Children arriving from Mexico via the international border between the U.S. and Mexico in San Ysidro, California on 27 April, 2009, are issued masks .

Mexicans wait in line at the National Institute of Respiratory Diseases in Mexico City wearing surgical masks to prevent the spread of swine flu which has swept the country and the world.

MEXCIO CITY, Mexico – The central region of Mexico is in the grip of an epidemic caused by an aggressive and never-before-seen mutation of the influenza virus called “swine flu”. So far it has caused at least 149 deaths, led to more than 1,995 hospital admissions and paralysed almost all social and public activities in the capital and across the country.

The World Health Organisation (WHO) has raised the international health alert from level three to four, with six being the highest level, in the face of what it considers a crisis with “pandemic potential”.

In statements to EFE, Mexican Health Minister José Angel Córdova acknowledged that the country is at a decisive point in the epidemic. “The number of cases will continue to rise, and we are reinforcing the preventative measures required for containment,” the minister said.

The region most severely affected by the epidemic is Mexico City. Authorities there have been forced to implement a health emergency plan which includes the complete suspension of state school activities from nursery through university level and the closure of cinemas, theatres, museums, shopping centres, bars, restaurants, places of worship and stadiums until 6 May, as measures to reduce the mass congregation of people.

El Universal reports that authorities are still analysing the possibility of suspending all economic activity in the capital, given that epidemiological studies have established that a 10-day period is necessary to break the virus transmission chain.

President Felipe Calderón has issued a decree authorising the Health Ministry to perform all actions necessary to control the epidemic, reports Excelsior, including isolating possible carriers of the virus, entering and establishing health cordons in homes or properties which represent a potential risk, and searching vehicles, luggage, equipment and instruments of all kinds.

Nevertheless, many Mexicans went to work as usual in the chaotic city, which has a population of almost 20 million, and buses were seen packed with people wearing masks, despite the risk of infection.

According to La Jornada, the WHO has warned of the possibility that the A/H1N1 virus, called “swine flu” owing to its origin in the mutation of the strain which affects pigs, may evolve and pose an even greater threat to the world’s population because it can be transmitted between humans through minor physical contact such as shaking hands, saliva or sneezing. The main symptoms are high fever, cough, sneezing, fatigue and general discomfort.

The U.S. has also declared a public emergency, after detecting eight cases in New York and seven in California; while countries such as Canada, France, Spain and New Zealand are investigating possible cases of the same virus.