Prevalence of Oestrus ovis(Diptera: Oestridae) in sheep from the São Paulo Central region, Brazil

Abstract

The heads of 139 slaughtered sheep were examined with the aim of determining Oestrus ovis prevalence and infestation intensity in the central region of the State of São Paulo, Brazil. Heads from slaughtered sheep were examined and the first (L1), second (L2) and third (L3) O. ovis larval instars were recovered from the nasal and sinus cavities. O. ovis larvae were detected in 13.7% of the sheep analyzed. The monthly mean intensity of infestation ranged from 1 to 10.2 larvae per infested head, with general mean intensity of 4.5 larvae/infested head. Of the total of 85 larvae, 21.2% were L1, 37.6% L2 and 41.2% L3. In conclusion, all different O. ovis larvae instars were recovered from slaughtered animals, which demonstrates the existence of favorable climatic conditions for the fly activity and larval development of O. ovis in sheep raised in the Central region of the State of São Paulo.Keywords: Oestrus ovis, sheep, prevalence. ResumoCom o objetivo de determinar a prevalência e intensidade de infestação por larvas de Oestrus ovis na região Central do Estado de São Paulo, 139 cabeças de ovinos obtidas de um abatedouro foram examinadas. As larvas O. ovis foram recuperadas da cavidade nasal e seios frontais, identificadas de acordo com o estádio larval e quantificadas. As larvas de O. ovis foram detectadas em 13,7% das cabeças examinadas e a intensidade média mensal de infestação variou entre 1 a 10,2 larvas/cabeça infestada, com média geral de 4,5 larvas/cabeça infestada. Do total de 85 larvas recuperadas, 21,2% eram larvas de primeiro estádio (L1), 37,6% de segundo (L2) e 41,2% de terceiro (L3). Em conclusão, todos os diferentes instares larvais de O. ovis foram recuperados de animais abatidos, o que demonstra a existência de condições climáticas favoráveis para a atividade da mosca bem como o desenvolvimento larval em ovinos criados na região Central do Estado de São Paulo.Palavras-chave: Oestrus ovis, ovino, prevalência.

Oestrus ovis infection of grazing sheep during summer in southern Chile

“…In evaluating the intensity of infection, the results coincide with those of Silva (2013), who found a mean of 4.5 larvae per head. Both the prevalence and intensity of infection could be related to optimal climatic condition during the season, in addition to the probable failure or lack of treatment against the parasite (Dorchies et al 1997).…”

“…The larvae collection was similar to those recorded by Arslan et al (2009) andSilva (2013), who both indicate that the numbers of L1 were much less than L2 and L3. Furthermore, they each conclude that most of the L3 larvae in the early summer, probably as a survival strategy, given that the larvae did not complete their cycle due to unfavorable weather conditions (Tabouret et al 2001).…”

“…Although Arslan et al (2009) found that animals older than three years showed a higher prevalence (52.4%), this is consistent with the direct relationship between age and risk of infection over time. In sheep under 1 year, the percentage of infection was lower, coinciding with the distributions observed for Arslan et al (2009) and Silva et al (2013). It could be considered that in southern Chile the infection of lambs is late because the optimal environmental conditions for the larval lay process of female flies begins around spring probably.…”

“…Research done in Morocco and Greece found similar prevalence rates (69.2% and 75.9%), although the weather in these countries are different (Pandey & Ouhelli 1984, Papadopolus et al 2010). However, the investigations performed by Silva et al (2013) in Brazil yielded an even lower prevalence (13.7%) despite the favorable climatic conditions where one would expect a higher prevalence.…”

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

“…In the State of Santa Catarina, southern region of Brazil sheep bot flies were also diagnosed, but it is worth noting that when average temperatures fell below 9.8 °C (49.64 °F), no O. ovis larvae were detected in the animals (RAMOS et al, 2006). Studies conducted by Cansi et al (2011), Schenkel et al (2012 and Silva et al (2012aSilva et al ( , 2013 reported presence of this parasite in the States of Goiás, Mato Grosso and São Paulo (central-western, central-western and southeastern regions of Brazil, respectively).…”