Phylogenetic and molecular characterization of coxsackievirus A24 variant isolates from a 2010 acute hemorrhagic conjunctivitis outbreak in Guangdong, China.

BACKGROUND: Acute hemorrhagic conjunctivitis is a common disease in China. As a notifiable disease, cases are registered by ophthalmologists on the AHC surveillance system. An AHC outbreak caused by CA24v was observed in Guangdong Province in 2007 by the National Disease Supervision Information Management System. Three years later, a larger outbreak occurred in Guangdong during the August-October period (2010). To characterize the outbreak and compare the genetic diversity of CA24v, which was determined to be the cause of the outbreak, the epidemiology and the molecular characterization of CA24v were analyzed in this study. RESULTS: A total of 69,635 cases were reported in the outbreak. 73.5% of index cases originated from students, children in kindergarten and factory workers, with the ≦ 9 age group at the highest risk. The male to female ratio was 1.84:1 among 0-19 years. 56 conjunctival swabs were collected to identify the causative agent from five cities with the AHC outbreak. 30 virus strains were isolated, and two of the genomes had the highest identity values (95.8%) with CA24v genomes. Four CA24v genotypes were identified by phylogenetic analysis for the VP1 and 3C regions. CA24v which caused the outbreak belonged to genotype IV. Furthermore, full nucleotide sequences for four representative isolates in 2010 and 2007 were determined and compared. 20 aa mutations, two nt insertions and one nt deletion were observed in the open reading frame, with 5'- and 3'- UTR respectively between them. CONCLUSIONS: CA24v was determined to be the pathogen causing the outbreak and belongs to genotype IV. VP1 is more informative than 3C(Pro) for describing molecular epidemiology and we hypothesize that accumulative mutations may have promoted the outbreak.

A large outbreak of hand, foot, and mouth disease caused by EV71 and CAV16 in Guangdong, China, 2009.

A large outbreak of hand, foot and mouth disease (HFMD) occurred in Guangdong, China, in 2009. A total of 92,749 cases were officially reported to the Center for Disease Control and Prevention of Guangdong (GDCDC). To clarify the pathogen causing the outbreak, 600 specimens, including stool, rectal swabs, vesicular swabs, cerebrospinal fluid, and throat swabs, were collected from 541 patients and subjected to one-step RT-PCR. Four hundred eighty-nine of 541 patient samples were positive for enterovirus. All positive samples were cultured on RD and Hep2 cells; 307 specimens displayed CPE. Sequence analysis of PCR fragment and typing real-time PCR indicated that these isolates included EV71 (56%), CAV16 (35.5%), CAV6 (2.0%), CAV10 (1.0%), CAV2 (0.7%), CAV4 (1.3%), Echo30 (0.7%), Echo25 (1.0%), Echo4 (0.3%), CBV5 (1.0%) and human rhinovirus (0.7%). 100% (12/12) of fatal cases and 97.2% (140/144) of severe cases carried EV71 and CAV16. The results implied that EV71 and CAV16 were mainly responsible for the outbreak. Comparison with the three global types of EV71 and the five clusters of genotype C showed that the sequences from mainland China (not including the Hong Kong region) are located in subgenogroup C-4 and originate from isolates from the Shenzhen area of Guangdong Province. Results from this study show that the C-4 genotype has been a prevalent pathogen in mainland China since 1998.

Maiden outbreak of chikungunya in Dongguan city, Guangdong province, China: epidemiological characteristics.

BACKGROUND: This study was conducted to identify epidemiological characteristics of the first documented CHIK fever outbreak in China and evaluate the effect of the preventive measures taken. METHODOLOGY/PRINCIPAL FINDINGS: From September 1 to October 29, 2010, China's first documented outbreak of CHIK fever occurred in the Xincun community of Wanjiang District of Dongguan city, Guangdong province; 253 case-patients were recorded, of which 129 were laboratory confirmed, with an attack rate of 1%. Before September 18(th) the number of CHIK fever cases remained relatively low in the Xincun community; from September 19(th) onwards, the number of cases increased drastically, with an outbreak peak on October 4(th). Cases were distributed across nine small village groups in the Xincun community, with an attack rate of 0-12% at the village level. The household attack rates ranged between 20% and 100%. No significant difference was found in the attack rate between males and females. There was a significant difference in the attack rate in different age groups (chi-square=18.35, p=0.005); highest in patients aged 60 years or older and the lowest in patients aged under 10. The major clinical characteristics of patients are fever (100%), joint pain (79%) and rash (54%). Phylogenetic analysis of the E1 gene on the five earliest confirmed cases showed that the strains of CHIKV isolated from their sera were highly homologous (up to 99%) with isogeneic strains isolated in Thailand in 2009. After control measures were taken, including killing adult mosquitoes and cleaning breeding habitats of Aedes mosquitoes, the Breteau index and Mosq-ovitrap index decreased rapidly, and the outbreak ended on October 29. CONCLUSION/SIGNIFICANCE: The infection source of the outbreak was imported. Cases showed obvious temporal, spatial, and population aggregation during the outbreak. Comprehensive control measures based on reducing the density of Aedes mosquitoes were effective in controlling the epidemic.