LONDON -- Global health officials are closely following a new respiratory virus related to SARS that is believed to have killed at least one person in Saudi Arabia and left another person in critical condition in Britain.

The germ is a coronavirus, from a family of viruses that cause the common cold as well as SARS, the severe acute respiratory syndrome that killed some 800 people, mostly in Asia, in a 2003 epidemic.

In the latest case, British officials alerted the World Health Organization on Saturday of the new virus in a man who transferred from Qatar to be treated in London. He had recently traveled to Saudi Arabia and is now being treated in an intensive care unit after suffering kidney failure.

Health officials don't know yet whether the virus could spread as rapidly as SARS did or if it might kill as many people.

"It's still (in the) very early days," said Gregory Hartl, a WHO spokesman. "At the moment, we have two sporadic cases and there are still a lot of holes to be filled in."

Hartl said it was unclear how the virus spreads. Coronaviruses are typically spread in the air but Hartl said scientists were considering the possibility that the patients were infected directly by animals. He said there was no evidence yet of any human-to-human transmission.

"All possible avenues of infection are being explored right now," he said.

So far there is no connection between the cases except for a history of travel in Saudi Arabia. SARS was first spread to humans from civet cats in China.

Hartl said no other countries have so far reported any similar cases to WHO.

Other experts said it was unclear how dangerous the virus is.

"We don't know if this is going to turn into another SARS or if it will disappear into nothing," said Michael Osterholm, a flu expert at the University of Minnesota. He said it was crucial to determine the ratio of severe to mild cases.

SARS hit more than 30 countries worldwide after spreading from Hong Kong. Osterholm said it was worrying that at least one person with the disease had died. "You don't die from the common cold," he said. "This gives us reason to think it might be more like SARS," which killed about 10 percent of the people it infected.

Britain's Health Protection Agency and WHO said in statements that the 49-year-old Qatari national became ill on Sept. 3, having previously traveled to Saudi Arabia. He was transferred from Qatar to Britain on Sept. 11 and is being treated in an intensive care unit at a London hospital for problems including kidney failure. Respiratory viruses aren't usually known to cause serious kidney problems.

The Health Protection Agency said it was unaware of any ties the patient had to Britain and that he likely was in a private clinic in the Middle East before being transferred to the London hospital. It said none of the health workers involved in his treatment had fallen ill.

WHO said virus samples from the patient are almost identical to those of a 60-year-old Saudi national who died earlier this year. The agency isn't currently recommending travel restrictions and said the source of infection remains unknown.

Saudi officials said they were concerned the upcoming Hajj pilgrimage next month, which brings millions of people to Saudi Arabia from all over the world, could provide more opportunities for the virus to spread. They advised pilgrims to keep their hands clean and wear masks in crowded places.

The Hajj has previously sparked outbreaks of diseases including the flu, meningitis and polio.

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Frank Jordans in Berlin and Abdullah Shihri in Riyadh, Saudi Arabia, contributed to this report.

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  • Bubonic Plague

    Yes, the black plague -- responsible for <a href="http://www.smithsonianmag.com/people-places/mall_aug99.html?c=y&page=2" target="_hplink">killing 56 million people in Europe the 14th century</a> -- is still around, but it isn't as deadly or prevalent as it was in Medieval times. Dr. Robert Gaynes, an infectious disease expert at Emory University and author of the book <a href="http://estore.asm.org/viewItemDetails.asp?ItemID=1036" target="_hplink">Germ Theory: Medical Pioneers in Infectious Diseases</a>, said that people contract the disease when they gain access to previously undistrubed ecosystems, thereby making "these types of diseases become evident as a result of animal contact." These days, the disease is most commonly spread by bites from fleas that are infected with Yersinia pestis. When the bacteria enters into a person's skin, it leads to headache, chills, and <a href="http://www.bt.cdc.gov/agent/plague/factsheet.asp" target="_hplink">swollen lymph glands</a>, according to the CDC. Early <a href="http://www.bt.cdc.gov/agent/plague/factsheet.asp" target="_hplink">treatment with antibiotics</a> is essential for survival, as the disease can cause respiratory failure and shock if left untreated. Every year, about 1,000 to 3,000 <a href="http://healthland.time.com/2011/05/10/first-case-of-bubonic-plague-in-2011-appears-in-new-mexico/" target="_hplink">bubonic plague cases</a> occur around the world, with 10 to 20 of those cases in the United States, <em>TIME</em> reported. The first 2011 case of bubonic plague was confirmed in May in a New Mexico man. The reason is murky for why black plague seems to be less deadly today than in the Medieval times, Weinberg said, but it probably has to do with more rats and unclean living conditions back then, as well as a lack of appropriate medicines. In addition, the bacteria back then may be different from the current form, he added.

  • Scarlet Fever

    <a href="http://www.medicinenet.com/scarlet_fever/article.htm#history" target="_hplink">Scarlet fever</a> was among the rash of diseases that commonly afflicted people in the 19th century (alongside yellow fever, rubella and measles), according to MedicineNet. Scarlet fever most often afflicts children, causing rash and fever. Fortunately, scarlet fever is a lot less common today than it was centuries ago, but it still can be deadly. Today, we now know that scarlet fever is just a form of group A streptococcus (strep), Weinberg said. But instead of just turning into a regular case of strep throat, scarlet fever manifests as a red skin rash. With antibiotics, the disease is easily treated, though complications can occur that <a href="http://www.medicinenet.com/scarlet_fever/article.htm#history" target="_hplink">can lead to sepsis</a> (bacteria in the blood, tissue or bone), according to MedicineNet. Just this summer, Reuters reported that a Hong Kong kindergarten was closed after tests revealed that a child there may have <a href="http://www.reuters.com/article/2011/06/21/us-scarletfever-china-idUSTRE75K14Q20110621" target="_hplink">died from scarlet fever</a>. Scarlet fever is relatively common in that part of the world, but this year a Hong Kong health department spokesman told Reuters that there seem to be more cases of it this year than in past years.

  • Whooping Cough

    <a href="http://articles.sfgate.com/2011-09-20/bay-area/30178479_1_whooping-cough-booster-shots-childhood-vaccine" target="_hplink">Whooping cough</a>, caused by the Bordetella pertussis bacteria, was a common illness among children in the early 1900s, according to HealthCentral. However, when the vaccine for whooping cough was introduced in the 1940s, cases dropped. But while whooping cough cases are still dramatically lower than 50 years ago, there are still cases that persist today possibly because the vaccine against the disease doesn't provide lasting protection later in life, Weinberg said. Another reason is that older people seem to be able to carry whooping cough in their throats without actually getting sick (due to being vaccinated at a younger age), but that whooping cough is then passed on to infants who haven't yet been vaccinated against the disease, Gaynes said. "This problem has led to a recent recommendation by [the] CDC to have adults get TDAP once as adults (it contains pertussis in the vaccine) and not just a tetanus booster, which is needed every ten years," Gaynes told HuffPost. Recent research presented just last month shows that the <a href="http://articles.sfgate.com/2011-09-20/bay-area/30178479_1_whooping-cough-booster-shots-childhood-vaccine" target="_hplink">protection from the whooping cough vaccine</a> is decreased dramatically once a child reaches age 8 or 9, the <em>San Francisco Chronicle</em> reported. <a href="http://www.cdc.gov/features/pertussis/" target="_hplink">Whooping cough is very contagious</a> -- spread by cough and sneezing -- and is so named because of the sound people who have it make when they cough. Last year, 27,550 people had whooping cough in the United States, according to the CDC. The disease is the deadliest for babies, as it can lead to pneumonia, convulsions and even death.

  • Polio

    Polio, the paralysis-causing disease that afflicted former president Franklin D. Roosevelt, isn't completely gone from the world today. However, it has been eliminated from the western world, Weinberg said. The Mayo Clinic reports that the last known <a href="http://www.mayoclinic.com/health/polio/DS00572" target="_hplink">case of polio in the U.S.</a> was in 1979. Polio is still present in <a href="http://www.who.int/mediacentre/factsheets/fs114/en/" target="_hplink">Afghanistan, Pakistan, India and Nigeria</a>, where unrest and dangerous conditions can make it more difficult to get everyone vaccinated against the disease, according to the World Health Organization. Recently, the WHO reported that a dangerous strain of polio -- called wild poliovirus type 1 -- had <a href="http://www.huffingtonpost.com/2011/09/20/polio-china-pakistan_n_971787.html" target="_hplink">made its way from Pakistan to China</a>. Polio<a href="http://www.mayoclinic.com/health/polio/DS00572" target="_hplink"> causes paralysis</a> and can make it hard to breathe, the Mayo Clinic reported. It can even lead to death.

  • Gout

    Gout has been known throughout history as the "<a href="http://www.bl.uk/learning/langlit/booksforcooks/1700s/1700sfood.html" target="_hplink">disease of kings</a>" and the "rich man's disease," as it was most commonly seem among the gluttonous rich in the 1700 and 1800s, according to the British Library. Gout is considered an ancient form of <a href="http://www.cdc.gov/arthritis/basics/gout.htm" target="_hplink">inflammatory arthritis</a>, and is caused by metabolic disorder that has not been properly controlled. It occurs when uric acid crystals build up in tissues and fluids, thereby leading to a red, swollen joint that is very painful, according to the Centers for Disease Control and Prevention. The condition is most common in overweight men and women who have gone through menopause. Gout rates have <a href="http://arthritis.webmd.com/news/20101110/gout-cases-on-the-rise-in-u-s" target="_hplink">been on the rise</a> since the 1960s, with cases doubling between 1960 and 1990 and then continuing to rise through 2008, according to WebMD. More than 8 million Americans currently have gout. WebMD reported that the <a href="http://arthritis.webmd.com/news/20101110/gout-cases-on-the-rise-in-u-s" target="_hplink">rise in gout cases</a> may be due to people living longer, as the condition is seen in women only after they have passed menopause. In addition, "you can go years with hyperuricemia and no symptoms. But at some point, enough uric acid accumulates to have a flare-up of gout, so if you're living longer you are more likely to reach that threshold," gout expert Dr. John S. Sundy told WebMD. In addition, Gaynes speculated that it may not even be that gout rates are actually rising -- rather, detection and diagnosis may have improved throughout the years.