An outbreak of gastroenteritis caused by poisonous Boletus mushroom in Sichuan, China, 2012 / 中华流行病学杂志

Objective To identify the source of infection and risk factors and to provide control measures regarding an outbreak of gastroenteritis involving 30 villagers.Who attended the same wedding party held on March 5th,2012,a survey was carried out.Methods Case was defined as having onset of vomiting,nausea,stomachache or diarrhea among the attendees of a wedding party.We randomly selected and interviewed 140 from 470 attendees on their symptoms and food exposures at the wedding.We compared food-specific attack rates (AR) for gastroenteritis in a retrospective cohort study.The leftover foods were tested for Salmonella,Shigella,and Staphylococcus aureus.The leftover Boletus mushrooms were examined and species determined by the Kunming Institute of Botany,Chinese Academy of Sciences.Results Of the 140 attendees 61％ (85) developed gastroenteritis.Case-attendees had vomiting (94％),nausea (89％),stomachache (53 ％),and diarrhea (51％).The AR among attendees who ate Boletus mushroom was 69％ (81/118),compared to 18％ (4/22) of those who did not (RR＝3.8,95％ CI:1.5-9.2).When comparing the ARs between the attendees on consumption of other foods,data did not show statistically significant differences.Among the 7 species of Boletus identified from the leftover mushrooms,3 (B.venenatus,B.sinicus and B.magnificus) were toxic.Store keepers bought dried or fresh mushrooms from local villagers who had picked up them from the mountains.Salmonella,Shigella,and Staphylococcus aureus tests on those leftover food showed negative results.Conclusion Poisonous Boletus mushroom contributed to this outbreak.We recommended that education should be targeted on mushroom-pickers regarding how to recognize the poisonous mushrooms.Regulations and laws should also be developed to facilitate the necessary process.

Non-airborne transmission during outbreak of pandemic (H1N1) 2009 among tour group members, China, June 2009 / 中华流行病学杂志

Objective During June 2-8, 2009, 11 cases of the novel influenza A (H1N1)occurred in Sichuan Province, China. We investigated this outbreak to identify the source of infection,mode of transmission and risk factors for infection. Methods The primary case, a U.S. citizen,developed disease on June 2. From June 3 to 5, she joined Tour Group A for a trip to Jiuzhaigou. We telephoned passengers of the three flights on which the primary case had traveled in China, and members of Tour Group A. We asked whether they had any influenza-like symptoms during May 27 to June 12. Health authorities placed passengers whose seats were within three rows of the primary case on flights and members of Tour Group A on medical observation, and isolated individuals if they developed symptoms. We used real-time RT-PCR to test the throat swabs from symptomatic persons for the novel influenza virus and defined a confirmed case as one with influenza-like symptoms and laboratory confirmation. A retrospective cohort investigation to identify the risk factors for infection was conducted. We interviewed all members of Tour Group A about their detailed contact history with the primary case. Results During June 5 to 6, 9 (30%) of the primary case' s 30 fellow tour group members developed disease, compared with none of her 87 fellow passengers to Jiuzhaigou and 1 of her 87 fellow passengers on the returning trip (when several of the members of Tour Group A were symptomatic). 56% of the tourists who had talked with the primary case in close range ( ＜2 m) for ≥2 minutes developed disease, whereas none of the 14 other tour group members developed disease (RR= ∞; exact 95%CI: 2.0- ∞ ). Having conversed with the primary case for ≥ 10 minutes (vs. 2-9 minutes) increased the risk by almost five fold (RR=4.8, exact 95%CI: 1.3-180). Conversely, other kinds of contact, such as dining at the same table, receiving chewing gum from the primary case and sharing bus rides or planes with the primary case played no roles during this outbreak. Conclusion This novel influenza A (H1N1) outbreak was caused by an imported case, and transmitted mainly via droplet transmission when the primary case was talking with her fellow tourists during a tour. These findings highlight the importance of preventing droplet transmission during a pandemic.

Outbreak of cholera associated with consumption of soft-shelled turtles, Sichuan province, China, 2009 / 中华流行病学杂志

Objective Vibrio cholera was extremely rare in Sichuan province (no cases in 2008). Any outbreak could indicate contamination through the food supply system. In July 2009, a hospital reported a cluster of 7 diarrhea patients; all attended the same banquet. One patient was confirmed to have Vibrio cholera (O139). We conducted this investigation to identify the source of this possible cholera outbreak. Methods We defined a suspect case as any banquet attendee with diarrhea ( ≥3 times/day). A confirmed case was a suspect case with a positive Vibrio cholera culture. We took stool samples or rectal swabs from all attendees for cholera culture and interviewed 272 banquet attendees about foods they ate at the banquet and kitchen workers about food preparation. Results 7.1% (24/337) of attendees developed cases within an average of 65 hours after eating. Three meals were served. All patients had the lunch whereas no patients only ate breakfast and/or dinner. Of 180 attendees who ate turtle meat 12% were case-patients, compared to 3.3% of 92 attendees who did not (RR=3.6,95%CI: 1.1-12). Of the 150 attendees who ate peanuts 13% were cases compared to 4.1%of 122 attendees who did not eat peanuts (RR=3.1,95%CI: 1.2-8.0). During preparation, the same utensil was used for fresh turtle meat and peanuts without washing in-between the process. Turtle meat and peanuts were stored for ＞ 16 hours at room temperature after cooking before consumption. All 33 turtles originated from commercial production in another province. Conclusion This outbreak was likely caused by poor food handling of commercially produced turtles. We proposed that to improve microbiologic monitoring of aquatic food animals, and raise the awareness of good handling practices at mass gathering in rural China.

Study on the natural foci of Marmota himalayana plague in Sichuan province / 中华流行病学杂志

Objective To explore the existence of natural loci on Marmota himalayana plague in Sichuan province and to provide basis for prevention and control of the disease. Methods Both epidemiological investigation and laboratory tests were used to provide the host animal and fleas of the vectors with Yersinia pestis carriers. Results 30 species of animals were found to belong to 10 orders. Ochotona curzoniae and M.himalayana were the most common ones while 7 species of the fleas belonged to 7 genera and 3 families. M.himalayana was the main reservoirs while Callopsylla dolabris and Oropsylla silantiewi served as vectors. The 13 Y.pestis were identified from 43 Marmota samples. 8 samples were identified under IHA, with the highest titer of herding-dogs serum as 1 : 10 240. 19 samples were F1 antigen positive using RIHA and the highest titer of M.himalayana serum was 1:409 600. The major foci was 4545 km2, distributed at Dege county in Sichuan province. Conclusion We have confirmed the existence of natural foci on M. Himalayana plague in Sichuan province.

An outbreak of human Streptococcus suis serotype 2 infections presenting with toxic shock syndrome in Sichuan, China / 中华流行病学杂志

<p><b>OBJECTIVE</b>In mid-July 2005, five patients presented with septic shock to a hospital in Ziyang city in Sichuan, China, to identify the etiology of the unknown reason disease, an epidemiological, clinical, and laboratory study were conducted.</p><p><b>METHODS</b>An enhanced surveillance program were established in Sichuan, the following activities were introduced: active case finding in Sichuan of (a) laboratory diagnosed Streptococcus suis infection and (b) clinically diagnosed probable cases with exposure history; supplemented by (c) monitoring reports on meningococcal meningitis. Streptococcus suis serotype 2 infection was confirmed by culture and biochemical reactions, followed by sequencing for specific genes for serotype and virulence factors.</p><p><b>RESULTS</b>From June 10 to August 21, 2005, 68 laboratory confirmed cases of human Streptococcus suis infections were reported. All were villagers who gave a history of direct exposure to deceased or sick pigs in their backyards where slaughtering was performed. Twenty six (38%) presented with toxic shock syndrome of which 15 (58%) died. Other presentations were septicaemia or meningitis. All isolates were tested positive for genes for tuf, species-specific 16S rRNA, cps2J, mrp, ef and sly. There were 136 clinically diagnosed probable cases with similar exposure history but incomplete laboratory investigations.</p><p><b>CONCLUSION</b>An outbreak of human Streptococcus suis serotype 2 infections occurred in villagers after direct exposure to deceased or sick pigs in Sichuan. Prohibition of slaughtering in backyards brought the outbreak to a halt. A virulent strain of the bacteria is speculated to be in circulation, and is responsible for the unusual presentation of toxic shock syndrome with high case fatality.</p>

Anlysis on features of dead cases with human Streptococcus suis infections / 中华流行病学杂志

<p><b>OBJECTIVE</b>To describe the clinical and epidemiological features of dead cases with human Streptococcus suis infections, and to find the target population for preventing death and the related indicators.</p><p><b>METHODS</b>Epidemiological investigation on human Streptococcus suis infections was implemented used unified questionnaires. Analysis on dead cases and survival cases (as contrast) was done.</p><p><b>RESULTS</b>The population with highest fatality rate was in 40-49 age group. 97.37% of dead cases had toxic shock syndrome. The mean interval from onset to admission was 0.76 days, and the mean course was 2.11 days. The progression among dead cases was faster than that among survival cases. Chief clinical manifestations of dead cases that are more frequent than survival cases are purpura (73.68%), diarrhea (50.0%), dyspnea (21.05%), conjunctival congestion (34.21%), etc. Renal impairment and liver involvement in dead cases were more significant than that in survival cases. No significant difference between mean incubation period, exposure rates of main risk factors in dead cases and in survival cases was found.</p><p><b>CONCLUSION</b>Preventing toxic shock syndrome might reduce the fatality rate. The target population for preventing death is aged > or = 40. Liver function and renal function testing might be indicators for monitoring the progression of human Streptococcus suis infections.</p>

Matched case-control study for risk factors of human Streptococcus suis infection in Sichuan Province, China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the potential risk factors of human infecting with Streptococcus suis.</p><p><b>METHODS</b>1: M matched case-control study was conducted. 29 human cases of Streptococcus suis infection in the early phase were included in the case group, Patients' family members, neighbors and peoples who had worked together with patients to handle deceased or sick pigs in the last week were recruited as matched controls. There were 147 controls in total. Both cases and controls received questionnaire investigation including the ways to contact sick/dead pigs. Conditional logistic regression was employed to analyze matching data.</p><p><b>RESULTS</b>According to the results of multivariate analysis, slaughtering (OR = 11.978, 95% CI: 3.355-42.756), carcasses cutting and processing (OR = 3.008, 95% CI: 1.022-8.849) sick/dead pigs were associated with cases related to human Streptococcus suis infection. The attributable risk proportion were 91.65% and 66.76% respectively. The other types of exposures to sick/ dead pigs, including feeding, selling, burying and eating, were not associated with the human Streptococcus suis infection in our study population.</p><p><b>CONCLUSION</b>Slaughtering, carcasses cutting and processing sick/dead pigs were important risky behavior for humans to be infected by Streptococcus suis.</p>