Oestrus ovis larval myiasis among goats in northern Jordan

From December 1998 to December 1999, heads of 520 local goats slaughtered at the Irbid, Ramtha and Howarra Abattoirs (northern Jordan) were examined for the three larval instars (L(1)-L(3)) of Oestrus ovis. Of 520 heads, 126 (24%) were infested with O. ovis larvae. All three larval instars were observed in both sexes; all age groups were infested in each month of the year. The mean age of the goats sampled was 1.5 years. The numbers of parasites infesting hosts showed a significant (P<0.05) correlation with sheep age (r(sp)=0.31-0.42) for all three larval instars. The numbers of larvae in each host followed an overdispersed distribution, which fit a negative-binomial model (but not a Poisson distribution). There were more parasites recorded in the presence of purulent discharge or laryngitis, fewer in the presence of catarrhal discharge and no association with pharyngitis sinusitis, or rhinitis.     

Genetic structure of Oestrus ovis populations in sheep and goats.

A genetic analysis using RAPD markers was performed on 12 natural populations of Oestrus ovis (Linné, 1761). Three-hundred and six O. ovis larvae (first, second and third instars) were randomly recovered in nasal cavities of sheep and goats naturally infected in Algeria, Ethiopia, France, Mauritania, Rumania and Tunisia and were analysed by 56 RAPD fragments. The results showed a high diversity within all samples. A significant genetic divergence was showed by discriminant analyses among the 12 populations sampled (p<0.0001). Moreover, discriminant analyses showed significant differentiation (p<0.0001) between O. ovis larva populations of sheep and goats and also among samples collected in the same region.     

Comparison of infection rates of Oestrus ovis between sheep and goats kept in mixed flocks

Oestrosis is a nasal myiasis of sheep and goats caused by larvae of the fly Oestrus ovis and can lead to severe clinical signs, which together with the disturbance caused by the adult fly may result into serious economic losses. Infection rates and larval burdens are always higher in sheep than in goats after either natural or artificial infestation. The aim of this study was to compare the host preference of the adult fly O. ovis between sheep and goats in mixed flocks, where they are kept together under the same husbandry conditions and hence, are very similarly exposed to the fly preference. Blood sera samples were collected from a total of 397 sheep and 335 goats, from 43 mixed flocks located at different regions of Greece. Antibodies specific to O. ovis IgG were measured by ELISA. A flock was considered positive when at least one individual was positive, i.e. showed a seropositivity of >or=20% in relation to positive control sera. A total of 193 (48.6%) sheep and 58 (17.9%) goats were found to be seropositive against O. ovis. Thirty-eight (88.4%) out of 43 flocks had at least one seropositive animal. The mean seroconversion against O. ovis in animals from the different flocks was 38.6% and 13.6% for sheep and goats, respectively, whereas the variance of infection within each flock was 0-100%. The mean seropositivity between sheep that were found to be positive or negative was 60.6% and 5.4%, respectively, whereas the corresponding values between goats were 35.2% and 5.2%, respectively. No significant difference in the seroconversion values was noted between flocks from the different areas (P=0.817), whereas a very significant difference was observed between animal species (P=0.001). However, there was no significant difference when seroconversion comparisons were made within samples of the same animals species, sheep or goats from different flocks of all the regions included in the study (P=0.695). The results of this study clearly demonstrate that O. ovis has a widespread distribution in Greece, and the seroprevalence is significantly higher in sheep than goats (P=0.001).     

Seroprevalence of Oestrus ovis infection in sheep in southwestern Germany

The aim of the survey was to determine the seroprevalence of Oestrus ovis infection in flocks in southwestern Germany. Serum samples collected from 1497 sheep (>6 months of age) of 110 flocks in 1997 and 1998 were examined for antibodies to crude somatic antigens of O. ovis second-stage larvae using an ELISA test. Data on the farm management were obtained by a questionnaire. Overall, 76% of the flocks had at least one seropositive animal, and the seroprevalence of anti-Oestrus antibodies was 50% in sheep. Flock size was the only risk factor significantly associated with the detection of antibodies. Larger flocks (>50 ewes) were more likely to be seropositive than smaller ones. These results show that Oestrus infections are widespread in sheep in southwestern Germany. Further investigations are required to estimate the economic importance of oestrosis and the efficiency of control measures.     

Nasal myiasis in a dog due to Oestrus ovis (Diptera: Oestridae)

Abstract

Extract

Oestrus ovis or nasal bot-fly, has larvae that are deposited as the first instar and develop in the nasal fossae and cranial sinuses of sheep, goats and some wild ruminants (Zumpt, 1965 Zumpt, E. 1965. Myiasisin Man and Animalsin the Old World London: Butterworths,.  [Google Scholar]). Once the larvae have matured they are sneezed out and pupariate in the soil. Occasionally, humans are affected by ocular myiasis (ophthalmomyiasis) and more rarely, nasal myiasis (Macdonald et al, 1999 Macdonald, PJ, Chan, C, Dickson, J, Jean-Louis, F and Heath, A. 1999. Ophthalmomyiasis and nasal myiasis in New Zealand: a case series. New Zealand Medical Journal, 112: 445–457. [PubMed], [Web of Science ®] , [Google Scholar]). The presence of O. ovis in dogs is also a rare occurrence (Zumpt, 1965 Zumpt, E. 1965. Myiasisin Man and Animalsin the Old World London: Butterworths,.  [Google Scholar]) and in such non-typical hosts it is usual for development of the larvae to proceed no further than the first instar. Exceptions have been noted in dogs, where third instar larvae were expelled (Lucientes et al, 1997 Lucientes, J, Ferrer-Dufol, M, Andres, MJ, Peribañez, MA, Gracia-Salinas, MJ and Castillo, JA. 1997. Canine myiasis by sheep bot fly (Diptera: Oestridae). Journal of Medical Entomology, 34: 242–243.  [Google Scholar]) or recovered from the nasal cavity at necropsy (Luján et al, 1998 Luján, L, Vázquez, J, Lucientes, J, Pañero, JA and Varea, R. 1998. Nasal myiasis due to Oestrus ovis infestation in a dog. Veterinary Record, 142: 282–283.  [Google Scholar]).     

Parasitism by Oestrus ovis: influence of sheep breed and nematode infections

Previous studies showed that Santa Ines (SI) hair sheep were more resistant to gastrointestinal nematode infections (GIN) than Ile de France (IF) sheep. The present experiment aimed to evaluate if that reported resistance difference against GIN also occurred against Oestrus ovis infestation and also to evaluate the influence of O. ovis infestation on the gastrointestinal nematodes (GIN) infections. SI (n=12) and IF (n=12) young male lambs were weaned at 2 months of age and moved to a paddock (0.3 ha) with Brachiaria decumbens grass, where they also received concentrate ration. The animals were kept together during the experimental period (September to early December 2009). Fecal and blood samples were taken from all animals every 2 weeks and body weight and nasal discharge score (oestrosis clinic signs) were recorded on the same occasion. In early December 2009, all lambs were sacrificed and O. ovis larvae and GIN were recovered, counted and identified according to the larval stage. All animals were infested by different larval instars of O. ovis without any statistical difference between breeds (P>0.05). The SI lambs had an average of 24.8 larvae, and the intensity of infection ranged between 14 and 39 larvae, while the IF lambs showed an average of 23.5 larvae with the minimum and maximum from 11 to 36 larvae, respectively. SI lambs presented the lowest nematode fecal egg counts (FECs) and the lowest mean numbers of Haemonchus contortus, Trichostrongylus colubriformis and Strongyloides papillosus, however, there was no significant differences between group means (P>0.05). Inverse relationship between numbers of O. ovis larvae and gastrointestinal nematodes was observed in both breeds. SI sheep showed a significant increase in blood eosinophils and total IgE serum levels and these variables were negatively correlated with nematode FEC. A negative correlation was observed between total IgE serum level and H. contortus burden in both breeds. In conclusion, there was no breed difference regarding O. ovis infestation and in each breed, animals with more nasal bot fly larvae tended to display smaller worm burden.     

Epidemiology of Oestrus ovis infection of sheep in the highveld of Zimbabwe

During a period of 13 months, 507 heads of sheep, obtained from an abattoir near Harare, were examined for infection with Oestrus ovis larvae. The prevalence of infection varied from 6 to 52%, the highest being in November and the lowest in April. The mean annual larval burden was 1.12. The maximum number of larvae recovered from a single head was 57 in the month of November. Two larval peaks were observed, the first and highest in November and the second in August/September. Some flies are present throughout the year, except in May. There are at least 3 generations of flies per year. The wet summer period from January to May seems to be unfavourable, as very few flies are present. There is no overwintering of first instar larvae in the heads of sheep.     

Nasal myiasis in a cat caused by larvae of the nasal bot fly, Oestrus ovis

An 8-year-old desexed male Burmese cat, which lived on a sheep-grazing property in central New South Wales, Australia, was presented following the sudden onset of dyspnoea, moist coughing and violent sneezing. The respiratory distress started several hours after the cat had made an outdoor excursion. Anterior rhinoscopy demonstrated small, white objects moving across oedematous and moderately inflamed nasal mucosa. These were retrieved via a series of vigorous nasal flushes and subsequently identified as larvae of the nasal bot fly, Oestrus ovis. The cat was treated with ivermectin followed by selamectin 7 days later. It went on to make a complete recovery over 2-3 weeks.     

Epidemiology of Oestrus ovis (Linneo, 1761) infestation in goats in Spain

This survey was conducted to determine the chronobiology and seroprevalence of nasal bot infestation (Oestrus ovis) in Spain and to identify the risk factors associated with this disease in caprine herds.

A total of 1590 sera from adult goats were collected at random on 175 farms in southwestern Spain. Sera were tested by ELISA, using crude protein from second stage larvae as antigen. The mean seroprevalence was 46.04% and mean percentage of optical densities was 41.83. These data indicate a high prevalence of this parasite in the investigated areas. The serological survey revealed that goats managed at higher altitudes, at meridians latitudes and on farms with small herds had a smaller probability of infestation. Eighty goat heads, obtained from abattoirs in the central region of Spain, were collected and examined for nasal botflies from February to October 2002. O. ovis larval stages were recovered from the nasal-sinus cavities of 23 goats, reaching a prevalence of 34.94%. The mean larval burden was 3.9 larvae per infested head. No first instars were found during February and March, when the second instar reached its larger count. The third instar was observed in very small number during the whole period of study, with one peak occurring in July–August. These data show the existence of a favourable period for the development of larval instars of O. ovis in goats that starts in February and finishes in September.     

Incidence of Oestrus ovis infestation in Borno-white Sahel goats in the semi-arid zone of Nigeria

Research conducted on the incidence of Oestrus ovis in Maiduguri showed that 53.8% of the 4,000 Borno-White Sahel goats examined were parasitised. The mean year-round infestation per goat was 2.03 larvae. Adult goats had a higher infestation rate than younger ones (60 versus 47.5%). Infestation rates for the females and males were 55.2 and 52.2%, respectively. Nevertheless there was no statistical significance between values for the different age and sex groups studied. Different larval stages were encountered throughout the year with a 3rd instar peak between May and September and a first instar peak from June to October suggesting a fly period between June and October.     

Parasites of comestic and wild animals in South Africa. II. Oestrus ovis in goats

During a period of 13 months, 130 goats' heads, obtained form the Johannesburg Municipal Abattoir, were examined for infestation with Oestrus ovis. Investation was present in 73,8% of the heads and the mean burden comprised 4,4 larvae. Such a small nuber of larvae were present that no clear seasonal incidence pattern could be determined. Pupal periods could be as long as approximately 60 days for flies hatching during October and May and as short as approximately 24 days for those hatching from December-February. The findings are compared with those obtained from surveys in sheep in south africa.     

Antioxidant enzymes in erythrocytes from goats seropositive to the sheep nose bot fly (Oestrus ovis L., Diptera: Oestridae) infection

Oestrus ovis (Diptera: Oestridae) causes an important cosmopolitan parasitosis of the nasal and sinusal cavities of sheep and goats called oestrosis. Our objective was to analyze the participation of erythrocytes in the antioxidant system in goats seropositive to O. ovis infection under field conditions. Fifty female goats naturally exposed to O. ovis infection from Baja California Sur, México, were blood-sampled. Erythrocytic intracellular content was obtained from blood plasma. Oestrosis serodiagnosis was determined by ELISA. Protein, hemoglobin (Hb), superoxide dismutase (SOD), mieloperoxidase (MPO), catalase (CAT), glutathione-S-transferase (GST), and lipid peroxidation in erythrocytes were determined in both seropositive and seronegative goats. Overall seroprevalence of O. ovis infection in goats was 56%. Positive significant (P<0.05) associations were observed among systemic IgG level and protein (0.34), hemoglobin (0.43), SOD (0.32), and MPO (0.41) in erythrocytes. Protein and hemoglobin concentrations, as well as SOD and MPO activities in erythrocytes were found significantly higher (P<0.05) in seropositive than in seronegative goats. By contrast, enzymatic activities of CAT and GST and lipid peroxidation values were similar in seropositive and seronegative groups. In conclusion, there was a systemic stimulation of Reactive Oxygen Species which was efficiently scavenged by erythrocytic antioxidant enzymes in goats seropositive to O. ovis infection.     

<Emphasis Type="Italic">Oestrus ovis</Emphasis> larval myiasis among sheep and goats in Central Oromia,Ethiopia

A study was conducted to determine the prevalence, larval burden, and associated gross pathological lesions of Oestrus ovis in sheep and goats slaughtered at Luna export abattoir in Central Oromia from November 2007 to March 2008. For this purpose, a total of heads of 431 goats and 369 sheep were thoroughly examined for the presence of first (L1), second (L2), and third (L3) larval stages according to standard procedures. O. ovis larvae were detected in 349(94.6%) sheep and 381(88.4%) goats. All three larval instars were observed in each study months. Statistically significant variation (χ ² = 29.2676, df = 6, P < 0.05) was observed in the prevalence of O. ovis among small ruminants of different origins. Likewise, statistically significant (χ ² = 68.3, df = 4, P < 0.05) difference was recorded in the prevalence of O. ovis in sheep and goats among different study months. The overall monthly prevalence ranged from 77.7% in November to 98.8% in March. The prevalence of O. ovis in small ruminants of less than 1 year of age was significantly (χ ² = 8, df = 1, P < 0.05) higher than those with greater than 1 year of age. An overall proportion of 33.8%, 40.1%, and 26.1% were recorded for L1, L2 and L3, respectively. Whereas 6.8 monthly mean larval burden per individual infested animal was noticed. Out of the total infested heads in goats, 33.6% had catarrhal discharges, 16.8% purulent exudates, 64.83% rhinitis, 68.77% sinusitis, 14.2% pharyngitis, and 9.2% bloody exudates. Similarly, of the total infested heads of sheep, 18.9% purulent exudates, 80.8% rhinitis, 71.9% sinusitis, 13.5% pharyngitis, and 7.7% bloody exudates gross lesions were recorded.