Parasitic bronchitis, also known as hoose, husk, or verminous bronchitis, is a disease of

sheep Sheep (: sheep) or domestic sheep (''Ovis aries'') are a domesticated, ruminant mammal 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 d ...

cattle Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are calle ...

goat The goat or domestic goat (''Capra hircus'') is a species of Caprinae, goat-antelope that is mostly 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 ...

s, and

swine Suina (also known as Suiformes) is a suborder of omnivorous, non-ruminant artiodactyl mammals that includes the domestic pig and peccaries. A member of this clade is known as a suine. Suina includes the family Suidae, termed suids, known in ...

caused by the presence of various species of parasite, commonly known as lungworms, in the

bronchial A bronchus ( ; : bronchi, ) is a passage or airway in the lower respiratory tract that conducts Atmosphere of Earth, air into the lungs. The first or primary bronchi to branch from the trachea at the Carina of trachea, carina are the right main b ...

tubes or in the

lung The lungs are the primary Organ (biology), organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the Vertebral column, backbone on either side of the heart. Their ...

s. It is marked by cough,

dyspnea Shortness of breath (SOB), known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing discomfort that ...

anorexia Anorexia nervosa (AN), often referred to simply as anorexia, is an eating disorder characterized by Calorie restriction, food restriction, body image disturbance, fear of gaining weight, and an overpowering desire to be thin. Individuals wit ...

and

constipation Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The Human feces, stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the ...

. Lungworms which cause parasitic bronchitis include

nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...

s of the

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

Dictyocaulus ''Dictyocaulus'' is a genus of nematode parasites of the bronchial tree of horses, sheep, goats, deer, and cattle. ''Dictyocaulus arnfieldi'' is the lungworm of horses, and ''Dictyocaulus viviparus'' is the lungworm affecting ruminants. ''Dict ...

'', '' Metastrongylus'', and '' Protostrongylus''. Hoose is essentially an infantile disease, almost always afflicting animals under one year of age. It can be diagnosed through fecal examination or taking a sputum sample and treated by killing the

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e and adults. In severe cases, additional

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy ...

s may be needed. The most effective prevention is via

vaccination Vaccination is the administration of a vaccine to help the immune system develop immunity from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. In stimulating ...

, especially important for

Cause

The cause for parasitic bronchitis is the

called ''

Dictyocaulus viviparus ''Dictyocaulus viviparus'' is a species of nematodes belonging to the family Dictyocaulidae. The species has cosmopolitan distribution In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of ...

''. In the infected animal's fecal matter the larvae later become infective. When animals eat in the infected pasture they ingest the parasite. As the larvae travel towards the

respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies grea ...

, they mature, and by the time they reach the lungs, they are full adults. Once they reach the

s the females lay eggs and once they hatch the new larvae travel up the windpipe to be swallowed and then expelled, repeating the cycle. Some high-risk conditions where ''D. viviparus'' is most commonly located are wet pastures with swampy areas, mainly between June and November.

Symptoms

The main symptoms include

breathing difficulties Shortness of breath (SOB), known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing discomfort that ...

and coughing. The respiratory rate will increase and the animal will cough frequently. There can be audible abnormal breathing sounds. Some animals will show major

weight loss Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat (adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other conn ...

. In cattle, there will be reduced milk production. When attempting to cough or expel air, the animal will continually take a position where its head, neck, and tongue are stretched out. They can also show a mild to high

fever Fever or pyrexia in humans is a symptom of an anti-infection defense mechanism that appears with Human body temperature, body temperature exceeding the normal range caused by an increase in the body's temperature Human body temperature#Fever, s ...

. In severe cases, it could result in the death of the animal.

Diagnosis

When diagnosing parasitic bronchitis, it is mainly based on the symptoms and grazing habits. There are multiple methods to diagnosing parasitic bronchitis. One of which is through fecal examination. Usually, either the Baermann technique or flotation is used. This is to detect any larvae that are in the

intestines 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 tract is the largest of the body's systems, after the cardiovascular system. ...

. Another method is by taking a

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 Cytopathology, cytological ...

sample. This is a mixture of saliva and mucus coughed up from the lungs.{{Cite web, date=2017-08-13, title=Sputum: Definition, colors, causes, and when to see a doctor, url=https://www.medicalnewstoday.com/articles/318924, access-date=2021-11-30, website=www.medicalnewstoday.com, language=en The sample is then examined for traces of eggs or larvae. This method is more sensitive than a fecal sample. Taking blood or milk samples could also prove the presence of the parasite. By using ELISA tests, any antibodies toward the parasite will be detected.

Treatment

In order to treat the parasite, all forms of

anthelmintic Anthelmintics or antihelminthics are a group of antiparasitic drugs that expel parasitic worms (helminths) and other internal parasites from the body by either stunning or killing them without causing significant damage to the host. They may also ...

s are effective in killing both the developing larvae and adult ''D.viviparus''. As soon as an animal is showing symptoms, they should be treated. If they aren't treated before it becomes severe then the animal may not respond to the medicine or if there are very high numbers of parasites then killing them could result in the airways being blocked by the dead larvae. In severe cases, some will require an additional

Prevention

The most effective method to prevent an outbreak is through

. The vaccination includes a small dose of irradiated infectious larvae. This is given orally in two doses four weeks apart. It is important to treat all animals such as

. Despite it being effective, small amounts of lungworm can still appear. Some other methods of prevention are avoiding wet pastures, rotating the use of grazing pastures, having a closed herd policy, and preventing any outside exposure.

References

Swine diseases Veterinary helminthology Ruminant diseases