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1.
Excretory-secretory products (ESP) of myiasis producing agents are involved in nutrition and development of larvae and are often immunogens. This study was carried out in order to define the antigenicity, the immunogenicity of Oestrus ovis ESP and the role of sheep immune response to ESP. Twenty-four six to eight month old female lambs were randomly allocated into two groups. The first one was immunised twice, four weeks apart, with excretory-secretory products of Oestrus ovis third instar larvae (L3ESP) in complete then incomplete Freund adjuvant. The second one served as a control, and received two injections of PBS plus complete and incomplete Freund adjuvant. Fifteen and twenty-eight days after the second immunisation, animals of both groups were experimentally challenged with O. ovis first instar larvae. Twelve days after the second experimental challenge, the twenty-four lambs were necropsied. The total number of O. ovis larvae, their stages of development, weights and sizes were recorded per animal and compared between the two groups. Establishment rates were very similar in both groups: 39% and 35% in control and vaccinated groups respectively but the percentage of developing stages was higher in the control group (13%) than in the vaccinated group (6%). It was concluded that the L3ESP immunisation of sheep did not protect against larval establishment but provided an inhibitory effect on larval growth.  相似文献   

2.
Antibody responses (IgG, IgM and IgA) against Oestrus ovis were analyzed in sheep and in first year grazing lambs from Sardinia (Italy) by an indirect-enzyme-linked immunoassay test and L2 O. ovis excretory/secretory antigens. Serum samples from 208 sheep were obtained prior to be slaughtered, and then heads were removed and cut open along their longitudinal axis to collect the parasites from the nasal cavities, turbinates and sinus. Besides this, blood samples were monthly collected from the lambs of G-1 (maintained under field conditions) and the lambs of G-2 (kept housed since birth to avoid Oestrus infestations) throughout a year. In the sheep, a positive significant correlation was observed between the number of first instar O. ovis larvae and the values of IgM, and between the second instar larvae and the IgG optical densities. In the lambs, all classes of antibodies increased significantly from July in G-1. The highest values of IgG were reached in September (IgG) and decreased in November-December. The IgM response peaked in November, and very low values of IgA were observed during the study. Matching these data with chronobiology of O. ovis in this region, we conclude that the first infection occurs on May, stimulating the production of humoral antibodies. The reduction of the IgG antibody levels starting from October means the beginning of the diapause while the IgM response seems to be associated to the presence of L1 in the nasal cavities. The data obtained led us to forecast an early treatment of the ovine on June-July, which should keep away from the maturation of O. ovis L1 larvae, avoiding the development of clinical lesions and interrupting the life cycle of this parasite.  相似文献   

3.
Larval midgut proteins of hematophagous parasites contain strong antigens that can be used for host immunization. This concept has been applied for immunization of Pelibuey sheep against Oestrus ovis L. (Diptera: Oestridae). The aim of this study was to examine the effect of immunization on larval establishment (LE) and development. Immunized lambs (I, n = 6) received two injections of crude gut membrane protein extracts (GMPE) from third instar larvae with Freund's incomplete adjuvant (FIA) on days 0 (Day of first immunization) and 21 (0.4 and 0.45 mg GMPE/lamb, respectively). The control group (C, n = 5) received physiological saline with FIA. Lambs were challenged with first instars on Day 29 (20 larvae) and Day 43 (25 larvae). Blood samples were collected biweekly and IgG titers were analyzed by ELISA. All lambs were slaughtered on Day 90 and number of larvae recovered, larval stage and larval weight were recorded at necropsy. No significant effect of immunization on LE (C = 28.9%; I = 31.0% P > 0.05) was observed. Antibody titers were higher in the immunized group on Day 28 (P < 0.05), but subsequently similar in both groups. Larval physiological age and weight were also significantly (P < 0.05) affected by immunization. Immunization of Pelibuey lambs with GMPE did not affect LE but did delay O. ovis larval development.  相似文献   

4.
The potential of Oestrus ovis larvae excretory-secretory products (ESP), crude extract, salivary gland contents (SGc) and digestive tube contents (DTc) proteins from O. ovis larvae as antigens in serological assay were analyzed and compared. This study demonstrated that excretory-secretory proteins were produced mainly by digestive tube and salivary gland. The main antigenic component of ESP was a 28kDa protein complex (pc28) synthesized by the salivary gland ring. After purification, its diagnostic value was estimated by an ELISA using sheep sera sampled in summer (n=30) and winter (n=69) in order to investigate the relative importance of wintering hypobiotic first instar larvae on animal responsiveness. ELISA test based on pc28 antigen was compared to a reference ELISA test based on second instar larvae crude extract. After comparison it appeared that the pc28 test was much more specific (87%) and more sensitive (90%) in summer. Anti-pc28 antibody titers were significantly higher in summer than in winter demonstrating the impact of summer developing larvae on the humoral systemic immune response. This data was correlated to the maturation of larvae in summer as the number of larvae at necropsy was significantly higher in winter, when the larval population is only represented by first instar larvae, than in summer. No correlation was observed between the mean antibody titers and the number of larvae.  相似文献   

5.
Larvae of Oestrus ovis (Diptera: Oestridae) are ubiquitous parasites of nasal and sinusal cavities of sheep and goats. According to the chronobiology of O. ovis infections in Sardinia and the seasonal pattern of the IgG response, the optimal period to investigate the relationships between O. ovis larval populations and intensity of local and systemic IgG antibody responses was mid-July in the summer season. Sarda x Lacaune ewes (n=186), divided into three ram-families were used in the study. Systemic and local IgG responses were measured by ELISA tests using second stage larval crude extracts (L2CE) and L2 (L2SGC) and L3 (L3SGC) salivary gland contents as coating antigens. The number of larval instars, larval length of L1, L2 and L3 larvae, and larval weight of L2 and L3 larvae were individually recorded after ewe necropsy. Negative correlations among larval establishment and/or larval development on the one hand and intensity of local or systemic IgG responses on the other hand were found in two out of three studied ram-families.  相似文献   

6.
The in vitro reactivity of monocyte-derived macrophages (MDM) from Oestrus ovis (O. ovis) artificially infested lambs and kids was determined by measuring their production of nitric oxide (NO) during the course of infestation. In both species, crude antigenic preparations obtained from O. ovis first instar larvae (L1) were found to significantly (P < 0.01) inhibit this NO production, whereas O. ovis second instar (L2) extract stimulated it. Furthermore, this NO production by MDM decreased during infestation and was related to blood eosinophilia. It appears that crude antigenic extract from O. ovis modified the NO activity of macrophages from lambs and kids infested with O. ovis larvae.  相似文献   

7.
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.  相似文献   

8.
Mixed parasitic infection of animals is a common phenomenon in nature. The existence of one species often positively or negatively influences the survival of the other. Our experimental study was started with the objectives to demonstrate the interaction of Haemonchus contortus and Oestrus ovis in relation to cellular and humoral immune responses in sheep. Twenty-two sheep of Tarasconnais breed (France) were divided into four groups (O, OH, H and C) of five or six animals. Group O and OH received 5 weekly consecutive inoculations with O. ovis L1 larvae (total = 82 L1) in the first phase of the experiment between days 0 and 28. On the second phase, groups OH and H received 5000 L3 of H. contortus on day 48 while group C served as our control throughout the experimental period. Parasitological, haematological, serological and histopathological examinations were made according to standard procedures and all animals were slaughtered at day 95. There was no significant variation in the number and degree of development of O. ovis larvae between the two infected groups. Furthermore, in tissues examined in the upper respiratory tract (nasal septum, turbinate, ethmoide and sinus), group O and OH has responded similarly on the basis of cellular inflammatory responses (blood and tissue eosinophils, mast cells and globule leucocytes (GL)) and serum antibody responses against the nasal bots. This may indicate that the presence of H. contortus in the abomasa of group OH had no marked influence over the development of O. ovis larvae in the upper respiratory tract. On the other hand, we have observed a significantly lower H. contortus female worm length, fecal egg count (FEC) and in utero egg count in animals harbouring the nasal bot (OH) than in the mono-infected group (H). This was significantly associated with higher blood eosinophilia, higher packed cell volume (PCV) and increased number of tissue eosinophils and globule leucocytes. We conclude that, the establishment of O. ovis larvae in the upper respiratory tract has initiated higher inflammatory cellular activity in group OH there by influencing the development and fecundity of H. contortus in the abomasum.  相似文献   

9.
Larvae of Oestrus ovis (Insecta: Diptera: Oestridae) are common parasites of nasal and sinus cavities of sheep and goats. During larval development, a specific immune reaction is initiated by the host with a humoral local and systemic response and the recruitment of eosinophils and mast cells in the upper airways mucosae. Nevertheless, the roles of these responses in the regulation of O. ovis larvae populations in sheep are not yet known. The aim of this study was to compare the establishment and the development of larvae as well as some inflammatory or immune parameters between different groups of half-sibling sheep: (i) a primed group experimentally infected twice before a challenge infection, (ii and iii) two groups infected once only and previously treated with a long-lasting cortico?d before the challenge (one group) or not (the other group). A fourth group of non-infected animals was added in the experimental design. The larval establishment rate was 23% in the cortico?d treated group compared to about 10% in the two other infected groups. Moreover, the larval development appeared more rapid in the cortico?d treated group than in the two other infected groups suggesting that the inflammatory response is involved in the regulation of O. ovis populations. By contrast, no differences in the establishment rates were shown in the primed group compared to the na?ve group (without cortico?d treatment) despite evidence of higher eosinophilia, serum specific IgG, and immediate hypersensibility to excretory-secretory products of larvae. The specific lymphocyte proliferation was reduced in the primed group compared to the na?ve one suggesting that an immuno-suppression occurs following repetitive O. ovis infections.  相似文献   

10.
Separate groups of 3 oestrid-free lambs were exposed to infestation on irrigated pasture for periods of approximalely 33 days each over30 months, and on dry-land pasture for approxomately 42 days over a period of 18 months. With some exceptions, the lambs slaughtered from October-June were found to be infested with Oestrus ovis while, with one exception, those slaughtered from July-September were free. A minimum of 4 sheeps' heads, obtained weekly over 24 months from the Pretoria Municipal Abattoir, was examined for infestation. Of a total of 542 heads examined, 73,4% were infested, having a mean burden of 15,2 larvae. Mean larval burdens were slightly greater in hornless than in horned sheep in Dorper-type than in Merino-type sheep, and in lambs than in sheep with 2 or more permanent incisors. The largest larval burdens were recovered from sheep slaughtered during May and June and the smallest during September and October. The greatest number of 1st instar larvae were recovered during May and June and the smallest during September, but those recovered during the latter month were the largest. With one exception, mature larvae which pupated after 21 March or before 16 August failed to hatch as viable flies. Those which pupated after 16 August hatched as flies after a pupal stage of approximately 50 days and the first flies to hatch were invariably recovered during the first 2 weeks of October. The pupal stage decreased to approximately 25 days during December and January and increased again to approximately 50 days for flies hatching during May. No flies hatched between 18 May and 1 Cctober. The following life cycle ofr Oestrus ovis is suggested: sheep are repeatedly infested from October-June; thereafter infestation survives in the sheeps' heads until August, mainly as 1st instar larvae, then as pupae and larvae until fresh infestation takes place during October.  相似文献   

11.
Concurrent infections of sheep with Oestrus ovis and trichostrongyles of the digestive tract are common in the field. Previous results have shown that a previous infection with O. ovis adversely affects worm populations of either Trichostrongylus colubriformis or Haemonchus contortus. However, no information was available to determine the influence of the succession of infections on the expression of interactions between these parasites located in remote anatomical sites. In order to investigate the role of these modulating factors, an experimental study was conducted on four groups of na?ve sheep, examining the consequences of a delayed infection with O. ovis on a pre-existing population of T. colubriformis. group T was infected four times with 4000 T. colubriformis larvae on days 0, 14, 28 and 42 of experiment; group O received multiple infections with O. ovis first instar larvae on days 42, 49, 56, 70 and 77; sheep from group TO received both infections and animals from group C remained as uninfected controls. Faecal egg counts and eosinophilia were measured weekly throughout the study. At necropsy (day 91), the mucosal cellular responses in the nasal cavities (septum, turbinates, ethmoid and sinus) and in the digestive tract (stomach and small intestine) from all animals were analysed from histological sections. Infection of the digestive tract with nematodes did not modify the biology of Oestrus populations, as measured by the number and weight of larvae. In contrast, infections with O. ovis after T. colubriformis infection was related to significant reductions (P < 0.01) in nematode egg excretion and worm burdens. These changes were associated with significant modifications in populations of mast cells, globule leucocytes and eosinophils in the respiratory and digestive tracts. These results indicate that an antagonistic interaction exists between the populations of O. ovis in the nasal cavities and T. colubriformis in the small intestine but that the order of succession of infections with the two parasites is not a major modulating factor for expression of interactions. They also confirm that parasitic infection in one particular anatomical site induces "at distance" inflammatory reactions of the whole mucosal system.  相似文献   

12.
A survey for oestrosis was carried out in the slaughterhouse at Messine (Sicily) from May 1996 to April 1998. The heads of sheep from local flocks were collected each month. A total of 841 heads were examined according to a validated procedure. 469 (55.8%) were infested by OEstrus ovis larvae. 4423 larvae were harvested: 1829 first instar larvae or L1 (41.4%), 1286 second instar larvae or L2 (29.1%) and 1308 third instar larvae or L3 (29.6%). The mean larval burden for infected sheep was 9.4 larvae with an average of 3.9 L1, 2.7 L2 and 2.8 L3. No period of hypobiosis was recorded. The proportions of larvae in each of the different larval stages was similar from January to September, however, from October to December the percentage of L1 was higher, indicating a period of slowed development. In order to lower the overall prevalence of this disease, it would be necessary to use a parasiticide effective against O. ovis, for all routine parasite control treatments.  相似文献   

13.
The sheep bot fly, Oestrus ovis, is a very common myiasis of nasal and sinus cavities of sheep and goats causing severe welfare and production implications. As the viability of O. ovis adult flies strictly depends on larval abilities to assimilate and to stock nutrients from the host, it was necessary to investigate proteolytic activities in larval excretory/secretory products (ESP). ESP of O. ovis larvae degrade mucosal and plasmatic components such as mucin, albumin or immunoglobulin G. A preliminary biochemical characterization, using substrate gel analysis and inhibitor sensitivity, demonstrated the presence of at least six major serine proteases (molecular weights from 20 to 100 kDa), mainly trypsin-like, secreted in the digestive tube of larvae. Their involvement in larval trophic activity and evasion from the host immune response is further discussed as O. ovis excretory/secretory serine proteases could represent potential vaccinal targets.  相似文献   

14.
During the period March 1996-July 1997, 417 heads of Awassi sheep slaughtered at the Irbid Abattoir (northern Jordan) were examined for the three larval instars (L1, L2 and L3) of Oestrus ovis. Of the 417 heads, 242 (58%) were infested with O. ovis larvae. Larval numbers were highly aggregated. The lowest number of larvae and the lower quartile were both zero, whilst the median was two and the upper quartile was 12. The highest number of larvae recovered from one head was 151. All three larval instars were observed in each month of the year. July and October had the highest proportions of L1, 75 and 78%, respectively, among infected animals (adjusted for age). The number of larvae increased with age. Infestation with live larvae was associated with inflammatory responses in the upper respiratory tract and with catarrhal or purulent discharge. The percentage of infested sheep and the mean monthly total number of larvae/sheep peaked in the warmer part of the year. Most larvae were L1 except during the spring when L2 and L3 predominated. Distribution analysis demonstrates that the numbers of larvae recovered in the sheep population followed a negative-binomial distribution. Furthermore, the negative-binomial constant k for each month correlated with the monthly prevalence.  相似文献   

15.
Concurrent infections of sheep with Oestrus ovis and trichostrongyles of the digestive tract are common in the field. In order to examine the possible occurrence of interactions between these two parasites and the consequences on parasite biology and the associated pathophysiological changes, an experimental study was conducted on four groups of na?ve sheep. Group O was infected repeatedly with O. ovis larvae from D0 to D42 of experiment; group T received a single infection of Trichostrongylus colubriformis on D49; sheep from group OT received both infections, and animals from group C remained uninfected as controls. Parasitological and pathophysiological parameters were measured regularly. At necropsy (D94), the mucosal cellular responses in the nasal cavities and digestive tract from all animals were analysed from histological sections. Infection of the digestive tract with nematodes did not modify the biology of Oestrus populations. In contrast, the presence of O. ovis was related to significant reductions in nematode egg excretion, worm fecundity and worm burdens. These changes were associated with significant modifications in tissular populations of mast cells, globule leucocytes and eosinophils in the respiratory and digestive tracts. These results indicate that parasitic infection in one particular anatomical site induces "at distance" inflammatory reactions of the whole mucosal system. The relationships between the cellular response and the changes in worm biology are discussed.  相似文献   

16.
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.  相似文献   

17.
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.  相似文献   

18.
The purpose of this experiment was to determine if an earlier infection with Oestrus ovis would down regulate an infection with Trichostrongylus colubriformis when the larvae of O. ovis were expelled from the nasal cavities of sheep by a specific treatment. Three groups of five lambs were used: group 1 was artificially infected with O. ovis larvae and later with T. colubriformis, group 2 received O. ovis larvae and later was treated with ivermectin 14 days before being infected with T. colubriformis. Group 3 was infected with T. colubriformis only. The criteria examined were: the effects on nematode egg excretion, worm fecundity, nematode burdens and the kinetics of blood eosinophils. Significant decreases of nematode egg excretion, worm fecundity, nematode burdens were observed in group 1 compared to group 3. However, no changes were observed in either group 2 or 3. In group 2 it was noted that antiparasitic treatment induced a rapid decrease in blood eosinophils to a range close to the non-infected control group and this was associated with the removal of the down regulation effects of nematode burdens. This experiment showed that there is no cross immunity between O. ovis and T. colubriformis and that eosinophils may act against any parasite without specific priming.  相似文献   

19.
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.  相似文献   

20.
Oestrosis, the nasal myiasis of sheep and goats, is caused by the larvae of Oestrus ovis L. 1758 (Diptera, Oestridae) that develop from the first to the third stage larva in the nasal cavities and frontal sinuses of affected animals. The authors report the results of an epidemiological study of oestrosis of sheep in Sardinia, Italy. Heads of 6-month to 10-year-old Sardinian sheep (n=566) from 124 free-ranging flocks were examined for the presence and location O. ovis larvae from December 1996 to November 1997. Larvae were collected, counted, and larval stages were identified. O. ovis larvae were found in 100% of examined flocks and in 91% (514/566) of examined sheep. The monthly prevalence ranged from 69% in May to 100% in July. First stage larvae were found in 82% (463) of all heads examined, second stage larvae in 65% (367) and third stage larvae in 10% (56). The majority of sheep harboured first stage larvae, with prevalences of over 80% throughout most of the study period. The prevalence of O. ovis found in this study of Sardinian sheep is the highest reported in the Mediterranean area. The high percentage of first stage larvae found throughout the entire study period may be due to a brief period of decreased rate of larval maturation, in particular in December 1996 (96%) and January-October 1997 (94%). Third stage larvae were consistently present, often however, with extremely low prevalences compared to total larval burden.  相似文献   

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