Some experts in infectious disease are warning that it may no longer be feasible to contain the new coronavirus which is circulating in China. If it does not stop there you could see the virus spread in a sustainable fashion in all over the world, and perhaps even join the ranks of respiratory viruses that regularly infect people.

"The more we learn about it, the greater is the possibility that the transmission could not be controlled with public health measures," said Dr. Allison McGeer, an infectious disease specialist based in Toronto who contracted SARS in 2003, and it helped Saudi Arabia Saudi controls multiple outbreaks hospital of MERS.

If that is the case, he said, "we are living with a new human virus, and we're going to find out if it will spread around the world." McGeer cautioned that because the true severity of outbreak still is not known, it is impossible to predict what would be the impact of this spread, although he noted that probably would pose significant challenges to the health care centers.

The pessimistic assessment comes from researchers who study the dynamics of the outbreak - the rate at which cases are increasing in China and come from China - as experts in infectious diseases that are analyzing the first published studies that describe cases to see if they are públicosherramientas health such as isolation and quarantine could be as effective in this outbreak, as they were in the SARS epidemic of 2003.

And the warnings have been realized when the united States reported at the weekend by finding three cases, the third, fourth and fifth in the country. Two were diagnosed in California. One is a traveller of Wuhan, which is believed to have started the outbreak, which was diagnosed in Orange County. The other is someone who visited Wuhan who was diagnosed in Los Angeles county. The fifth case was diagnosed in Arizona and is a student of Arizona State University; the person had also traveled to Wuhan.

The confirmed infections in China rose to almost 2.750 and the number of dead increased to 80.

The minister of health of China, Ma Xiaowei, warned Sunday that the virus seems to be becoming more transmissible, and that the country, which has taken draconian measures unprecedented to control the virus was entering a "crucial stage". The actions of China, which include the closure of flights and trains some of the cities affected and to effectively put tens of millions of people in quarantine, may not be sufficient to stop the virus, the experts said.

"Despite the enormous and admirable efforts in China and around the world, we have to plan for the possibility of the containment of this epidemic is not possible", said Neil Ferguson, a epidemiology of infectious diseases at Imperial College London who has published a series of modeling studies on the outbreak.

There can be up to 100,000 cases already in China, " said Ferguson to the Guardian newspaper on Sunday, adding that the model suggests that the number could be between 30,000 and 200,000 cases. "Almost certainly many tens of thousands of people are infected," he told the british newspaper.

The Bill and Melinda Gates Foundation announced Sunday it is donating $10 million to the response to the virus. Half of the money will be given to chinese groups to help in the containment efforts. The other half will be given to the African Centre for Disease Control to fund its efforts to assist african countries to prepare for having to deal with the new infection.

Also on Sunday, the Director General of the World Organization of Health, Tedros Adhanom Ghebreyesus, tweeted that he travels to Beijing to meet with chinese authorities to offer support and learn more about the outbreak.

Until now, the WHO has not declared the outbreak a global health emergency, although Tedros, as you know, has said that the spread of the new virus is a crisis for China and a risk to the countries beyond him.

WHO refused to qualify the outbreak as a global health emergency of international importance by the advice of a group of experts that met on Wednesday and Thursday, though those experts were divided on whether to declare a PHEIC.

This outbreak is caused by a virus, currently known as 2019-nCoV, which belongs to the same family as the virus that caused the SARS outbreak and cause sporadic outbreaks of cases of MERS in the Arabian Peninsula.The virus of SARS caused an outbreak explosive at the end of 2002 and early 2003, infecting more than 8,000 people worldwide and killing nearly 800 before it was contained. MERS has never caused a global outbreak of sustainability, although there have been a series of large outbreaks in hospital, including one in South Korea led by a business man who contracted the virus in the Middle East.

One of the breaks more fortunate than the world had with the SARS outbreak was the fact that the virus is not transmitted before people develop symptoms.

With some diseases, such as influenza and measles, persons who are infected but not yet feeling sick (people who still go to work or school, take public transportation, shop in malls or go to the cinema) can transmit the virus to other people.

You can expect that tools such as quarantine and isolation, which were key to controlling SARS, to stop the spread of a virus that can be transmitted during the period, from infection to symptoms.

Dr. Nancy Messonnier, director of the National Center of Immunization and Respiratory Diseases Centers for Control and Disease Prevention, said the agency is aware that the transmission of the virus within the united States may be on the horizon.

"We are inclined forward. And we have been in every step of the way with an aggressive stance towards all that we can do in the U.S.," said STAT. "And yet, those of us who have been around enough to know that everything we do might not be enough to prevent this from spreading in the US".To date, at least 14 countries and territories outside of mainland China have reported nearly 60 cases. It has not yet been notified of the spread of non-verified of these imported cases to others.

"In hours in which I am optimistic I think the fact that none of the other countries, including the united States, has seen a string of significant transmission sustained," said Messonnier. "But that doesn't mean that it's not going to come."

It also appears that the incubation time - the time from infection to development of symptoms - can be a little shorter than that of SARS, said McGeer, citing an article published Friday that described the transmission within a family in Hong Kong. With SARS, the majority of people developed symptoms about four or five days after infection, he said.

A short incubation period gives the health authorities less time to locate and quarantine people who have been exposed to the virus and are on the way of becoming infected.

The scientists who have been studying the genetic sequences of viruses from China and some other countries that have recorded cases have been calculated what is known as the reproductive rate of this outbreak: the number of people, on average, that each case will infect.

An outbreak with a reproductive number less than 1 will vanish. But several groups have calculated a reproductive rate for this current outbreak, known by the term R-naught or R0, in the range of 2 to 3 or more.

Trevor Bedford, a biologist computational Cancer Research Center Fred Hutchinson in Seattle, suggested that the estimates are sobering and point to the continued spread.

"If it is not contained in short, I believe that we are seeing a pandemic," said Bedford, although he cautioned that it is impossible to know at this point how serious the injury would be that type of event.

Dr. Tom Inglesby, director of the Center for the Safety of the Health of the School of Public Health, Johns Hopkins university, urged countries to begin to plan to address the global spread of the new virus. These plans must include efforts much more aggressive in order to develop a vaccine that has already been announced, he suggested.

"I'm not making a prediction that is going to happen," said Inglesby, although he pointed out that the mathematical modeling, the statements of the chinese authorities and the sharp increase in the numbers of infection make an argument for this possible outcome. "I think that only on the basis of those pieces of limited information, it is important for us to start a bit of planning around the possibility of this not contains".