Molecular epidemiology demonstrates that imported and local strains circulated during the 2014 dengue outbreak in Guangzhou, China

Abstract

The dengue virus (DENV) is a vital global public health issue. The 2014 dengue epidemic inGuangzhou, China, caused approximately 40,000 cases of infection and five deaths. We carried out a comprehensive investigation aimed at identifying the transmission sources in this dengue epidemic. To analyze the phylogenetics of the 2014 dengue strains, the envelope (E) gene sequences from 17 viral strains isolated from 168 dengue patient serum samples were sequenced and a phylogenetic tree was reconstructed. All 17 strains were serotype I strains, including 8 genotype I and 9 genotype V strains. Additionally, 6 genotype I strains that were probably introduced to China from Thailand before 2009 were widely transmitted in the 2013 and 2014 epidemics, and they continued to circulate until 2015, with one affinis strain being found in Singapore. The other 2 genotype I strains were introduced from the Malaya Peninsula in 2014. The transmission source of the 9 genotype V strains was from Malaysia in 2014. DENVs of different serotypes and genotypes co-circulated in the 2014 dengue outbreak in Guangzhou. Moreover, not only had DENV been imported to Guangzhou, but it had also been gradually exported, as the viruses exhibited an enzootic transmission cycle in Guangzhou.

Complete Coding Sequences of Dengue Virus Type 2 Strains from Febrile Patients Seen in Malindi District Hospital, Kenya, during the 2017 Dengue Fever Outbreak

“…Dengue virus (DENV), a mosquito-borne flavivirus, is the etiological agent of dengue fever (DF) ( 1 ). DENV is delineated into four serotypes (DENV-1 through DENV-4) that are further graded into the following distinct genotypes: Asian I (AI), Asian II (AII), Cosmopolitan (C), American (AM), Asian/American (AA), and Sylvatic (S) ( 2 , 3 ). Due to its ease of transmission and frequent occurrence, the DENV-2 genotypes are under changing evolutionary pressure, leading to the emergence of new lineages ( 4 ).…”

Genomic epidemiological characteristics of dengue fever in Guangdong province, China from 2013 to 2017

“…Since then, sporadic dengue fever epidemics has occurred in Hainan, Guangxi, Fujian, Zhejiang, and Yunnan provinces in mainland China [7][8][9]. Particularly, dengue infection is reported almost annually in Guangdong in recent years, contributing to more than half of dengue fever cases in China [10]. In 2014, an unprecedented dengue fever outbreak occurred in Guangdong Province, leading to more than 40,000 infective cases, although great efforts were made to prevent and control dengue infection [11,12].…”

Epidemiological Characterization of the 2017 Dengue Outbreak in Zhejiang, China and Molecular Characterization of the Viruses

“…Since the 1990s, dengue epidemics have spread gradually from Guangdong, Hainan, and Guangxi provinces in the southern coastal regions to the relatively northern and western regions including Fujian, Zhejiang, and Yunnan provinces. (Wu et al, 2010 ; Li et al, 2017 ). Since then, sporadic cases of DF have been reported almost every year in Zhejiang Province, and outbreaks occurred in the years 2004 and 2009 (Xu et al, 2007 ; Sun et al, 2011 ).…”

“…Dengue is a mosquito-borne viral infection causing a severe flu-like illness and, sometimes causing a potentially lethal complication called severe dengue (previously known as dengue hemorrhagic fever). The vast distribution of mosquito vectors, which is fueled by frequent human migration, and a lack of adequate listed vaccines and effective drugs have resulted in a dramatic increase in dengue virus (DV) infections, which have undergone 30-fold growth over the past 50 years (Li et al, 2017 ). One recent estimate has indicated 390 million dengue infections per year, of which 96 million manifest clinically (Bhatt et al, 2013 ).…”

“…Its genome is approximately 10,700 bp, comprising a single open reading frame that encodes three structural proteins (C, capsid; prM/M, precursor of membrane; and E, envelope) and seven non-structural proteins (NS1, NS2a, NS2b, NS3, NS4a, NS4b, and NS5) (Kuhn et al, 2002 ). DV can be grouped into four distinct serotypes (DV-1, DV-2, DV-3, and DV-4), each of which can be sub-classified into several genotypes on the basis of E gene sequences (Li et al, 2017 ).…”