Sunday, 10 August 2014

China's answer to Ebola: a lethal haemorrhagic fever that kills 20,000 people a year

by Michael Woodhead

Like many other countries, China has gone into a hysterical spin about the threat posed by Ebola virus disease.

Authorities have dusted off the useless thermal scanners last used in the avian flu outbreaks, and have started screening passengers arriving at from Africa at Chinese airports. And despite the World Health Organization saying that China does not need to be overly concerned about the disease, authorities have been issuing stern warnings to health workers about being vigilant for Ebola and also looking with suspicion on the African expats living in cities such as Guangzhou. The irony is that China has seen its own counterpart of Ebola virus disease, a killer disease that has been increasing dramatically in the last two years.

But first some background: Ebola is a haemorrhagic fever, caused by the Ebola virus, which belongs to the  Filoviridae family of RNA viruses. The virus comes from apes and bats and is only transmitted between humans by body fluids such as blood and saliva - in Africa it has been spread by hunters cutting up meat from infected animals, and spread to healthcare workers and close relatives to touch the dead bodies of Ebola victims at traditional African funerals. In the latest outbreak there have been 1323 confirmed and suspected cases of Ebola reported, and 729 deaths. That's a mortality rate of 55% according to my calculator.

What to make then of China's recent little remarked but lethal cases of haemorrhagic fever? In April, Dr Du Hong and colleagues from the Center for Infectious Diseases, Tangdu Hospital, Xian, described the horrific symptoms of some of the 356 patients who had been treated at their hospital for  "hemorrhagic fever with renal syndrome" (HFRS),  a disease caused by Hantavirus that is spread by rats (or more specifically in their droppings, which may become aerosolised and spread to anyone working near where rats have been active).

The symptoms are similar to Ebola: fever, circulatory collapse with hypotension, hemorrhage, but also with acute kidney failure (hence the name renal syndrome). The difference between Ebola and HFRS is that the Hantavirus disease has a death rate of 'only' 40%. For China, which has had about 50,000 cases of HFRS annually, that means about there have been, at a conservative estimate, 20,000 deaths from Hanta virus every year. Makes the 730 Ebola deaths in Africa look fairly insignificant doesn't it? And as with Ebola, there is no treatment or vaccine for Hantavirus, only supportive care.

And that's not all. China has other types of haemorrhagic fever. This month The Lancet carries a report of the emergence of one, known as "severe haemorrhagic fever with thrombocytopenia". This is a viral disease spread by ticks, caused by the SFTS phlebovirus in the Bunyaviridae family. According to Dr Liu Quan and colleagues from the State Key Laboratory of Veterinary Etiological Biology, Lanzhou, SFTS was first reported in 2010 and has since been found in 11 provinces of China, with about 2500 reported cases, and an average case-fatality rate of 7%. That's about 175 deaths. As the study authors say with some understatement: "The disease has become a substantial risk to public health".

China is the epicentre for Hantavirus haemorrhagic fever in the world, but it is not the only country affected. The disease is also seen in Europe and the US - a Denver man died of the infection just this week. But with tens of thousands of Chinese people dying every year from this terrible haemorrhagic disease, perhaps China ought to worry more about curbing Hantavirus - and the rats that carry it - rather than panicking over the threat from an African outbreak of Ebola.

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