Infection-interactions in Ethiopian village chickens

Chickens raised under village production systems are exposed to a wide variety of pathogens, and current or previous infections may affect their susceptibility to further infections with another parasite, and/or can alter the manifestation of each infection. It is possible that co-infections may be as important as environmental risk factors. However, in cross-sectional studies, where the timing of infection is unknown, apparent associations between infections may be observed due to parasites sharing common risk factors. This study measured antibody titres to 3 viral (Newcastle disease, Marek's disease and infectious bursal disease) and 2 bacterial (Pasteurella multocida and Salmonella) diseases, and the infection prevalence of 3 families of endo- and ecto-parasites (Ascaridida, Eimeria and lice) in 1056 village chickens from two geographically distinct populations in Ethiopia. Samples were collected during 4 cross-sectional surveys, each approximately 6 months apart. Constrained ordination, a technique for analysis of ecological community data, was used to explore this complex dataset and enabled potential relationships to be uncovered and tested despite the different measurements used for the different parasites. It was found that only a small proportion of variation in the data could be explained by the risk factors measured. Very few birds (9/1280) were found to be seropositive to Newcastle disease. Positive relationships were identified between Pasteurella and Salmonella titres; and between Marek's disease and parasitic infections, and these two groups of diseases were correlated with females and males, respectively. This may suggest differences in the way that the immune systems of male and female chickens interact with these parasites. In conclusion, we find that a number of infectious pathogens and their interactions are likely to impact village chicken health and production. Control of these infections is likely to be of importance in future development planning.     

实验性鸡大肠杆菌病病理学动态变化

用致病性大肠杆菌O18分离株和／或低致病性禽流感病毒（Mildly pathogenic avian influenza virus ,MPAIV)接种10－12日龄SPF鸡。在接种后1－96h进行临床症状与大体病理变化、组织学观察发现：大肠杆菌接种组、MPAIV接种组和健康接种组除扑杀鸡外未见鸡死亡，MPAIV与大肠杆菌混合接种组除扑杀鸡外死亡率为24％。混合接种组的病变比大肠杆菌接种组出现的时间早，恢复也慢，各脏器的病理变化更严重。MPAIV主要引起各实质器官的坏死，结果表明，大肠杆菌经气管内接种后试验鸡主要表现为呼吸道的炎症反应；MPAVI可使鸡大肠杆菌病严重化。     

Changes in peripheral blood leukocyte subpopulations in piglets co-infected experimentally with porcine reproductive and respiratory syndrome virus and porcine circovirus type 2

Porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) are pathogens, which can significantly affect the swine industry worldwide. Field surveys suggest that simultaneous PRRSV and PCV2 infection is common in pigs. The objective of this study was to measure the changes in peripheral blood leukocyte subpopulations in piglets co-infected experimentally with PRRSV and PCV2, in order to analyze the synergistic influence of co-infection on the immune system. Changes in peripheral blood leukocyte subpopulations were systematically measured by flow cytometry (FCM). The levels of antibodies to PRRSV and PCV2 were detected by indirect Enzyme-Linked ImmunoSorbent Assay (ELISA) and the indirect fluorescent antibody test (IFA), respectively. Serum viral loads were measured using real-time PCR. The results showed that piglets co-infected with PRRSV and PCV2 exhibited slower generation and lower levels of antibodies to PRRSV and PCV2, and increased amounts and a prolonged presence of both PRRSV and PCV2 in serum, in comparison to the piglets infected with either virus alone. The major finding in our study was that the total and differential leukocyte counts, including white blood cells (WBCs), monocytes, granulocytes and lymphocytes (T, B and NK cells, as well as T-cell subpopulations), dramatically decreased early during co-infection with PRRSV and PCV2 for about two weeks, in contrast with animals singly infected with either PRRSV or PCV2. These results suggest that PRRSV and PCV2 co-infection results in a synergistic decrease in immune cells in the peripheral blood of piglets. These data contribute to the understanding of the immunosuppressive effects resulting from PRRSV and PCV2 co-infection in pigs.     

一例猪瘟混合感染副猪嗜血杆菌和猪蛔虫的案例诊治

2019年11月底,湖北某商品猪场保育猪只出现厌食、消瘦、呼吸困难、咳嗽等症状,偶有病猪急性死亡,为查找病因,控制疫情,减少损失,依次通过流行病学调查、病理剖检和实验室检测,最终确定该发病猪场为感染猪瘟病毒,进而继发感染Hps-4混合感染,并伴随蛔虫感染导致。通过筛选敏感药物治疗,优化生产管理,成功控制了此次疫情。该案例对此次疫情进行了分析总结,就加强生物安全建设,优化养殖管理,实现生产质量可控提供了参考建议。也为猪瘟混合感染呼吸系统细菌性疾病的防控提供参考。     

猪繁殖与呼吸综合征·猪瘟和猪圆环病毒Ⅱ型混合感染的鉴定及病原特性分析

[目的]鉴定由猪瘟病毒（CSFV）、猪繁殖与呼吸综合征病毒（PRRSV）、猪圆环病毒Ⅱ型（PCV2）引发的猪疫病并进行病原特性分析。[方法]采集湖南湘潭（编号为HN/XT）发病猪的组织和脏器,进行DNA、RNA提取,然后进行PCR扩增、测序;同时采用细胞分离技术进行毒株的分离、鉴定。[结果]测序分析结果表明,CSFV、PRRSV和PCV2与目前流行毒序列及GenBank下载序列氨基酸同源性分别为90%、94%和96%左右,可见该次猪病疫情至少是由CSFV、PRRSV和PCV23种病毒混合感染引起。[结论]该研究可对当前危害养猪业混合感染疾病的流行病学研究和净化控制提供数据。     

Isolation and characterization of a rhabdovirus from co-infection of two viruses in mandarin fish

Co-infection of two viruses has been observed in mandarin fish (Siniperca chuatsi), but the two viruses have not been characterized. In this study, a rhabdovirus has been isolated from the co-infected two viruses extracted from the diseased mandarin fish, and its morphological structure and partial biochemical and biophysical characteristics have been observed and analyzed. The isolated rhabdovirus has a typical bullet shape, and is therefore called S. chuatsi rhabdovirus (SCRV). And, the isolated rhabdovirus produced a higher titer (10^8.5 TCID₅₀ ml^− 1) than did the co-infecting viruses (10^6.5 TCID₅₀ ml^− 1). Subsequently, the viral genome RNA was extracted, and used as template to clone the complete nucleoprotein (N) gene by RT-PCR amplification. Cloning and sequencing of the SCRV N protein revealed 42%-31% amino acid identities to that of trout rhabdovirus 903/87 and the rhabdoviruses in genus Vesiculovirus. SDS-PAGE separation of the isolated SCRV and other two rhabdoviruses also revealed obvious polypeptide profile difference. Moreover, the anti-SCRV N protein antibody was prepared, and the anti-SCRV N protein antibody only could recognize the SCRV N protein, whereas no antigenicity was detected in other two rhabdoviruses. The data suggested that the SCRV should be a rhabdovirus member related to the genus Vesiculovirus in the Rhabdoviridae.     

Genotyping of Haemophilus parasuis from diseased pigs in China and prevalence of two coexisting virus pathogens

From December 2003 to July 2006, a total of 131 (28.4%) Haemophilus parasuis strains were isolated from 462 cases examined in our diagnostic laboratory. These strains were isolated from clinically diseased pigs, and 50 of them along with 15 reference strains of all known serovars were subjected to PCR–FRLP (restriction fragment length polymorphism) analysis by tbpA gene. The analysis of the 1.9-kb tbpA amplicon using TaqI, AvaI and RsaI endonucleases produced 9 RFLP patterns for the15 reference strains and 13 patterns for the 50 field isolates. And the first three prevalent genotypes in China were DBN (38%), ABN (18%) and DBP (12%). Meanwhile, co-infection of H. parasuis, PRRSV and PCV2 was examined in the 462 pig herds. It is indicated that 11.5% cases (53), 27.9% cases (129) and 4.8% cases (22) were infected only by H. parasuis, PRRSV and PCV2, respectively; and 19.2% cases (89) and 3.0% cases (14) were co-infected with two or all of the three pathogens, respectively; the rest 33.6% cases (155) were not infected by any of the three pathogens. It is confirmed that H. parasuis existed widely in southeast China with numerous genotypes.     

Occurrence and species level diagnostics of Campylobacter spp., enteric Helicobacter spp. and Anaerobiospirillum spp. in healthy and diarrheic dogs and cats

In order to study the occurrence and co-infection of different species of Campylobacter, enteric Helicobacter and Anaerobiospirillum in dogs and cats and define a possible association between these microrganisms and gastrointestinal disorders, 190 dogs and 84 cats, either healthy or with diarrhea, were sampled between 2002 and 2003. Thirty-three C. upsaliensis, 17 C. jejuni, 2 C. helveticus, 1 C. lari isolates from dogs and 14 C. helveticus, 7 C. jejuni, 6 C. upsaliensis isolates from cats were identified using species-specific PCR and phenotypic tests. Whole cell protein profile analysis, phenotypic tests, PCR-RFLP of gyrB and a phylogenetic study of partial groEL and 16S rRNA sequences were used to identify 37 H. bilis, 22 H. canis and 14 H. cinaedi in dogs and 12 H. canis, 5 H. bilis and 2 H. cinaedi in cats. Whole cell protein profile analysis, phenotypic tests and species-specific PCR of 16S rRNA were used to identify 14 A. succiniciproducens, 12 A. thomasii isolates and one unidentified Anaerobiospirillum sp. isolate in dogs and 3 A. thomasii isolates in cats. Fifty-two animals (19%) were positive for the isolation of more than one genus. No significant statistical correlation was found between any isolates of Campylobacter, Helicobacter or Anaerobiospirillum spp. or the various co-infection rates, and the presence of diarrhea in either dogs or cats. Campylobacter isolates were also tested for antibiotic resistance using the agar dilution method.     

First identification of Sarcocystis tenella (Railliet, 1886) Moulé, 1886 (Protozoa: Apicomplexa) by PCR in naturally infected sheep from Brazil

Sarcocystis tenella is a dog–sheep protozoan parasite, causing a widespread enzootic muscle parasitosis and neurological disease mainly in lambs. This parasite is pathogenic to sheep and important to the economical production of sheep. The present study was initially aimed to determine Toxoplasma gondii infection and the occurrence of co-infection with other Apicomplexa parasites in 602 Brazilian sheep. Twenty of these sheep were positive with antibodies to T. gondii by MAT and IFAT-IgG tests, positive with PCR-RFLP genotyping at multiple loci, and parasites were isolated from mice infected with sheep tissue samples. Two additional sheep born in Brazil, a 2-year-old female Polwarth (Ideal) sheep, a breed originated from Australia (#1), and a 1-year-old male Corriedale sheep, a breed originated from New Zealand and Australia (#2) were positive to T. gondii antibodies by serum tests, and PCR, but negative for bioassay in mice. In genotyping at 12 loci, sheep #1 sample and #2 presented positive results only for some markers. PCR-RFLP of 18S ribosomal RNA (18S rRNA) was performed in all 22 animals to identify the possibility of co-infection of T. gondii with other Apicomplexa parasites, such as S. tenella, Neospora caninum and Hammondia hammondi, resulting in a T. gondii profile for the first 20 animals and a unique genotyping profile for sheep #1 and #2, identical to S. tenella. The 18S rRNA PCR products (310 bp) were sequenced and blasted to GenBank database at NCBI. Both samples were identical to S. tenella 18S rRNA gene (GenBank accession number L24383-1). These results suggest the existence of co-infection of S. tenella with T. gondii in ewes from Brazil.