Influenza is an acute respiratory infectious disease caused by influenza virus. It usually exhibits seasonal transmission, but the novel influenza strain can lead to a pandemic with severe human health and socioeconomic consequences. Early warning of influenza epidemic is an important strategy and means for influenza prevention and control. On the basis of reviewing the main influenza surveillance and early warning systems, this study summarizes the principles, applications, advantages and disadvantages, and development prospects of common influenza early warning models, in order to provide reference for research and application of early warning technology for influenza and other acute respiratory infectious diseases.
Humans ; Influenza, Human/epidemiology* ; Pandemics/prevention & control*

Humans ; Influenza A virus ; Influenza Vaccines ; Influenza, Human ; epidemiology ; prevention & control ; virology

Disease Outbreaks ; Humans ; Influenza, Human ; epidemiology ; prevention & control

China ; epidemiology ; Humans ; Influenza Vaccines ; Influenza, Human ; epidemiology ; prevention & control ; therapy

OBJECTIVEWe conducted both quick surveillance and evaluation programs within one week after the novel H7N9 influenza cases had been released by the Ministry of Health (MOH), to get the basic information on H7N9 virus in Guangzhou.

METHODSWe sampled live birds from food markets and the natural habitat of birds to detect H7N9, H5 and H9 viruses. We interviewed workers from both markets and natural habitats. We also reviewed records on pneumonia patients with unknown causes from the surveillance system, to find clues related to the identification of severe pneumonia.

RESULTSWe sampled 300 specimens from 49 stalls in 13 food markets and a natural habitat but none showed H7N9 positive result. A chopping block was detected positive of carrying H5 avian influenza virus, while another 4 specimens including a chicken cage, a duck cage, a chopping block and a pigeon cage were detected positive of carrying H9 avian influenza virus. In the past month, no sick, dead birds or ILI cases among the workers were discovered. 21.2% (7/33) of the stalls did not follow the set regulations for prevention. 10.3% (4/39) of the stalls had the cages cleaned, 4 days after the inspection. 3.7% (2/54) of the workers wore masks and 40.7% (22/54) of them wore gloves during the slaughtering process. 102 bird feces specimens were tested negative on H7N9 virus. No pneumonia cases with unknown reason were identified. From April 3(rd) to 17(th), we found 26 severe pneumonia cases but with negative results on influenza A (H7N9).

CONCLUSIONAccording to the data and information from 1) lab tests, 2) pneumonia cases with unknown reasons under the surveillance system, 3) the identification of severe pneumonia cases, and 4) preventive measures and actions taken by the workers, we inferred that no H7N9 virus or related cases were found prior to April in Guangzhou. However, the risk of H7N9 epidemic does exist because of the following reasons:1) improper market management process, 2) negligent behavior of the workers and 3) potential trend of the national situation, suggesting strategies related to poultry markets management, health education and preventive measures against the avian influenza need to be strengthened.

Cardiovascular risk and related medical burden due to influenza in patients with chronic disease were higher than those of healthy subjects. As a result, influenza vaccination is recommended as a strategy for secondary prevention in cardiovascular disease by major cardiovascular organizations, but the prevalence of influenza vaccination in these population is still low. Whether influenza vaccine can prevent cardiovascular events such as myocardial infarction and death is still controversial based on current evidences from observational studies and case-control studies, which may result from study desion,subjects selection,outcome definition and sample size issues. Recent meta-analysis showed that influenza vaccination may reduce cardiovascular risk, but large-scale random controlled trials with adequately power should be conducted to confirm these findings as well as the target population for this strategy further.
Cardiovascular Diseases ; epidemiology ; prevention & control ; Humans ; Influenza Vaccines ; therapeutic use ; Influenza, Human ; epidemiology ; prevention & control ; Risk Factors ; Secondary Prevention ; Vaccination

Animals ; Birds ; virology ; China ; epidemiology ; Humans ; Influenza A virus ; classification ; pathogenicity ; Influenza Vaccines ; Influenza in Birds ; epidemiology ; prevention & control ; Influenza, Human ; epidemiology ; prevention & control

China ; epidemiology ; Epidemics ; prevention & control ; Humans ; Influenza, Human ; epidemiology ; prevention & control

China ; epidemiology ; Disaster Planning ; organization & administration ; Disease Outbreaks ; prevention & control ; Humans ; Influenza A Virus, H1N1 Subtype ; Influenza, Human ; epidemiology ; prevention & control

Animals ; Birds ; China ; epidemiology ; Humans ; Influenza A Virus, H5N1 Subtype ; physiology ; Influenza A Virus, H7N7 Subtype ; physiology ; Influenza A Virus, H9N2 Subtype ; physiology ; Influenza A virus ; physiology ; Influenza, Human ; epidemiology ; prevention & control