Changying Lin

Etiology of acute diarrhea due to enteropathogenic bacteria in Beijing, China.

OBJECTIVES Acute diarrhea is of great concern due to considerable morbidity and mortality worldwide. The causative bacteria leading to acute diarrhea in general population remains unclear in China. This study was conducted to determine the etiology of acute diarrhea using a sentinel hospital-based surveillance network in Beijing. METHODS Active surveillance was implemented from April 2010 to December 2011 on two random days per week by enrolling every tenth diarrheal patients admitted to seventeen intestinal clinics. Shigella spp., Vibrio spp, Salmonella spp., diarrheagenic Escherichia coli and other genera of bacteria, were investigated from 4803 outpatients with acute diarrhea by microbiological methods. RESULTS The pathogenic bacteria recovered out from fecal samples of 968 (20.2%) patients had the following profile: Shigella spp. (5.9%) was the most prevalent pathogen, Vibrio parahaemolyticus (5.2%), Salmonella spp. (3.9%) and enteropathogenic E. coli (EPEC) (0.9%) had from the second to fourth highest prevalence, respectively. Of the 55 co-infections detected, V. parahaemolyticus was the most common pathogen from 28 cases (50.9%), with the main combination of V. parahaemolyticus and Salmonella. The highest proportion of all causative bacteria was found in adults aged 20-39 year and in summer as well as early autumn. The clinical symptoms associated with specific bacterial infection, such as fever, abdominal pain, tenesmus, nausea, vomiting, and watery and bloody stool, were observed frequently in diarrheal patients. CONCLUSION Shigella spp., V. parahaemolyticus, Salmonella spp., and EPEC are important enteropathogenic bacteria causing acute diarrhea in Beijing. To execute reasonable interventions, the comprehensive and continuous surveillance is needed to identify the prevalence of different enteropathogeic bacteria.

Excretion of enterovirus 71 in persons infected with hand, foot and mouth disease

BackgroundHand, foot and mouth disease (HFMD) is a common illness in young children. It also can be seen in adults occasionally. Enterovirus 71 (EV71), a pathogen that causes not only HFMD but also neurological complications and even death, has caused many HFMD outbreaks in China. However, till now the data about the duration of EV71 shedding is very limited.ResultsA total of 136 throat swabs and fecal samples were collected from 27 children and 3 adults, which includs 7 close contacts, 9 mild cases and 14 severe cases,. The participants were divided into three groups namely, severe case group, mild case group and close contact group. All the samples were assayed with real-time polymerase chain reaction (PCR). Kruskal-Wallis Test was employed to compare the difference in duration of viral RNA shedding among three groups. The results showed that significant difference in duration of EV71 shedding was found among three groups (P < 0.01). The longest duration of EV71 shedding in fecal samples is 54 days and 30 days in throat swabs.ConclusionsHFMD is characterized by extended excretion of EV71. Our results suggest that the duration of EV71 shedding is correlated with the severity of the disease. EV71 shedding through feces can persist more than 54 days. Prolonged virus shedding is a potential risk factor of proliferating HFMD epidemic.

Characterization of Coxsackievirus A6- and Enterovirus 71-Associated Hand Foot and Mouth Disease in Beijing, China, from 2013 to 2015

Background: Etiology surveillance of Hand Foot and Mouth disease (HFMD) in Beijing showed that Coxsackievirus A6 (CVA6) became the major pathogen of HFMD in 2013 and 2015. In order to understand the epidemiological characteristics and clinical manifestations of CVA6-associated HFMD, a comparison study among CVA6-, EV71- (Enterovirus 71), and CVA16- (Coxsackievirus A16) associated HFMD was performed. Methods: Epidemiological characteristics and clinical manifestations among CVA6-, EV71- and CVA16-associated mild or severe cases were compared from 2013 to 2015. VP1 gene of CVA6 and EV71 from mild cases, severe cases were sequenced, aligned, and compared with strains from 2009 to 2015 in Beijing and strains available in GenBank. Phylogenetic tree was constructed by neighbor-joining method. Results: CVA6 became the predominant causative agent of HFMD and accounted for 35.4 and 36.9% of total positive cases in 2013 and 2015, respectively. From 2013 to 2015, a total of 305 severe cases and 7 fatal cases were reported. CVA6 and EV71 were responsible for 57.5% of the severe cases. Five out six samples from fatal cases were identified as EV71. High fever, onychomadesis, and decrustation were the typical symptoms of CVA6-associated mild HFMD. CVA6-associated severe cases were characterized by high fever with shorter duration and twitch compared with EV71-associated severe cases which were characterized by poor mental condition, abnormal pupil, and vomiting. Poor mental condition, lung wet rales, abnormal pupil, and tachycardia were the most common clinical features of fatal cases. The percentage of lymphocyte in CVA6-associated cases was significantly lower than that of EV71. High percentage of lymphocyte and low percentage of neutrophils were the typical characteristics of fatal cases. VP1 sequences between CVA6- or EV71-associated mild and severe cases were highly homologous. Conclusion: CVA6 became one of the major pathogens of HFMD in 2013 and 2015 in Beijing. Epidemiological characteristics, clinical manifestations of CVA6-, EV71- and CVA16-associated cases in this study enriched the definition of HFMD caused by different pathogens and shed light to accurate diagnosis, appropriate treatment and effective prevention of HFMD.

A swimming pool-associated outbreak of pharyngoconjunctival fever caused by human adenovirus type 4 in Beijing, China

Patients with swimming pool-acquired human adenovirus (HAdV) infections usually manifest characteristic clinical features that include fever, pharyngitis, and conjunctival inflammation, syndromically referred to as pharyngoconjunctival fever (PCF). HAdV types 3, 4, and 7 are most commonly associated with PCF. This article reports an outbreak of PCF that involved 55 students and staff at a university in Beijing, China. Fifty patients had used the same swimming pool 2 weeks before the onset of symptoms. HAdV type 4 was identified from patient eye and throat swabs and concentrated swimming pool water samples. Partial hexon gene sequences obtained from the water samples were 100% identical to the sequences obtained from the swab samples, which clustered with HAdV-4 within species E. Swimming pool water contaminated with HAdV-4 was the most likely source of infection, although one instance of likely person-to-person transmission was noted.

Spatial, temporal, and space-time clusters of hemorrhagic fever with renal syndrome in beijing, china

As only few cases each year, the distribution of hemorrhagic fever with renal syndrome (HFRS) had thought to be sporadic using the traditional statistical method. The cases reported between 2007 and 2012 through notifiable disease system were analyzed using SaTScan software. The spatial, temporal and space-time distribution of HFRS cases and clusters of high risk at township level was explored. The clusters in northern remote suburb, south of central urban and northern urban fringe were identified. When clusters were found, we could find evidence of risk factors easily and provide proper prevention methods ultimately. The cluster methods may have wider applications in the diseases with few cases.