卵形巴贝斯虫在长角血蜱幼虫体内的发育观察

文献报道,巴贝斯虫可经卵传递。然而有关经卵传递时巴贝斯虫的形态学研究尚未见报道。本实验以长角血蜱成虫对卵形巴贝斯虫感染牛饱血脱落后的次代幼虫叮咬除脾实验牛,对幼蜱体内卵形巴贝斯虫的发育进行形态学观察,同时幼蜱叮咬后实验牛末梢血液进行观察研究。     

实验感染牛末梢红细胞内卵形巴贝西虫裂殖子的形态学观察

以感染有卵形巴贝西虫的长角血蜱幼虫叮咬感染实验除脾牛,对其末梢红细胞内卵形巴贝西虫的裂殖子的形态及感染率进行了观察。裂殖子可分6个类型,除以往报道的单梨子型、双梨子型、分裂型及退行型之外,还观察到了杆菌型及棒型虫体,随感染率的上升,单梨子型和杆菌型增加,随感染率的下降,棒型及退行型增加。据此认为,虫体的形态与发育阶段有关。根据杆菌型、棒型虫体的出现认为,接种卵形巴贝西虫虫血感染与阳性蜱叮咬感染,其卵形巴贝西虫在牛体内的发育并不相同。     

双芽巴贝斯虫在长角血蜱肠内发育的形态学研究

以耳袋法将长角血蜱(Haemaphysalis longicornis)幼虫饲于实验感染双芽巴贝斯虫(Babesia bigemina)牛,幼虫饱血后24h内,其肠管内容物中红细胞内、外见有单梨子型(3.5～4.5μm×1.2～2.6μm)和双梨子型(4.1～4.8μm×1.8～3.0μm)两种裂殖体.饱血后24～48h,随着裂殖体细胞膜及核变性而发生形态变化.48～72h,绝大多数裂殖体出现溶解.72h后,这些裂殖体从肠道消失.其后,在蜱肠上皮及血淋巴中也未能找到双芽巴贝斯虫体.本实验从形态学上证明双芽巴贝斯虫在长角血蜱若虫肠道内不能发育.     

实验性牛卵形巴贝西虫病的研究

本实验以感染有卵形巴贝西虫(Babesia ovata)的长角血蜱(Haemaphysalis longicornis)幼蜱、叮咬感染实验除脾牛。结果,幼蜱叮咬后第6天,牛未梢血红细胞内首次观察到了卵形巴贝西虫裂殖子,第12天感染率出现高峰为9.05%,随后即下降,第15天虫体从未梢血中消失。实验感染牛主要临床表现为稽留高热,呼吸急促,血尿,可视粘膜苍白黄染,高度贫血。血液学检查Hb降至380/L,PCV降至10%,红细胞降至1.80×10~(12)/L。     

湖南省需步县南山牧场长角血蜱的发育史观察

经观察，长角血蜱雌虫１月份和８月份在兔体饱血时间为６－９ｄ，８月份和９月份在牛体饱血期为４－７ｄ，饱血雌虫产卵前期为７－１０ｄ，产卵期为１７－２７ｄ，产卵数３１２－１２６８粒，卵孵化期为１６－２１ｄ。幼虫８月份在兔体饱血期为５－７ｄ，９月份为３－４ｄ，８月份在牛体饱血期为３－５ｄ，９月份为２－２．５ｄ。饱血幼虫蜕化期８月份为１６－１９ｄ，９月份为１０－１７ｄ。     

延边某地长角血蜱和全沟硬蜱体内东方泰勒虫的分子生物学检测

为调查吉林省延边地区自然生境内游离蜱携带东方泰勒虫的情况,以东方泰勒虫主要表面蛋白基因(MPSP)基因为靶基因,采用PCR方法对延边地区自然生境内的游离蜱DNA进行扩增。在长角血蜱的DNA中检测了东方泰勒虫,检出率为29%;而全沟硬蜱中没有检测到东方泰勒虫。结果表明,自然生境中的游离长角血蜱体内携带着东方泰勒虫。     

家兔抗长角血蜱免疫模型的建立及对长角血蜱成蜱生长发育的影响

每隔2周用长角血蜱成蜱定量感染家兔,成功构建了具有不同抵抗力的家兔免疫模型。ELISA检测结果表明,家兔血清中的抗体效价从初次叮咬后第3周开始呈阳性,随着叮咬次数的增加抗体水平逐渐上升,第11周时达到高峰。具有一定抵抗力的家兔对长角血蜱成蜱的吸血和生长发育影响显著,其抗体水平与长角血蜱成蜱在兔体的吸血周期、死亡率成正相关,与雌蜱的饱血脱落率、饱血体重成负相关。结果进一步证明,蜱的唾液腺是其主要的免疫器官之一。家兔抗体水平的持续期足以使长角血蜱完成一个世代,可以满足试验需求,是抗蜱免疫研究理想的阳性对照模型。同时,血清中特异性抗体的效价也可以作为判断动物对长角血蜱抵抗力强弱的重要指标之一。     

Detection of a Babesia sp. genotype closely related to marsupial-associated Babesia spp. in male Haemaphysalis shimoga from Sarawak,Malaysian Borneo

In this study, Babesia screening was conducted in 55 rodents and 160 tick samples collected from primary forests and an oil palm plantation in Sarawak, Malaysian Borneo. PCR targeting the 18S ribosomal DNA revealed the presence of Babesia spp. DNA detected in two questing male Haemaphysalis shimoga ticks collected from the oil palm plantation. Sequence analysis revealed that both sequences were identical and had 98.6% identity to a Babesia macropus sequence obtained from Eastern grey kangaroos (Macropus giganteus) in Australia. Phylogenetic tree revealed clustering with marsupial-associated Babesia spp. in the Babesia sensu stricto clade. Whether or not H. shimoga is the competent vector and the importance of the Babesia sp. detected in this study warrants more investigation.     

Biology,ecology and distribution of the tick,Haemaphysalis longicornis Neumann (Acari: Ixodidae) in New Zealand

Haemaphysalis longicornis is the only tick in New Zealand that infests livestock. Throughout its range H. longicornis is exposed to and exhibits tolerance to a wide range of environmental conditions, although it flourishes more in moist, warm-temperate environments. This review examines aspects of the biology, physiology and ecology of H. longicornis that determine its distribution and seasonal activity in New Zealand, based on laboratory and field studies. Examples are also drawn from studies outside New Zealand for comparative purposes, especially in the context of seasonal activity as seen in less temperate latitudes. The tick is able to withstand a wide range of temperature, from its developmental threshold of ～12°C to nearly 40°C at its lethal limit, but its tolerance of dehydration is less wide, especially in the larva and adult, the former especially being the stage that largely determines suitable biotopes for the tick and its present distributional limits.

The importance of H. longicornis to the New Zealand livestock industry has recently increased through the establishment and spread of Theileria orientalis Ikeda among dairy and beef cattle, although the tick has always posed production-limiting problems for cattle, deer and to a lesser extent, sheep. The tick's role as a vector of theileriosis and how aspects of the tick's biology affect the spread and maintenance of this disease are discussed. It is proposed that, of available wildlife hosts, the brown hare with its wide-ranging habits, is an important disseminator of ticks.

Currently control of ticks is difficult partly because of their wide host range, overlapping activity periods of stadia, and also because the greater part of their annual cycle is spent on pasture. This means that acaricides alone do not satisfactorily reduce tick populations or provide comprehensive protection to stock, so integrated management combining pasture management with good husbandry and chemical prophylaxis is advocated.     

The Effects of Salivary Gland Extracts from <Emphasis Type="Italic">Boophilus microplus</Emphasis> Ticks on Mitogen-stimulated Bovine Lymphocytes

The effect of salivary gland extract (SGE) from the tick Boophilus microplus was examined in mitogen-stimulated lymphocytes in vitro. SGE was added to lymphocytes of seven cattle together with the mitogens concanavalin A (ConA), phytohaemagglutinin (PHA) and pokeweed mitogen (PWM). Semi-purified B cells from another seven cattle were stimulated with the mitogen lipopolysaccharide (LPS). PHA and ConA stimulated proliferation of lymphocytes to the same extent, but the inhibition due to SGE of Boophilus microplus on the proliferative response stimulated by PHA (39.0% ± 9.3%) was less than the inhibition of proliferative response stimulated by ConA (75.4% ± 6.9%). In contrast, SGE of B. microplus stimulated the proliferation of B cells in the presence of LPS in a dose-dependent manner. Enhanced stimulation of B cells by SGE at >4 μg in culture was greater than twice that observed when B cells were stimulated by LPS alone. SGE does not have a direct suppressive effect on bovine B cell proliferation; however, in vivo the effectiveness of B cell responses might be influenced by other immune factors, such as cytokine profiles.     

Development of Babesia ovata in the midgut of the tick, Haemaphysalis longicornis

Studies were made on the development of Babesia ovata in the midgut of the nymphal tick vector, Haemaphysalis longicornis. In 12 hr post-repletion, merozoites were observed outside of erythrocytes infected with B. ovata in the contents of the midgut of the tick. After that, these merozoites were transformed into ring-forms which were comparatively large ring 2-3 microns in diameter. Within 48-72 hr post-repletion, ring-form protozoa developed into spherical form 4-5 microns in diameter. Within 3-4 days post-repletion, fission-forms were transformed into fission-bodies 2-3 microns in diameter. Within 4-6 days post-repletion, fission-bodies developed into bizarre-forms 6-7 microns in diameter. At this time, elongated form protozoa which were considered as microgametes, 6-8 microns in length, are also seen. Within 6-8 days post-repletion, round-formed protozoa which were considered as zygotes in 9-10 microns in diameter were observed in the gut. About 10 days after repletion, those round-formed protozoa were transformed into vermicule-formed and round-formed protozoa, 13-15 microns in length, appeared again in the gut epithelial cells.     

Undifferentiated Sarcoma of the Salivary Gland in a Mongolian Gerbil (Meriones unguiculatus)

A subcutaneous mass was found in the lower ventral neck region of a 55-week-old male Mongolian gerbil (Meriones unguiculatus). Histopathologically, the mass involved salivary glands and featured diffuse proliferation of pleomorphic neoplastic cells with large necrotic foci. The lesion was well demarcated from the surrounding tissue, although invasive growth to fibrous septa was occasionally observed. The neoplastic cells were mainly arranged in irregular sheets with severe cellular atypia, round to oval nuclei and varying amounts of eosinophilic cytoplasm. Mitotic figures and multinucleated giant cells were frequent. Immunohistochemical analysis revealed that the neoplastic cells were strongly positive for vimentin and S-100 and negative for NSE, cytokeratin, α-SMA, c-kit, factor VIII, CD34, α-1-antitrypsin, lysozyme and MSR-A. Based on the results, the mass was diagnosed as an undifferentiated sarcoma of the salivary gland. To the best of our knowledge, this is the first report of such a tumor in Mongolian gerbils.     

Transmission of Babesia spp by the cattle tick (Boophilus microplus) to cattle treated with injectable or pour-on formulations of ivermectin and moxidectin

OBJECTIVE: To assess the efficacy of ivermectin and moxidectin to prevent transmission of Babesia bovis and Babesia bigemina by Boophilus microplus to cattle under conditions of relatively intense experimental challenge. DESIGN: Naive Bos taurus calves were treated with either pour-on or injectable formulations of either ivermectin or moxidectin and then exposed to larvae of B microplus infected with B bovis or larvae or adults of B microplus infected with B bigemina. One calf was used for each combination of haemoparasite, B microplus life stage, drug and application route. PROCEDURE: Groups of calves were treated with the test drugs in either pour-on or injectable formulation and then infested with B microplus larvae infected with B bovis or B bigemina. B bigemina infected adult male ticks grown on an untreated calf were later transferred to a fourth group of animals. Infections were monitored via peripheral blood smears to determine haemoparasite transmission. RESULTS: Cattle treated with either pour-on or injectable formulations of ivermectin and moxidectin became infected with B bovis after infestation with infected larvae. Similarly, larvae infected with B bigemina survived to the nymphal stage to transmit the haemoparasite to animals treated with each drug preparation. Cattle treated with pour-on formulations of ivermectin and moxidectin then infested with adult male ticks infected with B bigemina did not become infected with B bigemina whereas those treated with the injectable formulations of ivermectin and moxidectin did show a parasitaemia. CONCLUSIONS: Injectable or pour-on formulations of ivermectin and moxidectin do not prevent transmission of Babesia to cattle by B microplus. Use of these drugs can therefore not be recommended as a primary means of protecting susceptible cattle from the risk of Babesia infection.