Cases of Human Swine Influenza in United States and Mexico

25 Apr 2009

In Mexico, as of 23 April 2009, an outbreak involving 854 cases of atypical pneumonia has been reported, including 59 deaths. Some of these have been identified as swine Influenza A (H1N1). Most of the cases have occurred in central Mexico (especially Mexico City) but there have been cases in states along the U.S.-Mexico border.

2 In the US, there have been a total of 8 laboratory confirmed cases of swine influenza (6 in California and 2 in Texas). 6 cases had self-limited illness and 1 was hospitalized. No deaths have been reported. No recent exposure to pigs has been identified for any of the patients. In one case, there was a history of recent travel to Mexico.

3 Preliminary genetic analysis of the influenza viruses have identified them as swine influenza A (H1N1 viruses), containing genetic pieces from swine influenza viruses from North America, Europe and Asia, avian influenza viruses from North America, and human influenza viruses. This particular genetic combination of swine influenza virus segments has not been recognized previously. The US CDC laboratory has identified the same strain of swine influenza A (H1N1) in specimens from patients with respiratory disease in Mexico as that identified in the U.S. cases.

4 These reports raise concerns about human-to-human spread of a novel influenza virus.

What is Swine influenza?

5 Swine flu (swine influenza) is a respiratory disease of pigs caused by type A influenza virus that regularly causes outbreaks of influenza in pigs. Swine flu viruses do not normally infect humans. However, sporadic human infections with swine flu have occurred (most commonly in persons with direct exposure to pigs) and there have been documented cases of human-to-human spread of swine flu. Symptoms of swine flu in humans are similar to symptoms of regular human seasonal flu. An early symptom is high fever, and this can be followed by cough, sore throat, runny nose, and sometimes breathlessness a few days later.

Situation in Singapore

6 There are currently no known cases of human swine flu in Singapore. Nonetheless, the Ministry has informed all medical practitioners and healthcare institutions of the outbreak of human swine flu in the USA and Mexico, and alerted them to be vigilant for any suspect cases during this period. MOH is monitoring the situation closely and will update the public should there be any new developments.

Advice from MOH

7  Members of the public are advised to seek immediate medical attention if they develop symptoms of swine flu within seven days of travel to California or Texas in USA, or to Mexico.

8 The public is advised to maintain high standards of personal hygiene, such as washing hands frequently with soap and water, especially after contact with respiratory secretions (e.g. after sneezing and coughing). Those who are sick with respiratory illnesses should avoid crowded areas and wear masks if possible.