* Confirmed cases in Saudi Arabia up by a third in past week
* Health minister was replaced on Monday
* Authorities unsure of reason for sudden surge in cases
By Angus McDowall
RIYADH, April 22 (Reuters) - Saudi Arabia has discovered another 17 cases of Middle East Respiratory Syndrome (MERS), as the total number of confirmed infections of the SARS-like disease has jumped by a third in the kingdom in the past week.
King Abdullah replaced the health minister, Abdullah al-Rabeeah, on Monday amid growing public disquiet at the spread of the disease, which was discovered two years ago and kills around a third of sufferers.
Rabeeah said on Sunday he did not know why there had been a surge but said it might be part of a seasonal pattern since there had also been a rise in infections last April and May.
However, the jump is of particular concern as Saudi Arabia is expected to have a large influx of pilgrims from across the world in July during the Muslim fasting month of Ramadan, followed in early October by the arrival of millions of people to perform the annual Haj in Mecca and Medina.
Jeddah, Saudi Arabia's second-largest city where many of the new cases have been discovered, is the main entry point for pilgrims visiting nearby Mecca, site of the holiest places in Islam but where there have been no confirmed cases so far.
Last year's Haj passed without any new infections being identified.
The 17 new cases, announced late on Monday on the Health Ministry website, bring the total number of Saudi infections to 261, of whom 81 have died. Combined with the other 49 cases announced in recent days, they represent a jump of 34 percent in the number of laboratory confirmed infections within a week.
Seven of the 17 new cases were in Jeddah. Six were in Riyadh, including one who died, while three were in Medina and one was in the northern city of Tabuk.
Saudi authorities last week issued several statements aimed at reassuring the public that there was no immediate cause for concern at the latest outbreak and that it had not met international definitions of an epidemic.
However, Labour Minister Adel Fakieh, who has been appointed as acting health minister, was shown in several newspapers on Tuesday touring one of the main hospitals in Jeddah, a display that seemed aimed at countering accusations from some Saudis on social media that the authorities had not taken the situation seriously enough.
Rabeeah said on Sunday Saudi Arabia was still opening its borders for foreign visitors, including pilgrims, and that the authorities were taking "all the scientific precaution measures to ensure the safety and well being of our nation".
He said there was not yet any medical reason to change the preventative measures already in place, such as travel restrictions or closures of some medical facilities where clusters of cases have occurred, to contain the spread.
MERS has no vaccine or anti-viral treatment, but international and Saudi health authorities say the disease, which originated in camels, does not transmit easily between people and may simply die out.
Jeddah, like most Saudi cities, has areas within its boundaries where camels are free to graze.
Fakieh has become a prominent figure in Saudi politics in recent years after pushing sweeping reforms in employment policy aimed at getting more young Saudis into jobs.
(Editing by Alison Williams)