The outbreak of the new virus transmitted from human to human that has killed up to 60 people and infected hundreds in Mexico and infected eight in the United States is a “serious situation” with a “pandemic potential”, the head of the World Health Organization said Saturday.

In Mexico City, where 13 of 20 confirmed deaths occurred, officials said no deaths from swine flu had been registered on Friday, but reassurances came amid the severest public health measures seen here since a 1985 earthquake.

Meanwhile in the United States, where eight non-fatal infections occurred in Texas and California, reports said that 75 students in New York being treated for flu-like symtoms had recently traveled to Mexico, but no swine flu case was confirmed.

“A new virus is responsible” for the cases reported in Mexico and the United States, WHO Director General Margaret Chan said in a telephone press conference Saturday.

How the situation will evolve is “unpredictable,” she said, urging other countries to “increase vigilance”.

“This virus has clearly a pandemic potential,” Chan added.

Mexican Health Minister Jose Angel Cordova confirmed 20 deaths from swine flu late Friday and said authorities were probing another 48 who had died with similar symptoms.

Health officials have been investigating more than 1,000 possible swine flu infections.

Apart from the capital, four other deaths were in central San Luis Potosi, two in Baja California, in northwest Mexico, and one in Oaxaca, in the southeast.

But Cordova added that it was “an epidemic, not a pandemic.”

Mexican President Felipe Calderon said that the government would decree necessary emergency or preventative measures.

Authorities on Friday launched a huge campaign to prevent the spread of the virus, urging people to avoid contact in public.

In Mexico City, schools closed for up to a week, according to the health minister, and numerous public venues, including museums and sports stadia were closed to the public.

Mexico City Mayor Marcelo Ebrard said late Friday that 553 sporting and cultural events had been canceled for at least 10 days to avoid large public gatherings.

The capital did not register any deaths on Friday, Armando Ahued, the local health minister said Saturday.

“The good news is that sick people are reacting adequately to the medication,” Ahued said, without giving further details.

Mexico City authorities initially announced a mass vaccination campaign using regular human flu vaccines, but later admitted that the WHO had advised them that it was better to use antiviral medicines, and said they had more than one million doses of suitable drugs.

The CDC website states that there is no vaccine to specifically protect humans from swine flu, only to protect pigs.

The US Centers for Disease Control and Prevention (CDC) said tests show some of the Mexican victims died from the same new strain of swine flu that affected eight people in Texas and California, who later recovered.

The WHO, which was to send a team of experts to Mexico, said Friday that most Mexican cases had occurred in otherwise health young adults.

“Because there are human cases associated with an animal influenza virus, and because of the geographical spread of multiple community outbreaks, plus the somewhat unusual age groups affected, these events are of high concern,” the Swiss-based body said in a statement.

Seven other countries on the continent on Friday adopted preventative measures to try to avoid the spread of the virus to their territory.

In Mexico City, medical teams were on stand-by at the international airport, and all passengers had to fill out a health questionnaire.

Human outbreaks of H1N1 swine influenza virus were recorded in the United States in 1976 and 1988, when two deaths were recorded, and in 1986. In 1988 a pregnant woman died after contact with sick pigs, according to the WHO.

In recent years, the global focus for a pandemic has shifted to the H5N1 bird flu virus, which has spread from poultry to humans and killed 257 of the 421 people infected by the virus since 2003.

If a pig is simultaneously infected with a human and an avian influenza virus, it can serve as a “mixing vessel” for the two viruses that could combine to create a new, more virulent strain.

Mexico seeks to reassure over deadly swine flu

But the government has lifted a quarantine on a second hog farm after tests by experts from the World Health Organisation (WHO), World Organisation for Animal Health (OIE) and Food and the Agriculture Organisation (FAO) showed no more signs of the disease.

The country has more than 13 million heads of swine and the discovery of Ebola-Reston on two hog farms north of Manila was isolated, the government said.

“There is ongoing viral transmission in Bulacan … as a precautionary measure, depopulation will be carried out in the Bulacan farm,” Health Secretary Francisco Duque told reporters, referring to the farm just north of Manila.

The government said 6,000 pigs would be killed, burned and buried as experts sought to determine the source of Ebola-Reston in pigs as well as pig-to-pig and from pig-to-human transmission. Duque said 147 human samples have been tested for Ebola, but only six have tested positive. But all six remain healthy, he added.

“Ebola-Reston poses a low risk to human health at this time,” Duque said.

It is the first time the virus has been found outside monkeys and the first time it has been found in pigs. The virus had previously jumped from monkeys to humans but this was the first case of a jump from hogs.

The Ebola-Reston virus was found in the Philippines as early as the late 1980s and 25 people were found infected after contact with sick monkeys. But only one developed flu-like symptoms and later recovered.

Manila to slaughter 6,000 pigs to stop Ebola spread

Experts had fanned out to Beijing’s neighboring city of Tianjin and Heibei province, which surrounds the capital and where the dead woman had bought ducks, the ministry said in a statement on its website (www.agri.gov.cn).

“After tests for the virus and an epidemiological investigation, no trace of the bird flu virus was found in these three areas,” it said.

The 19-year-old died of the H5N1 virus after gutting ducks, which experts say highlights the role and risks of waterfowl in the transmission of the virus to humans.

It was the first such death in the country in almost a year, and the 21st to date in China.

The virus is generally more active during the cooler months between October and March, although the new Chinese case points to holes in surveillance of the virus in poultry.

Experts also say that many species of ducks are natural reservoirs of the virus and unlike chickens, they show no signs of disease.

China’s Agriculture Ministry said it would step up an inoculation campaign and surveillance for the disease.

“The ministry has many times demanded that every part of the country must maintain a high state of alert to prevent the spread of bird flu and other animal viruses,” it said.

The H5N1 strain remains largely a disease among birds but experts fear it could change into a form that is easily transmitted among people and kill millions of people worldwide.

With the world’s biggest poultry population and hundreds of millions of farmers raising birds in their backyards, China is seen as crucial in the global fight against bird flu.

China finds no bird flu outbreak after new death | Industries | Health & Drugs | Reuters

The U.S. Centers for Disease Control and Prevention is trying to trace the source of the outbreak, which began in September. The Department of Agriculture, state health officials and the Food and Drug Administration are also involved.

The CDC said poultry, cheese and eggs are the most common source of this particular strain, known as Salmonella typhimurium.

“It is often difficult to identify sources of foodborne outbreaks. People may not remember the foods they recently ate and may not be aware of all of the ingredients in food. That’s what makes these types of investigations very difficult,” said CDC spokesman David Daigle.

Daigle did not specify how many people were hospitalized, but the percentage he gave puts that figure at about 70.

“Because foods of animal origin may be contaminated with Salmonella, people should not eat raw or undercooked eggs, poultry, or meat. Persons also should not consume raw or unpasteurized milk or other dairy products. Produce should be thoroughly washed,” he said.

Only Ohio state health officials have agreed to have their state named as one of those affected, with an estimated 50 cases.

Every year, approximately 40,000 people are reported ill with salmonella in the United States, the CDC says, but it said many more cases are never reported.

There have been several recent high-profile outbreaks of foodborne illness in the United States, including a strain of Salmonella carried by peppers from Mexico and that sickened 1,400 people from April to August of 2007 and an E. coli epidemic in 2006, traced to California spinach, that killed three.

Salmonella-contaminated dry pet food sickened at least 79 people, including many young children, in October and November.

Salmonella outbreak sickens 388 across U.S.: CDC | Health | Reuters

WHO Western Pacific Director Shigeru Omi said Hong Kong authorities have responded well by suspending poultry imports for 21 days and starting the slaughter of 80,000 birds after three chickens found dead at a farm Monday tested positive for the H5 virus group. Further tests are being conducted to see if they had the deadly H5N1 strain.

“This is an indication that we have to remain vigilant,” Omi said on the sidelines of a WHO book launch in Malaysia. “Constant vigilance is the key.”

Omi said the outbreak in Hong Kong was “not unexpected because the virus is still circulating in the world, and certainly in this part of the world.”

At least 246 people have died of bird flu worldwide since 2003, according to WHO.

Twenty countries had outbreaks of the disease during the first nine months of 2008, down from 25 during the same period last year, U.N. officials have said.

Some officials worry that the public has largely lost interest because the virus has not mutated into a much-feared form that could spread easily among people. It remains hard for people to catch, with most human cases linked to contact with infected birds.

International Herald Tribune

Arthur Yap, agriculture secretary, and Francisco Duque, health secretary, said the Ebola Reston virus, which had never been found in pigs before, presented a low health risk for humans and was different from the deadly African variety.

The World Health Organisation was reported to be looking into whether there was any chance humans could have become infected.

The outbreak could deal a blow to Philippine plans to build a pork export industry. The government halted an inaugural shipment of frozen pork to Singapore and quarantined three swine farms.

Pork vendors in public markets in Manila sought to assure buyers that their products had passed government inspection and met safety standards.

“December is the month when we sell the most pork at relatively higher price,” said Evelyn Reyes, who operates a small pork stall in Quezon City. “I really hope the government does a good work of calming people’s fears about the Ebola virus.”

Pork accounts for more than half of the average 61g of meat consumed daily by each Filipino.

The virus was first discovered in 1989 in macaque monkeys imported from the Philippines by a laboratory in Reston, Virginia. Scientists are trying to determine how the virus spread to pigs.

FT.com

Poorly maintained sewerage systems and a lack of clean water have allowed the waterborne intestinal disease to thrive. The deepening political and economic crisis in Zimbabwe has crippled the country’s health system. The W.H.O. warned that the outbreak was likely to continue as water and sanitation conditions were worsening. The aid group Doctors Without Borders has warned that 1.4 million people are at risk.

NYTimes.com

The World Health Organization says the disease appears to be a form of hemorrhagic fever.

It says tests have proved negative for Ebola, Lassa fever, Rift Valley fever, Marburg fever and other main types of hemorrhagic fever.

WHO spokesman Gregory Hartl says the first death on Sept. 13 was a tour guide who had fallen ill in Zambia before being evacuated to South Africa. Two further deaths on Sept. 30 and Oct. 4. involved a paramedic and a nurse who treated the woman.

Hartl said Friday that 121 people are being monitored and WHO hopes to receive further test results by Sunday.

South Africa: Mystery hemorrhagic fever kills 3 – CNN.com

The World Health Organization says the disease appears to be a form of hemorrhagic fever.

It says tests have proved negative for Ebola, Lassa fever, Rift Valley fever, Marburg fever and other main types of hemorrhagic fever.

WHO spokesman Gregory Hartl says the first death on Sept. 13 was a tour guide who had fallen ill in Zambia before being evacuated to South Africa. Two further deaths on Sept. 30 and Oct. 4. involved a paramedic and a nurse who treated the woman.

Hartl said Friday that 121 people are being monitored and WHO hopes to receive further test results by Sunday.

South Africa: Mystery hemorrhagic fever kills 3 – CNN.com

However, local authorities in Babil province insist the real figure is much higher and have complained that the government in Baghdad has been slow in responding to the outbreak.

Health Ministry official Dr. Ihsan Jaafar said the figure of confirmed cases was based on an examination of samples taken from the victims over the last week. He said one death – a 60-year-old man – had been confirmed.

He gave no date for the death or for when the outbreak was first reported.

“There are other suspect cases but 90 percent of them appear to be diarrhea,” he said.

In the provincial capital of Hillah, a member of the ruling provincial council, Hassan Tofan, gave a much higher figure. He said that at least 300 cholera cases have been reported in Babil and that 10 people died recently.

The council issued a statement criticizing the provincial health department and the Health Ministry in Baghdad for being “so idle in measures to prevent the speared of disease,” Tofan said.

He said local authorities had ordered all ice plants and many juice stands to close to prevent the spreading of the disease.

Cholera is endemic in Iraq, which lacks facilities to supply clean drinking water, especially in the countryside. Last year, a cholera outbreak in northern Iraq killed 14 people.

Cholera is a gastrointestinal disease typically spread by drinking contaminated water. It can cause severe diarrhea that, in extreme cases, can lead to fatal dehydration. It is preventable by treating drinking water with chlorine and improving hygiene conditions.