Oestrus ovis | |
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The larva and fly of the sheep-nostril-fly (Oestrus ovis) | |
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Species: | O. ovis |
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Oestrus ovis | |
Oestrus ovis, the sheep bot fly, is a widespread species of fly of the genus Oestrus . It is known for its parasitic predation and damage to sheep, deer, goats and sometimes cattle. There have also been many records of horse, dog [1] and human infestation. In some areas of the world it is a significant pest which affects the agricultural economy. [2]
The adult fly is a bee-sized insect about 10 to 12 millimetres (3/8–½ inches) long, slightly hairy with a banded, dark grey body and dull yellow head and legs. [3] It is widely distributed across the world wherever sheep, deer and goats are found. This includes North America, Central America, the area round the Mediterranean Sea, The Middle East, Australia, Brazil and South Africa. Incidence of the fly in northern Europe has decreased in recent years. [4]
Sheep bot flies commence life as eggs within the female which are fertilised and hatch to larvae of 1 mm within the body of the female. The female then deposits a few larvae, while on the wing, within a tiny mucous drop, directly into a nostril of the host animal. The larvae then make their way up the nasal passage in the mucosa and enter a nasal sinus. During this time it will develop, grow and moult into a second larval stage or instar. It then continues to develop up to 20mm (approximately 4/5 inch) in length with a dark stripe across each segment. When the larva is fully developed it moves down the nasal passage and drops to the ground where it buries itself and pupates. The length of time the larva takes to mature depends on the ambient temperature. This may be 25–35 days in warm weather but up to 10 months in colder climates. The pupa takes from 3–9 weeks to mature, again dependent on climatic conditions, after which the adult burrows up to the surface, takes to the wing and commences mating. The adults do not feed during their 2–4 weeks of adult life though they may take water. [3]
Sheep are the principal hosts. The presence of the fly with its distinctive buzzing can alert mature animals who may attempt to run away, walk with their noses near the ground [3] or have been recorded forming a circle with their noses in the middle and near the ground. [3] [4] If the fly successfully places eggs in the nostril of sheep the animal may feel the larvae after a few days and attempt to remove them by tapping their muzzles on the ground. They will also snort and stamp their front feet in annoyance. [3] Once the larvae have infested the nasal passage and sinuses, usually up to 15 larvae but can be up to 80, they cause irritation to the mucosa, which causes mucous discharge, swelling of the internal membranes of the nose, possibly impairment of breathing but largely discomfort and distraction to the sheep who may reduce or stop grazing and subsequently lose weight and condition. [4] This can in some cases lead to malnutrition and death [3] Sometimes mature larvae are unable to escape from the nasal sinus and die. This may then lead to a septic sinusitis affecting the animal's condition. [4] and the possibility of death from general septicaemia. [3]
In developed countries sheep and other domestic animals can be given preventative medication in the form of drenches. These have a variable effect because reinfestation from neighbouring territory is common. In isolated flocks of animals control can be more effective. [4]
There have been widespread reports of human infestation going back over decades, and probably centuries. [5] Most commonly they are shepherds living in close proximity to the sheep [6] but there are records of hapless visitors being subject to infestation and carrying the parasites home to their native country. [7] The effects can usually be treated easily with medical attention or medication.
The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nasal cavity is the uppermost part of the respiratory system and provides the nasal passage for inhaled air from the nostrils to the nasopharynx and rest of the respiratory tract.
Botflies, also known as warble flies, heel flies, and gadflies, are a family of flies known as the Oestridae. Their larvae are internal parasites of mammals, some species growing in the host's flesh and others within the gut. Dermatobia hominis is the only species of botfly known to parasitize humans routinely, though other species of flies cause myiasis in humans.
Gasterophilus, commonly known as botfly, is a genus of parasitic fly from the family Oestridae that affects different types of animals, especially horses, but it can also act on cows, sheep, and goats. A case has also been recorded in a human baby.
Nasal polyps (NP) are noncancerous growths within the nose or sinuses. Symptoms include trouble breathing through the nose, loss of smell, decreased taste, post nasal drip, and a runny nose. The growths are sac-like, movable, and nontender, though face pain may occasionally occur. They typically occur in both nostrils in those who are affected. Complications may include sinusitis and broadening of the nose.
Myiasis, also known as flystrike or fly strike, is the parasitic infestation of the body of a live animal by fly larvae (maggots) that grow inside the host while feeding on its tissue. Although flies are most commonly attracted to open wounds and urine- or feces-soaked fur, some species can create an infestation even on unbroken skin and have been known to use moist soil and non-myiatic flies as vector agents for their parasitic larvae.
Warble fly is a name given to the genus Hypoderma: large flies which are parasitic on cattle and deer. Other names include "heel flies", "bomb flies" and "gadflies", while their larvae are often called "cattle grubs" or "wolves." Common species of warble fly include Hypoderma bovis and Hypoderma lineatum and Hypoderma tarandi. Larvae of Hypoderma species also have been reported in horses, sheep, goats and humans. They have also been found on smaller mammals such as dogs, cats, squirrels, voles and rabbits.
The name deer botfly refers to any species in the genus Cephenemyia, within the family Oestridae. They are large, gray-brown flies, often very accurate mimics of bumblebees. They attack chiefly the nostrils and pharyngeal cavity of members of the deer family. The larva of Cephenemyia auribarbis, infesting the stag, is called a stagworm. The genus name comes from the Greek kēphēn, drone bee, and myia, fly.
The human botfly, Dermatobia hominis, is a species of botfly whose larvae parasitise humans. It is also known as the torsalo or American warble fly, though the warble fly is in the genus Hypoderma and not Dermatobia, and is a parasite on cattle and deer instead of humans.
The human nose is the most protruding part of the face. It bears the nostrils and is the first organ of the respiratory system. It is also the principal organ in the olfactory system. The shape of the nose is determined by the nasal bones and the nasal cartilages, including the nasal septum which separates the nostrils and divides the nasal cavity into two. On average, the nose of a male is larger than that of a female.
A sinus is a sac or cavity in any organ or tissue, or an abnormal cavity or passage caused by the destruction of tissue. In common usage, "sinus" usually refers to the paranasal sinuses, which are air cavities in the cranial bones, especially those near the nose and connecting to it. Most individuals have four paired cavities located in the cranial bone or skull.
Cordylobia anthropophaga, the mango fly, tumbu fly, tumba fly, putzi fly, or skin maggot fly, is a species of blow-fly common in East and Central Africa. It is a parasite of large mammals during its larval stage. C. anthropophaga is found in the subtropics of Africa and is a common cause of myiasis in humans in the region.
Cochliomyia is a genus in the family Calliphoridae, known as blowflies, in the order Diptera. Cochliomyia is commonly referred to as the New World screwworm flies, as distinct from Old World screwworm flies. Four species are in this genus: C. macellaria, C. hominivorax, C. aldrichi, and C. minima. C. hominivorax is known as the primary screwworm because its larvae produce myiasis and feed on living tissue. This feeding causes deep, pocket-like lesions in the skin, which can be very damaging to the animal host. C. macellaria is known as the secondary screwworm because its larvae produce myiasis, but feed only on necrotic tissue. Both C. hominivorax and C. macellaria thrive in warm, tropical areas.
Chrysomya bezziana, also known as the Old World screwworm fly or screwworm, is an obligate parasite of mammals. Obligate parasitic flies require a host to complete their development. Named to honor the Italian entomologist Mario Bezzi, this fly is widely distributed in Asia, tropical Africa, India, and Papua New Guinea. The adult can be identified as metallic green or blue with a yellow face and the larvae are smooth, lacking any obvious body processes except on the last segment.
The nasal mucosa lines the nasal cavity. It is part of the respiratory mucosa, the mucous membrane lining the respiratory tract. The nasal mucosa is intimately adherent to the periosteum or perichondrium of the nasal conchae. It is continuous with the skin through the nostrils, and with the mucous membrane of the nasal part of the pharynx through the choanae. From the nasal cavity its continuity with the conjunctiva may be traced, through the nasolacrimal and lacrimal ducts; and with the frontal, ethmoidal, sphenoidal, and maxillary sinuses, through the several openings in the nasal meatuses. The mucous membrane is thickest, and most vascular, over the nasal conchae. It is also thick over the nasal septum where increased numbers of goblet cells produce a greater amount of nasal mucus. It is very thin in the meatuses on the floor of the nasal cavities, and in the various sinuses. It is one of the most commonly infected tissues in adults and children. Inflammation of this tissue may cause significant impairment of daily activities, with symptoms such as stuffy nose, headache, mouth breathing, etc.
Cephenemyia ulrichii or the moose botfly, also called the elk botfly, moose nose botfly or moose throat botfly, is a large botfly that resembles a bumblebee. In the wild, they attack chiefly the nostrils and pharyngeal cavity of moose, but have been found in other deer species. There have also been several cases of C. ulrichii squirting their larvae into the eyes of human beings, a somewhat painful event that requires medical attention to forestall any possibility of serious damage.
Mites that infest and parasitize domestic animals cause disease and loss of production. Mites are small invertebrates, most of which are free living but some are parasitic. Mites are similar to ticks and both comprise the order Acari in the phylum Arthropoda. Mites are highly varied and their classification is complex; a simple grouping is used in this introductory article. Vernacular terms to describe diseases caused by mites include scab, mange, and scabies. Mites and ticks have substantially different biology from, and are classed separately from, insects. Mites of domestic animals cause important types of skin disease, and some mites infest other organs. Diagnosis of mite infestations can be difficult because of the small size of most mites, but understanding how mites are adapted to feed within the structure of the skin is useful.
Cordylobia rodhaini, also known as the Lund's fly, derived its common name from captain Lund, who was the first European to show symptoms of the disease caused by the larvae of the same fly. Lund’s fly belongs to the genus Cordylobia, flies from the family Calliphoridae. The larvae of the Lund’s fly are parasites of thinned-skinned mammals, especially the Gambian rat, mona monkey and small antelopes and are only accidental parasites of humans. The adult flies feeds on rotting fruits, vegetables and animal feces, and are most abundant in the wet season. Like many tropical insects they are most active in the dark periods and have the greatest activity early in the morning and late in the evening while resting typically between 8am to 5pm. The Lund’s fly are largely confined to tropical Africa, especially the rainforest areas in Sub-Saharan Africa. As a result of human migration, though, the parasitic infections they cause have been recorded in other continents, including Europe and Asia.
Many species of flies of the two-winged type, Order Diptera, such as mosquitoes, horse-flies, blow-flies and warble-flies, cause direct parasitic disease to domestic animals, and transmit organisms that cause diseases. These infestations and infections cause distress to companion animals, and in livestock industry the financial costs of these diseases are high. These problems occur wherever domestic animals are reared. This article provides an overview of parasitic flies from a veterinary perspective, with emphasis on the disease-causing relationships between these flies and their host animals. The article is organized following the taxonomic hierarchy of these flies in the phylum Arthropoda, order Insecta. Families and genera of dipteran flies are emphasized rather than many individual species. Disease caused by the feeding activity of the flies is described here under parasitic disease. Disease caused by small pathogenic organisms that pass from the flies to domestic animals is described here under transmitted organisms; prominent examples are provided from the many species.
Cuterebra fontinella, the mouse bot fly, is a species of New World skin bot fly in the family Oestridae. C. fontinella is typically around 1 cm (0.39 in) in length with a black and yellow color pattern. C. fontinella develops by parasitizing nutrients from its host, typically the white-footed mouse. C. fontinella has even been known to parasitize humans in rare cases. Individuals parasitized by C. fontinella will develop a large bump on the skin that is indicative of parasitization.
Gasterophilus nasalis is a species of the genus Gasterophilus and family Oestridae. This species is found worldwide, but prominently present within the summer months. This species of G. nasalis primarily targets equines, such as horses, donkeys and the plains zebra. However, it's known that it targets cattle as well, along with mild cases of companion animals.
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