Case-Control Study of Risk factors associated with H7N9 virus infections - PowerPoint Presentation

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Case-Control Study of Risk factors associated with H7N9 virus infections(89 cases, 340 controls)

Transmission route of H7N9 virus: avian to human70% of cases had contact with poultry or related environment before illness onset

Viruses isolated from human cases shared high homology with the viruses isolated from live market with epidemiological link

Ecological analysis on the virus in environment and virus in human: the probable virus transmission route of H7N9 virus is wholesale live market—retail live market—human

Chen Y, Liang W, Yang S, et al

. Lancet,2013,381(9881):1916-1925.Bao C J, Cui L B, Zhou M H, et al. N Engl J Med,2013,368(24):2337-2339.

Poultry: Probable Source of H7N9 Virus InfectionProbable animal reservoir：chicken, duck, pigeon

Pig: tested negative (-)

Province

chicken

duck

pigeon

environment

Total

Shanghai1003720Jiangsu1102013Zhejiang820010Anhui01001Henan00022Shandong00033Jiangxi10001Guangdong10001Fujian00011Total31351352

Data Source: Animals H7N9 surveillance results released by MOA

Gao

H N, et al. N

Engl

J Med,2013,368(24):2277-2285.

Whole blood cells testing:

leucocytopenia

(46%),

lymphocytopenia (88%), thrombocytopenia (73%)Blood biochemistry testing: D-dimer↑(90%), LDH↑(82%), C-reactive protein↑(73%)，AST↑(66%)，myoglobin↑(55%)Chest X-ray：more than half cases have bilateral pneumonia (54%) , bilateral ground-glass opacities and consolidation were the most common radiologic findingsMain clinical features of human H7N9 cases（N=111） hemoptysis

Underlying medical conditions and complications（N=111）

Gao

H N, et al. N

Engl

J Med,2013,368(24):2277-2285.

Cowling BJ, Jin L, Lau

EH, et al.

Lancet. 2013 Jul 13;382(9887):129-37.

Comparison Epidemiology of Human Infection with H7N9 and H5N1 Viruses in Mainland China

A

:

M

ean incubation period of H7N9

and H5N1

is 3

.1 and 3.3 days

B: Time interval from onset to hospitalization for H7N9 and H5N1 cases is similarC: Median onset to laboratory confirmation delay is shorter for H7N9 virus (due to the improved lab diagnosis capacity）D: Median time from hospital admission to death for H7N9 cases is longer (improved treatment capacity）E: Median time from hospital admission to discharge for H7N9 cases is longerComparison of incubation period, illness onset to admission, illness onset to laboratory confirmation, hospital admission to death, and hospital admission to discharge between H7N9 and H5N1密度密度密度密度密度Cowling BJ, Jin L, Lau EH, et al. Lancet. 2013 Jul 13;382(9887):129-37.

Prevention and control measuresFor provinces with case reported, or virus detected from animal or environment samples

Close the live poultry market

Limit the cross-provincial poultry movement

Poultry slaughter: once confirmed with positive H7N9 virus infection in poultry by MOA

Health education: hand washing, behavior change for poultry consumption and processing

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Possibility of H7N9 outbreak in future H7N9 virus is low pathogenic in poultry

difficult to timely detect the outbreak and effectively prevent the transmission

in poultry

Human case occurred in Hebei and Guangdong in July and in Zhejiang in October, indicating that the virus remains circulation in poultryIf H7N9 has similar seasonality with other avian flu

Low virus activity in hot season, but in the coming winter and spring, virus circulation in poultry may be increasingly active If poultry exposure behavior of population do not change, H7N9 outbreaks in human will likely occur again

The next steps for prevention and control Continue to enhance epidemiology and virology surveillance timely detect the signal of changing avian-human or human-human transmission extent of H7N9 virus,

monitor and assess the risk of human to human transmission

Assess aerosol and other environmental routes of transmission in markets and on farms and how to reduce risk of environmental exposure to virus

evaluate the disease severity and risk factors for infection, illness and severity, monitor the change of antiviral resistance Improve the lab diagnosis capacity for human infection with avian influenza in health-care facilitiesEnhance surveillance and control on virus transmission among poultry

Improve the model of poultry farming, establish long-term mechanism for controlling of virus transmission among poultry including environmental spreadForbid selling and slaughter of live poultry in wet markets at big cities in China graduallyPoultry slaughter in designated placeImplement regular-break and strict hygiene control measures in live poultry market if live poultry market closing is not applicable

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