To provide professionals the technical support on field infection source investigation of human cases infected with avian influenza A (H5N1) virus.
Summarize the infection source investigation methods of previous 40 laboratory confirmed human H5N1 cases in mainland China.
Among 40 human H5N1 cases, instead of three (7.50%) unclear infection sources cases, before illness onset, 21 (52.50%) cases had direct or indirect sick or dead poultry exposure history, 14 (35.00%) cases had wet poultry market or poultry production exposure history, and 2 (5.00%) cases had human H5N1 cases exposure. The primary investigation hints of cases having sick or dead poultry exposure included living in rural area (95.2%), household and/or surrounding environment (85.71%), adult (66.67%), female (66.67%) and housework (61.90%). While the primary investigation hints of cases having wet poultry market or poultry production exposure included adult (85.71%), living in urban area (78.57%) and dietary habits (50.00%).
Any one of human H5N1 cases could have totally different characteristics and exposures. Infection source investigation of human H5N1 cases should fully consider each possibility, conduct investigation in combination with the actual situation and use different investigation methods in flexible ways.
Chin Prev Med. 11/2012; 13(11):879-880.
ABSTRACT: Pandemic influenza A (H1N1) 2009 virus spread rapidly around the world in 2009. We used multiple data sources from surveillance systems and specific investigations to characterize the transmission patterns of this virus in China during May-November 2009 and analyze the effectiveness of border entry screening and holiday-related school closures on transmission. In China, age distribution and transmission dynamic characteristics were similar to those in Northern Hemisphere temperate countries. The epidemic was focused in children, with an effective reproduction number of ≈1.2-1.3. The 8 days of national holidays in October reduced the effective reproduction number by 37% (95% credible interval 28%-45%) and increased underreporting by ≈20%-30%. Border entry screening detected at most 37% of international travel-related cases, with most (89%) persons identified as having fever at time of entry. These findings suggest that border entry screening was unlikely to have delayed spread in China by >4 days.
Emerging Infectious Diseases 05/2012; 18(5):758-66. · 6.79 Impact Factor
ABSTRACT: Data on risk factors for severe outcomes from 2009 pandemic influenza A (H1N1) virus infection are limited outside of developed countries.
We reviewed medical charts to collect data from patients hospitalized with laboratory-confirmed 2009 H1N1 infection who were identified across China during the period from September 2009 through February 2010, and we analyzed potential risk factors associated with severe illness (defined as illness requiring intensive care unit admission or resulting in death).
Among 9966 case patients, the prevalence of chronic medical conditions (33% vs 14%), pregnancy (15% vs 7%), or obesity (19% vs 14%) was significantly higher in those patients with severe illness than it was in those with less severe disease. In multivariable analyses, among nonpregnant case patients aged ≥ 2 years, having a chronic medical condition significantly increased the risk of severe outcome among all age groups, and obesity was a risk factor among those <60 years of age. The risk of severe illness among pregnant case patients was significantly higher for those in the second and third trimesters. The risk of severe illness was increased when oseltamivir treatment was initiated ≥ 5 days after illness onset (odds ratio, 1.42; 95% confidence interval, 1.20-1.67). For persons <60 years of age, the prevalence of obesity among case patients with severe illness was significantly greater than it was among those without severe illness or among the general population.
Risk factors for severe 2009 H1N1 illness in China were similar to those observed in developed countries, but there was a lower prevalence of chronic medical conditions and a lower prevalence of obesity. Obesity was a risk factor among case patients < 60 years of age. Early initiation of oseltamivir treatment was most beneficial, and there was an increased risk of severe disease when treatment was started ≥ 5 days after illness onset.
Clinical Infectious Diseases 02/2011; 52(4):457-65. · 9.15 Impact Factor
ABSTRACT: To explore a sampling method which could reflect iodine deficiency disorders (IDD) status at provincial level and discover risk areas with non-iodized salt problem.
Baseline data of Iodized salt from Gansu and Fujian provinces were analyzed with Monte Carlo method both at county and prefecture levels respectively. True positive rate and false positive rate were also calculated.
With data from 7 - 8 villages or 4 - 5 townships counties at risk could be discovered. The true positive rate was around 80% and false positive rate was around 20%. At prefecture level, when randomly selecting and checking 3 counties, the samples would satisfy the discovery of all the risk areas with non-iodized salt problem.
We suggested that the sampling method of iodized salt investigation in national IDD surveillance as follows: to randomly choose 3 counties at each prefecture, 4 townships at each county, 2 villages at each township and 10 salt samples by household survey. The coverage rate of iodized salt in a province could be calculated by post-weighted method with population number.
Zhonghua liu xing bing xue za zhi = Zhonghua liuxingbingxue zazhi 09/2002; 23(4):262-4.