Integrated Morphological, Hematological, Histopathological, and Molecular Characterization of Cutaneous Myiasis in Sheep in Basrah Governate, Iraq

Cutaneous myiasis, also known as flystrike or blowfly strike, occurs when parasitic fly larvae (maggots) hatch from eggs deposited in damp, soiled, or wounded wool and feed on the living tissue of the host. Traumatic myiasis in sheep is a serious animal welfare problem that imposes substantial economic losses on the global livestock industry through reduced meat and wool production. Despite its impact, few studies have combined clinical, morphological, haematological and histopathological findings with molecular confirmation of the causative larvae in domestic sheep. This study aimed to characterize cutaneous myiasis in sheep in the Basrah governorate, Iraq, through an integrated clinical, morphological, haematological, histopathological, and molecular (PCR) approach. A total of 88 sheep with skin lesions and 15 clinically healthy sheep (control group) were examined. The predominant clinical findings among the 70 confirmed sheep were lethargy and general weakness, pale mucous membranes, inappetence, cutaneous wounds, foul odour, localized wound pain, swelling with erythema, wound exudation, visible larvae within the skin and local hyperthermia, each recorded in 100% of cases. Among 88 infected sheep, larvae from 70 were identified to species level by morphological and molecular (COX-1 gene) examination, comprising four species: Chrysomya bezziana (37.14%), C. albiceps (28.57%), C. megacephala (18.57%), and Calliphora vicina (15.71%). Infected sheep showed a significant increase (P ≤ 0.05) in white blood cell count (22.99 ± 4.83 × 10³/µL) and significant decreases in RBC (7.35 ± 0.75 × 10⁶/µL), Hb (7.55 ± 0.68 g/dl), PCV (23.00 ± 2.10%), and MCV (31.29 ± 1.72 Fl) compared with controls. Consistent with microcytic, normochromic anaemia of inflammation, coagulation parameters (D-dimer, platelet count, fibrinogen) were also significantly elevated, while LDH remained unchanged. Histopathological examination revealed extensive destruction of the epidermis and dermis with dense inflammatory cell infiltration. These results showed that cutaneous myiasis in sheep was a systemic disease with complex clinical, haematological, and coagulation abnormalities rather than a localized skin lesion. This highlights the need for early clinical diagnosis, combined morphological–molecular confirmation, and timely intervention to reduce economic losses and improve welfare in sheep-rearing areas (Basrah governorate).