感染链

感染链（infection chain）指感染传播需要的三个环节，即感染源、传播途径和易感染群，这三个环节组成感染链。细菌、病毒、其它感染因子的存在和传播，必定具备一定的因素和条件。疾病必须在一定条件下才能传播给其他人，这些条件包括：①必须具备感染因子；②感染因子必须有生存的地方（感染源），很多引起疾病的微生物（致病微生物）在人体内繁殖，然后在人与人之间传播，一些微生物通过污染的食物或水、排泄物、或被感染的动物和昆虫咬伤传播。

成都市人感染猪链球菌病的流行病学调查及防制

目的：明确人感染猪链球菌病的传染来源、途径、流行特征，为制定预防控制措施提供依据。方法：由经过培训的现场流行病学人员，用统一的流行病调查表和诊断标准进行调查。结果：发现病人26例，病死猪为传染源，96％的病例的感染途径主要为经手部伤口。在宰杀、洗切病死猪的过程中感染，潜伏期通常为2～3d，养猪的农民、屠宰人员、切洗分割和搬运病死猪内的人员为本病的高暴露人群占90％以上；发病高峰为7～8月、病例间无时间、空间聚集和人与人传播的联系；人感染猪链球菌病的病原体为猪链球菌病2型。结论：切断人与病（死）猪等家畜接触为主的综合性防治措施是有效的。

大链壶菌感染对致倦库蚊幼虫体内元素的影响

目的 了解大链壶菌感染对致倦库蚊幼虫体内元素的影响 ,从无机化学角度探讨大链壶菌 (L agenidiumgiganteum)灭蚊的可能机制。 方法 采用原子发射光谱仪 ,测定正常蚊幼虫 (对照组 )与感染大链壶菌后不同时期蚊幼虫 (实验组 )组织与生命活动有关的 18种元素含量的变化。 结果 感染 0 h(即加入大链壶菌块后 30～ 4 8h,幼虫体表布有黑化点 ,为初始感染 ) ,实验组的 Ca、Cu含量明显低于对照组 ,Co、Cd含量明显高于对照组。感染 2 4 h,实验组和对照组间有 16种元素含量有明显差异 ,其中 Ca、Mg、Na、P、Fe、Zn、Cu、Mn、Cr含量明显低于对照组 ,K、Mo、Co、Ni、Al、Cd、Pb含量明显高于对照组。感染 4 8h,除 Sr外 ,17种元素含量与对照组间均有明显差异。 结论 大链壶菌感染蚊幼虫后 ,使多种维持正常生命活动的元素呈降低趋势 ,而一些重金属等有害元素在体内储积。这可能是影响蚊幼虫正常生命活动以致死亡的重要原因。

新生儿B族链球菌感染发病机制及治疗(综述)

B族链球菌(Group B streptococci,GBS)是威胁新生儿生命的主要致病菌之一。具有发病率、病死率高的特点,自七十年代初已引起世界范围内关注。国外对GBS发病机制及治疗研究发展很快,本文就这方面内容加以综述。

甲链感染及抗链球菌脱氧核糖核酸酶B（ADNaseB）测定的价值

在进行甲组乙型溶血性链球菌（GAS）流行病学调查时，对GAS感染后产生的抗体抗链球菌脱氧核糖核酸酶（B（ADNaseB)进行了为期一年的追踪观察。结果显示重庆地区的ADNaseBGMT水平城乡分别为117u/ml与101u/ml，正常值最高限为200u/ml,≥240u/ml为异常值，城乡GAS感染率分别为26.2%与23.2%。ADNaseB、GAS感染率、风湿热9RF）发病率形成密切的联系。

甲链感染及抗链球菌脱氧核糖核酸酶B（ABDNaseB）测定的价值

在进行甲组乙型溶血性链球菌（GAS）流行病学调查时，对GAS感染后产生的抗体抗链球菌脱氧核糖核酸酶B（ADNaseB)进行了为期一年的观察，结果显示出重庆地区的ADNaseB GMT水平城乡分别为117u/ml与101u/ml，正常最高限为200u/ml,240u/ml为异常值，城乡GAS感染率分别为26．2％与23．2％，ADNaseBGAS感染率，风湿热（RF）发病率表成密切的联系。

长链PCR技术评价^(60)Co-γ射线灭活病毒的研究

目的探讨用长链PCR技术评价60Co-γ射线辐照灭活伪狂犬病毒(pseudorabies virusPRV),后残余病毒感染性的可行性。方法针对PRV糖蛋白gD基因前后的保守区设计预计产物长短不一的5对引物,用PCR扩增经不同剂量60Co-γ射线照射后的PRV核酸,并同时以细胞感染法做平行对照。结果60Co-γ射线辐射对PRV核酸的破坏有剂量依赖性,随着60Co-γ射线剂量的增加,PRV核酸被破坏程度增加,剂量≥20kGy时完全被灭活。5条不同长度PCR扩增产物中,只有长片段3.9kb的检出与细胞培养结果一致。结论γ射线对PRV核酸的损伤程度随γ射线剂量增加而增大;用长链PCR(3.9kb)来评价经60Co-γ射线辐照灭活病毒后残余病毒的感染性是可行的。

Update on occult hepatitis B virus infection

The event of mutations in the surface antigen gene of hepatitis B virus(HBV) results in undetectable hepatitis B surface antigen with positive/negative anti-hepatitis B core(anti-HBc) antibody status in serum and this phenomenon is named occult hepatitis B infection(OBI). The presence of anti-HBc antibody in serum is an important key for OBI tracking, although about 20% of OBI cases are negative for anti-HBc antibody. The diagnosis of OBI is mainly based on polymerase chain reaction(PCR) and real-time PCR assays. However, real-time PCR is a more reliable method than PCR. OBI is a great issue for the public health problem and a challenge for the clinical entity worldwide. The persistence of OBI may lead to the development of cirrhosis and hepatocellular carcinoma. With regard to OBI complications, the screening of HBV DNA by the highly sensitive molecular means should be implemented for:(1) patients with a previous history of chronic or acute HBV infection;(2) patients co-infected with hepatitis C virus/human immunodeficiency virus;(3) patients undergoing chemotherapy or anti-CD20 therapy;(4) recipients of organ transplant;(5) blood donors;(6) organ transplant donors;(7) thalassemia and hemophilia patients;(8) health care workers;(9) patients with liver related disease(cryptogenic);(10) hemodialysis patients;(11) patients undergoing lamivudine or interferon therapy; and(12) children in time of HBV vaccination especially in highly endemic areas of HBV. Active HBV vaccination should be implemented for the close relatives of patients who are negative for OBI markers. Thus, the goal of this review is to evaluate the rate of OBI with a focus on status of high risk groups in different regions of the world.

RELATIONSHIP BETWEEN HUMAN PARVOVIRUS B19 INFECTION AND APLASTIC ANEMIA

Objective. To explore the relationship between human parvovirus B19 (HPV B19) infection and aplastic anemia (AA) and to investigate the role of HPV B19 in the occurrence of AA. Methods. The presence of HPV B19 DNA was detected in the peripheral blood samples of 60 patients with AA (children 38 and adults 22) by nested polymerase chain reaction (PCR) assay, and 30 healthy persons were selected as control. Results. Sixteen (26.7％ ) of 60 AA cases were HPV B19 DNA positive, while all the samples in the control group were negative for HPV B19 (P = 0.000914). Among the case group, the positive rates of HPV B19 DNA were 21.4％ (6 / 28), 30.0％ (3 / 10), 20.0％ (1 / 5) and 35.3％ (6 / 17) in children acute AA (AAA), children chronic AA (CAA), adults AAA and adults CAA patients respectively, which were significantly higher than that in the control group. Furthermore, there was no remarkable difference between children AA and adults AA in the 16 HPV B19 DNA positive patients; neither was there between AAA and CAA. Conclusions. HPV B19 infection is not only correlated with the occurrence of children AAA and CAA, but also with adults AAA and CAA, and might be an important viral cause for AA in humans.

Crimean-Congo Hemorrhagic Fever: An Overview

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic viral infection that is a serious threat to humans. The disease is widely distributed in Africa, Asia, and Europe and has developed into a serious public health concern. Humans become infected through the bites of ticks, by contact with a patient with CCHF, or by contact with blood or tissues from viremic livestock. Microvascular instability and impaired hemostasis are the hallmarks of the infection. Infection in human begins with nonspecific febrile symptoms, but may progress to a serious hemorrhagic syndrome with high mortality rates. Enzyme-linked immunoassay (ELISA) and polymerase chain reaction (PCR) are the most used and specific tests for the diagnosis. The mainstay of treatment is supportive. Although definitive studies are not available, ribavirin is suggested to be effective especially at the earlier phase of the infection. Uses of universal protective measures are the best way to avoid the infection. In this review, all aspects of CCHF are overviewed in light of the current literature.

Biovars and Serotypes of Ureaplasma Urealyticum among Chinese Women Undergoing Routine Gynecologic Exam, Women with Sexually Transmitted Infections, and Female Sex Workers

Objectives: To characterize the distribution pattern of biovars and scrotypes or Ureaplasma urealyyicum in normalhealthy women, sexually transmitted infections clinic clients,and in sex workers. Methods: We cultured cervical swabs taken from 261physical check-up clients, 599 STI clinic outpatients and 98 sexworkers using commercial selective medium. Some positivecultures were further biotyped and serotyped by PCR. Results: (1) U. urealyticum is more commonly isolated in sexworkers (90.8%) than in the physical check-up group (60.9%)or the STI outpatient group (61.3%) (P<0.001). (2) Biovar 1of U. 'realyticum (95.0%), especially single infection ofserotype 1. 3, and 6 of biovar 1, is commonly found in healthywomen. (3) Biovar 2 infection of U urealyticum is moreprevalent in sex workers (28.1%) and STI outpatients group(26.6%) than that in the physical check-up group (4.9%) (P<0.001). (4) Mixed infection caused by more than one serotypeof U urealyticum increased from physical check-up group(8.6%) to STI utpatients (12.4%) to sex workers (23.9%) (P<0.01). (5) There is no statistically significant difference in thedistribution of serotype 1, 3, and 6 of biovar 1 among thesethree groups (P=0.763). (6) The PCR method described here isrelatively simple, rapid and specific for the biotyping andserotyping of biovar 1 of U urealyticum. Conclusion: We should pay more attention to biovar 2 andmixed infections of U. urealyticum than single infection ofhiovar 1 in clinic practice. PCR is a good method for biotypingand serotvping.

In vivo Inhibition of NAS Preparation on H9N2 Subtype AIV

NAS preparation, a kind of Chinese herbal medicine found by the Yunnan Eco-agricultural Research Institute, has potential antiviral activity. In this paper, the inhibiting effect of NAS preparation on H9N2 subtype Avian influenza virus (AIV) was investigated in vivo. Chickens infected with H9N2 virus were treated with NAS preparation for 4 days. The virus was then detected by hemoagglutination (HA) test and reverse transcription polymerase chain reaction (RT-PCR). The results showed that no H9N2 virus could be detected at the 7th day when the chickens were treated with 0.2g/kg/d or 0.1g/kg/d of NAS preparation. However the virus could be detected in other chickens without NAS preparation treatment. This result suggested that NAS preparation may be a potential drug candidate to control infection of H9N2 subtype AIV in chickens.

Identification of 11 STD Pathogens in Semen Using Polymerase Chain Reaction （PCR） and ＂Flow-through＂ Hybridization Technology

The transmission of sexually transmitted infection （STI） pathogens from an infected donor to the recipient of a semen donation in assisted conception may result not only in acute infection but also in long-term reproductive complications or adverse outcomes of pregnancy including infection of the offspring. Semen samples were obtained by masturbation into sterile containers. Samples were subjected to semen analysis within one hour of collection and processed for freezing within two hours of collection. The sperm motility was determined. After DNA extraction the PCR was performed and amplicons are subsequently hybridized to pathogen-specific capturing probes via ＂Flow-through＂ hybridization. During our study we came across with the STI pathogens present in semen and main cause of infertility was note. It was also observed that route for the transfer for these STI pathogens were the men working in other cities and visited commercial sex workers and their complained for infertility. We have reported our data that after the normal sperm count in semen samples of men with infertility or subfertility they were infected with Chlamtdia trachomatis, Neisseria gonorrhoeae, and Mycoplasma hominis. In our study all the 11 pathogens were detected which cause serious reproductive complications and infection in their offspring.

Investigation on Infectious Agents of Aborted Pig Fetuses and Its Correlation with PRRSV MLV Vaccine

Infectious agents causing aborted fetus problems in domestic pigs were investigated in this study. More than 10 different infectious agents were known to cause abortion in swine and the major eight viruses among them were inspected. One hundred twelve samples of aborted fetuses from nine provinces in South Korea were collected during April to November, 2013 in this study for the diagnosis of infectious agents causing abortions in pigs. Eight major infection viruses were examined in this study mainly using various diagnostic kits and reverse transcriptase polymerase chain reaction （RT-PCR）. Positive rate of the detection differed from each viruses. In this study, the main focus was the porcine reproductive and respiratory syndrome virus （PRRSV）, which took the second large portion in the positive rate of detection, and then its ORF5 gene was compared with modified live virus （MLV） vaccine strain to figure out the influence of vaccine on disease. Between four positive samples＇ sequence, two of them were 99.9%-100% similar to MLV vaccine strain and two other samples were 88.6%-92.7% similar. Similarity rate of the sequences between the vaccine and virus from aborted fetuses are very crucial, because it implies that abortion in swine can be made due to the usage of vaccine not only by the infection of field virus, and if MLV vaccine actually do have an impact on the infection, usage of the vaccine should be reconsidered.

Detection of Streptococci in the Throat Swabs from Upper Respiratory Tract Infections in Kurdistan Region

The study was conducted for the detection of streptococcus bacteria of two groups of people with pharyngitis and tonsillitis. All the plates with α-haemolytic and β-haemolytic colonies were identified by conventional methods. β-haemolytic colonies was further identified by observing its sensitivity towards bacitracin disc tested on sheep blood agar plate. Alpha-hemolytic colonies on blood agar plate were identified with optchin disc. Different bacteria which included Streptococcus pyogenes, S. agalactiae, S. pnenmoniae and S. celis that had proportions 48.57%, 51.43%, 59.1% and 40.9% respectively isolated by the sensitivity test （depends on agents bacitracin and optchin）. Isolates of beta-Streptococcal which included S. pyogenes at child group （A） and the isolates alpha- Streptococcal which included S. pnenmoniae at adults group （B） showed marked rise.