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1.
Two to four impala in the Nylsvley Nature Reserve were culled each month from February 1975-February 1976. Two trematode species, 1 cestode species and 13 species of nematodes were recovered from these antelope. Of these, Fasciola gigantica, Gongylonema pulchrum, Haemonchus placei and Trichostrongylus falculatus are new records for impala. In general, H. placei, Longistrongylus sabie and Impalaia tuberculata exhibited a similar pattern of seasonal occurrence. Adult worms were present during November-February, while marked inhibition in the development of large numbers of 4th stage larvae occurred from April-September or October. Cooperia hungi, Cooperioides hamiltoni and Cooperloides hepaticae followed a similar pattern, but inhibition in the 4th larval stage was not as marked and lasted from June-September. No seasonal pattern of prevalence could be determined for Trichostrongylus spp. The worm burdens of young impala increased with the age of the animals and reached a peak when the impala were 1 year old.  相似文献   

2.
Exsheathed infective larvae (L 3) of 19 species of nematodes were tested for infectivity in either sheep or cattle after they had been frozen in 0,9% NaCl solution, stored for a relatively short time in the gas phase of liquid nitrogen and subsequently thawed. In addition, 13 of these species were tested after similar storage for up to 18 months. In sheep, Haemonchus contortus, Ostertagia circumcincta, Trichostrongylus axei, Trichostrongylus colubriformis, Nematodirus spathiger and Oesophagostomum columbianum were viable after 2 years of cryopreservation, a mean of greater than 90% of the L 3 being alive when thawed after this period. Similar results were obtained with Chabertia ovina L 3 after 18 months and with Marshallagia marshalli, Trichostrongylus falculatus and Dictyocaulus filaria, after a short period of freezing. On the other hand, Gaigeria pachyscelis and Strongyloides papillosus survived freezing for up to 7 months but neither was viable at the end of this period, nor was exsheathed G. pachyscelis viable without freezing. Most of these infestations were established by inoculating the infective larvae into the abomasum and/or duodenum. M. marshalli, T. falculatus and C. ovina also proved infective after oral dosing. D. filaria, the only other species tested by this route, was not infective when dosed per os after thawing. The infective larvae of the bovine nematodes, Haemonchus placei, Ostertagia ostertagi, Nematodirus helvetianus, Oesophagostomum radiatum, Cooperia pectinata and Cooperia punctata survived freezing for a mean of 26 months, greater than 90% being alive on thawing, but infectivity was generally lower than with the same genera in sheep. Even when not frozen, exsheathed Bunostomum phlebotomum was non-infective. When Cooperia spp. after thawing were tested for infectivity by the oral route, more worms developed in one calf infested orally than in another infested by inoculation into the duodenum. Ova of H. contortus, M. marshalli, O. circumcincta, T. colubriformis, T. falculatus, N. spathiger, C. ovina, H. placei, O. ostertagi, Cooperia spp. and N. helvetianus were recovered from the faeces of animals infested with cryopreserved L 3. No ova of O. columbianum or O. radiatum were recovered from faeces, because differential larval counts were performed before they were patent. Nevertheless, gravid females were obtained post-mortem. Frozen L 3 of N. helvetianus were used to re-establish a pure strain in calves, 2,3 million ova being recovered from infestations with 10 670 L 3 frozen for 26 months. The infectivity of the progeny of frozen L 3 was tested with M. marshalli and C. ovina. In both instances infectivity was high and the worms which developed also produced ova, thus completing the cycle. This appears to be the first report of infective larvae of parasitic nematodes retaining their infectivity after being frozen in liquid nitrogen (gas phase) for longer than 2 years. This is also apparently the first time that M. marshalli T. colubriformis, T. falculatus, T. axei, N. spathiger, C...  相似文献   

3.
Sheep and alpacas of similar age groups (6, 18 and 36+ months) were grazed for 16 weeks on pasture contaminated by lambs. Faecal egg counts, bulked larval cultures, lungworm larvae in faeces, dag scores, liveweight changes and nematode larvae on pasture were measured. Chabertia, Oesophagostomum, Cooperia, Ostertagia and Haemonchus and Trichostrongylus larvae were cultured from both the sheep and the alpacas. For the respective age groups, the alpacas had lower liveweight gains (10, 32 and 47 g/d vs 88, 84 and 120 g/d), peak faecal egg counts (384, 50 and 60 epg vs 1500, 500 and 140 epg) and faecal contamination of the perineum than the same ages of sheep. These results suggest alpacas became less affected with gastrointestinal nematodes than sheep.  相似文献   

4.
Infective larvae of selected batched of the following nematode species from sheep and cattle were examined for survival and infectivity (by injection into either the abomasum, the duodenum, or the jugular vein) after having been stored in liquid nitrogen for 103-136 months: Haemonchus contortus, Haemonchus placei, Ostertagia circumcincta, Ostertagia ostertagi, Marshallagia marshalli, Cooperia spp., Trichostrongylus axei, Trichostrongylus colubriformis, Trichostrongylus falculatus, Nematodirus spathiger, Nematodirus helvetianus, Oesophagostomum columbianum, Oesophagostomum radiatum, Chabertia ovina and Dictyocaulus filaria. Excluding D. filaria, a mean of 97.7% of the ovine and 96.0% of the bovine nematode larvae were alive when thawed. Compared with previous investigations in this series, little or no reduction occurred with time in either the survival or the viability of the nematodes from cattle, or in the survival of those from sheep. In contrast, the larvae developed poorly in sheep, possibly owing to parenteral treatment of the animals with ivermectin at a dosage of 0.4 mg kg-1, either 6 or 8 days before they were infected.  相似文献   

5.
The efficacy of oxfendazole was tested in naturally infected Sokoto-Gudali calves at a dosage of 2.8 mg per kg. At this dosage level, oxfendazole showed 100 per cent efficacy against adult and immature forms of Haemonchus spp, Trichostrongylus spp, Bunostomum phlebotomum and Oesophagostomum radiatum. Although efficacy of 100 per cent was recorded for the adult form of Cooperia spp, only 48 per cent reduction was recorded for its immature stages. Similarly, a percentage reduction of 75 was recorded for adult Trichuris spp. No larvae hatched out of a seven-day vermiculite culture of faeces collected from the treated calves 24 h after treatment.  相似文献   

6.
Worm egg counts of yearling Angora or Merino wethers grazing in mixed flocks at either 4/ha or 8/ha were observed over a 5 month period. Based on faecal egg counts infection levels in the sheep increased for the first 3 months and then decreased as the animals developed resistance. Egg counts in the goats did not decrease during the experiment. Post mortem worm counts indicated that there was a significant host species--stocking rate interaction on worm burdens of Haemonchus contortus adults and Ostertagia circumcincta adults and larvae. Goats had more H. contortus and O. circumcincta adults than sheep at the 8/ha stocking rate. At 4/ha goats had fewer O. circumcincta fourth stage larvae than sheep. There was no stocking rate effect on the numbers of Trichostrongylus axei or T. colubriformis. Sheep had more T. axei and fewer T. colubriformis than goats.  相似文献   

7.
The helminths of 3 blue duikers, Cephalophus monticola, from 3 nature reserves in Natal were collected, counted and identified. Taenia hydatigena larvae, a race of Cooperia rotundispiculum, gongylonema angistris, Trichostrongylus falculatus and Trichostrongylus rugatus appear to be new parasite records for blue duikers in South Africa.  相似文献   

8.
An investigation into the seasonal changes in the population structure of Haemonchus and Trichostrongylus in tracer goats was conducted over 12 months at Serdang, an area in southern West Malaysia with year-round tropical rainfall. Successive groups of parasite-free tracer goats were grazed for a month alongside naturally infected adult goats and necropsied for worm counts 14 days after their removal from pasture. No hypobiotic larvae of Trichostrongylus were recovered. Hypobiotic larvae of Haemonchus were evident during each month of the year but accounted for only a very small proportion of the total Haemonchus burden. Very low levels were encountered from December through to June. Comparatively higher levels of hypobiosis were observed thereafter with a peak of 7.4% in September. The factors responsible for hypobiosis were not clearly defined but the phenomenon was associated with increasing levels of soil moisture storage. Host resistance, adult worm population of tracers and population of ingested L3 were ruled out as possible inducing factors.  相似文献   

9.
Between January 1999 and December 2000 faecal samples from 16264 cattle at 12 dipping sites in the highveld and nine in the lowveld communal grazing areas of Zimbabwe were examined for gastrointestinal (GI) nematode and cestodes eggs, and coccidia oocysts. Strongyle larvae were identified following culture of pooled faecal samples collected at monthly intervals. The effects of region, age, sex and season on the prevalence of GI nematodes, cestodes and coccidia were determined. Faecal egg and oocyst counts showed an overall prevalence of GI nematodes of 43%, coccidia 19.8% and cestodes 4.8%. A significantly higher prevalence of infection with GI nematodes, cestodes and coccidia was recorded in calves (P < 0.01) than in adults. Pregnant and lactating cows had significantly higher prevalences than bulls, oxen and non-lactating (dry cows) (P < 0.01). The general trend of eggs per gram (epg) of faeces and oocysts per gram (opg) of faeces was associated with the rainfall pattern in the two regions, with high epg and opg being recorded during the wet months. The most prevalent genera of GI nematodes were Cooperia, Haemonchus and Trichostrongylus in that order. Strongyloides papillosus was found exclusively in calves. Haemonchus was significantly more prevalent during the wet season than the dry season (P < 0.01). In contrast, Trichostrongylus was present in significantly (P < 0.01) higher numbers during the dry months than the wet months, while Cooperia and Oesophagostomum revealed no significant differences between the wet and dry season. These findings are discussed with reference to their relevance for strategic control of GI parasites in cattle in communal grazing areas of Zimbabwe.  相似文献   

10.
Arrested development of Haemonchus, Cooperia and Trichostrongylus spp. was studied in (1) 14 naturally infected and eight experimentally infected West African Dwarf (WAD) goats reared in the derived savanna zone of eastern Nigeria and (2) 55 naturally infected slaughter goats obtained from the savanna and sahel regions of northern Nigeria. Six of the WAD goats carried natural infections of H. contortus and T. colubriformis and eight other (tracer) goats acquired their infections from a grass paddock artificially contaminated with H. placei, C. pectinata and C. punctata, during May to October. Another three WAD goats were artificially infected with mixed cultures of L3 of the latter three nematodes, while five goats were inoculated with 1500-2000 L3 of H. contortus harvested from cultures incubated at 25-30 degrees C for 8 days either in the dark or under normal laboratory conditions. Approximately 41% (9/22) of the infected WAD goats harboured arrested larvae of Haemonchus and/or Cooperia. No arrested larvae of Trichostrongylus were found in the six animals that were infected with this nematode. The level of inhibition varied from 0.4 to 20% and only three animals showed greater than 10% inhibition. This very low level of inhibition occurred in naturally and experimentally acquired infections, irrespective of the time of year. In the case of Haemonchus, the species and strain of the parasite and infection with L3 cultured in the dark also appeared not to influence the level of inhibition. By contrast, 65.5% (36/55) and 5.5% (3/55) of the northern savanna and sahel goats harboured arrested larvae of H. contortus and T. colubriformis, respectively. The mean percentage inhibition of the former was low (2-25%) during most of the rainy season (June-August) and high (75-90%) during the late rains and the dry season (October-April). The lowest and highest mean percentage inhibitions occurred during July and November, respectively.  相似文献   

11.
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12.
The influence of daily doses of 0.05–0.1 mg fenbendazole/kg body weight on egg development was tested in twenty-seven lambs artificially infected with Haemonchus contortus plus Trichostrongylus colubriformis or Ostertagia circumcincta, as well as in two additional sheep naturally infected with Nematodirus spp.Atypical eggs were detected before a reduction in the number of eggs. Atypical eggs had blastomeres of different sizes and shapes; knot-like, crater-like or bubble-like. In isolated cases eggs with atypical first larvae were recognizable. Morphologically changed eggs occurred in the reproductive organs of female O. circumcincta worms.None, or only a very small number of third stage larvae, could be cultured from the faeces of treated sheep.  相似文献   

13.
The length of the sheath extension of third stage (L(3)), infective larvae of Trichostrongylus rugatus is reported. The total length and length of the sheath extension of L(3) recovered from the faeces of sheep originating from two localities in South Australia were measured. The total length of larvae was 615-722 microm and the length of the sheath extension was 46-56 microm (mean 51.5). The larvae of T. rugatus comprised up to 72% of the larvae recovered. Worm free sheep were infected with larvae from the two localities and L(3) were recovered following culture of faeces from these experimentally infected animals. L(3) measured 640-746 microm in total length with a sheath extension of 46-56 microm (mean 51.4). Adult nematodes recovered from gastro-intestinal tracts were identified as T. rugatus. The length of the sheath extension used in conjunction with the total length is a characteristic that enables confident differentiation of infective larvae of T. rugatus from other Trichostrongylus species infecting sheep in southern Australia and Haemonchus contortus.  相似文献   

14.
The helminths of 77 nyala, Tragelaphus angasii, from 4 game reserves in Natal, were collected, counted and identified. Ten nematode species and 4 nematode genera, a trematode species and paramphistomes, and 2 cestode genera were recovered from the antelope. Of these, a Cooperia rotundispiculum race, Gaigeria pachyscelis, a Gongylonema sp., Haemonchus vegliai, Impalaia tuberculata, an Oesophagostomum sp., a Setaria sp., Trichostrongylus deflexus, Trichostrongylus falculatus, the larval stage of a Taenia sp., a Thysaniezia sp. and Schistosoma mattheei are new parasite records for this host. Individual nematode helminth burdens varied from 3 to 13 493 and the total mean nematode burden was 700. The mean burdens of nyala from Mkuzi were the largest and those from animals from the Umfolozi Game Reserve and the False Bay Park the smallest. Ostertagia harrisi was the most prevalent nematode, and it was also the most numerous in nyala from Umfolozi, Mkuzi and False Bay. A race of Cooperia rotundispiculum was the most numerous in nyala from Ndumu. No clear-cut trends in the seasonal abundance could be discerned for any of the worm species recovered in this study.  相似文献   

15.
A survey was carried out to determine the prevalence and seasonal abundance of the egg and adult stages of nematode parasites of sheep and goats in the semi-arid zone of north-eastern Nigeria between January and December 2002. Faecal samples collected from 102 sheep and 147 goats and examined by the modified McMaster technique using saturated solution of sodium chloride as the floating medium revealed that 44 (43.1%) and 82 (55.8%) of the samples, respectively, contained at least one nematode egg type. Three nematode egg types were recovered with strongyle egg type (22.5% in sheep and 35.4% in goats) being the most prevalent followed, respectively, by Trichuris (5.9% in sheep and 4.1% in goats) and Strongyloides (4.9% in sheep and 4.1% in goats) egg types. Mean faecal egg counts were generally moderate in both sheep (1052+/-922 strongyle, 1000+/-590 Strongyloides and 380+/-110 Trichuris eggs, respectively, per g of faeces) and goats (2092+/-3475 strongyle, 958+/-854 Strongyloides and 683+/-512 Trichuris eggs, respectively, per g of faeces) and showed the same trend irrespective of the age or sex of the animals. The prevalence and counts of strongyle nematode eggs showed a definite seasonal sequence that corresponded with the rainfall pattern in the study area during the period. In both sheep and goats, counts of strongyle egg type increased with the rains and reached peak levels at about the peak of the rainy season in September. The other egg types encountered during the study did not show much variation with the season of the year. Out of the 45 sheep and 75 goats examined at necropsy, 27 (60%) and 39 (52%), respectively, contained adult nematode species. Seven genera of adult nematodes including Strongyloides, Trichostrongylus, Haemonchus, Trichuris, Cooperia, Oesophagostomum and Bunostomum species were encountered during the study. Bunostomum species were recorded only in sheep. Adult worm burdens were generally low and showed seasonal variation that corresponded with the rainfall pattern in the study area during the period. Haemonchus and Trichostrongylus species attained peak counts together in both goats (June) and sheep (August). Strongyloides species were encountered throughout the year in both sheep and goats irrespective of the season. Other genera of nematodes encountered occurred in very low numbers and did not allow any meaningful comparison of seasonal sequence. The results suggest that Haemonchus, Trichostrongylus and Strongyloides species may be the major contributors to small ruminant helminthiasis in the study area.  相似文献   

16.
Sentinel calves were placed in pastures for 1 month in two environmentally dissimilar areas of the Texas Gulf Coast to determine the seasonal transmission of various gastrointestinal nematodes. Transmission was determined for Cooperia spp, Haemonchus placei, Ostertagia ostertagi, and Trichostrongylus axei. Large numbers of Cooperia spp were acquired from May through November, with the peak of transmission occurring in July and August. Haemonchus placei was encountered on both field sites but was transmitted in large numbers only at one site, during August. Ostertagia ostertagi was acquired primarily from November through May, with the peak of transmission occurring in January and February. January through March was the period when the greatest numbers of Ostertagia larvae undergoing arrested development were acquired. Trichostrongylus axei was abundance in December and January at one field site. In general, trends of transmission were the same in both areas, indicating that weather conditions were most important than vegetation type in larval transmission.  相似文献   

17.
Sheep grazed on natural pastures heavily infested with infective larvae of Haemonchus contortus. Sixty-eight weaned Merinos were divided into 6 groups on Day 0 (23 November 1977), and on Day +14 (7 December) 79 Merinos were divided into 7 groups. There were 2 groups of undosed controls and other groups were either dosed with infective larvae of Trichostrongylus axei (bovine strain) only on Days 0 and +14, or in combination with H. contortus, or with subsequent doses of H. contortus, 28 days later. One group (Group 12) was dosed with T. axei and treated with a subcutaneous injection of di-iodonitrophenol (DNP) on Day +14. With the exception of 2 sheep, the sheep of the first 6 groups survived until slaughter in March and April 1978, while many sheep (43) of the latter 7 groups died or were killed in extremis from March-May. T. axei dosed on 23 November (Day 0) protected Group 2 by greater than 50% in greater than 50% of sheep. In the latter 7 groups the best results were achieved when DNP was combined with predosing with T. axei. The poor results were probably due either to delayed predosing with T. axei or a massive challenge in the wettest summer on record.  相似文献   

18.
Strongylid gastrointestinal nematodes are an important cause of disease and economic loss in small ruminants. These parasites are particularly important in the eastern United States where the bloodsucking parasite Haemonchus contortus is the predominant species. Sheep and goats are infected with gastrointestinal nematodes while grazing and the biology of the infective larvae on the pastures is important in planning effective control programs. Fecal egg counts can be used to monitor control programs and drug efficacy and evaluate levels of pasture contamination.  相似文献   

19.
Gastro-intestinal parasitism of creole cows and calves, Limousin x creole cross calves and Brahman x creole cross calves was recorded during seasons of calving in a native grazing system in Guadeloupe, a wet tropical area. Calvings were pooled during the dry season for two herds and during the rainy season for two other herds. For each calving season, calves of one herd were drenched monthly with anthelmintic. A marked periparturient rise in egg excretion was observed in cows. Coccidial infection was always present in calves, but no clinical signs were observed. The main parasites during the first 2 months of life were Strongyloides papillosus and Toxocara vitulorum. Then, Haemonchus placei, Trichostrongylus spp. and Cooperia spp. were the dominant species encountered. Brahman cross calves were the most heavily infested animals. There was no clear relationship between third stage larvae (L3) population size on pasture and worm burdens in calves, except during the second month of life. Despite medium levels of infestation, parasitism inhibited the growth of creole calves: -10.5 kg of bodyweight at weaning (-59 g day-1 of daily bodyweight gain from birth to weaning). The pathological effects of subclinical parasitism were confirmed by a lower packed cell volume and albuminaemia in parasitized calves than in treated calves.  相似文献   

20.
A total of 96 abomasa from sheep and goats at the Zagazig abattoir, Sharkia Province, Egypt, were examined, during the four climatic seasons from April 1986 to March 1987, for the presence of adult and larval nematodes. Adults of Trichostrongylus axei were most numerous followed by adult Haemonchus contortus. Adult Ostertagia sp. and Parabronema skrjabini were less prevalent. There was no significant difference between sheep and goats in infection rates, but worm burdens of the nematodes other than Ostertagia sp. were significantly higher (P less than 0.05) in sheep than in goats. The animals were uniformly infected with these parasites throughout the year as there were no significant differences in the incidence or intensity of infections between the four seasons. The numbers of larvae recovered from the wall of the abomasa were small in relation to the total adult worm population throughout the year with a slight increase during the summer. Hypobiosis, therefore, seems not to be important in the life cycle of abomasal nematodes of sheep and goats in Sharkia Province, Egypt.  相似文献   

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