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.

Diagnosis of Oestrus ovis infestation in sheep by PCR and enzyme-linked immunosorbent assay.

The aim of this study was to assess the suitability of PCR and ELISA as diagnostic method in young sheep naturally infested by Oestrus ovis larvae. The experiment was carried out from December 2020 to April 2021 with 39 lambs divided into two groups: infested (n = 26) and control treated group (n = 13). The infested group did not receive treatment against oestrosis, and the control group was treated with closantel (10 mg/kg orally) every 28 days in order to keep the animals as free as possible of O. ovis infestation. The clinical signs varied among animals regardless of the number of recovered larvae of each lamb, however, the thick mucus and mucopurulent nasal discharge scores were less frequent in lambs from treated group. There was no correlation between the nasal discharge score and the number of O. ovis recovered larvae (R² = 0.012, P = 0.165). Three control treated animals only presented first instar larvae (L1) (1 - 4 larvae/animal) which were smaller than L1 found in the lambs of the infested group. Ninety-two percent of the lambs from infested group (24/26) were parasitized by O. ovis with number ranging from 1 to 54 larvae per animal. A gradual increase in plasma IgG (anti-antigen of O. ovis larvae) levels of animals from infested group after the third week of the trial was observed, whereas the control lambs had low levels of IgG until the end of the experiment. The PCR had low sensitivity (26 %) and high specificity (100 %), and it presented poor agreement (k = 0.177) with the larvae detection after the lamb slaughter. The oestrosis clinical signs were not related to larvae infestation intensity and ELISA showed a greater advantage over the PCR technique in identifying animals that are carrying O. ovis.

First Study of Pharingomyia picta and Cephanemyia auribarbis in Wild Populations of Red Deer (Cervus elaphus) in Portugal.

Nasopharyngeal myiasis in red deer has never been studied in Portugal. For this reason, from December 2015 to February 2016 a study was derived on hunted red deer in Idanha-a-Nova county to evaluate the Diptera larvae presence. During the initial examination on the spot, the larvae was analysed at the nasopharynx. When present, larvae were collected for further species identification. The infestation prevalence was 50.6 ± 7.61% (CI 95%), and the mean parasitism intensity was 11.38 larvae per affected host. Two larvae species were found, Pharyngomyia picta and Cephenemyia auribarbis, both on single or concomitant infection, with the first species having a higher prevalence and mean infestation intensity than the second. The larvae's prevalence was significantly higher (X2 = 4.35; p = 0.0370) in males (62.16 ± 11.05%) than in females (41.30 ± 10.06%). Within age groups, younger animals showed a higher prevalence. This study shows the presence of P. picta and C. auribarbis larvae in the wild red deer population in Portugal for the first time. The high parasitic prevalence and mean intensity highlight the importance of this parasitosis in this wild species. For this reason, more scientific research is required to accurately assess its prevalence in other geographic areas, and evaluate the risk factors as well effects of this parasitosis on the deer population.

Oestrus ovis in Ecuador: Importance in the Andean sheep farming.

AIM: This study aimed to determine the prevalence of Oestrus ovis in sheep meant for meat commercialization in the main slaughterhouse of the country. MATERIALS AND METHODS: Between October 2015 and December 2015, we assessed the occurrence of Oestrus myiasis in the main slaughterhouse localized in Quito. In total, 80 sheep heads were randomly inspected and necropsied. Larvae were removed from nasal cavities and paranasal sinuses and cleaned. ANOVA (generalized linear model) was used to estimate the relationship between sex, age, and place of origin and presence or absence of parasite larvae. RESULTS: Morphological identification confirmed that 19% (15/80) of the examined animals were positive for Oestrus ovis; from the positive cases, 21% were young animals <12 months old. We found that statistical differences by animal sex, males, were most infested 93% (14/15) than females 7% (1/15). Larvae's L2 were more abundant than other stages (62 of the total 149). 14 of the infested animals were from the Andean places at > 2500 meters above sea level (m.a.s.l.), and only one case from the coastal region at 250 m.a.s.l. with tropical environmental conditions. CONCLUSIONS: Our results showed evidence of the presence of myiasis caused by O. ovis in Andean and coastal places in Ecuador and its adaptation to different environmental conditions from that reported previously in temperate regions from Europe and Africa.

Oestrose: uma parasitose emergente em pequenos ruminantes no Nordeste do Brasil / Nasal bot: an emerging parasitic disease in small ruminants in the Brazilian Northeast

No período de janeiro de 2011 a dezembro de 2014 foram diagnosticados 9 surtos (A, B, C, D, E, F, G, H e I) de Oestrus ovis em pequenos ruminantes no estado da Bahia. No surto A obteve-se 0,5% (1/200); B 2,2% (2/90); C 0,8% (1/120); D 2% (2/100); E 1% (1/100); F 3% (1/33); G 0,6% (1/150); H 2,5% (5/200); I com 11,4% (8/70) em ovinos e 5% (2/40) em caprinos. Os sinais clínicos associados ao parasitismo pelas larvas nos surtos foram respiração ruidosa, espirro seguido de secreção nasal catarral, inquietação, movimentação excessiva da cabeça e andar em círculo. Macroscopicamente havia nos seios e conchas nasais hiperemia, edema da mucosa e presença de larvas. Todas as larvas coletadas dos cornetos e conchas nasais variavam desde o primeiro ao terceiro estágio de desenvolvimento. Algumas larvas L3 coletadas nas necropsias foram incubadas e o imago obtido das pupas mediram aproximadamente 10mm de cor acinzentada e abdômen escurecido. Realizada análise descritiva das condições climáticas, ano e positividade de casos de oestrose, demonstrou que a ocorrência tem tendência de crescimento com os anos (p˂0,001) e que houve casos com menor média de temperatura mínima (p˂0,001), possibilitando o desenvolvimento da mosca de O. ovis, demonstrando que houve a introdução da mosca enTtre o rebanho de ovinos e caprinos do estado da Bahia, e que as condições climáticas são ideais para perpetuação da espécie.(AU)

From January 2011 to December 2014 were diagnosed 9 outbreaks of Oestrus ovis infection in small ruminants (Outbreaks A-I) in the State of Bahia. The incidence of oestrosis in sheep in outbreak A was 0.5% (1/200), in B 2.2% (2/90), in C 0.8% (1/120), in D 2% (2/100), in E 1% (1/100), in F 3% (1/33), in G 0.6% (1/150), in H 2.5% (5/200), and in I 11.42% (8/70), and 5% (2/40) in goats. Clinical signs associated with parasitism were wheezing, sneezing followed by catarrhal nasal secretion, some restlessness, excessive head movement and walking in circles. The breasts and turbinates were hyperemic, with mucosal edema and presence of O. ovis larvae. All larvae collected from the turbinates ranged from the first to the third stage of development. Some L3 larvae collected at necropsy were incubated and the gray colored Imago with dark abdomen obtained from the pupae measured about 10mm. A descriptive analysis of the climatic conditions was carried out; in the year of investigation the incidence of O. ovis infection has grown (p<0.001), and the lowest mean minimum temperature (p<0.001) caused the development the O. ovis fly, so that there was an introduction of an increased number of these flies into the sheep and goat flocks in state of Bahia with the ideal climatic conditions for their perpetuation.(AU)