Gene analysis connects Cambodian EV-71 to Asian outbreaks

Jul 27, 2012 (CIDRAP News) – A preliminary genetic analysis of enterovirus serotype 71 (EV-71) isolates from Cambodia suggests that the virus is part of ongoing EV-71 outbreaks in Asia and is similar to those in other countries in the region, including Vietnam.

Writing in a ProMED Mail post yesterday, Philippe Buchy, MD, PhD, who heads the virology unit at the Pasteur Institute in Cambodia, wrote that the lab analyzed three randomly selected isolates from patients in different parts of Cambodia over 4 weeks.

Genetic sequencing showed that the viruses aligned with sequences from strains isolated in Vietnam in 2011 and 2012, in Shanghai in 2011 and 2012, and from those in other Asian countries that have been submitted to GenBank. He added that phylogenetic analysis suggests that the EV-71 sequences from Cambodia cluster with EV-71 genotype C4 strains recently isolated in Vietnam and are closely related to those detected in China.

Buchy said further genetic studies continue, but it's useful to know that the strains in Cambodia are part of an ongoing outbreak of hand, foot, and mouth disease (HFMD) across the region, an important consideration given that Cambodia doesn't have enough data to gauge the true case-fatality rate of its EV-71 outbreak.

ProMED Mail is the online reporting system of the International Society for Infectious Diseases.

In a comment accompanying the post, ProMed moderator Craig Pringle, PhD, a virologist and emeritus professor at the University of Warwick in England, proposed that, based on the institute's phylogenetic findings, some of the subgenotypes should be reclassified. This would include designating the C4 subgenotype as a new genotype D, he said.

He said scientists await the results of further isolate analysis, especially of genotype C4 and any possible relation to clinical severity.

In other developments, Beat Richner, MD, founder and head of Kantha Bopha Children's Hospitals in Cambodia—where many of the country's EV-71 patients with encephalitis and severe lung complications were treated—yesterday lashed out for the second time against the World Health Organization (WHO) for statements it made during the outbreak.

He said the WHO statements created panic and gave the impression that steroid treatment made some of the children's conditions worse.

In a letter posted on his Facebook page, he wrote that all 72 children treated at Kantha Bopha had encephalitis, which must be treated with steroids to ease brain swelling. He pointed out that HFMD lesions are a symptom that can be caused by an array of viruses and that the severely ill patients the hospital treated didn't have the lesions.

Richner said the patients' cause of lung destruction in the last 6 hours of their lives still isn't clear.

See also:

Jul 26 ProMED Mail post

Jul 26 Beat Richner letter on Facebook

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