In medicine, infectious disease or communicable disease is disease caused by a biological agent such as by a virus, bacterium or parasite. This is contrasted to physical causes, such as burns or chemical ones such as through intoxication.

Basics

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Infectious diseases are the invasion of a host organism by a foreign replicator, generally microorganisms, often called microbes, that are invisible to the naked eye. Microbes that cause illness are also known as pathogens. The most common pathogens are various bacteria and viruses, though a number of other microorganisms, including some kinds of fungi and protozoa, also cause disease. Prions are borderline, and memes would not usually be considered in this scope. An infectious disease is termed contagious if it is easily transmitted from one person to another.

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BMC Infectious Diseases - Latest Articles

Is a single dose of meningococcal serogroup C conjugate vaccine sufficient for protection? Experience from the Netherlands
Patricia KaaijkArie van der EndeGuy BerbersGermie van den DobbelsteenNynke Rots Wed, 08 Feb 2012 00:00:00 -0000
Background: The first meningococcal serogroup C (MenC) conjugate vaccine was licensed in 1999 and introduced in the United Kingdom. Countries that have implemented the MenC vaccine since then in their national immunisation programmes use different schedules. Nevertheless, all involved countries seem to experience substantial declines in the incidence of MenC disease.DiscussionSince 2001, the MenC conjugate vaccine has been implemented in the Netherlands by offering a single dose to all children aged 14 months. Prior to the introduction of the vaccine into the national immunisation programme, a catch-up vaccination campaign was initiated in which a single dose of the MenC conjugate vaccine was offered to all children aged from 14 months up to and including 18 years. Since then, there has been no report of any case of MenC disease among immunocompetent vaccinees. Administration of a single dose of MenC conjugate vaccine after infancy could be beneficial considering the already complex immunisation schedules with large numbers of vaccinations in the first year of life. The present paper deals with the advantages and critical aspects of a single dose of the MenC conjugate vaccine.SummaryA single dose of MenC conjugate vaccine at the age of 14 months in combination with a catch up vaccine campaign appeared to be a successful strategy to prevent MenC disease in the Netherlands, thereby confirming that a single dose of the vaccine could sufficiently protect against disease. Nevertheless, this approach can only be justified in countries with a relatively low incidence of serogroup C meningococcal disease in the first year of life. Furthermore, a good surveillance programme is recommended for timely detection of vaccine breakthroughs and outbreaks among non-vaccinees, since long-term protection after a single dose in the second year of life cannot currently be guaranteed.
Group B streptococcal carriage, serotype distribution and antibiotic susceptibilities in pregnant women at the time of delivery in a refugee population on the Thai - Myanmar border
Claudia TurnerPaul TurnerLinda PoNaw ManerAruni De ZoysaBaharak AfsharAndroulla EfstratiouPaul HeathFrancois Nosten Wed, 08 Feb 2012 00:00:00 -0000
Background: Group B Streptococcus (GBS) is the leading cause of neonatal sepsis in the developed world. Little is known about its epidemiology in the developing world, where the majority of deaths from neonatal infections occur. Maternal carriage of GBS is a prerequisite for the development of early onset GBS neonatal sepsis but there is a paucity of carriage data published from the developing world, in particular South East Asia. Methods: We undertook a cross sectional study over a 13 month period in a remote South East Asian setting on the Thai-Myanmar border. During labour, 549 mothers had a combined vaginal rectal swab taken for GBS culture. All swabs underwent both conventional culture as well as PCR for GBS detection. Cultured GBS isolates were serotyped by latex agglutination, those that were negative or had a weak positive reaction and those that were PCR positive but culture negative were additionally tested using multiplex PCR based on the detection of GBS capsular polysaccharide genes. Results: The GBS carriage rate was 12.0% (95% CI: 9.4-15.0), with 8.6% positive by both culture and PCR and an additional 3.5% positive by PCR alone. Serotypes, Ia, Ib, II, III, IV, V, VI and VII were identified, with II the predominant serotype. All GBS isolates were susceptible to penicillin, ceftriaxone and vancomycin and 43/47 (91.5%) were susceptible to erythromycin and clindamycin. Conclusions: GBS carriage is not uncommon in pregnant women living on the Thai-Myanmar border with a large range of serotypes represented.
A large, population-based study of age-related associations between vaginal pH and human papillomavirus infection
Megan ClarkeAna Cecilia RodriguezJulia GageRolando HerreroAllan HildesheimSholom WacholderRobert BurkMark Schiffman Wed, 08 Feb 2012 00:00:00 -0000
Background: Vaginal pH is related to genital tract inflammation and changes in the bacterial flora, both suggested cofactors for persistence of human papillomavirus (HPV) infection. To evaluate the relationship between vaginal pH and HPV, we analyzed data from our large population-based study in Guanacaste, Costa Rica. We examined vaginal pH and the risk of HPV infection, cytological abnormalities, and C. trachomatis infection. Methods: Our study included 9,165 women aged 18-97 at enrollment with a total of 28,915 visits (mean length of follow-up = 3.4 years). Generalized estimating equations were used to evaluate the relationship between vaginal pH and HPV infection (both overall and single versus multiple types) and low-grade squamous intraepithelial lesions (LSIL), the cytomorphic manifestation of HPV infection. The relationship between enrollment vaginal pH and C. trachomatis infection was assessed by logistic regression. Results were stratified by age at visit. Results: Detection of HPV was positively associated with vaginal pH, mainly in women <35 years (p-trend = 0.009 and 0.007 for women aged <25 and 25-34 years, respectively). Elevated vaginal pH was associated with 30% greater risk of infection with multiple HPV types and with LSIL, predominantly in women younger than 35 and 65+ years of age. Detection of C. trachomatis DNA was associated with increased vaginal pH in women <25 years (OR 2.2 95% CI 1.0-5.0). Conclusions: Our findings suggest a possible association of the cervical microenvironment as a modifier of HPV natural history in the development of cervical precancer and cancer. Future research should include studies of vaginal pH in a more complex assessment of hormonal changes and the cervicovaginal microbiome as they relate to the natural history of cervical neoplasia.

pubmed: 0019-9567

Chlamydia muridarum T cell antigens and adjuvants that induce protective immunity in mice.
Yu H, Karunakaran KP, Jiang X, Shen C, Andersen P, Brunham RC Chlamydia muridarum T cell antigens and adjuvants that induce protective immunity in mice. Infect Immun. 2012 Jan 30; Authors: Yu H, Karunakaran KP, Jiang X, Shen C, Andersen P, Brunham RC Abstract Major impediments to a Chlamydia vaccine lie in discovering T cell antigens and polarizing adjuvants that stimulate protective immunity. We previously reported the discovery of three T cell antigens (PmpG, PmpF and RplF) via immunoproteomics that elicited protective immunity in the murine genital tract infection model against Chlamydia infection after adoptive transfer of antigen-pulsed dendritic cells). To expand the T cell antigen repertoire necessary for a Chlamydia vaccine, we evaluated 10 new Chlamydia T cell antigens discovered via immunoproteomics in addition to the 3 antigens reported earlier as a molecular subunit vaccine. We first tested five adjuvants including three cationic liposome formulations [DDA/MPL, DDA/TDB (CAF01) and DDA/MMG (CAF04)], Montanide ISA720/CpG-ODN1826 and Alum using PmpG protein as a model T cell antigen in the mouse genital tract infection model. The results showed that the cationic liposomal adjuvants DDA/MPL and DDA/TDB elicited the best protective immune responses characterized by multifunctional CD4+ T cells coexpressing IFN-γ and TNF-α and reduced infection by over three logs. Using DDA/MPL as adjuvant, we found seven of 13 Chlamydia T cell antigens (PmpG, PmpE, PmpF, Aasf, RplF, TC0420 and TC0825) conferred protection better than or equal to the reference vaccine antigen MOMP. Pools of membrane/secreted proteins, cytoplasmic proteins and hypothetical proteins were tested individually or in combination. Immunization with combinations protected as well as the best individual protein in that combination. The T cell antigens and adjuvants discovered in this study are of further interest in the development of a molecularly defined Chlamydia vaccine. PMID: 22290151 [PubMed - as supplied by publisher]
Detection of established virulence genes and plasmids to differentiate Borrelia burgdorferi strains.
Chan K, Casjens S, Parveen N Detection of established virulence genes and plasmids to differentiate Borrelia burgdorferi strains. Infect Immun. 2012 Jan 30; Authors: Chan K, Casjens S, Parveen N Abstract Borrelia burgdorferi sensu stricto is the major causative agent of Lyme disease in the United States while B. garinii and B. afzelii are more prevalent in the Europe. The highly complex genome of B. burgdorferi is comprised of a linear chromosome and a large number of variably sized linear and circular plasmids. Many plasmids of this spirochete are unstable during its culture in vitro. Given that many of the B. burgdorferi virulence factors identified to date are plasmid-encoded, spirochetal plasmid content determination is essential for genetic analysis of Lyme pathogenesis. Although Polymerase Chain Reaction (PCR)-based assays facilitate plasmid profiling of sequenced B. burgdorferi strains, the rapid genetic content determination strategy for non-sequenced strains has not been described yet. In this study, we combined pulse field gel electrophoresis and Southern hybridization for detection of genes encoding known virulence factors, ribosomal DNA spacer restriction fragment length polymorphism types (RST), ospC group determination, and sequencing of the variable dbpA and ospC genes. We show that two strains isolated from the same tick and both originally named N40, are in fact very distinct. Furthermore, we failed to detect bbk32, which encodes a fibronectin-binding adhesin in one "N40" strain. Thus, two distinct strains were isolated from the same tick that show different plasmid profile as determined by PFGE and PCR and vary in their ospC and dbpA sequence. However, both belong to RST3B group. PMID: 22290150 [PubMed - as supplied by publisher]
Involvement of mannose receptor and the p38 MAPK signaling pathway of micro integral membrane protein after enteropathogenic Escherichia coli infection.
Liu Z, Ma Y, Moyer MP, Zhang P, Shi C, Qin H Involvement of mannose receptor and the p38 MAPK signaling pathway of micro integral membrane protein after enteropathogenic Escherichia coli infection. Infect Immun. 2012 Jan 30; Authors: Liu Z, Ma Y, Moyer MP, Zhang P, Shi C, Qin H Abstract Micro integral membrane protein (MIMP) has been shown to adhere to mucin and antagonize the adhesion of enteropathogenic Escherichia coli (EPEC) to epithelial cells, however, the mechanism has not been fully elucidated. In this study, we further identified the receptor of MIMP on NCM460 cells, and investigated the mechanism (p38 MAPK pathway) following the interaction of MIMP and its corresponding receptor mannose receptor. We first identified the target receptor of MIMP on the surface of NCM460 cells using immunoprecipitation/mass spectrometry (IP/MS) technology. We also verified the mannose receptor and examined degradation and activation of the p38 mitogen-activated protein kinase (MAPK) signaling pathway. Results indicated that MIMP adhered to NCM460 cells by binding to the mannose receptor, and inhibited the phosphorylation of p38 MAPK stimulated after EPEC infection via inhibition of the toll-like receptor-5 pathway. These findings indicated that MIMP relieve the injury of NCM460 cells after enteropathogenic Escherichia coli infection through the mannose receptor and inhibition of the p38 MAPK signaling pathway, both of which may therefore be potential therapeutic targets for intestinal diseases, such as inflammatory bowel disease. PMID: 22290149 [PubMed - as supplied by publisher]
Hyper-induction of host Interferon β by a Listeria monocytogenes strain naturally over-expressing the multi-drug efflux pump MdrT.
Schwartz KT, Carleton JD, Quillin SJ, Rollins SD, Portnoy DA, Leber JH Hyper-induction of host Interferon Subscribe to Infectious_Diseases RSS feed