[Risk factors for influenza A (H1N1)-associated pneumonia on hospitalized people less than 18 years old in China, 2009-2010].

OBJECTIVE: To describe the epidemiological and clinical features of hospitalized people less than 18 years old with influenza A (H1N1)-associated pneumonia and associated risk factors. METHODS: Through Chinese Reporting System of Influenza A (H1N1), children aged under 18 years who were hospitalized with laboratory confirmed influenza A (H1N1), case report forms and related information on pneumonia were collected between 1 September 2009 and 4 July 2010. Epidemiological and clinical characteristics including demographics, underlying chronic diseases, treatment, complications and clinical outcome etc. were described. Hospitalized children with pneumonia were compared with those without the above mentioned features, through the univariate and multivariate analysis. RESULTS: There were 4240 influenza A (H1N1)-associated hospitalized children with case report forms identified. Of the 4107 influenza A (H1N1)-associated hospitalized children with related information on pneumonia shown in the case report forms, 2289 (55.7%) of them had pneumonia. Hospitalized children with influenza A (H1N1)-associated pneumonia had a younger median age (4.9 year old), when compared with those without pneumonia (13.1 year old, P<0.0001). When compared with the hospitalized children without pneumonia, those hospitalized children with pneumonia were more likely to require intensive care unit care, using mechanical ventilation equipment to develop ARDS, respiratory failure or leading to death. Data from multivariate analysis showed that children aged<6 months (OR=7.08, 95%CI: 4.15-12.06) between 6 and 23 months (aOR=8.26, 95%CI: 6.10-11.20) or between 2 to 4 year old (aOR=9.53, 95%CI: 7.39-12.29) were more likely to develop pneumonia than children aged 5 to 17. Factors as having asthma (OR=12.19, 95%CI: 5.18-28.72), cardiovascular disease (OR=5.19, 95%CI: 1.94-13.90), chronic renal diseases (OR=2.14, 95%CI: 1.02-4.53), chronic hepatic diseases (OR=5.26, 95%CI: 1.40-19.81) and allergy (OR=2.54, 95%CI: 1.64-3.93) were significantly associated with influenza A (H1N1)-associated pneumonia. Risk of complication with pneumonia had an increase when oseltamivir treatment was initiated>2 days after the onset of illness. CONCLUSION: Pneumonia was a common complication among children hospitalized with influenza A (H1N1). Hospitalized children with influenza A (H1N1)-associated pneumonia were more likely to develop either severe clinical courses or outcomes than those without pneumonia.

[Epidemiological characteristics on the clustering nature of pandemic (H1N1) 2009 in China].

OBJECTIVE: To study the epidemiological characteristics on the clustering nature of pandemic (H1N1) 2009 in China. METHODS: Time and place distribution of pandemic (H1N1) 2009 on the nature of clustering through data from Public Health Emergency Management Information System were described. RESULTS: As of August 10, 2010, 2773 pandemic (H1N1) 2009 clusters, a total of 77 363 cases (including 20 deaths) were reported in the mainland of China. The most reported number of clusters was from schools and kindergartens with the total number of 2498 (accounted for 90.08% of the total number). Middle schools appeared the have the most clusters (1223, accounting for 48.96%). The number of clusters reported in the southern provinces (cities) accounted for 77.03% of the total, and was more than that in the northern provinces (cities). Two reported peaks in the southern provinces (cities) were in June and November, 2009, respectively. There was only one reported peak in the northern provinces in September, 2009. CONCLUSION: Time and place distribution characteristics on the clusters of pandemic (H1N1) 2009 were similar to the seasonal influenza, but the beginning of winter peak was much earlier and intensity of reporting was much higher on the clusters of pandemic (H1N1) 2009 than that of seasonal influenza.

Surveillance for Creutzfeldt-Jakob disease in China from 2006 to 2007.

BACKGROUND: Human transmissible spongiform encephalopathies (HTSE), or Creutzfeldt-Jakob disease (CJD), is a group of rare and fatal diseases in central nervous system. Since outbreak of bovine spongiform encephalopathy (BSE) and variant CJD, a worldwide CJD surveillance network has been established under the proposition of WHO. In China, a national CJD surveillance system has started since 2002. The data of CJD surveillance from 2006 to 2007 was analyzed. METHODS: Total 12 provinces are included in CJD surveillance system. The surveillance unit in each province consists of one or two sentinel hospitals and the provincial CDC. All suspected CJD cases reported from CJD surveillance were diagnosed and subtyped based on the diagnostic criteria for CJD issued by WHO. RESULTS: Total 192 suspected CJD cases were reported and 5 genetic CJD, 51 probable and 30 possible sporadic CJD (sCJD) cases were diagnosed. The collected sCJD cases distribute sporadically without geographical clustering and seasonal relativity and the highest incidences in both probable and possible sCJD cases appeared in the group of 60-69 year. The most common three foremost symptoms were progressive dementia, cerebellum and mental-related symptoms. The probable sCJD patients owning both typical EEG alteration and CSF protein 14-3-3 positive have more characteristic clinical syndromes than the ones having only one positive. The polymorphisms of codon 129 of all tested reported cases shows typical patterns of Han Chinese as previous reports, that M129M are predominant whereas M129V are seldom. CONCLUSION: Chinese CJD patients possessed similar epidemiological and clinical characteristics as worldwide.

[Study on the characteristic of Surveillance Creutzfeldt-Jakob disease patients from January to August in 2006 in China].

OBJECTIVE: To describe the incidence condition and characteristic of Creutzfeldt-Jakob disease (CJD) in China. METHODS: The clinical and epidemical information of patients from China CJD surveillance network was analyzed. Blood and cerebrospinal fluid (CSF) specimens from these patients were differently collected to be used to detect the 14-3-3 protein in the CSF and to analyze the PRNP gene. RESULTS: Ten possible and 8 probable clinically diagnosed CJD patients were found. These patients had sporadic CJD. There were no geographic clustering and occupational risk with these patients. The mean age at onset of disease was approximately 60 years. The male to female ratio was approximately 1:1; rapidly progressive dementia was the main early symptom, which was present in 44% of patients. CONCLUSION: The geographic distribution, occupation, the ratio of male to female and the mean age of onset were consistent with the characteristics of sporadic CJD.

[The first confirmed human case of avian influenza A (H5N1) in mainland, China].

OBJECTIVE: To ascertain the causation of a family cluster involving two undefined pneumonia cases, a 12-year-old girl and her brother, reported October, 2005 in Xiangtan county, Hunan province. METHODS: Information on epidemiology and clinical manifestation of the cases was collected from interviewing the keyman and referring to related medical records. The environment exposure of the cases to their households and the timeline of the illness were reproduced, using this information. Medical check-up was undergone among the close contacts of the cases and on sick/dead poultry. Throat swab of the cases were collected and tested by both RT-PCR and real-time PCR to detect viral nucleic acids of A/H5N1, and were then inoculated into special pathogen free (SPF) embryonated hens' eggs. Serum of the cases including acute and convalescent phases were also collected and tested by microneutralization and haemagglutination-inhibition (HI) assays to detect H5-specific antibodies. RESULTS: Both the girl and her brother developed fever 2 and 4 days after sudden deaths of chickens being raised in the same house. Both of them had developed pneumonia and the girl died from acute respiratory distress syndrome (ARDS) complicated with multi-organ failure. The boy survived and subsequently discharged from hospital. An eighth-day serum from the girl tested H5 antibody negative, while 4-fold and greater increased in antibody titers were detected in serum from the boy using microneutralization and HI assays in sequential acute and convalescent sera. Of 192 cases, only one doctor who cared for the girl during hospitalization had upper respiratory symptoms but tested negative for H5N1 by microneutralization assay. CONCLUSION: The boy was the first confirmed human case of avian influenza A (H5N1) in the mainland of China and his sister was diagnosed clinically. The most probable explanation of these two cases was that the transmission of H5N1 virus from infected poultry within the same household environment. No evidence of human-to-human transmission was noted in the family cluster.

[Study on a fatal pregnant woman died from by avian influenza (H5N1)].

OBJECTIVE: To ascertain the causation of a pregnant woman with undefined pneumonia reported from the People's Hospital of Tongling city in Anhui province on November 2005. METHODS: Epidemiological and clinical information of the case was collected from the keypersons close to the case and referring to the medical record. A medical observation was carried out on the close contacts of the case and sick or dead poultry. Tracheal aspirates being collected were tested by both RT-PCR and real-time PCR to detect viral nucleic acids of A/H5N1, and were inoculated into special pathogen free (SPF) embryonated hens' eggs. RESULTS: The pregnant woman was found to have been contacted with the sick/dead poultry directly on the 4th day before onset of illness. All the 122 close contacts were healthy after a 10-day medical observation. The major clinical features of the case were viral pneumonia with rapidly developed leukopenia and lymphopenia. The progress to acute respiratory distress syndrome and multiple organ dysfunction syndromes was found at clinical presentation. HA and NA gene of A/H5N1 virus were positive. The 8 gene fragments of A/Anhui/1/2005 (H5N1) isolated from the tracheal aspirates had not carried genes from a human virus through reassortment, and the receptor-binding site of the hemagglutinin was polybasic cleavage site. CONCLUSION: This was the first documented case of H5N1 infection in pregnant woman. The immunotolerant state of pregnancy might have predisposed to the fatal outcome of the patient.

[Laboratory diagnoses of the first confirmed human case of avian influenza A (H5N1) in the mainland of China].

BACKGROUND: To determine the etiologic agent of an atypical pneumonia human case admitted to Xiangtan City hospital, Hunan Province in Oct. 2005. METHODS: The patient's respiratory tract samples and serum were collected. Throat swabs were tested by microneutralization and hemagglutination-inhibition assays. RESULTS: The results of nucleic acid detection of all respiratory samples were negative and virus isolation was also negative. The H5-specific antibodies of convalescence showed a 4-fold greater rise than acute phase. CONCLUSION: The atypical pneumonias case was confirmed as the first human case of avian influenza A (H5N1) infection in the mainland of China.

[Antigenic and genetic study of influenza virus (H1N1) circulated in China in 2004-2005].

BACKGROUND: To analyze the genetic and antigenic characteristics of hemagglutinin (HA) gene of human influenza (H1N1) virus isolated from the mainland of China since 2004 to 2005. METHODS: The single-way hemagglutination inhibition (HI) tests were used to test the antigenic characteristics, and the HA1 gene was sequenced based on the antigenic results. RESULTS: The single-way HI results showed that no virus isolates had 4-folds greater HI titer compared with A/Shanghai/1/1999 (H1N1) in 2004, but there was 6.3% virus had 4-fold greater difference in 2005. The HA1 sequence data showed that the H1N1 virus had the following amino acid mutations such as 54 K > R, 90 T > K, 101 Y > H, 149 R > K, 169 V > A, 190 D > N, 212 R > K, 219 K > R, 245 W > R, 246 Y > F, 258 T > N, 318 V > A and the 54 and 190 amino acids located in antigenic group of HA1. CONCLUSION: The H1N1 virus was changing in antigenic and genetic characteristics.

[An outbreak of human Streptococcus suis serotype 2 infections presenting with toxic shock syndrome in Sichuan, China].

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

[Anlysis on features of dead cases with human Streptococcus suis infections].

OBJECTIVE: 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. METHODS: Epidemiological investigation on human Streptococcus suis infections was implemented used unified questionnaires. Analysis on dead cases and survival cases (as contrast) was done. RESULTS: 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. CONCLUSION: 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.

[Matched case-control study for risk factors of human Streptococcus suis infection in Sichuan Province, China].

OBJECTIVE: To study the potential risk factors of human infecting with Streptococcus suis. METHODS: 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. RESULTS: 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. CONCLUSION: Slaughtering, carcasses cutting and processing sick/dead pigs were important risky behavior for humans to be infected by Streptococcus suis.