* Middle East virus has killed 45 among 90 confirmed cases
* SARS virus belongs to the same coronavirus family
* Health risk to haj pilgrims "very low" - WHO
By Kate Kelland
LONDON, July 26 (Reuters) - Despite its high current deathrate, the Middle East Respiratory Syndrome (MERS) that emergedin Saudi Arabia last year is unlikely to cause a SARS-likeepidemic because it is not spreading as easily, scientists saidon Friday.
In the fullest clinical analysis yet of the new virus, British and Saudi researchers said that while there are manysimilarities between MERS and severe acute respiratory syndrome(SARS) - which emerged in China in 2002 and killed around 800people worldwide - there are also important differences.
The MERS coronavirus, which can cause coughing, fever andpneumonia, emerged last year and has spread from the Gulf toFrance, Germany, Italy, Tunisia and Britain. The World HealthOrganisation (WHO) puts the latest global toll at 45 deaths from90 laboratory-confirmed cases.
The WHO issued its travel guidance on Thursday for pilgrimsgoing to the annual haj in Saudi Arabia and said the health riskposed by the MERS virus was "very low".
Ali Zumla, a professor of infectious diseases andinternational health at University College London, said the evidence from his study suggested a large MERS epidemic withmany hundreds of deaths was unlikely.
"It is very unlikely any epidemic will ensue. The publicneeds to be reassured," he told Reuters. "MERS is unlikely tospread as rapidly, and therefore also unlikely to kill as manypeople (as SARS)."
He noted that MERS was first identified 15 months ago andthere have been 90 cases reported so far. SARS, spread far morerapidly, infecting more than 8,000 people between November 2002and July 2003.
MILDER CASES POSSIBLY MISSED
An earlier study of how the MERS virus infects people foundthat the receptors it binds to are common in the lungs and lowerrespiratory tract and but not in the nose, throat and upperrespiratory tract. Some experts think this is why MERS is notcurrently spreading easily from one person to another.
The study found that MERS killed around 60 percent of thepatients it infected who also had other underlying illness suchas diabetes and heart disease.
But Ziad Memish, Saudi Arabia's deputy public healthminister, who led the research, said this high death rate "isprobably spurious due to the fact that we are only picking upsevere cases and missing a significant number of milder orasymptomatic cases".
"So far there is little to indicate that MERS will follow asimilar path to SARS," he said.
The vast majority of MERS cases have been in Saudi Arabia orlinked to people who contracted the virus there.
The new research, published in The Lancet InfectiousDiseases journal, is the largest case series to date andincluded 47 cases of confirmed MERS infections from Saudi Arabiabetween Sept 1, 2012, and June 15, 2013.
By combining clinical records, laboratory results, andimaging findings with demographic data, the researchers found atrend of older patients, more men, and patients with underlyingmedical conditions who succumb to the disease.
As with SARS, MERS patients had a wide spectrum of symptoms.Most of those admitted to hospital had fever, chills, cough,shortness of breath and muscle pain. A quarter also hadgastrointestinal symptoms, including diarrhoea and vomiting.
But unlike with SARS, most MERS cases were in people withunderlying chronic medical conditions including diabetes, highblood pressure, heart disease and chronic renal disease.
A study by French researchers last month said MERS had notreached pandemic potential and may just die out. (Reporting by Kate Kelland; Editing by Andrew Heavens)