Seasonality of goat warble fly infection by Przhevalskiana silenus (Diptera, Oestridae) in Italy

Among factors that negatively impact on livestock, parasite infections represent a serious challenge to the health, welfare, productivity and reproduction of goats. In Mediterranean countries for example larvae of Przhevalskiana silenus (Diptera, Oestridae) cause a myiasis known as goat warble fly infestation that may induce significant economic losses to goat productions. In this study carcasses of 580 goats (551 females and 29 males) from 48 farms, regularly slaughtered in southern Italy, were examined for P. silenus presence across two years (from January 2011 to December 2012). For each carcass, the skin and subcutaneous tissues were examined for larvae of P. silenus and, when retrieved, specimens were counted and classified according to their developmental stage. Overall, P. silenus larvae were detected in 42 (87.5%) out of 48 farms and in 285 (49.1%) out of 580 goats. The number of larvae ranged from 1 to 38 per infested goat, with a mean of 5.2 larvae (±4.8). A total of 1209 larvae were retrieved of which 385 were identified as first stage (L1), and 394 and 430 as second (L2) and third (L3) stage, respectively. The prevalence rate of infestation was significantly higher in younger goats compared to older (p = 0.0298). Dynamic of larvae in inspected animals showed different patterns being higher in August, November and March for L1, L2 and L3, respectively.Results of this study showed that P. silenus infection is widespread among farms of the study area. Nevertheless, as it occurs in other Mediterranean countries, P. silenus infection is still an overlooked infestation in Italy and more awareness on this infection and adequate control strategies are advocated.