Serratospiculiasis in Captive Falcons in the Middle East: A Review

Abstract

Serratospiculiasis is a parasitic disease produced by filarial nematodes of the genus Serratospiculum in the subfamily Dicheilonematinae. This genus comprises at least 9 different species grouped according to the length of the spicules. In the Middle East, S seurati has been the only species of this genus positively identified to date in captive falcons. Serratospiculum seurati has an indirect life cycle, like other filarioids. In a previous study, the larval life cycle of S seurati was replicated in 5 different species of beetles. More recently, 2 additional invertebrate species (a beetle and a wood louse) that occur where falcons are maintained were added. Serratospiculum seurati is transmitted in captivity by ingestion of infected beetles. After beetle ingestion, the L3 larvae are released from their capsule and penetrate the wall of the proventriculus and ventriculus. Histopathologic evidence suggests that the migration to the air sac system is direct. After reaching the air sacs, the L3 larva undergoes 2 molts to produce the L5 or immature adult filarial worm. Adult parasites breed and produce large numbers of embryonated ova, which are coughed out through the trachea to the mouth, swallowed, then excreted in the feces. Histopathologic findings in infected birds normally demonstrate the presence of adult filarial worms, larvae, and embryonated ova within tissues. Numerous parasitic stages in the lung periphery are associated with mild focal hemorrhages, focal necrosis, and mild to moderate macrophage infiltration. Adult filarial parasites are commonly observed on both sides of the collagen-muscle fiber layer immediately below the epithelial or mesothelial section of the air sacs. In several birds with severe infections, S seurati was associated with pneumonia, airsacculitis, and early lesions of aspergillosis. Ivermectin has been routinely used at the dosage of 1 mg/kg SC repeated 1 or 2 weeks later without observing any detrimental effects. Currently, the anthelmintic agent moxidectin, administered in tablet form, is undergoing trials for the control of S seurati infections in captive falcons.