LAUSR

The composition, prevalence, and seasonal dynamic of Gasterophilus species were studied at the slaughterhouse of Constantine region (East Algeria) in 128 horses over an 18 months period. Our survey revealed that 124 (96.9%) horses were infected with a mean intensity of 161 larvae of Gasterophilus spp. Four species of Gasterophilus were identified; Gasterophilus intestinalis and G. nasalis were by far the predominant species with 95.3% and 77.3% respectively, followed by G. haemorrhoidalis (14.0%) and G. pecorum (10.1%). The age, sex, and breed of horses did not affect the distribution of the infection. Second-stage larvae (L2) of G. intestinalis were absent between April and July and present in higher numbers between December and February. In addition, third-stage larvae (L3) were few in number, mainly from September to November, a consequence of their fecal elimination and suggesting that the effective period of adult activity of G. intestinalis is autumn. Therefore, the population dynamics of G. nasalis shows that its activity is two months longer and occurs earlier than that of G. intestinalis. The incidence of G. pecorum infection was linked to the rainiest months.