine is an organic compound that consists of a six-membered ring containing two opposing nitrogen atoms. Piperazine exists as small alkaline deliquescent crystals with a saline taste....
may be administered to chickens in the feed (0.2-0.4%) or water (0.1-0.2%), or as a single treatment (50–100 mg/bird). However, piperazine
Piperazine
Piperazine is an organic compound that consists of a six-membered ring containing two opposing nitrogen atoms. Piperazine exists as small alkaline deliquescent crystals with a saline taste....
is quite in effective for young chickens, while tetramisole is 89-100% effective for chicken of different ages. More recent drugs such as albendazole
Albendazole
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...
and levamisole
Levamisole
Levamisole is an anthelminthic and immunomodulator belonging to a class of synthetic imidazothiazole derivatives. It was discovered at Janssen Pharmaceutica in 1966...
are also highly effective. Fenbendazole
Fenbendazole
Fenbendazole is a broad spectrum benzimidazole anthelmintic used against gastrointestinal parasites including roundworms, hookworms, whipworms, the taenia species of tapeworms, pinworms, aelurostrongylus, paragonimiasis, strongyles and strongyloides and can be administered to sheep, cattle,...
is also very effective, 99.2-100% and 69.0-89.6% effective at administration doses of 60.6 ppm and 30.3 ppm. Ivermectin was also demonstrated to be 90 and 95% effective against immature and adult worms, respectively.