Gasterophilus intestinalis | |
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Adult Gasterophilus intestinalis | |
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G. intestinalis eggs on the foreleg of a horse | |
Scientific classification ![]() | |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Diptera |
Family: | Oestridae |
Genus: | Gasterophilus |
Species: | G. intestinalis |
Binomial name | |
Gasterophilus intestinalis de Geer 1776 | |
Synonyms [1] | |
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Gasterophilus intestinalis, also known as horse bot fly, is a species of insect of the family Oestridae, [2] and is found worldwide. [3] The adults, which have a bumblebee-like appearance, are prominently active in the summer. [4] G. intestinalis is primarily a parasite of horses, mules and donkeys. [5]
The eggs of G. intestinalis are pale yellow in color, [6] and 1–2 mm (0.039–0.079 in) long. [4] The larvae are yellow or tan. [3] Adults, which are 10–15 mm (0.39–0.59 in) long, [5] look superficially like hairy bumblebees, with a noticeable ovipositor at the end of the abdomen. [4]
The female fly cements individual eggs onto hairs of the forelimbs and shoulders of horses, mules and donkeys. [6] [5] Each female lays up to 1000 eggs. [6] In order to hatch, the eggs must be licked by the host animal. [5] If taken into the host's mouth during grooming, the egg will hatch in the mouth. [5] If not, the first instar larva will migrate to the mouth. [5] The larvae develop in the tissue the tongue, [3] in tunnels within 1.5 mm (0.059 in) of the surface. [7] Second instar larvae are swallowed and pass into the host's stomach, [3] and attach to the non-glandular region of the stomach. [8] The larvae remain in the stomach for 8–10 months, [5] before maturing into third instar larvae. [3] In the spring, the third stage larvae pass out of the host in the feces. [3] Pupation takes place in the soil for a duration of 3–5 weeks, until the adults emerge. [5] Adults are active for only a few weeks in the summer, [4] and, lacking functional mouthparts, live only for a short time. [5]
Clinical signs are uncommon in host animals. [3] Large numbers of larvae in the stomach can cause pain in the stomach, [3] and, rarely, extremely large infestations may cause an obstruction at the outflow from the stomach to the duodenum. [7] The larvae are usually found incidentally when the host's stomach is examined by endoscope. [3] Often the only sign of infestation is the finding of larvae in the feces. [4] The main impact on the host is the nuisance of the adults as they repeatedly land on the legs when attempting to lay eggs. [4]
Parasiticides which are effective against the larvae include macrolytic lactones, such as ivermectin and moxidectin, and organophosphates, such as metrifonate (also known as trichlorphon) and dichlorvos. [6] The best time to deworm horses against Gasterophilus intestinalis is after the first hard frost. This hard frost will kill the females so no new eggs can be laid on the horse that can be ingested. Meaning that the dewormer is acting on the larva attached to the stomach and will also decrease the amount of larva shed in the feces in the spring. [9]
Although deworming is the best treatment and prevention of bot flies, horse owners can take other steps to prevent bot fly egg ingestion. This can be done by manually removing the eggs from the horse's leg using specialized tools, such as bot knives. [9] However, it is important to wash your hands after physically removing the eggs because there is a possibility of the larvae burrowing into the human skin. [10] In addition to removing the eggs manually, there are a few management changes that can be made to decrease the amount of bot flies. Since part of the life-cycle is spent developing in the manure, manure should be removed from horse's pens regularly and composted before place on pasture land. If possible, rotational grazing with different species is beneficial. Lastly, making sure feed and water are free from contamination with manure. [9]
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.
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Myiasis is the parasitic infestation of the body of a live animal by fly larvae (maggots) which 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.
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Habronema muscae is an internal stomach parasite that is most commonly found in horses. It is the most common cause of cutaneous ulcerative granulomas in the horse. It is in genus Habronema.
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Toxocara canis is a worldwide-distributed helminth parasite of dogs and other canids. The name is derived from the Greek word "toxon," meaning bow or quiver, and the Latin word "caro," meaning flesh. They live in the small intestine of the definitive host. In adult dogs, the infection is usually asymptomatic but may be characterized by diarrhea. By contrast, massive infection with Toxocara canis can be fatal in puppies, causing diarrhea, vomiting, an enlarged abdomen, flatulence, and poor growth rate.
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 has been endemic in the subtropics of Africa for more than 135 years and is a common cause of myiasis in humans in the region.
The microfilaria is an early stage in the life cycle of certain parasitic nematodes in the family Onchocercidae. In these species, the adults live in a tissue or the circulatory system of vertebrates. They release microfilariae into the bloodstream of the vertebrate host. The microfilariae are taken up by blood-feeding arthropod vectors. In the intermediate host the microfilariae develop into infective larvae that can be transmitted to a new vertebrate host.
Trichuris vulpis is a whipworm that lives in the large intestine of canines in its adult stages. Out of different types of worms, Trichuris vulpis is one of the smaller worms with a size ranging from 30–50 mm in length. As the name suggests, the worm has a whip-like shape with distinct features including a small, narrow anterior head, which is the digestive part of the worm, and a larger posterior tail, which is the reproductive part of the worm. Eggs from T. vulpis are oval shaped with bipolar plugs and contain a thick outer shell. Their sizes range from 72–90 μm in length and 32–40 μm in width. Because of their thick outer shell, T. vulpis eggs are very resistant to environmental extremes such as freezing or hot temperatures, thus allowing for their long viability in the outside world.
Parascaris equorum is a species of ascarid that is the equine roundworm. Amongst horse owners, the parasites are colloquially called "Ascarids". This is a host-specific helminth intestinal parasite that can infect horses, donkeys, and zebras. Horses up to six months of age are the most susceptible to infection. After this time, infection rates begin to decline and is extremely uncommon in horses over twelve months of age. It cannot infect humans or other animals. It is yellow-white in color, and females can become as large as 15 inches (38 cm) in length. Found worldwide, P. equorum is one of the most difficult equine parasites to kill, requiring larger doses of more powerful anthelmintic medications than are needed for other equine parasites.
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