* Warning is first of its kind in kingdom
* Experts say camels most likely animal source of infection
* Saudi cases of potentially fatal virus near 500
* Disquiet about spread of disease grows in run-up to Ramadan (Updates with latest cases)
By Sylvia Westall
KUWAIT, May 11 Saudi Arabia said people handling camels should wear masks and gloves to prevent spreading Middle East Respiratory Syndrome (MERS), issuing such a warning for the first time as cases of the potentially fatal virus neared 500 in the kingdom.
Health experts say camels are the most likely animal source of infection for the disease, which the Saudi Health Ministry said on Sunday three more people had caught and four had died from.
First reported two years ago in Saudi Arabia, MERS is a coronavirus like SARS, which originated in animals and killed around 800 people worldwide after first appearing in China in 2002. There is no vaccine or anti-viral treatment against it.
Around a third of the 483 diagnosed with MERS in Saudi Arabia have died.
Saudi Arabia is still the focal point of the outbreak, although cases have been reported in other Middle Eastern countries, in Europe and in the United States, which had its first confirmed case last month.
The link between human cases and camels - which have a special place in Saudi society - is the subject of extensive study among scientists abroad. But it has been relatively absent from much of the official domestic debate.
In a statement, the Agriculture Ministry advised people not to come into contact with camels unless necessary and to wash hands before and after if they did, as well as wearing face masks, state news agency SPA said on Sunday.
"It is advisable to wear protective gloves, especially when dealing with births or sick or dead (camels)," it said, according to SPA.
It also advised only eating cooked camel meat and to boil camel milk before consuming it.
The statement urged people to report symptoms of MERS in camels immediately.
Only one of dozens of people working near an auction pen in Riyadh's camel market on Sunday was wearing a mask, and there were no signs of any official visit from the authorities, a Reuters photographer said.
Public disquiet in Saudi Arabia has grown amid rumours on social media sites about a lack of transparency from officials about the spread of the disease.
The recent upsurge in reported cases is also of wider concern, not least because of the influx of visitors from around the world expected in July during the Muslim fasting month of Ramadan, and again during the annual Haj pilgrimage in October.
In a move the Health Ministry said was aimed at countering the spread of the virus, Riyadh on Tuesday replaced the head of the King Fahd Hospital in Jeddah, where many of the new cases have been recorded.
The World Health Organisation said outbreaks of MERS in the city's two main hospitals were partly due to breaches in its recommended infection prevention and control measures.
After a five-day mission in Saudi Arabia, WHO also said there has been no significant change in the virus' ability to spread. Scientists say MERS does not transmit easily between people.
The Health Ministry first linked MERS with camels at a news conference last month, but the Agriculture Ministry statement was the first official notification for those working with the animals.
Camels provide a link to an important but vanishing nomadic tradition in Saudi Arabia. They can be traded for thousands of dollars and some are entered into races which are popular across the Gulf region.
Traders, breeders, vets and handlers at the main animal market in Riyadh told Reuters last month authorities had given them no advice or warning about the link between camels and MERS.
Saudi Arabia, a U.S.-ally and conservative absolute monarchy, allows little public dissent and is often secretive about subjects seen as politically sensitive. (Editing by Angus McDowall and Sophie Hares)