An epidemiological investigation on a food-born outbreak of noroviru caused by Sydney 2012 G II.4 strain / 中华流行病学杂志

<p><b>OBJECTIVE</b>To identify the source of infection, route of transmission and risk factors related to a cluster of acute gastroenteritis cases in a university of Guangzhou.</p><p><b>METHODS</b>Cases were identified according to the definition. Descriptive epidemiological approaches and case-control study designs were employed in the analysis. All the samples were tested for norovirus by RT-PCR. Positive samples were subjected to both nucleotide sequence and homology analysis.</p><p><b>RESULTS</b>A total of 141 cases related to norovirus gastroenteritis were identified in January 8 to 21, 2013, with the attack rate as 8.5 per thousand (141/16,600). The peak in morbidity was seen on January 8 to 9. No clustering was found in different classes or dormitories. Results from the case-control study revealed that early cases were infected in Restaurant A (OR = 3.46, 95% CI: 1.07-11.16) and the cold shredded chicken set meal (OR = 17.82, 95% CI: 4.46-78.17) served at lunch (OR = 4.34, 95% CI: 1.18 -17.37) on January 7 was under suspicion. A total of 266 samples, including rectal swabs from the patients and kitchen wokers, leftover food and environmental swabs, were collected. Twenty-one samples (collected from 17 persons) were positive for norovirus by RT-PCR. About 29.6% (8/27) of the kitchen workers in the Restaurant A were tested positive for the virus. The pathogen was identified as the new norovirus genotype II.4 variant, termed Sydney 2012. The virus strains isolated from the patients among student and staff and the kitchen workers were 100% identical in their nucleotide sequence.</p><p><b>CONCLUSION</b>This was the first reported acute gastroenteritis outbreak caused by the new norovirus genotype II.4 variant, Sydney 2012, which showed that the food was contaminated by the asymptomatic kitchen workers who carried the virus.</p>

Risk evaluation on H7N9 avian influenza in Guangzhou, China / 中华流行病学杂志

<p><b>OBJECTIVE</b>We 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.</p><p><b>METHODS</b>We 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.</p><p><b>RESULTS</b>We 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).</p><p><b>CONCLUSION</b>According 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.</p>

Investigation on the source of infection regarding an avian influenza (H5N1) case in Hong Kong that returning from Guangzhou / 中华流行病学杂志

Objective We conducted an epidemiologic investigation to determine the source of infection on an avian influenza (H5N1) case who returned from Guangzhou,in Hong Kong.Methods Data related to epidemiologic investigation,medical observation on close contacts,Syndromic Surveillance on poultry salesmen,emergency monitoring,detection of the samples,source tracing on potential Avian influenza virus (H5,H7,H9) infected people,situation on environment pollution by avian influenza virus in the markets etc.were gathered.The determination of infection source was through comparing the different genes between the case and positive environmental samples.Results The infected case witnessed the procedure of how a live duck was killed,in market A in Guangzhou during May 17th to 19th.The case was diagnosed as respiratory tract infection in 2 Third-grade-Class A hospitals in Guangzhou on May 23th and 24th.The diagnosis was made as Avian influenza cases on May 26th after going back to Hong Kong.23 close contacts and 34 markets poultry salesmen did not show any ILI related symptoms.However,2 poultry salesmen from the markets nearby the place where the Avian influenza case stayed,were detected having positive H9 avian influenza antibody,with the H9 positive rate as 6.06％ (2/33).Among the environmental samples in the 2 markets nearby home of the patient,chopping block was found to have carried H5,with positive rate as 9.8％(5/51) while poultry cage was found to carry H9,with the positive rate as 2.0％(1/51).A H5 positive sample was found with clade 2.3.2.1,same to the case,from a chopping block at the market B where the sources of poultry was the same as market A.Conclusion The source of infection seemed to come from the markets in Guangzhou,that calling for the strengthening of poultry market management,for avian influenza prevention.History related to contact of poultry should be gathered when a diagnosis of respiratory tract infection was made.Timely sampling and testing should be made to improve the sensitivity of diagnosis.

Epidemiological characteristic of first case of locally identified A/H1N1 secondary cases caused by imported source of infection in China / 中华流行病学杂志

Objective To study the first locally identifcd A/HINI secondary cases outbreak in China. Methods Interview and field investigation were integrated to describe the whole process of transmission on each case and to illustrate the relationships between the onset of the disease and the retated factors. Results Two contact persons appearanced fever and whose throat swabs were tested positive to H1N1 viral nucleic acid. The two had a history of contact in a short distance with the initial imported case without any protective measure in the poor air ventilation. The patients clinical situation was slight. The incubation was between 37 hours and 57 hours. No other new case was found after intervention as isolation and antisepsis were taken. Conclusion This event was proved to be an outbreak of local A/H1N1 secondary cases caused by the imported case. The main mode of transmission was personal contact in a short distance without protection, through air and droplet. The locus with poor air ventilation was high risk place. Contact persons should be observed seven days and tested continuously.Infectivity and pathogenicity of the A/H1N1 virus were limited and appeared weakened by generations. Patient's condition was related with persistence and frequency of contact with the infection sources. Enhancing management of contact persons, health education, early diagnose, early treatment and early insulation were effective measures of controling and prenventing the spread A/H1N1.