“It is not yet clear how people are becoming infected, or where the virus might come from,” Juan Lubroth, FAO’s Chief Veterinary Officer, said in a news release.

“We do not have enough information to identify with certainty the virus’ origin. Confirming the source and mechanisms of transmission and spread are key to developing ways to reduce the risks posed by this virus to humans or other countries.”

Coronaviruses are a family of viruses that affect primarily birds and mammals. Some strains cause mild disease, while a limited number are more harmful such as the Severe Acute Respiratory Syndrome (SARS). The MERS coronavirus has been shown to cause acute respiratory illness in humans, but has not yet been shown to cause disease in animals.

FAO underlined that the potential role of animals in the spread of MERS required further investigation. This comes after a study led by the National Institute for Public Health and the Environment of the Netherlands found antibodies for the MERS coronavirus in camel blood samples.

The samples for the study were taken in areas where human cases have not been reported, and in some cases, the tested camels have been isolated from other camels for many years.

“These antibody findings indicate that the MERS virus, or a similar coronavirus, occurs in some camels and potentially other species,” FAO said. “However, the only way to know with any certainty if the virus affecting humans is the same as the virus possibly affecting camels (or any other animal) is to isolate the virus in different species and compare them genetically.”

FAO urged countries to invest in efforts to better understand virus sources and mechanisms of transmission and spread, and said it is ready to support national and regional efforts to identify the source.

The Rome-based agency added that it is in close communication with national authorities as well as the World Health Organization (WHO) and the World Organisation for Animal Health (OIE) and is monitoring the situation closely.

The Emergency Committee is made up of international experts to provide technical advice to the WHO Director-General in the context of a “public health emergency of international concern” (PHEIC). Depending on the circumstances, the Emergency Committee may advise on whether or not a PHEIC is occurring . If the Director-General determines that the event constitutes a PHEIC, the Emergency Committee will then provide advice on appropriate Temporary Recommendations of health measures to be implemented by States Parties. As a PHEIC proceeds, the Emergency Committee continues to provide advice to the Director-General on termination of the PHEIC, and the modification and termination of Temporary Recommendations. All decisions on these issues are taken by the Director-General.

Coronaviruses are a large family of viruses that includes viruses that may cause a range of illnesses in humans, from the common cold to SARS. Viruses of this family also cause a number of animal diseases.

The Middle East respiratory syndrome coronavirus (MERS-CoV) has not been previously identified in humans. There is very limited information on transmission, severity and clinical impact with only a small number of cases reported thus far.

Since April 2012, there have been 64 laboratory-confirmed cases of human infection with Middle East respiratory syndrome coronavirus (MERS-CoV); 72% have been male. Thirty-eight of the confirmed cases have died. Affected countries in the Middle East include Jordan, Saudi Arabia, the United Arab Emirates (UAE), and Qatar. Cases have also been reported by four countries in Europe, France, Germany, the United Kingdom (UK) and Italy, and by one country in North Africa, Tunisia. All of the European and North African cases have had a direct or indirect connection to the Middle East. However, in France, the UK, Tunisia and Italy, there has been limited local transmission among close contacts who had not been to the Middle East.

Among the new laboratory-confirmed cases of MERS-CoV reported since the last update on 31 May 2013, three have been reported by Italy. In this cluster, the index case, a 45-year-old Italian resident, travelled to Amman, Jordan in mid-April. He developed mild respiratory symptoms one day before returning home to Italy in late May. He was admitted to hospital with pneumonia 3 days after returning home. Nasopharyngeal (NP) and throat swabs taken on the day following admission were positive for MERS-CoV. He had no underlying chronic medical conditions, but was noted to be obese. He recovered and was discharged home after a week in hospital. Contact monitoring was conducted in Italy, and two developed respiratory symptoms: a 42-year-old co-worker and a 14-month-old close relative. Both tested positive for MERS-CoV. The two contacts had each been exposed to the 45-year-old man on a single day, and their illnesses began 3 and 4 days, respectively, after that exposure. Both had mild illnesses and recovered uneventfully. Follow up was also done on close contacts in Amman, Jordan. Four symptomatic and six asymptomatic contacts had NP swabs collected for testing; all were negative for MERS-COV.

The Ministry of Health in Saudi Arabia has also notified WHO of additional laboratory-confirmed cases of MERS-CoV with onset in late May and early June. These include cases from the Ta’if Governorate, Wadi Al-Dawaser, and Hafar Al-Batin; the first reported from these areas. The more recent cases were similar in age and sex to previously reported cases, except for a 2-year-old with chronic pulmonary disease from Jeddah.

Although the exact timing and nature of exposures that result in infection is usually unknown, for those cases for which exposure is known or strongly suspected, the incubation period for laboratory confirmed cases of MERS-CoV is generally less than one week. However, in at least one case the known exposure occurred 9 to 12 days prior to onset of illness. Further evidence in cases exposed over a range of time suggests that, at least in a minority of cases, the incubation period may exceed one week but is less than two weeks.

Evidence is also accumulating to suggest that nasopharyngeal swabs are less sensitive for detecting infection with MERS-CoV than specimens taken from the lower respiratory track. Currently, no head-to-head comparisons are available on the two approaches to diagnosis. However, in a number of patients, NP swabs have been negative at one point during the course of illness while lower respiratory specimens were positive at another time during the same illness. In addition, in several clusters, patients who were strongly suspected of having MERS-CoV infection because of direct exposure and severe respiratory illness had NP swabs that tested negative, while other confirmed cases in the cluster had lower respiratory track specimens that tested positive.

“From the information available thus far, it appears that the novel coronavirus cannot be easily transmitted from person to person,” it said in a statement.

The 49-year-old man in the new case was sickened by a coronavirus, from a family of viruses which causes most common colds but also includes the virus that causes SARS or severe acute respiratory syndrome was transferred from Qatar for treatment in London. He had recently travelled to Saudi Arabia, where another man died of a similar illness earlier this year.

No new confirmed cases of infection with the virus have since been reported, the WHO said. The United Nations health agency said it was working with international partners to understand the public health risk better.

SARS which emerged in China in 2003 killed around a tenth of the 8,000 people it infected worldwide.

The WHO’s clinical guidance to its 194 member states says health workers should be alert to anyone with acute respiratory syndrome and requiring hospitalisation who had been in the Middle East where the virus was found or in contact with a suspected or confirmed case within the previous 10 days.

The U.N. agency has not recommended any travel restrictions in connection with the new virus, but said it was working closely with Saudi authorities on health measures for Muslims making the haj pilgrimage to Mecca.