An Infectious Disease with an Initial 30 Percent Mortality Rate Identified in China — an Impressive Piece of Epidemiology

© 2011 Peter Free

 

17 March 2011

 

 

A new, possibly tick-borne, disease

 

Xue-Jie Yu and a very large group of colleagues identified a previously unknown, rather nasty, infectious disease in China, now called SFTSV (severe fever with thrombocytopenia syndrome virus).

 

Their efforts began after severe fever with thrombocytopenia syndrome (SFTS) — a description of symptoms, rather than causation — showed up in Hubei and Henan provinces beginning in late March 2009.  The initial case fatality rate was relatively high at 30 percent:

 

We isolated a novel virus, designated SFTS bunyavirus, from patients who presented with fever, thrombocytopenia, leukocytopenia, and multiorgan dysfunction.

 

RNA sequence analysis revealed that the virus was a newly identified member of the genus phlebovirus in the Bunyaviridae family.

 

Electron-microscopical examination revealed virions with the morphologic characteristics of a bunyavirus.

 

The presence of the virus was confirmed in 171 patients with SFTS from six provinces by detection of viral RNA, specific antibodies to the virus in blood, or both.

 

Serologic assays showed a virus-specific immune response in all 35 pairs of serum samples collected from patients during the acute and convalescent phases of the illness.

 

© 2011 Xue-Jie Yu et al., Fever with Thrombocytopenia Associated with a Novel Bunyavirus in China, New England Journal of Medicine [NEJM], doi: 10.1056/NEJMoa1010095 (16 March 2011) (paragraph split)

 

This is an admirably written paper.

 

 

Ticks as a source of infection (vector)?

 

Epidemiological investigation showed the presence of the RNA sequences from the newly identified virus in 10 of 186 Haemaphysalis longicornis ticks that were gathered from domestic animals in the region.

 

There was no evidence of person-to-person transmission.

 

 

A pertinent editorial comment in the New England Journal of Medicine puts the finding in context

 

Editorialist Heinz Feldmann observed that China’s huge population, its peoples’ proximity to wild and domestic animals, and dynamics of the markets in which the animals are traded, make the nation a probable center for the emergence and reemergence of infectious diseases.  SARS (severe acute respiratory syndrome) and influenza provide examples.

 

More broadly:

 

Similar problems exist in regions of Southeast Asia, as exemplified by the recent avian influenza outbreak and the emergence of Nipah virus in Malaysia in 1999.

 

As the world was preparing for an avian influenza pandemic, we were blindsided by the 2009 influenza A (H1N1) outbreak.

 

This history clearly emphasizes the need for vigilance, awareness, and preparedness with respect to infectious diseases and the mind-set for expecting the unexpected.

 

Surveillance systems for notorious pathogens such as influenza have been established, but future systems that are based on clinical syndromes (e.g., respiratory, gastrointestinal, hemorrhagic, hepatic, or encephalitic) should be strengthened.

 

Collected data should be shared with national, regional, and global reference networks.

 

© 2011 Heinz Feldmann, Truly Emerging — A New Disease Caused by a Novel Virus, New England Journal of Medicine [NEJM], doi: 10.1056/NEJMe1102671 (16 March 2011)

 

 

Surveillance and identification are not easy things to do in underdeveloped regions

 

It seems unlikely that there will be a sea change in epidemiological surveillance, given much of the world’s poverty.

 

If improvements are to come soon, the developed world will have to contribute in ways that can be adapted to less technologically-endowed infrastructures.