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Other Names: Myiasis, Fly Blown
Flystrike, also known as myiasis, is a condition where flies lay their eggs in the chicken's skin or body cavities, resulting in the hatching larvae (maggots) eating the surrounding tissue. Flystrike usually occurs in open wounds or below the vent in chickens with feces-coated feathers, as these are both attractive mediums for flies to lay their eggs. Once the eggs hatch, the maggots immediately start to feed on the bird's cutaneous or underlying tissue, causing significant pain and serious damage. Chickens infested with maggots are literally being eaten alive, and can die from tissue destruction.
Flystrike is more of a risk for chickens living in tropical or subtropical regions, but can occur anywhere with populations of flies. Any fly species can cause flystrike, although some species are more aggressive and cause more damage than others.
Flystrike occurs very quickly and needs to be addressed as an emergency. This is because flies reproduce extremely fast---the eggs only require 8 to 12 hours to hatch.
Flystrike Treatment in Chickens
Treatment of flystrike requires the complete removal of all visible larvae, surgical debridement of the infested wound bed, intensive rinsing with antiseptic solutions, and consistent dressing changes on a daily basis.
Irrigation of the wound is usually necessary for lesions with holes and cavities for maggots to hide in. Care should be taken not to rupture any of the maggots during their removal. Fifteen percent chloroform in olive oil or another oil may help to immobilize the larvae and facilitate their removal. It is important that each maggot is physically removed, rather than killed outright with a topical agent. This is because any dead maggots left inside the bird can cause secondary bacterial infection.
Complications of flystrike include local destruction, invasion into deep tissues, and secondary bacterial infection.
Case 1: Flystrike (cutaneous myiasis) in a Turkey A case of cutaneous myiasis was reported in a 3.5-month-old turkey. The bird was invaded by a very large number of maggots on their posterior half. The maggots killed the bird and consumed all the flesh within 48 hours. Microscopic examination of the maggots revealed that they belonged to Lucilia sericata (a dipterous fly). Ref
Case 2: Flystrike (cutaneous myiasis) in a Owl In October 2008, a wounded owl was referred by the environmental department of Chaharmahal-Bakhtiary province to the clinic of veterinary science at Shahrekord University in west central Iran. During the initial examination, clinical signs were extensive with a wound under the right wing. The wound was infested with 40 white conical maggots, 3-9 mm in length, which led to a diagnosis of myiasis in the owl. The maggots were carefully collected from the wound using sterile forceps and were kept in 70% ethanol and transferred to the laboratory of parasitology where the diagnosis was undertaken by the observation of posterior and anterior spiracle and cephalopharyngeal apparatus. According to key diagnostic features for maggots in birds, the larvae were identified as Lucilia sericata and Lucilia cuprina (Diptera: Calliphoridae). The wound was treated using usual acaricides, but due to the severity of the infestation and because of the delay in referring the animal to the clinic, it died 3 days post-treatment. Ref
Case 3: Otomyiasis in a Geese Otomyiasis was diagnosed in the right ear of a 3-month-old goose. 23 of 25 larvae were in the meatus acusticus externus, and 2 larvae were under the skin. The larvae were in the third larval stage of Sarcophaga spp. by microscopic examination. Ref
Case 4: Traumatic myiasis in a Chickens A 1.5 year old Rhode Island Red rooster was infested with a large number of maggots of the species Chrysomyia bezziana on and around the vent to keel region. Ref
Case 5: Traumatic myiasis in a Geese Myiasis was recorded in 26 flocks of geese. The first cases were observed at the end of May, the last ones in August. Most birds (16/26) were infested in August. Each affected goose had only one lesion, which was located more frequently on the wings (14/26) than on any other body. In seven geese, Wohlfahrtia magnifica (Diptera: Sarcophagidae) was the only myiasis-causing species. In these cases the detransformed mean number of larvae per wound was 18.1 (range 5–40). Lucilia sericata (Diptera: Calliphoridae) was found to be solely responsible for the lesions of 12 birds, with detransformed mean of 94.0 (range 2–893) larvae per goose. The larvae of this species appeared to be generally less invasive than those of W. magnifica, but in three cases they were also deeply embedded in the wounds. In seven geese larvae of both fly species developed together in and around the wounds. With the exception of one lesion, there were more larvae of W. magnifica (detransformed mean of 21.8 with a range of 1–55) than that of L. sericata (detransformed mean of 11.2 with a range of 2–61) in these mixed infections. Predisposing conditions for development of traumatic myiasis in geese included plucking of feathers, other injuries and bacterial infections (e.g. inflammation of the phallus). Ref
Case 6: Urogenital myiasis in a Chickens In an exploratory investigation of ectoparasites of poultry commercial broiler chicken with age ranging from 4 to 7 weeks at different seasons of the year was found to suffer from urogenital myiasis varying from 0.52- 2.62% with an average of 1.34% infestation. Data was generated from a total 4450 broiler chicken where 60 birds were found infested with urogenital myiasis in different seasons of the year, monsoon being the most preferred one. Laboratory bred larvae completed life cycle in 13-18 days at room temperature (20.3-320C) and relative humidity of 85%. Larvae collected from lesions were identified as Chrysomya bezziana and the adult flies were emerged from those larvae were also morphologically identical to C. bezziana. Subsequently molecular characterization of the larvae was conducted. Results of BLAST showed the query sequence having 99% similarity with C. bezziana. Ref
Case 7: Wound myiasis in a Flamingo A 3-yr-old female Flamingo was suffering in her left wing, leading to an extensive discharging wound. The wound was heavily infested by maggots (fly larvae). The examination of external morphological characters of the second and third-instar larvae, posterior spiracles and internal cephalopharyngeal skeleton, led to the identification of the Calliphora spp. fly genus. Treatment consisted of removal of the larvae and surgical debridement, then spray of antibiotic and toxic drug. Following removal of larvae and treatment, the symptoms completely resolved within the last hour and remained asymptomatic several weeks later. Ref