Risk assessment strategies for early detection and prediction of infectious disease outbreaks associated with climate change.

A new generation of surveillance strategies is being developed to help detect emerging infections and to identify the increased risks of infectious disease outbreaks that are expected to occur with climate change. These surveillance strategies include event-based surveillance (EBS) systems and risk modelling. The EBS systems use open-source internet data, such as media reports, official reports, and social media (such as Twitter) to detect evidence of an emerging threat, and can be used in conjunction with conventional surveillance systems to enhance early warning of public health threats. More recently, EBS systems include artificial intelligence applications such machine learning and natural language processing to increase the speed, capacity and accuracy of filtering, classifying and analysing health-related internet data. Risk modelling uses statistical and mathematical methods to assess the severity of disease emergence and spread given factors about the host (e.g. number of reported cases), pathogen (e.g. pathogenicity) and environment (e.g. climate suitability for reservoir populations). The types of data in these models are expanding to include health-related information from open-source internet data and information on mobility patterns of humans and goods. This information is helping to identify susceptible populations and predict the pathways from which infections might spread into new areas and new countries. As a powerful addition to traditional surveillance strategies that identify what has already happened, it is anticipated that EBS systems and risk modelling will increasingly be used to inform public health actions to prevent, detect and mitigate the climate change increases in infectious diseases.

The histopathology of freezing injury to the rat spinal cord. A light microscope study. I. Early degenerative changes.

In an effort to develop a method of tissue injury which would provide a model for the study of axonal regrowth in adult mammalian central nervous system (CNS), we have analyzed the effects of freezing in the dorsal columns of more than 200 rat spinal cords. The effects of temperature and time of exposure upon the size, shape, distribution and histologic characteristics of the lesion have been assessed during the first seven days following the injury. The upper threshold for injury occurs at -3 degrees C for 15 minutes. Between -3 degrees C and -12 degrees C the tissue changes vary in extent and characteristics. Selective damage to axons and myelin occurs with sparing of the supportive cells followed by proliferation of a cellular matrix. At seven days, the lesions produced by -8 degrees C for 15 to 60 minutes have neither axons nor myelin sheaths and consist of a dense cellular matrix of macrophages and presumed glial cells. With these tissue characteristics, and the preservation of tissue continuity without obstructive barriers, this model would appear to be potentially suitable for the study of axonal regrowth potential in mammalian CNS.

The histopathology of freezing injury to the rat spinal cord. A light and electron microscope study. II. Repair and regeneration.

We utilized a recently developed model of spinal cord injury in which freezing of the rat dorsal column produced axonal injury with sparing and proliferation of the supporting tissue. We examined the progress of the reparative and regenerative processes for 15, 30 and 60 days after the injury. In transverse and sagittal sections at the proximal middle, and distal injury zone and at the zone of Wallerian degeneration we have demonstrated an apparent outgrowth of axons which makes its appearance between 15 and 30 days following injury and increases in amount between 30 and 60 days. The myelination of these fibers is bimodal with Schwann cells predominating in the subpial region, and oligodendrocytes in the deeper regions. Growth into the Wallerian zone is significantly less but does occur at 30 days increasing only slightly at 60 days despite extensive clearing of the breakdown products. We believe that the conditions created by this method of injury provide a suitable model for the study of repair and regeneration of mammalian central nervous tissue.