Recent Trends in Emerging Infectious Diseases

摘要

Infectious diseases are the worlds greatest killers that present one of the most significant healthand security challenges facing the global community. On April 15 and April 17, 2009, novel swineorigininfluenza A (H1N1) virus (S-OIV) was identified in specimens obtained from twoepidemiologically unlinked patients in the United States. The same strain of the virus wasidentified in Mexico, Canada, and elsewhere. Enhanced surveillance was implemented in theUnited States for human infection with influenza A viruses that could not be subtyped. Specimenswere sent to the Centre for Disease Control and Prevention for real-time reverse-transcriptasepolymerase-chain-reaction confirmatory testing for S-OIV. The S-OIV was determined to have aunique genome composition that had not been identified previously. This virologic analysisallowed for the development of a polymerase-chain-reaction (PCR) test to determine whether, inany given person, illness with the protean manifestations of cough, fever, sore throat, diarrhea,and nausea could be confirmed as a case. Armed with this critical tool, clinicians andepidemiologists are able to make case assignments to define and track the outbreak and todetermine disease severity.WHO declared the start of the Influenza A (H1N1) pandemic on June 11, 2009. The Director-General of WHO raised the influenza pandemic alert to the highest level - Phase 6 - on theguidance and advice from an Emergency Committee established for this purpose under theInternational Health Regulations (IHR). As of 31 of July 2009, 168 countries and overseasterritories/communities have reported at least one laboratory confirmed case of pandemic (H1N1)09. All continents are affected by the pandemic. Total cases reported were 162380 with 1154deaths. The declaration of a pandemic essentially means wide geographic spread and does notindicate any change in the severity of the illness. Currently the severity of the pandemic has beenassessed as "moderate" globally. In vast majority of cases the virus produces mild disease. In asmall proportion of people the illness can become severe and fatal.There are important tools with which to fight this outbreak: a clear case definition, an awarehealth care system, and an informed public.Swine Influenza (swine flu) is a respiratory disease of pigs caused by type A influenza thatregularly cause outbreaks of influenza among pigs. Swine flu viruses do not normally infecthumans, however, human infections with swine flu do occur, and cases of human-to-humanspread of swine flu viruses has been documented. Laboratory testing has found the swineinfluenza A (H1N1) virus susceptible to the prescription antiviral drugs oseltamivir and zanamivir.In our daily life we are surrounded by a wealth of microorganisms, the majority of which arenonharmful. Human existence would be impossible without these micro-organisms, which playcritical roles in processes as diverse as photosynthesis, nitrogen fixation, production of vitamins inthe human intestine and decomposition of organic matter. They are the sole, true recyclers of ourplanet. Microorganisms are also the major driving force behind the evolution of life. Throughoutevolution, human being, like all mammalian species, has maintained an intimate relationship withthe microbial world. We have survived thanks to the efficient defense mechanisms we havedeveloped against potentially dangerous microorganisms. Pathogenic microorganisms are stillhere because they have found ways of avoiding elimination by their host or by the microbialcompetition. Successful pathogens have developed strategies to enter the body and reach andchoose their favourite niche, while defying the powerful human immune systems.Humans have lived with emerging and re-emerging pathogens since before the dawn ofcivilization. Is the situation worse now than in past decades or centuries? The answer is probablyyes because there are billions more of us and some of our activities allow such infections toappear a