[Factors affecting transmission of contagious diseases]. / Infektioiden tarttuvuustekijät.

Factors affecting transmission of contagious diseases There are differences in the transmission rate of infectious diseases. The mathematic estimates of the transmission rate of various contagious diseases are impossible to predict. The Basic reproduction number, the so-called Ro-value tends to extrapolate the number of persons who can get infected from one person. To prevent some contagious diseases, a high rate of herd immunity is required. This immunity is achieved by mass vaccination. Infections are transmitted by aerosol, drop, fecalo-oral, blood or contact routes. Nosocomial infections are transmitted usually by contact or fecalo-oral routes whereas the majority of healthcare related infections are transmitted by contact with infected blood or through aerosol transmission.

A review of serological tests to assist diagnosis of reactive arthritis: critical appraisal on methodologies.

On a population-based level, the incidence of reactive arthritis (ReA) is 0.6-27/100,000. The definition of ReA varies and its pathogenesis is not yet clear. Attempts in basic immunology to suggest hypotheses for proliferation of forbidden B cell clones, molecular mimicry, and involvement of cross-reactive antibodies are helpful but not sufficient. Importantly, for the clinical diagnosis of the preceding infection, serology is widely used. Unfortunately, the accuracy of associations between serologic findings and clinical conclusions is plagued by poor standardization of methods. So far, few attempts have been done to examine the pitfalls of different approaches. Here, we review several serologic techniques, their performance and limitations. We will focus on serology for Yersinia, Campylobacter, Salmonella, Shigella, and Chlamydia trachomatis because these bacteria have a longer history of being associated with ReA. We also address controversies regarding the role of serology for some other bacteria linked to autoimmune disorders.