Haemonchus contortus
Encyclopedia
Haemonchus contortus, also known as red stomach worm, wire worm or Barber's pole
worm, is very common parasite and one the most pathogenic nematode
of ruminant
s. Adult worms are attached to abomasal
mucosa and feed on the blood. This parasite is responsible for anemia
, bottle jaw, and death of infected sheep and goats, mainly during summer months in warm, humid climates.
Females may lay over 10,000 eggs a day, which are secreted from the animal via the faeces. After hatching from their eggs, H. contortus larva
e molt
several times, resulting in an L3 form that is infectious
for the animals. They can take up these larvae when eating grass leaves. The L4 larvae, formed after another molt, suck blood in the abomasum of the animal, potentially giving rise to anaemia and oedema, which eventually can lead to death.
The infection, called Haemonchosis, causes large economic losses for farmers around the world, especially for those living in the warmer climates. Antihelminthics are used to combat these, and other, worm infections for a long time, but resistance
of the parasites
against these chemicals
is growing.
Sheep, goats and other ruminants become infected when they graze and eat grasses containing the L3 infecting larvae. The infecting larvae pass through the first three stomachs to reach the abomasum. There the L-3 sheds its cuticle and burrows into the internal layer of the abomasum where they develop into L-4, usually within 48 hours, or pre-adult larvae. The L-4 larvae then molts and develops into the L-5 adult form. The male and female adults mate and live in the abomasum, where they feed upon the blood.
claimed that they have patented formulations of food containing Sericea lespedeza, commonly referred to as Chinese bush clover, which will ameliorate the effects of the worms on sheep. Some particular breeds of sheep, such as the Gulf Coast Native
from the Southern United States, have been shown to have developed special resistance to H. contortus.
Barber's pole
A barber's pole is a type of sign used by barbers to signify the place or shop where they perform their craft. The trade sign is, by a tradition dating back to the Middle Ages, a staff or pole with a helix of colored stripes...
worm, is very common parasite and one the most pathogenic 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...
of ruminant
Ruminant
A ruminant is a mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first compartment of the stomach, principally through bacterial actions, then regurgitating the semi-digested mass, now known as cud, and chewing it again...
s. Adult worms are attached to abomasal
Abomasum
The abomasum, also known as the maw, and the rennet-bag, and the read, is the fourth and final stomach compartment in ruminants. It secretes rennin - the artificial form of which is called rennet, and is used in cheese creation....
mucosa and feed on the blood. This parasite is responsible for anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
, bottle jaw, and death of infected sheep and goats, mainly during summer months in warm, humid climates.
Females may lay over 10,000 eggs a day, which are secreted from the animal via the faeces. After hatching from their eggs, H. contortus 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 molt
Ecdysis
Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...
several times, resulting in an L3 form that is infectious
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
for the animals. They can take up these larvae when eating grass leaves. The L4 larvae, formed after another molt, suck blood in the abomasum of the animal, potentially giving rise to anaemia and oedema, which eventually can lead to death.
The infection, called Haemonchosis, causes large economic losses for farmers around the world, especially for those living in the warmer climates. Antihelminthics are used to combat these, and other, worm infections for a long time, but resistance
Antibiotic resistance
Antibiotic resistance is a type of drug resistance where a microorganism is able to survive exposure to an antibiotic. While a spontaneous or induced genetic mutation in bacteria may confer resistance to antimicrobial drugs, genes that confer resistance can be transferred between bacteria in a...
of the 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...
against these chemicals
Chemical substance
In chemistry, a chemical substance is a form of matter that has constant chemical composition and characteristic properties. It cannot be separated into components by physical separation methods, i.e. without breaking chemical bonds. They can be solids, liquids or gases.Chemical substances are...
is growing.
Morphology
The oocyte is yellowish in color. The egg is approximately 70–85 μm long by 44 μm wide, and the early stages of cleavage containing between 16–32 cells. The adult female is 18–30 mm long and is easily recognized by its trademark “barber pole” coloration. The red and white appearance is due to the fact the Haemonchus contortus is a blood feeder and is due to the white ovaries that coil around the intestines which are filled with blood. The male adult worm is much smaller at 10–20 mm long and displays the distinct feature of a well-developed copulatory bursa, containing an asymmetrical dorsal lobe and a Y shaped dorsal ray.Life cycle
The adult female worm can release between 5,000 – 10,000 eggs which will be passed out in the feces. Eggs then develop in moist conditions in the feces and continue to develop into the L1 (rhabditiform), and L-2 juvenile stages by feeding on bacteria in the dung. The L-1 stage usually occurs within 4–6 days under the optimal conditions of 24–29 °C. The L-2 rhabditform sheds its cuticle and then develops into the L-3 filiariform infective larvae. The L-3 have a protective cuticle, however under dry hot conditions will not survive long. The L-3 then crawl up the blades of wet grass and wait to be ingested by a grazing animal.Sheep, goats and other ruminants become infected when they graze and eat grasses containing the L3 infecting larvae. The infecting larvae pass through the first three stomachs to reach the abomasum. There the L-3 sheds its cuticle and burrows into the internal layer of the abomasum where they develop into L-4, usually within 48 hours, or pre-adult larvae. The L-4 larvae then molts and develops into the L-5 adult form. The male and female adults mate and live in the abomasum, where they feed upon the blood.
Prevention
It is said that a common type of clover may be a preventative or palliative for the disease. Joan Burke, a scientist at the ARS Dale Bumpers Small Farms Research Centre in Booneville, ArkansasBooneville, Arkansas
Booneville is a city in Logan County, Arkansas, United States, and the county seat of its southern district. As of the 2010 census, the city had a total population of 4,082....
claimed that they have patented formulations of food containing Sericea lespedeza, commonly referred to as Chinese bush clover, which will ameliorate the effects of the worms on sheep. Some particular breeds of sheep, such as the Gulf Coast Native
Gulf Coast Native
The Gulf Coast Native is a breed of sheep native to the U.S. states bordering the Gulf Coast. Also occasionally known as the Louisiana Scrub, Pineywoods Native or simply Gulf Coast sheep, the breed is a mix of many of the sheep varieties which populated the Southern United States during the...
from the Southern United States, have been shown to have developed special resistance to H. contortus.
Pathogenicity
The nematode piercing the abomasum causes a number of significant complications in the infected ruminants that can lead to death. The infected animals can display severe dehydration, diarrhea, unthrifty appearance, lethargy, depressed low energy behavior, rough hair coat and uncoordinated movements. Furthermore, significantly reduced growth and poor reproductive performance has been observed. The accumulation of fluid in the abdomen, gut wall, thoracic cavity and submandibular tissue – a phenomenon commonly called "bottle jaw”, also is a common association with this infection. Severe blood loss, white mucous membranes, and anemia/low PCV are common complications of the infection.Other sources
- Newton, S. 1995. Progress on vaccination of Haemonchus contortus. International Journal of Parasitology, 25: 1281–1289.
- Roberts, L., J. Janovy. 2000. Foundations of Parasitology. US: The McGraw Hill Companies, Inc..
- Fetterer, R., M. Rhoads. 1996. The role of the sheath in resistance of Haemonchus contortus infective stage larvae to proteolytic digestion. Veterinary ParasitologyVeterinary Parasitology (journal)Veterinary Parasitology is a peer-reviewed scientific journal in the discipline of veterinary parasitology. It is the official organ of the American Association of Veterinary Parasitologists, the European Veterinary Parasitology College, and the World Association for the Advancement of Veterinary...
, 64: 267–276. - Dorny, P., A. Batubara, M. Iskander, V. Pandey. 1996. Helminth infections of sheep in North Sumatra, Indonesia. Veterinary Parasitology, 61: 353–358.