HOME

TheInfoList



OR:

''Dictyocaulus'' is a
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of
nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant- parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a bro ...
parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson h ...
s of the
bronchial A bronchus is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi pronounced (BRAN-KAI) to branch from the trachea at the carina are the right main bronchus and the left main bronchus ...
tree of
horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...
s,
sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to domesticate ...
,
goat The goat or domestic goat (''Capra hircus'') is a domesticated species of goat-antelope typically kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the a ...
s,
deer Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the re ...
, and
cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Adult females are referred to as cows and adult ...
. ''Dictyocaulus arnfieldi'' is the lungworm of
horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...
s, and ''Dictyocaulus viviparus'' is the lungworm affecting
ruminant Ruminants (suborder Ruminantia) are hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The ...
s.


''Dictyocaulus viviparus'': lungworm of cattle, deer

''Dictyocaulus viviparus'' is the most common lungworm of cattle; the infection is also known as ''husk'' or ''
parasitic bronchitis Parasitic bronchitis, also known as hoose, husk, or verminous bronchitis, is a disease of sheep, cattle, goats, and swine caused by the presence of various species of parasite, commonly known as lungworms, in the bronchial tubes or in the lun ...
''. Although classified as the same parasite, some people believe that the ''D. viviparus'' of deer and elk should be reclassified as a different species, including ''D. eckertii'' in New Zealand. However, both species have been shown capable of cross-infecting cattle and cervids (at least in New Zealand) . The parasite has a simple but interesting life cycle, with dispersal facilitated by a fungus. Adult ''D. viviparus'' worms reside in the bronchial tree of the animal's
lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of ...
s. They lay eggs into the airways (
bronchi A bronchus is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi pronounced (BRAN-KAI) to branch from the trachea at the carina are the right main bronchus and the left main bronchus. ...
). These eggs are coughed up and subsequently swallowed by the host. The eggs hatch into Stage 1 larvae (L1) in the
gastrointestinal tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and ...
of the
ruminant Ruminants (suborder Ruminantia) are hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The ...
host. These L1 larvae are shed in the
feces Feces ( or faeces), known colloquially and in slang as poo and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a rela ...
or
manure Manure is organic matter that is used as organic fertilizer in agriculture. Most manure consists of animal feces; other sources include compost and green manure. Manures contribute to the Soil fertility, fertility of soil by adding organic ma ...
. In the feces, larvae mature through two stages and become infective as L3 stage larvae. Cattle feces supports the growth of ''
Pilobolus ''Pilobolus'' is a genus of fungi that commonly grows on herbivore dung. Life cycle The life cycle of ''Pilobolus'' begins with a black sporangium that has been discharged onto a plant substrate such as grass. A herbivorous animal such as a ...
'' sp.
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...
. The L3 larvae of ''D. viviparus'' invade the inside of these fungi, and wait in the fungal
sporangium A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cy ...
. When the fungus sporulates, the larvae are dispersed as much as 10 feet in a pasture. Cattle grazing then ingest the L3 larvae. These larvae go through the intestinal system and penetrate the intestinal wall. They use the
lymphatic system The lymphatic system, or lymphoid system, is an organ system in vertebrates that is part of the immune system, and complementary to the circulatory system. It consists of a large network of lymphatic vessels, lymph nodes, lymphatic or lymphoid ...
to reach the mesenteric
lymph node A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that includ ...
s, where they mature once again into L4 stage larvae. The L4 larvae use the blood supply and the lymphatic system to reach the lungs, where they become adults. The life cycle is completed.


Symptoms of ''Dictyocaulus viviparus''

Symptoms of ''D. viviparus'' can include coughing, rapid shallow breathing, expiratory dyspnea, tactile fremitus, serous nasal discharge, pyrexia, increased pulse rate, weight loss, and diarrhea.


Diagnosis of ''Dictyocaulus viviparus'' infection

# Microscope detection of L1 larvae in feces # Microscope detection of eggs or larvae in the coughed up
sputum Sputum is mucus that is coughed up from the lower airways (the trachea and bronchi). In medicine, sputum samples are usually used for a naked eye examination, microbiological investigation of respiratory infections and cytological investigatio ...
or
bronchoalveolar lavage Bronchoalveolar lavage (BAL) (also known as bronchoalveolar washing) is a diagnostic method of the lower respiratory system in which a bronchoscope is passed through the mouth or nose into an appropriate airway in the lungs, with a measured amoun ...
fluid from affected animal # Blood serology test for worm antigens (available in some countries / states)


Treatment of lungworm infections

Treatment of a ''D. viviparus'' infection should be considered if chances of reinfection are high. This would include situations with high stocking rates, longer grazing seasons, and grazing on pastures where infected cattle have grazed. If treatment is decided,
ivermectin Ivermectin (, '' EYE-vər-MEK-tin'') is an antiparasitic drug. After its discovery in 1975, its first uses were in veterinary medicine to prevent and treat heartworm and acariasis. Approved for human use in 1987, today it is used to treat i ...
,
albendazole Albendazole (also known as albendazolum) is a broad-spectrum anthelmintic and antiprotozoal agent of the benzimidazole type. It is used for the treatment of a variety of intestinal parasite infections, including ascariasis, pinworm infection, ho ...
,
fenbendazole Fenbendazole is a broad spectrum benzimidazole anthelmintic used against gastrointestinal parasites including: giardia, roundworms, hookworms, whipworms, the tapeworm genus '' Taenia'' (but not effective against '' Dipylidium caninum'', a comm ...
, febantel and other anthelmintics will target the lungworm. Pasture management should take into consideration the infectiveness of these organisms since the larvae can survive in the soil for extended periods of time.


''Dictyocaulus arnfieldi'' in horses and donkeys

''Dictyocaulus arnfieldi'' is similar to ''D. viviparus'' in cattle, but only affects
equid Equidae (sometimes known as the horse family) is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. All extant species are in the genus '' Equus' ...
s. Donkeys usually show no disease and can be silent carriers (and shedders) of this parasite, which causes clinical signs in horses. Routine deworming of horses and donkeys may help prevent cross infection when kept together. Pastures that housed donkeys may be infected with lungworm larvae. As a result, horses and donkeys should not be grazed together. These drugs are given with three weeks intervals between treatments.


References


Further reading

NADIS Lungworm
{{Taxonbar, from=Q957759 Strongylida Ruminant diseases Veterinary helminthology Parasites of equines