First Report of Adult Brachylaima sp. (Digenea: Brachylaimidae) Parasitizing Wild Pigeons (Columba livia) in the United Arab Emirates

Abstract

Background: We aimed to present the morphometric analysis of adult Brachylaima sp. infect wild pigeons, Columba livia, in the United Arab Emirates (UAE).

Methods: Brachylaima sp. specimens were collected from the intestinal tracts of 5 C. livia in Al Ain City, UAE, from 2023 to 2024. After extraction and preservation in 70% ethanol, 15 specimens were stained with acetocarmine, dehydrated, cleared, and permanently mounted for detailed microscopic analysis. Their morphology was systematically measured and compared to existing data for other Brachylaima species.

Results: The adult Brachylaima sp. revealed an elongated cylindrical body with rounded ends. Oral and ventral suckers were equally sized and muscular, with the oral sucker at the anterior end and the ventral sucker in the anterior body quarter. A short pre-pharynx led to a spherical pharynx, with no observed esophagus. Tubular digestive ceca bifurcated posterior to the pharynx, extending laterally to the body’s terminus. Two oval, tandem testes occupied the posterior quarter, larger than the ovary positioned between them. A tubular cirrus pouch and seminal vesicle lay anterior to the anterior testis. A small seminal receptacle adjoined the ovary’s posterior margin. The uterus formed a convoluted loop ascending toward the pharynx before descending to a genital pore near the anterior testis, filled with ovoid operculated eggs. Vitelline follicles spanned bilaterally from the ventral sucker to the anterior testis. The excretory ducts are connected to a tubular vesicle between the ceca, ending in a subterminal pore.

Conclusion: Given the medical importance of Brachylaima, further experimental and molecular studies are critical to resolve its taxonomy, life cycles, and transmission dynamics in arid ecosystems.