Occurrences of Oestrus ovis parasitism in necropsied sheep in the Umuarama microregion, Paraná, Brazil.

Rafael Silveira Carvalho,Maycon Araújo Ruivo,Breno Cayeiro Cruz,Marcos Henrique Alcantara Colli,Antônio Campanha Martinez,Barbara Cristina Mazzucatto,Gustavo Felippelli,Alvimar José Da Costa,Weslen Fabricio Pires Teixeira,Valdomiro Pereira,Willian Giquelin Maciel,Vando Edésio Soares,Welber Daniel Zanetti Lopes

doi:10.1590/s1984-29612015044

Abstract

Between January 2007 and September 2013, 71 sheep belonging to 12 farms in the Umuarama microregion, State of Paraná, were evaluated regarding presence of Oestrus ovis larvae, during necropsies. The farms from which these animals originated were visited and the owners and employees were interviewed. Occurrences of O. ovis parasitism in sheep were diagnosed for the first time on this microregion. Of the 71 animals, 12 (16.9%) were parasitized by O. ovis, with mean intensity of 2.25 larvae per infested head (1 to 8 larvae/infested head). There was a high correlation (0.81, p=0.0346) between the number of larvae and the macroscopic lesions observed in these animals' nasal cavities, such that sheep with more than 3 larvae may contain mucupurulent secretions or epistaxis. From the interviews conducted, it was found that all the farm owners were applying chemical parasite control methods (helminths and/or O. ovis), administered to all animals in the herds every 30 days (91.6% of the producers), using derivatives of macrocyclic lactones and/or benzimidazoles/imidazothiazoles. Further studies need to be conducted in this particular region, in an attempt to elucidate the prevalence of O. ovis parasitism in herds.

Highlights

Sheep meat is a production segment with consumer demand that is higher than what is offered in Brazil, leading to importation from other countries in order to fulfill internal needs (RISSI et al, 2010)
Oestrus ovis L. (Diptera: Oestridae) is a cosmopolitan parasite that is responsible for cavitary myiasis
O. ovis females deposit their larvae in nostrils during the hotter periods of the day, which is a cause of stress in itself, due to the irritating action of the adult flies

Summary

Introduction

Sheep meat is a production segment with consumer demand that is higher than what is offered in Brazil, leading to importation from other countries in order to fulfill internal needs (RISSI et al, 2010). Afterwards, the larvae use their hooks and spikes to quickly move towards the nasal and frontal conchae (YILMA & DORCHIES, 1991) This may damage the mucosa, thereby leading to inflammation and production of mucous exudates, which makes it difficult for animals to breathe and possibly opens the way to secondary infections (DORCHIES et al, 1998). In Brazil, the larval cycle is around 30 days (SILVA et al, 2012a) It ends when larvae in L3 leave the nostrils and reach the pupal stages, from which adult flies emerge. At the field level, accumulated mucus and constant sneezing are the main clinical signs of infections caused by this parasite’s larvae (ANGULO-VALADEZ et al, 2011)

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Conclusion