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

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.Keywords: Cavitary myiasis, Oestrus ovis, sheep. ResumoDe janeiro de 2007 a setembro de 2013, foram avaliados, durante a necropsia, 71 ovinos pertencentes a 12 propriedades rurais da microrregião de Umuarama, Paraná, Brasil, quanto à presença de larvas de Oestrus ovis. Entre outubro e dezembro de 2013, as 12 propriedades de onde os animais eram provenientes foram visitadas, e os proprietários e funcionários foram entrevistados. A ocorrência do parasitismo por O. ovis em ovinos foi constatada pela primeira vez em propriedades rurais da microrregião de Umuarama, Estado do Paraná. Dos 71 animais, 12 (16,9%) estavam parasitados por O. ovis, com intensidade média de parasitismo de 2,25 larvas por cabeça infestada (1 a 8 larvas). Foi possível verificar correlação elevada (0,81, p=0,0346) apenas entre o número de larvas versus lesões macroscópicas observadas na cavidade nasal desses animais, de modo que ovinos com mais de 3 larvas continham secreção mucopurulenta ou epistaxe na cavidade. Quando da entrevista constatou-se que todos os proprietários fazem controle químico contra parasitas (helmintos e/ou O. ovis) e esse. controle é feito a cada 30 dias por 91,6% dos produtores, que utilizam derivados de lactonas macrocíclicas e/ou benzimidazóis/imidatiazóis. Futuros estudos ainda precisam ser realizados nesta região, na tentativa de elucidar a prevalência de parasitismo por O. ovis nos rebanhos.Palavras-chave: Miíase cavitária, Oestrus ovis, ovinos.

Oestrus ovis in Ecuador: Importance in the Andean sheep farming

“…Our findings showed 19% of the prevalence of O. ovis in the highlands of Ecuador. Previously, other studies carried out in South America showed a prevalence of oestrosis of 13.7% and 16.9% in Brazil [10,21], 60% in Chile [12], and 33.4% in Mexico [14]. All these studies were carried out in different geographical and ecologic zones with different climatic conditions to our study.…”

The global and regional prevalence of oestrosis in sheep and goats: a systematic review of articles and meta-analysis

“…Among the selected articles, 18 articles reported the prevalence of oestrosis in both sheep and goats [1, 7, 21, 23, 29–42], 40 articles in sheep [3, 19, 20, 22, 43–78] and 8 articles reported only in goats [79–86]. Based on the origin of samples, 50 studies were from abattoirs [3, 19–22, 29–41, 43, 45–63, 65, 70, 73, 75, 77, 79–85], 10 from farms [1, 44, 64, 67–69, 74, 76, 78, 86], 3 from free ranging flocks [66, 71, 72] and 3 from mixed flocks [7, 23, 42]. Based on the method of diagnosis, 56 studies used necropsy [1, 19–22, 29–38, 40–63, 65, 66, 70–77, 79–85], 4 used ELISA [7, 23, 64, 69] and 6 used combined or other methods [3, 39, 67, 68, 78, 86].…”

“…In goats, the lowest individual prevalence was reported as 13.06% (95% CI: 11.59–14.54%) in Iran [84] and the highest individual prevalence was reported as 88.40% (95% CI: 85.38–91.42%) in Ethiopia [30]. The longest study duration was 80 months [74] while the shortest study duration was 2 months [39].

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Prevalence of Oestrus ovis (Diptera: Oestridae) in sheep from Ituiutaba, south-east region of Brazil

“…According to Barroso et al (21) , the major part of the larvae studied by him were found in the horn septa, also located in small quantities throughout the maxillary sinus, olfactory area, and the frontal and the post-orbital septa. Yet, Mustafa et al (19) report a higher incidence for the nasal concha and septa, the trachea, and the paranasal sinus, followed by the horn septum, the ethmoid conchae, the choana, the oral cavity, and the oropharynx, while Carvalho et al (30) mention only the nasal cavity and the frontal sinus as regions of collection. Supplementary information to the position of the larvae is provided by different researchers, in accordance with the stage of development observed.…”

“…Recently, and ever more often, the enhanced systems of production create conditions for the appearance of oestrosis in stocks of small ruminants (25) , boosted by a rapid expansion of this farming, and which fosters new hotbeds of infection (15,32) . As a consoling factor, the mortality caused by this parasite is very low or hardly ever takes place (30) , both because the lesions are mild in nearly all cases (3) and, in accordance with the quantity of larvae, they tend not to cause clinical symptomatology in the specimens (19) . Perhaps due to that, and in a disquieting manner, this is a disease that is overlooked in Brazil (12) , and which accounts for the decrease in the production of meat and milk on the part of these animals (24,33) .…”