A study of an enzootic focus of sheep babesiosis (Babesia ovis, Babes, 1892)

Morbidity and mortality due to Babesia ovis in sheep flocks grazing in an enzootic area of Israel occur yearly, about 2 weeks after detection of adult Rhipicephalus bursa ticks on the animals. Disease incidence peaks in May, but lasts throughout the active period of the adult ticks in the spring-summer months of April–July. No clinical cases of babesiosis have been registered during the active period of the preimaginal stages of R. bursa, from October to February. Incidence of parasitaemia during the spring-summer months was variable, ranging between 2 and 25%. However, in the winter months the incidence of parasitaemia in hoggets increased considerably, reaching 4–60% of the animals.

A positive serological response to B. ovis was found in 84.5% of the hoggets and 88.9% of the ewes. In ewes, the prevalence of the serological response showed no marked seasonal variations. Colostral sera of 67.5% and 75% of the ewes and hoggets, respectively, were serologically positive for B. ovis. No antibodies were detected in the sera of lambs less than 3–4 months of age. The epizootiology of sheep babesiosis appears to differ from that of bovine babesiosis.     

中国不同地区羊吕氏泰勒虫分子流行病学调查及遗传进化分析

为了解吕氏泰勒虫在中国不同地区山羊和绵羊中的流行情况,本研究应用基于吕氏泰勒虫18S rRNA基因位点的PCR检测方法,对采自中国河南、甘肃、陕西、山西、贵州、云南、新疆7个地区的281份羊血液样品进行检测,并对阳性样品测序以进行序列分析。结果显示,羊吕氏泰勒虫总感染率为35.23%（99/281）。不同采样点羊吕氏泰勒虫感染率差异极显著（P<0.01）,其中河南省羊吕氏泰勒虫感染率最高（98%,49/50）,新疆最低（0）。绵羊和山羊吕氏泰勒虫感染率分别为51.67%（31/60）和30.77%（68/221）,差异极显著（P<0.01）;放牧羊吕氏泰勒虫感染率（41.55%,86/207）极显著高于舍饲羊（17.57%,13/74）（P<0.01）;羊吕氏泰勒虫感染率在春、夏、秋及冬四季分别为56.00%（28/50）、42.75%（59/138）、9.43%（5/53）和17.50%（7/40）,差异极显著（P<0.01）;≥ 12月龄和<12月龄羊吕氏泰勒虫感染率分别为33.50%（67/200）和39.51%（32/81）,差异不显著（P>0.05）。此外,遗传进化分析表明,本研究获得的羊吕氏泰勒虫分离株与中国流行的吕氏泰勒虫分离株同源性高达99.60%以上,且位于同一分支上。本研究为进一步了解中国不同地区羊吕氏泰勒虫的流行现状及分布提供了重要参考依据。     

国内部分省市肉兔及蜱虫携带土拉杆菌的流行病学调查

本调查旨在探明土拉杆菌在国内部分省份的流行情况。利用本实验室建立的土拉杆菌通用及亚种PCR检测研究方法，对国内肉兔饲养密度比较大的省份和牛羊存栏的部分省市开展了肉兔和蜱虫中土拉杆菌的检测，并对阳性样本进行了土拉杆菌亚种的鉴定和基因测序验证。研究结果表明，肉兔肝脏组织和牛羊携带蜱虫中土拉杆菌DNA检测阳性，其中218份肉兔样本中12份阳性（阳性率5.5%），490份蜱虫样本中15份阳性（阳性率3.1%）；从地区分布来看，山东、河南、四川肉兔病料检测阳性，云南、山东蜱虫阳性率高；PCR检测显示其亚种为F.h，为土拉杆菌毒力较强的亚种。本次调查显示土拉杆菌在肉兔、蜱虫中存在，山东、云南地区存在土拉杆菌病公共卫生安全风险，应引起有关科研院校、医疗单位和政府部门的高度重视。     

Epidemiological Investigation of Francisella tularensis Transmitted by Rabbits and Ticks in Some Provinces of China

The aim of this investigation was to find out the prevalence of Francesella tularensis in some provinces of China. Using the general and subspecies PCR detection method for Francesella tularensis established in our laboratory, PCR detection of Francesella tularensis in rabbits and ticks was carried out in provinces with high-density rabbits feeding and some provinces and cities with sheep and cattle stock. The results showed that DNA detection of Francesella tularensis from rabbit tissues and ticks carried by cattle and sheep was positive. 12 out of 218 rabbit samples were positive (5.5% positive rate), and 15 tick samples were positive (3.1%) of 490 tick samples. In terms of geographical distribution, most of the positive rabbit samples were from Shandong, Henan and Sichuan province, however, ticks collected from Yunnan and Shandong province showed a higher positive rate. PCR detection showed that Francesella tularensis subspecies in this investigation was F.h, which was a subspecies with strong toxicity. This investigation revealed that Francesella tularensis presented in rabbits and ticks, public health and safety risks of Francesella tularensis existed in Shandong and Yunnan province, which should be paid more attention by the relevant scientific research institutions, medical institutions and government departments.     

Duration of immunity, efficacy and safety in sheep of a recombinant Taenia ovis vaccine formulated with saponin or selected adjuvants.

The efficacy and safety of a recombinant Taenia ovis protein was tested in sheep using 13 different adjuvant formulations, including oil adjuvants, aluminium salts, saponin, Iscoms and DEAE-dextran. The oil adjuvants, saponin and DEAE-dextran gave the highest antibody responses and greatest degree of protection against challenge infection with T. ovis eggs. Duration of immunity studies with a saponin based vaccine showed that highly significant protection (>90% reduction of cyst numbers) was achieved when sheep were challenge infected one month after immunisation. Significant protection (79%) was still present when sheep were challenged 6 months after immunisation. The optimum dose for this batch of saponin was 10 mg, which stimulated a peak antibody titre of 38,400, 4 weeks after immunisation and did not cause injection site reactions. Dialysed saponin was shown to retain its adjuvant properties and allowed an increase in dose to 30 mg without site reaction, resulting in a peak antibody titre of 51,200.     

Discrimination between sheep antibodies to Brucella melitensis and to Brucella ovis

When preparations containing smooth Brucella abortus lipopolysaccharide (LPS) were used as antigens in an ELISA, strong positive reactions were obtained with sera from sheep infected with Brucella melitensis or with Brucella ovis. Oxidation of the LPS with sodium metaperiodate greatly reduced the extent of the cross-reactions with antisera to B. ovis, with little effect on the reactions with antisera to smooth B. melitensis. Periodate oxidation of hot saline extract (HSX) antigen of B. ovis markedly reduced its reactivity in ELISA with anti-B. ovis sera and eliminated cross-reactivity with anti-B. melitensis sera. The reactivity of HSX was maintained after treatment with proteinase K.

A simple ELISA system, in which replicate samples from a single serum dilution were tested in parallel against both B. ovis HSX antigen and periodate-oxidised smooth phase B. abortus LPS, was evaluated. It was found to discriminate well between antibodies induced by vaccination or virulent infection with B. melitensis strains and those induced by infection with B. ovis.     

Seroprevalence of Toxoplasma gondii infection in sheep and alpacas (Llama pacos) in Chile.

Serum samples from 408 sheep from different regions of Chile and 447 alpacas (Llama pacos) from the north of the country were tested for Toxoplasma gondii antibodies. The indirect haemagglutination test (IHAT) was used in both species and the indirect immunofluorescence test (IIFT) was also used on the sheep samples in order to compare the performance of the tests in that species. In both tests, titers ≥1:16 were considered diagnostically significant. Sera from 49 sheep (12%) were positive to T. gondii antibodies by the IHAT. When using the IIFT, 114 sheep sera (28%) were positive. The different results obtained in sheep sera between the tests were significant (p<0.0001). No differences were observed between geographical locations or sex of the sampled sheep regarding serological detection of T. gondii antibodies in sheep. As expected, adult sheep showed higher T. gondii reactivity than young sheep (p=0.0008). The corrected prevalence of toxoplasmosis in alpaca was 16.3% (32 positive out of 447). The rather low prevalence in alpacas may be associated with their extensive management as well as the extreme climatic conditions of The Andes which apparently would not be favorable for the transmission of the parasite.     

The Isolation,Identification and Phylogenetic Analysis of Theileria

Bovine theileriosis was a kind of hemo-protozoan diseases that seriously hindered the sustainable development of cattle industry.In the present study, the infection of Theileria was detected using microscopic examination and species-specifc PCR of T.annulata, T.sergenti and T.sinensis from 18 blood samples collected from a breeding cattle farm in China.Then ITS and MPSP genes were amplified and cloned using universal primers of ITS and allele-specific primers of 4 major piroplasm surface protein (MPSP) from the positive samples.The sequences were used to make alignment, polymorphism and phylogeny analysis.The results showed that 3 samples were positive for Theileria and the 3 positive samples were all the T.sergenti infection.The amplification of allelic MPSP gene of T.sergenti from the 3 positive samples showed that two of them were single infection by Ikeda-type and another one was co-infection with both Chitose-type and Ikeda-type, while Buffeli-type and Thai-type were not detected.Moreover, on the basis of phylogenetic tree constructed with MPSP gene sequences, types 1 and 2 of MPSP were confirmed to be present in the cattle farm.The results revealed that there were T.sergenti infection in the breeding cattle farm, and these parasites at least with 2 allelic MPSP gene types were present, which indicated that the immune prevention and control of the disease became more complicated.Our research laid foundation of the further study on T.sergenti infection and disease prevention and control.     

牛泰勒虫的分离鉴定及进化分析

牛泰勒虫病是严重危害养牛业可持续发展的血液原虫病,本试验采用血涂片镜检和特异性PCR检测技术,对中国某种牛场的18份血样进行了泰勒虫检测,然后分别用ITS基因通用引物和4种MPSP等位基因特异性引物自阳性样品中扩增出对应的基因,克隆测序后,进行序列比对和进化分析,确定泰勒虫基因型。结果显示,自18份牛血样中检出3份阳性样品,且全为瑟氏泰勒虫感染;3个阳性样品的瑟氏泰勒虫MPSP等位基因扩增结果显示,1个阳性样品为I (Ikeda) 和C (Chitose)型的混合感染,另2个样品为I型单一感染,而均无B (Buffeli)和Thai型;用扩增的MPSP基因测序,构建进化树,确认其感染的瑟氏泰勒虫存在MPSP 1型和2型。这些结果表明,该种牛场存在瑟氏泰勒虫感染,且同时存在2种MPSP等位基因型;MPSP等位基因的复杂性可能使该病的免疫防控更加困难。本试验结果为深入研究瑟氏泰勒虫感染情况及免疫防控提供了数据支持,并为养防一体做好监控。     

The sensitivity of PCR and serology in different Theileria parva epidemiological situations in Rwanda

Theileria parva is the causative agent of a lethal tick-borne disease of cattle occurring in eastern, central and southern Africa. Variations in the sensitivity of the serological and molecular tests with seasonal vector occurrence and discrepancies between low PCR prevalence and high T. parva vector density are a setback to estimate true prevalences. Therefore, the objectives of the present studies were to evaluate (1) the sensitivity of three serological tests (IFAT, ELISA and SELISA) and one molecular test (PCR) in the diagnosis of chronic T. parva infections in four different agro-ecological zones of Rwanda and (2) the effect of tick challenge and animal's age on the sensitivity of PCR. Blood samples from 635 bovines were collected in four agro-ecological zones of Rwanda. All sera were screened using the IFAT, ELISA, SELISA and PCR. The binary results of the four diagnostic tests were introduced separately for each agro-ecological zone in a Bayesian model to estimate the prevalence of T. parva infections and the sensitivity of the four diagnostic tests. All test specificities were set to 100%. The estimated T. parva prevalence was much higher (83–85%) than estimations based on single diagnostic tests. The estimated sensitivity of serological tests was relatively constant and ranged from 57 to 75% in the various areas. The sensitivity of PCR showed more pronounced variations, ranging from 66% in the low T. parva transmission (high land) zones compared to 24% in the highly vector infested (low land) zones. Calves and adult cattle (n = 194) were also sampled in regularly and irregularly dipped herds in the low land region. The apparent T. parva prevalence detected by PCR was significantly higher in calves than in adult cattle and in herds regularly treated with acaricides, while no significant differences were found with IFAT. The conditional probability that a sample was positive at PCR while it was positive at IFAT was significantly lower in adults. The implication of these findings in the use of diagnostic assays for epidemiological studies is discussed.     

Investigation of Molecular Etiology of Theileria equi Infection in Three Herds

To explore the prevalence of Theileria equi (T.equi) infection in horse in Guizhou province, the antibody level and 18S rRNA gene were detected from blood samples of Guizhou pony, Southwest horse and Yili horse using competitive ELISA and PCR methods.Giemsa-stained blood smear was prepared to observe T.equi in red blood cells.Intact protozoans of T.equi were observed in red blood cells of horses at Giemsa-stained slide smears with a detection rate of 12.5%.The 18S rRNA gene fragment of T.equi was detected in Guizhou pony, Southwest horse and Yili horse, and the consistent rates with the known nucleotide sequence were 97% to 100%.The PCR result indicated that the positive rates of T.equi in Guizhou pony (76.62%) and Yili horse (73.81%) were similar, which were higher than that in Southwest horse (33.33%).Furthermore, the antibody levels against T.equi in Guizhou pony (24.68%) and Southwest horse (12.12%) were lower than that in Yili horse (31.71%).A weak correlation between the antibody level and the blood physicochemical indexes was calculated from Guizhou pony and Southwest horse, including weak positive correlations with neutrophils numbers, gamma-glutamyl transferase and creatine kinase levels, and weak negative correlations with the numbers of red blood cell, white blood cell, platelet and lymphocyte and contents of hemoglobin.It suggested that a higher proportion of T.equi infection present in three herds.     

3个马群感染马泰勒虫的分子病原学调查

试验采用显微镜观察、PCR和竞争性酶联免疫吸附试验(competitive enzyme-linked immunosorbentassay,cELISA)等方法对贵州矮马、西南马和伊犁马的马泰勒虫病的感染状况进行研究。结果显示,从32份新鲜的血液涂片中,观察到形态完整的马泰勒虫(Theileria equi)虫体,检出率12.5%。从贵州矮马、西南马及伊犁马3个马群血液总DNA中都检测到马泰勒虫的18S rRNA基因片段,与已知序列的同源性为97%~100%;相比之下,贵州矮马与伊犁马的阳性率相近,分别为76.62%和73.81%,西南马较低,仅为33.33%。另外,经cELISA检测,与伊犁马(31.71%)相比,贵州矮马和西南马血液中抗马泰勒虫抗体的阳性率较低,分别为24.68%和12.12%,并与两个马群的血液理化指标存在一定的联系:与中性细胞数量、γ-谷氨酰转移酶和肌酸激酶的含量呈弱正相关;与红细胞、白细胞、血小板、淋巴细胞数量及血红蛋白含量呈弱负相关。这些研究结果提示3个马群中均存在较高比例的马泰勒虫感染。     

绿木霉对币斑病菌的生长抑制作用及对镉的耐受性

木霉菌是具有广阔应用前景的生防制剂，可用于多种植物病害的防治，也可作为重金属的吸附剂。本研究从北京多种草地类型中分离到83株木霉菌株。本研究对8种木霉菌进行了拮抗币斑病菌的平皿试验，其中哈茨木霉152-22、脐孢木霉192-49和绿木霉192-45菌株利用其对空间和营养的竞争能力以及分泌的非挥发性和挥发性物质，显著抑制了币斑病菌的生长。此外，采用梯度试验(0~350 mg·L^-1)研究了这些菌株对高浓度镉胁迫的耐受性。随着镉浓度的增加，虽然三种木霉菌的生长均受到一定程度地抑制，但绿木霉192-45菌株表现出较强的镉耐受能力。这说明绿木霉菌对镉胁迫和币斑病菌均具有较强抗性。综上所述，绿木霉192-45可以在镉富集和币斑病频发的复合胁迫草地中发挥至关重要的作用。     

Detection of Babesia ovis by PCR in Rhipicephalus bursa collected from naturally infested sheep and goats

Polymerase chain reaction (PCR) was used to assess the presence and the frequency of Babesia ovis infection in the adult Rhipicephalus bursa and their hosts in Elazig province located in eastern Turkey. Tick and blood samples were collected from 32 sheep and 28 goats of four selected herds. A total of 226 R. bursa were randomly selected from the collected ticks and their salivary glands were dissected out in 0.85% saline under stereo microscope. DNA amplification method revealed that the frequency of B. ovis infections in the ticks and the small ruminants were 16.37% (37/226) and 6.66% (4/60), respectively. Three positive products, two of which were from the salivary glands of R. bursa and the other from sheep blood were purified from agarose gel and sequenced. The results showed that nucleotide sequences were identical to the previously reported nucleotide sequences of B. ovis. It is concluded that R. bursa might play an important role in the field as a natural vector of the parasite.     

四川省甘孜州牦牛梨形虫感染情况的调查

试验旨在调查甘孜藏族自治州（甘孜州）全部18个县（市）牦牛梨形虫的感染情况。2018年6月至11月采集甘孜州18个县（市）临床健康牦牛全血1 381份,采用靶向18S rRNA的巢式PCR进行梨形虫核酸检测,并挑选梨形虫核酸检测阳性样本PCR产物共计124份测序鉴定虫种。结果显示,1 381份牦牛样本中梨形虫核酸阳性样本438份,平均阳性率为31.72%,其中半农半牧业县1 093份牦牛样本中梨形虫核酸阳性样本385份,平均阳性率为35.22%,纯牧业县288份牦牛样本中梨形虫核酸阳性样本53份,平均阳性率为18.40%;124份牦牛梨形虫核酸阳性样本中鉴定出感染的虫种有中华泰勒虫76份、吕氏泰勒虫25份、东方泰勒虫3份、绵羊泰勒虫2份、双芽巴贝斯虫1份和水牛泰勒虫1份,其中中华泰勒虫感染率为61.29%,吕氏泰勒虫感染率为20.16%。本试验结果表明,甘孜州牦牛梨形虫感染率较高,不同地区之间存在差异,优势虫种为中华泰勒虫和吕氏泰勒虫,为甘孜州牦牛梨形虫病防控提供了重要参考。     

Isolation and Identification of Toxoplasma gondii Isolates from Cats in Eryuan and Nujiang

The assay was aimed to isolate Toxoplasma gondii (T.gondii) strains from stray cat in Eryuan and Nujiang of Yunnan province.The cat tissues (heart,liver,lung and brain) were digested by acid pepsin solution,intraperitoneally inoculated in Kunming mice,passaged at least 3 generations,and followed by specific PCR amplification of partial B1 gene using species-specific primers.Three T.gondii isolates were isolated from 18 stray cats,PCR result showed that we got the specific target band,and the sequence result of the specific PCR product showed that it was ribosome B1 gene sequence of T.gondii. Homology comparison analysis showed that the isolates was 100.0% homology with T.gondii B1.The method of inoculation into the mice with the tissues that was digested by acid pepsin solution was an effective way to isolate T.gondii strain from animals,and the specific PCR assay was an accurate method for the rapid identification of T.gondii.     

Prevalence of Toxocara cati and other parasites in cats' faeces collected from the open spaces of public institutions: Buenos Aires, Argentina

Toxocarosis is a worldwide parasitic infection that affects both cats and dogs. Toxocara cati (Schrank, 1788) syn.Toxocara mystax (Zeder, 1800) prevalence was studied in faeces from stray cats collected from the open spaces of public institutions of Buenos Aires city, both building and surrounding open spaces are fenced off. Of the 465 samples obtained from March to June of 2005, 58.3% were found to have parasite eggs. The following parasites were identified from the 271 positive samples: T. cati (61.2%), Cystoisospora spp. (20.3%), Trichuris spp. (17.0%), Toxascaris leonina (15.1%), Ancylostoma spp. (14%) and Aelurostrongylus abstrusus (2.6%). T. cati prevalence was 35.7% (95% confidence interval: 31.2–40.1), with a 42.2% single isolations. The most frequent combination was T. cati and Cystoisospora spp. (9%). More than half the areas studied showed over 40% prevalence. Seventy-one percent of the collected samples were fresh with a variable moist consistency and 29% were older with a dry consistency. A statistically significant association was found between sample consistency and presence of parasites (χ² = 10.81; p = 0.001) as also between sample consistency and presence of T. cati (χ² = 11.27; p = 0.0007). Moist consistencies were significantly different from the rest: consistency (wet or dry) versus parasites (z = 1.95; p = 0.02) (95% confidence interval: 0.004–0.203); consistency (wet or dry) versus T. cati (z = 3.25; p = 0.0006) (95% confidence interval: 0.075–0.254). The cat population that inhabits these public green spaces contaminates the environment, thus transforming them into dangerous spaces with a variable rate for the human population that spends time in these places.     

Detection of acid production from carbohydrates by Riemerella anatipestifer and related organisms using the buffered single substrate test

One hundred and twenty-one Riemerella anatipestifer field strains from wild birds, domesticated poultry and pigs were examined for their ability to produce acid from carbohydrates by using conventional biochemical and buffered single substrate (BSS) test methods. The type strains of the species R. anatipestifer and taxometrically related genera Chryseobacterium and Bergeyella were included in the study. In contrast to 10 indole-positive R. anatipestifer variant strains, only a few of the 111 typical indole-negative R. anatipestifer strains produced acid from dextrin (32%), glucose (17%), maltose (14%) and trehalose (5%) when the conventional test procedure was used. Using the BSS test all the field isolates and the type strain of R. anatipestifer produced acid from one or more carbohydrates, most of them from dextrin (96%), maltose (91%), glucose (87%), mannose (83%), less frequently from fructose (38%) and only in some cases from trehalose (19%). One hundred and six (87%) of the R. anatipestifer strains could be assigned to 8 biovars, based on the diversity of the carbohydrate acidification patterns. The remaining 16 R. anatipestifer isolates gave delayed reactions and displayed 13 different carbohydrate acidification profiles. The Chryseobacterium and Bergeyella type strains also produced acid from more carbohydrates when the BSS test was used. The BSS-carbohydrate acidification pattern of the Chryseobacterium indologenes strain was similar to that of R. anatipestifer biovar 3.     

Larval salivary gland proteins of the sheep nasal bot fly, (Oestrus ovis L.), are major immunogens in infested sheep

Tissue extracts from larval instars of the sheep nasal bot, Oestrus ovis, were resolved by gel electrophoresis under both native and denaturing conditions. Polypeptides resolved under these conditions were tested by immunoblotting against sera of infested sheep. Of all tissues examined in this study, salivary glands proved to be major immunogens in infested sheep. Salivary gland polypeptides were also detected in the washing solution as larval secretory products (LSP). To a minor extent, a few polypeptides from the larval cuticle were also found to be immunogenic, but they did not contribute to LSP. These results were further corroborated by nasal infestation of rabbits that also developed specific antibodies against larval salivary gland polypeptides from Oestrus ovis.     

C5a-C5aR轴在鸭疫里氏杆菌感染致鸭肝损伤中的作用

本试验旨在阐明C5a-C5aR轴在鸭疫里氏杆菌（Riemerella anatipestifer）感染致雏鸭肝损伤中的作用。将保存的鸭疫里氏杆菌复苏培养，同时制备鸭抗凝血，将鸭疫里氏杆菌与鸭抗凝血混匀，分别与抗C5a抗体和抗C5aR抗体孵育后进行全血试验，利用ELISA检测C5a及各炎性因子表达水平；利用鸭疫里氏杆菌感染雏鸭，同时分别用抗C5a抗体和抗C5aR抗体处理进行动物试验，采集主要组织进行病理组织学检查；采集雏鸭外周血和肝组织进行细菌计数；采集外周血分离血清后，进行血清酶活性检测，应用ELISA检测血清C5a及炎性因子水平；采集肝组织，利用荧光定量PCR检测主要炎性因子mRNA转录水平。结果显示，在全血试验和动物试验中，与R.anatipestifer组相比，R.anatipestifer +anti-C5a组和R.anatipestifer +anti-C5aR组C5a、TNF-α、IL-6和IL-1β表达水平显著降低（P<0.05）；阻断C5a-C5aR轴可显著降低鸭疫里氏杆菌感染雏鸭的发病率和死亡率，同时减轻雏鸭心、肝和脾组织损伤；阻断C5a-C5aR轴能显著降低鸭疫里氏杆菌感染雏鸭外周血和肝细菌数及谷丙转氨酶（alanine aminotransferase，ALT）和谷草转氨酶（aspartate aminotransferase，AST）水平；荧光定量PCR检测发现，与R.anatipestifer组相比，R.anatipestifer +anti-C5a和R.anatipestifer +anti-C5aR组C5aR、Sphk1、FGL2、TNF-α和IL-1β mRNA转录水平显著降低（P<0.05）。本研究成功证实C5a-C5aR轴激活有助于鸭疫里氏杆菌感染雏鸭，阻断C5a-C5aR轴可显著减轻雏鸭组织损伤和炎症反应，为进一步研究抗鸭疫里氏杆菌感染药物提供新思路。