Oestrus ovis in Ecuador: Importance in the Andean sheep farming

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.

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

Abstract Among the diseases which can afflict the nasal cavities of small ruminants, oestrosis stands out. In Brazil, more specifically in its South-East region, the reports are limited only to the State of São Paulo and to the municipality of Araxá, Minas Gerais. Therefore, it has been sought to assess the parasitic prevalence of Oestrus ovis in sheep farmed in the municipality of Ituiutaba, Minas Gerais-Brazil, while correlating the larval size and stage, and its anatomical localization. Eighty-eight hemiheads of healthy Santa Inês/Dorper crossbreds Ovis aries have been used at random. The larvae in view were then collected and fixated to be quantified and analyzed in regard of size and stage of development. It is concluded that the oestrosis is an existing problem in the municipality of Ituiutaba, this being the first complete study on the prevalence of this parasite in the State of Minas Gerais. By anatomical distribution, only the differences of total larval averages between the frontal sinus and the ventral nasal meatus, the common nasal meatus and the nasopharynx have been significant. In size, the significant difference has been there only upon comparison between the size and the larval stage, information that is crucial for a better understanding of the cyclic progression, of the clinical symptomatology, and animal prophylaxis.

Human myiasis in Ecuador

We review epidemiological and clinical data on human myiasis from Ecuador, based on data from the Ministry of Public Health (MPH) and a review of the available literature for clinical cases. The larvae of four flies, Dermatobia hominis, Cochliomyia hominivorax, Sarcophaga haemorrhoidalis, and Lucilia eximia, were identified as the causative agents in 39 reported clinical cases. The obligate D. hominis, causing furuncular lesions, caused 17 (43.5%) cases distributed along the tropical Pacific coast and the Amazon regions. The facultative C. hominivorax was identified in 15 (38%) clinical cases, infesting wound and cavitary lesions including orbital, nasal, aural and vaginal, and occurred in both subtropical and Andean regions. C. hominivorax was also identified in a nosocomial hospital-acquired wound. Single infestations were reported for S. haemorrhoidalis and L. eximia. Of the 39 clinical cases, 8 (21%) occurred in tourists. Ivermectin, when it became available, was used to treat furuncular, wound, and cavitary lesions successfully. MPH data for 2013–2015 registered 2,187 cases of which 54% were reported in men; 46% occurred in the tropical Pacific coast, 30% in the temperate Andes, 24% in the tropical Amazon, and 0.2% in the Galapagos Islands. The highest annual incidence was reported in the Amazon (23 cases/100,000 population), followed by Coast (5.1/100,000) and Andes (4.7/100,000). Human myiasis is a neglected and understudied ectoparasitic infestation, being endemic in both temperate and tropical regions of Ecuador. Improved education and awareness among populations living in, visitors to, and health personnel working in high-risk regions, is required for improved epidemiological surveillance, prevention, and correct diagnosis and treatment.

Human myiasis is a neglected disease caused by ectoparasitic infestations of the skin, cavities and wounds by larvae of a wide variety of dipteran flies. Here, we review available data on human myiasis in Ecuador using a national registry of 2,187 cases and other information sources (39 clinical cases). We conclude that myiasis is endemic in both temperate and tropical regions of the country with greatest endemicity in the tropical lowlands of the Amazon (estimated annual incidence of 23 cases/100,000 population). Almost half clinical cases were cutaneous furuncular myiasis caused by Dermatobia hominis, which produced single lesions that were treated successfully with oral ivermectin followed by manual extraction. Also relatively common were infestations by Cochliomyia hominivorax, found in tropical and temperate regions in the Andean highlands, which infested wounds and cavities, occasionally involving hundreds of larvae and causing severe tissue damage when unrecognized. Our data shows that myiasis is a significant and unrecognized health problem in Ecuador, is likely to be significantly under-reported, and requires improved awareness among affected populations and improved education among health professionals for its diagnosis, treatment, and recognition of fly species.