Warble fly

The fly lays eggs on the forelegs of large animals. The eggs hatch within a week and penetrate the skin, where they migrate throughout the connective tissues (H. bovis) or to the esophagus (H. lineatum). After a few months, the larvae travel back to the skin surface and cause swellings called "warbles". They remain under the skin, and when destroyed by pressure, the larvae can cause large purulent swellings, or anaphylaxis. Upon emergence, the fly leaves holes in the skin. Large numbers of such punctures can render cattle hides valueless. The migrating larvae can cause damage to meat, as the tunnels they make in the muscle fill with a substance known as "butcher's jelly". Other cases appear in medical literature. Myiasis of the human eye can be caused by H. tarandi, a parasite of reindeer. It is known to cause uveitis, glaucoma and retinal detachment. H. lineatum and H. sinense may also infest humans. ==Treatment and prevention==

Warble flies have been eradicated in many countries, beginning with Denmark and West Germany, in the 1960s. It was eradicated in the United Kingdom in 1990. It is a notifiable disease. It may have been eradicated from Belgium. The warble fly remains present in North Africa. From the 1980s, the preventive treatment is easier, by subcutaneous use of mainly long acting ivermectin formulations, but administration of ivermectin is strongly discouraged later than 8–12 weeks before the anticipated first appearance of grubs on the back, because adverse reactions may occur when migrating larvae are killed, like severe inflammation linked to putrefaction of dead larvae in their resting sites. == See also ==