Oestrus ovis larval myiasis among sheep and goats in Central Oromia, Ethiopia

Retrospective study of Oestrus ovis larvae infestation in small ruminants in Grenada, West Indies

Oestrosis is a nasal cavity myiasis caused by Oestrus ovis larvae from Oetrus ovis diptera flies in small ruminants. The presence of the larvae in the nasal cavity is known to cause rhinitis and sinusitis which can negatively impact the productivity of small ruminants. The aim of the present study was to estimate the prevalence of Oestrus ovis larvae infestation in sheep and goats presented for necropsy. We reviewed necropsy records of sheep and goats submitted to the Veterinary Pathology diagnostic laboratory at St. George's University from 2001 to 2017. Out of 104 goat necropsy cases, Oestrus ovis larvae were observed in 8 goats giving a prevalence of 7.7% (95% confidence interval (CI):3.38% to 14.6%). Similarly, from the 47 sheep necropsies, Oestus ovis larvae were observed in 4 sheep (8.5%) (95% CI: 2.83% to 20.46%). There was no significant difference in Oestrus ovis larvae infestation rates between sheep and goats (p = 1.000, Fisher's exact test). Oestrosis was an incidental finding in all the small ruminants examined at necropsy. This is the first report on Oestrus ovis larvae infestation in small ruminants in Grenada.

Prevalence of Oestrus ovis in small ruminants from the eastern Iberian Peninsula. A long-term study

Oestrus ovis is an obligate parasite that causes myiasis in domestic ruminants, being commonly found in the Mediterranean area. From 2009 to 2019 a total of 3476 heads of culling sheep and goats from the Mediterranean coast of Spain were examined for the presence of O. ovis. The total prevalence was 56.3%, significantly higher in sheep than in goats (61.2% and 43%, respectively). Differences were found in the mean annual prevalence, with the highest value being registered in 2018 (61.7%) and the lowest in 2012 (50.3%). Autumn, for sheep, and winter, for goats, were the seasons with the highest number of infested specimens. Temperature, but not rainfall, was found to be associated with prevalence (p < 0.05). Most L1 were found in the anatomic region I (septum, meatus, and ventral conchae), while L2 and L3 were mainly located in regions II (nasopharynx, ethmoid labyrinth, and dorsal conchae), and III (sinuses). The overall intensity was 12.8 larvae per head, significantly higher in sheep (13.3) than in goats (3.5). Our results confirm the high prevalence of O. ovis in sheep and goats in this geographic area over the last decade, with the trend increasing in recent years in association with higher mean temperatures.

Prevalence and Associated Risk Factors of Ovine Oestrosis in Dendi District of Central Ethiopia

Background

Ovine oestrosis is an economically important and widely distributed parasitic disease of sheep that is caused by Oestrus ovis larvae across the world. Despite the fact that Oestrus ovis is a common parasite in Ethiopia and that there are many sheep in the study area, there is no information on the prevalence, larval burden, predilection sites, and risk factors associated with Oestrus ovis infestation in sheep in the Dendi district of West Shewa Zone, Ethiopia.

Methods

A cross-sectional study was conducted from November 2017 to April 2018, to estimate the prevalence, risk factors, and larval burden, and identify common predilection sites for Oestrus ovis larvae. A total of 180 sheep heads were randomly selected from five purposely selected restaurants in Ginchi town, Dendi district, transported to the laboratory, opened with a hand saw, and visually examined for infestations. The larvae were collected from positive sheep heads and counted. The sites where the larvae were obtained were recorded. The data were analyzed using SPSS version 20 software.

Results

Of the total of 180 examined sheep heads, 104 (57.8%) were infested with larvae of Oestrus ovis. In the study, a statistically significant difference (p > 0.05) was not observed in the prevalence of Oestrus ovis in relation to all considered risk factors such as sex, age, and origin of sheep. From 104 infested sheep, a total of 664 larvae were detected in different parts of sheep heads. The mean larval intensity per infected animal with Oestrus ovis was 6.38. In this study, the minimum and maximum numbers of larvae recovered were 1 and 26, respectively. The nasal cavity, nasal sinus and frontal sinus were the predilection sites of Oestrus ovis larvae identified in this study.

Conclusion

Oestrosis is an important and common parasitic disease of sheep in the study area.

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

Background

Oestrosis, caused by the larvae of Oestrus ovis, commonly known as sheep nose bot, is an obligatory cavitary myiasis of sheep and goats. Oestrus ovis is a widespread parasite, but little is known about the prevalence of oestrosis at the global and broad geographical levels. The present study aimed to explore the epidemiology of oestrosis at the global and regional level to estimate prevalences and their associated factors using a systematic approach. This is, to the author’s knowledge, the first meta-analysis of oestrosis in sheep and goats.

Methods

Published articles were obtained from nine electronic databases (PubMed, CAB Abstracts, Web of Science, Scopus, UCB library, Medline, Biosis Citation Index, Indian journals and Google Scholar) reporting the prevalence of O. ovis in sheep and goats from 1970 to 2018. Pooled prevalences were estimated using a random effect meta-analysis model.

Results

Sixty-six studies were eligible, and data from 40,870 sheep and 18,216 goats were used for quantitative analysis. The random effect estimated prevalence of oestrosis at the global level in sheep was 51.15% (95% CI: 42.80–59.51%) and in goats was 42.19% (95% CI: 33.43–50.95%). The pooled prevalence estimates for Africa, Asia, Europe and the Americas were 47.85% (95% CI: 36.04–59.66%), 44.48% (95% CI: 33.09–55.87%), 56.83% (95% CI: 48.92–64.74%) and 34.46% (95% CI: 19.90–49.01%), respectively. Heterogeneity (I² > 80%) was detected in most pooled estimates.

Conclusions

Oestrosis is highly prevalent in many geographical regions of the world, especially in Europe and Africa. Factors that contribute to the pooled prevalence estimate of oestrosis need to be emphasised in any survey to estimate the true prevalence of oestrosis. Furthermore, there is a need for immunisation or implementation of other preventive measures to reduce the burden of oestrosis in sheep and goats and to improve the health and welfare status.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3597-2) contains supplementary material, which is available to authorized users.

Doenças da cavidade nasal em pequenos ruminantes no Distrito Federal e no Estado de Goiás

Resumo As enfermidades que acometem a cavidade nasal de pequenos ruminantes podem causar prejuízos aos rebanhos de ovinos e caprinos na região central do Brasil. Foi realizado estudo retrospectivo dos laudos de necropsia do Laboratório de Patologia Veterinária da Universidade de Brasília (LPV-UnB) nos anos de 2003 a 2014 para verificar a ocorrência das doenças que acometeram a cavidade nasal de pequenos ruminantes. Foram analisados 463 protocolos de ovinos e 75 de caprinos totalizando 538 casos. Seis ovinos (6/463 1,29%) foram necropsiados com rinite granulomatosa micótica ou oomicótica e 22 animais do estudo (22/538; 4,08%) tiveram o diagnóstico de oestrose, sendo 86,36% ovinos e 13,64% caprinos. As rinites piogranulomatosas em ovinos ocorreram em áreas alagadas, com abundante material vegetal em decomposição. Os ovinos com pitiose rinofacial apresentaram como principais alterações aumento de volume na região nasal devido a extensas lesões granulomatosas associadas a necrose tecidual, caracterizadas por inúmeros macrófagos e polimorfonucleares circundando centros necróticos contendo o agente envolto por reação de Splendore-Hoeppli. Os ovinos com conidiobolomicose exibiram extensas áreas de necrose e inflamação piogranulomatosa, associadas à presença de hifas fúngicas na nasofaringe e também na região peribulbar e exoftalmia. A maioria dos animais com oestrose não apresentou alterações clínico-patológicas significativas, apesar de serem encontradas larvas principalmente nos seios e conchas nasais, traqueia e seio paranasal. A importância dessas enfermidades ainda é pouco conhecida na região, sendo de grande relevância que as condições clínico-patológicas e epidemiológicas sejam elucidadas para o diagnóstico, o controle e a prevenção, para evitar a expansão e prejuízos para os rebanhos.

Surto de Oestrus ovis em ovinos em Mato Grosso

Oestrus ovis é um parasito cosmopolita que pode acometer ovinos e caprinos. A fase parasitária inicia-se após as fêmeas adultas depositarem suas larvas nas narinas dos hospedeiros. O objetivo deste trabalho foi de descrever os aspectos clínicos, epidemiológicos, macroscópicos e microscópicos de um surto de oestrose em ovinos no estado de Mato Grosso. Os principais sinais clínicos observados foram espirros e descarga nasal. Macroscopicamente havia hiperemia e edema da mucosa nasal. Os achados microscópicos eram caracterizados por hiperemia e edema moderado a acentuado e difuso, associados a infiltrado leve a moderado predominante de mastócitos e eosinófilos na submucosa. Embora a doença fosse observada em um grande número de animais a mortalidade observada nos surtos ocorreu devido à infestação por Haemonchus contortus e pneumonia.

Prevalence of ovine and caprine oestrosis in Ambo, Ethiopia

A study was carried out to estimate the prevalence, larval burden and risk factors of ovine and caprine oestrosis from December 2007 to May 2008 on 554 heads of randomly selected sheep and goat slaughtered at Ambo town, Western Shoa, Ethiopia. The results show an overall prevalence of 59.9% with infection rate of 69.8% and 47.3% in sheep and goats respectively. No statistically significant difference in the prevalence was noted with regard to the assumed risk factors like sex, nose color, face color, horned versus polled, origin, and months (p > 0.05). Sheep were nearly twice more likely to be infected as compared to goats (p = 0.0001, odds ratio (OR) = 1.975). Age of the animals was found to be protective (OR = 0.579; 95% confidence interval = 0.393, 0.853; p = 0.006). As compared to very fat animals, poor (p = 0.040, OR = 4.834), medium (p = 0.049, OR = 4.198), and fat (p = 0.022, OR = 5.795) body condition animals are more likely to be infected by Oestrus ovis larvae. Nasal and sinus cavity pathology is positively correlated with the total larval count (r = 0.56, p < 0.0001). Out of a total of 3,770 larvae collected, 57.5% were L1, 30.8% L2, and 11.7% L3 larvae. All the three larval instars were seen throughout the study months. It is concluded that oestrosis is a common problem in the study area and more prevalent in sheep than goats, in adult than young, and in animals with poor body condition.