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China faces significant dengue threat
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Dengue virus can persist in China up to 8 years, according to a genomic analysis published in the American Journal of Tropical Medicine and Hygiene. In addition, a variety of dengue strains are present throughout the year in China.
“We now have compelling evidence that dengue can persist in China — in some cases up to 6 to 8 years,” Rubing Chen, PhD, assistant professor, department of pathology, at the University of Texas Medical Branch, said in a press release. “Further, we found a surprisingly complex and diverse mix of viral subtypes represented in China, a factor that can mean greater risk of epidemic dengue in the future.”
Chen and her colleague Guan-Zhu Han, PhD, at Nanjing Normal University in China, looked at envelope gene sequences of dengue viruses from China for each of the four serotypes using the public Genbank database in June 2015. The researchers analyzed 687 strain sequences of dengue virus serotype 1, 526 of serotype 2, 660 of serotype 3, and 478 of serotype 4.
“Selecting envelope gene sequences rather than complete genomes allowed us to maximally sample dengue virus genetic diversity,” the researchers wrote.
The researchers found about 50 variants of DEN-1, more than 20 variants of DEN-2, and only a few variants of DEN-3 and DEN-4. They also found multiple variants of DEN-1 and DEN-2 during the 2014 Guangdong province outbreak.
“Even within the same year, a person can catch dengue more than once if distantly related variants are circulating in the same region,” Chen said in the release. “That’s why we become concerned about public health when many variants are found, as was the case in our study.”
In addition, the researchers found that the same group of DEN-1 Guangdong strains persisted yearly from 2006 to 2014. The strains moved rapidly between different cities of that province.
“The complicated dengue virus genetic diversity, long-term local persistence of dengue virus serotype 1 in Guangdong province, and the rapid movement of dengue viruses as well as its widespread vector Aedes albopictus suggest that China is facing a substantial dengue threat with potential invasion into broader areas,” Chen and Han wrote. “Will the local dengue virus strain prevail? Or will imported strains replace it due to less effective herd immunity? We will keep a close eye on the coming season.” – by Will Offit
Disclosures: Chen and Han report receiving research funding from the Institute for Human Infections and Immunity at the University of Texas Medical Branch at Galveston. Han reports receiving research funding from the Priority Academic Program Development of Jiangsu Higher Education Institutions.
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