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Home News centre National Press Releases 2009 Press Releases ›  Reports of swine influenza in Mexico and US - an update

Reports of swine influenza in Mexico and US - an update

25 April 2009

Human cases of swine influenza A (H1N1) virus infection have been identified in California and Texas in the Unites States and in four districts in Mexico.


No cases of swine flu have been identified in the UK or anywhere in Europe.

The reported events in the US and Mexico are unusual and warrant further investigation and vigilance on the part of other countries.

More investigation and testing is needed to determine the severity of the disease and the ease with which it can spread. These investigations are currently underway by Mexican and US authorities with the support of the World Health Organization (WHO).

The HPA is monitoring this situation closely and is working with the UK government to review the current incident and any threat it poses to UK public health.
 
There has been no change to the WHO pandemic alert level which is currently at WHO Phase 3.
 
There is currently a very low level of flu activity in the UK. The HPA and the NHS have systems in place, which will alert public health authorities of any unusual strain circulating in the UK.

Testing has shown that the human swine influenza H1N1 can be treated with the antiviral oseltamavir (Tamiflu®) and zanamivir (Relenza®).

There are no current travel restrictions on those who are planning to visit the affected areas of Mexico and/or the United States*. However, it is always good practice to follow respiratory and hand hygiene such as:
 
Covering your nose and mouth when coughing or sneezing, using a tissue when possible.
Disposing of dirty tissues promptly and carefully.
Maintaining good basic hygiene, for example washing hands frequently with soap and water to reduce the spread of the virus from your hands to face or to other people.
Cleaning hard surfaces (eg door handles) frequently using a normal cleaning product.
Making sure your children follow this advice.

Travellers to affected areas are advised to consult a doctor immediately if they show signs of flu-like symptoms.

Anyone who has recently travelled to the affected areas and is experiencing influenza like illness should stay at home to limit contact with others, and seek medical advice from a local health professional or by contacting NHS Direct.


 

Swine influenza in Mexico & US: Questions & Answers


What is swine influenza?
Swine Influenza is a respiratory disease of pigs caused by type A influenza viruses. Outbreaks of swine influenza happen regularly in pigs. People do not normally get swine influenza, but human infections can and do happen. Most commonly, human cases of swine influenza happen in people who are around pigs but it’s possible for swine influenza viruses to spread from person to person also.
Recently, cases of human infection with swine influenza A (H1N1) viruses have been reported in Southern California and near San Antonio, Texas. In addition, isolation of the same virus from cases in an outbreak in Mexico has indicated more widespread human-to-human transmission.


Is this swine flu virus contagious?
It has been determined that this virus is contagious and is spreading from human to human. However, at this time, it not known how easily the virus spreads between people.


How common are cases of swine influenza?
Infection with swine influenza virus has been detected occasionally in humans since the 1950s and human disease is usually clinically similar to disease caused by infections with human influenza viruses.
Cases of swine influenza in humans usually occur after a history of exposure to pigs, i.e. direct or close contact with infected pigs. Person-to-person transmission, as suspected in the cases currently under investigation in the US and Mexico, have been previously reported but appear to be rare.
There have been no cases identified in the UK for at least ten years.
Through the regular seasonal influenza surveillance that is done in Europe, a single case was reported in November 2008 in Spain, with mild symptoms.
In the US there is an active swine influenza surveillance programme to monitor pig viruses as they see more diversity in viruses than in any other country.


What are the symptoms of swine influenza?
The symptoms of swine influenza in people are similar to the symptoms of regular human seasonal influenza infection and include fever, fatigue, lack of appetite, coughing and sore throat. Some people with swine flu have also reported vomiting and diarrhoea.


What is the difference between seasonal influenza, avian influenza, swine influenza and an influenza pandemic?
Influenza viruses are commonly circulating in the human and animal environment. Different strains can cause illness in humans, bird and pigs.
Seasonal influenza is caused by influenza viruses that are adapted to spread in humans (human influenza). Humans have some natural immunity to the strains that are in common circulation, and this immunity can be boostered by immunisation with a seasonal influenza vaccine.
Avian influenza is caused by influenza viruses adapted for infection in birds. Similarly, swine influenza is caused by influenza viruses adapted for infection in pigs.
These illnesses all elicit the same respiratory symptoms in their hosts. Sometimes, humans and animals can pass strains of influenza back and forth to one another, such as when humans become ill with avian or swine influenza, usually from direct contact with animals who are ill.
Mixing of human and animal influenza viruses can lead to the development of changed viruses with the ability to cause infection and spread in the human population. There may be little or no immunity in the human population to these new viruses.
An influenza pandemic is defined as a new or novel influenza virus that spreads easily between humans. When new influenza viruses are introduced into the environment, humans don’t have any natural immunity to protect against them. Therefore, there is a risk that that new influenza viruses could develop into a pandemic if the virus passes easily from human-to-human.


Is this the next influenza pandemic?
It is too early to say whether the cases in Mexico and the US will lead to a larger outbreak or could represent the appearance of potential pandemic strain of influenza virus.
There is currently insufficient evidence to understand the extent to which cases in Mexico and the US are firmly linked or to make a complete assessment of the health implications of this new virus.
The Director-General of the World Health Organization (WHO) is the decision maker in terms of declaring an influenza pandemic and elevating the global stages of pandemic alert. Experts from around the world are working in close collaboration with WHO to help determine what risk this situation poses to global public health.


Is treatment available?
Testing has shown that the human swine influenza H1N1 is sensitive to can be treated with the antivirals oseltamavir (Tamiflu) and zanamivir (Relenza).


What measures can I take to prevent infection?
General infection control practices and good respiratory hand hygiene can help to reduce transmission of all viruses, including the human swine influenza. This includes:
· Covering your nose and mouth when coughing or sneezing, using a tissue when possible.
· Disposing of dirty tissues promptly and carefully.
· Maintaining good basic hygiene, for example washing hands frequently with soap and water to reduce the spread of the virus from your hands to face or to other people.
· Cleaning hard surfaces (e.g. door handles) frequently using a normal cleaning product.
· Making sure your children follow this advice.


If someone who has been to the affected areas of Mexico and/or the U.S is feeling sick what should they do?
Anyone who has recently travelled to the affected areas and is experiencing influenza like illness should stay at home to limit contact with others, and seek medical advice from a local health professional or by contacting NHS Direct.

 


Ends

Notes to Editors

*The affected areas are as follows:
San Diego County, California, USA
Imperial County, California, USA
San Antonio, Texas, USA
Federal District of Mexico City, Mexico
San Luis Potosi, Mexico
Mexicali, Mexico
Oaxaca, Mexico

 

More information for UK travellers visiting or returning from the Unites States and/or Mexico can be found on the FCO website -

http://www.fco.gov.uk/en/travelling-and-living-overseas/travel-advice-by-country/north-central-america/mexico


 

Last reviewed: 28 April 2009