Heterakis gallinarum
Encyclopedia
Heterakis gallinarum is a nematode
parasite that lives in the cecum
of domestic fowl, particularly in ground feeders such as domestic chicken
s and turkey
s. It causes infection that is mildly pathogenic. However it often carries a protozoa
n parasite Histomonas meleagridis
which causes of histomoniasis, blackhead disease
. Transmission of H. meleagridis is through the H. gallinarum egg. H. gallinarum is approximately 1–2 cm in length with sharply pointed tails and a preanal sucker. The parasite is a diecious species
with marked sexual dimorphism
. Males are smaller and shorter, measuring ~9 mm in length, with a unique bent tail. Females are stouter and longer, measuring ~13 mm in length, with a straight tail end.
involving birds such as chickens, turkeys, ducks, geese, grouse
, guineafowl
, partridges, pheasants and quails as definitive hosts. Eggs of H. gallinarum are passed in feces
by the host. At optimal temperature (22°C), they become infective in 12–14 days and remain infective for years in soil. Upon ingestion by a host, the embryonated eggs hatch into second-stage juveniles in the gizzard
or duodenum
and are passed to the ceca
. Their development is completed in the lumen
, however, some may enter the mucosa and remain for years without further development. The prepatent time is 24–30 days. Earthworms and houseflies are considered a paratenic host as they can ingest the egg in feces
and a juvenile may hatch in tissues, which stays dormant until eaten by bird
s.
, primarily of poultry
. Their eggs are found to live for years in soil making it difficult to eliminate H. gallinarum from a domestic flock. Earthworms may ingest the eggs of H. gallinarum and contributes to the cause of infections in poultry
. Although the eggs are themselves infective, they can develop further into a second infective larval stage. This development occurs at approximately 27°C and takes 2–4 weeks.
of Histomonas meleagridis
, the causal pathogen
of enterohepatitis "blackhead" of turkeys. H. meleagridis stays viable while inside the egg of H. gallinarum. Heavy infection in pheasants indicated gross lesions characterized by congestion
, thickening, petechial haemorrhages of the mucosa, intussusception
, and nodules
in the cecal
wall. In addition under microscopy
, chronic diffuse typhlitis, haemosiderosis, granulomas with necrotic
center in the submucosa
and leiomyomas in the submucosa
, muscular and serosa associated with immature H. gallinarum worms were observed.
in the cecum
and the submucosa of the cecum
. During heavy infections, intestinal
walls may thicken and exhibit marked inflammation
. In egg-laying hens
, heavy infection significantly reduces egg production. Diagnosis commonly is through the presence of eggs in host feces
. Effective treatment is by using mebendazole
, which is normally distributed to a flock of birds in their food and water. In addition, rearing the birds on hardware cloth assist in the elimination this parasite. Free-range chickens can also be infected.
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...
parasite that lives in the cecum
Cecum
The cecum or caecum is a pouch, connecting the ileum with the ascending colon of the large intestine. It is separated from the ileum by the ileocecal valve or Bauhin's valve, and is considered to be the beginning of the large intestine. It is also separated from the colon by the cecocolic...
of domestic fowl, particularly in ground feeders such as domestic 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...
s and turkey
Turkey (bird)
A turkey is a large bird in the genus Meleagris. One species, Meleagris gallopavo, commonly known as the Wild Turkey, is native to the forests of North America. The domestic turkey is a descendant of this species...
s. It causes infection that is mildly pathogenic. However it often carries a protozoa
Protozoa
Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...
n parasite Histomonas meleagridis
Histomonas meleagridis
Histomonas meleagridis is species of parasitic protozoan that infects a wide range of birds including chickens, turkeys, peafowl, quail and pheasants, causing blackhead disease, infectious enterohepatitis, or histomoniasis. H. meleagridis can infect many birds but it is most deadly in turkeys...
which causes of histomoniasis, blackhead disease
Blackhead disease
Blackhead disease is a commercially important avian disease that affects chickens, turkeys and other poultry birds. The disease carries a high mortality rate and primarily affects the liver and cecum. It is a form of histomoniasis which is transmitted by the protozoan parasite Histomonas meleagridis...
. Transmission of H. meleagridis is through the H. gallinarum egg. H. gallinarum is approximately 1–2 cm in length with sharply pointed tails and a preanal sucker. The parasite is a diecious 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...
with marked 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:...
. Males are smaller and shorter, measuring ~9 mm in length, with a unique bent tail. Females are stouter and longer, measuring ~13 mm in length, with a straight tail end.
Life cycle
H. gallinarum has a direct 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...
involving birds such as chickens, turkeys, ducks, geese, grouse
Grouse
Grouse are a group of birds from the order Galliformes. They are sometimes considered a family Tetraonidae, though the American Ornithologists' Union and many others include grouse as a subfamily Tetraoninae in the family Phasianidae...
, guineafowl
Guineafowl
The guineafowl are a family of birds in the Galliformes order, although some authorities include the guineafowl as a subfamily, Numidinae, of the family Phasianidae...
, partridges, pheasants and quails as definitive hosts. Eggs of H. gallinarum are passed in 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:...
by the host. At optimal temperature (22°C), they become infective in 12–14 days and remain infective for years in soil. Upon ingestion by a host, the embryonated eggs hatch into second-stage juveniles in the gizzard
Gizzard
The gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ found in the digestive tract of some animals, including birds, reptiles, earthworms and some fish. This specialized stomach constructed of thick, muscular walls is used for grinding up food; often rocks are...
or 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...
and are passed to the ceca
Cecum
The cecum or caecum is a pouch, connecting the ileum with the ascending colon of the large intestine. It is separated from the ileum by the ileocecal valve or Bauhin's valve, and is considered to be the beginning of the large intestine. It is also separated from the colon by the cecocolic...
. Their development is completed in the lumen
Lumen (anatomy)
A lumen in biology is the inside space of a tubular structure, such as an artery or intestine...
, however, some may enter the mucosa and remain for years without further development. The prepatent time is 24–30 days. Earthworms and houseflies are considered a paratenic host as they can ingest the egg in 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:...
and a juvenile may hatch in tissues, which stays dormant until eaten by bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s.
Epidemiology
H. gallinarum is geographically distributed worldwide commonly found in chickens, turkeys, and many other species of 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...
, primarily 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"...
. Their eggs are found to live for years in soil making it difficult to eliminate H. gallinarum from a domestic flock. Earthworms may ingest the eggs of H. gallinarum and contributes to the cause of infections 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"...
. Although the eggs are themselves infective, they can develop further into a second infective larval stage. This development occurs at approximately 27°C and takes 2–4 weeks.
Pathogenesis
H. gallinarum infection is itself is mildly pathogenic. However, H. gallinarum plays the role of carrier in 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 Histomonas meleagridis
Histomonas meleagridis
Histomonas meleagridis is species of parasitic protozoan that infects a wide range of birds including chickens, turkeys, peafowl, quail and pheasants, causing blackhead disease, infectious enterohepatitis, or histomoniasis. H. meleagridis can infect many birds but it is most deadly in turkeys...
, the causal pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
of enterohepatitis "blackhead" of turkeys. H. meleagridis stays viable while inside the egg of H. gallinarum. Heavy infection in pheasants indicated gross lesions characterized by congestion
Congestion
Congestion generally means excessive crowding.Congestion may refer to:* congestion in heart failure, a term to describe low cardiac output seen in heart failure.* Nasal congestion, the blockage of nasal passages due to swollen membranes...
, thickening, petechial haemorrhages of the mucosa, intussusception
Intussusception
Intussusception may refer to:* Intussusception * Intussusception...
, and 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 the cecal
Cecum
The cecum or caecum is a pouch, connecting the ileum with the ascending colon of the large intestine. It is separated from the ileum by the ileocecal valve or Bauhin's valve, and is considered to be the beginning of the large intestine. It is also separated from the colon by the cecocolic...
wall. In addition under microscopy
Microscopy
Microscopy is the technical field of using microscopes to view samples and objects that cannot be seen with the unaided eye...
, chronic diffuse typhlitis, haemosiderosis, granulomas with necrotic
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...
center in the submucosa
Submucosa
In the gastrointestinal tract, the submucosa is the layer of dense irregular connective tissue or loose connective tissue that supports the mucosa, as well as joins the mucosa to the bulk of underlying smooth muscle .-Contents:Blood vessels, lymphatic vessels, and nerves will run through...
and leiomyomas in the submucosa
Submucosa
In the gastrointestinal tract, the submucosa is the layer of dense irregular connective tissue or loose connective tissue that supports the mucosa, as well as joins the mucosa to the bulk of underlying smooth muscle .-Contents:Blood vessels, lymphatic vessels, and nerves will run through...
, muscular and serosa associated with immature H. gallinarum worms were observed.
Diagnosis & Treatment
Primary infections are usually inapparent. Secondary infections are characterized by the formation of nodulesNodule (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 the cecum
Cecum
The cecum or caecum is a pouch, connecting the ileum with the ascending colon of the large intestine. It is separated from the ileum by the ileocecal valve or Bauhin's valve, and is considered to be the beginning of the large intestine. It is also separated from the colon by the cecocolic...
and the submucosa of the cecum
Cecum
The cecum or caecum is a pouch, connecting the ileum with the ascending colon of the large intestine. It is separated from the ileum by the ileocecal valve or Bauhin's valve, and is considered to be the beginning of the large intestine. It is also separated from the colon by the cecocolic...
. During heavy infections, intestinal
Intestine
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...
walls may thicken and exhibit marked inflammation
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
. In egg-laying hens
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...
, heavy infection significantly reduces egg production. Diagnosis commonly is through the presence of eggs in host 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:...
. Effective treatment is by using mebendazole
Mebendazole
Mebendazole or MBZ is a benzimidazole drug developed by Janssen Pharmaceutica and marketed as Vermox, Ovex, Antiox, and Pripsen...
, which is normally distributed to a flock of birds in their food and water. In addition, rearing the birds on hardware cloth assist in the elimination this parasite. Free-range chickens can also be infected.