Health Professionals

Clinical Updates

29 April 2009

Swine influenza in humans: Update 2

Current status of the outbreak. Cases of human swine influenza A (H1N1) continue to be identified in countries throughout the world. The WHO does not consider containment of the outbreak as a feasible goal, and is focused on mitigation of the consequences of the outbreak [1]. They do not recommend closure of borders. The influenza pandemic alert level remains at level 4 [2].

Countries reporting laboratory-confirmed cases are listed in the table below. In addition, there are many persons worldwide with an influenza-like illness (ILI) who are currently being evaluated for swine influenza.

Country

Date of Last Report

Confirmed Cases

Deaths

Austria [3]

29 April 2009

1

0

Canada [4]

28 April 2009

13

0

Germany [5]

29 April 2009

3

0

Israel [1]

28 April 2009

2

0

Mexico [1]*

28 April 2009

26

7

New Zealand [6]

29 April 2009

6

0

Spain [7]

29 April 2009

4

0

United Kingdom [8, 9]

28 April 2009

3

0

United States [10]

29 April 2009

91

1

* there are nearly 2,000 suspect cases being investigated

Transmission and clinical illness

Influenza viruses are usually transmitted person to person by respiratory droplets when an infected person coughs in close proximity (less than one to two meters) to others [11]. Contact with contaminated surfaces may also be a mode of transmission. The incubation period and time of infectivity are not entirely known for swine influenza. They are expected to be similar to those of seasonal influenza which has an incubation period of one to four days and an infectivity time form the day before the onset of symptoms to seven days after development of illness. Children may be contagious for longer periods.

Symptoms of swine influenza are similar to typical influenza and include fever, cough, sore throat, body aches, headache, chills and fatigue. Some report diarrhoea and vomiting. Infection has ranged from asymptomatic and mild to severe with pneumonia and death [12]. Those at higher risk for complications are expected to be the same groups as for seasonal influenza: infants, the elderly, persons with HIV infection, and those with chronic medical conditions.

Swine influenza isolates in samples from infected persons have been killed by the anti-viral drugs oseltamivir and zanamivir, but not amantadine or rimantadine.

A case definition used for the surveillance of respiratory illness to aid in the detection of human swine influenza is: fever ³38°C or history of fever, plus two or more of the following symptoms: cough, sore throat, runny nose, muscle aches or pains, headache [13].

Advice for travellers

The Foreign and Commonwealth Office has advised travellers to defer non-essential travel to Mexico. There are no other travel restrictions at present, and the WHO has recommended not closing international borders.

Influenza is transmitted via the respiratory route and travellers should exercise sensible precautions:

  • it is prudent that if you are ill with a respiratory illness to delay travel
  • follow public health guidance at your destination
  • avoid crowding or mass gatherings
  • avoid close contact (within 2 meters) with persons who are ill with an ILI
  • wash hands with soap and water; use waterless alcohol-based hand gels when soap and water is not available
  • avoid touching your nose, mouth or eyes, to prevent the spread of germs
  • cover your nose and mouth with a tissue when you cough or sneeze and dispose of the tissue promptly
  • keep hard surfaces (e.g. door handles, countertops) clean using a normal cleaning solution
  • assure that children follow similar advice
  • swine influenza is not passed through properly handled and prepared pork; the virus is killed by cooking to temperatures of 70°C
  • there is little evidence of the effectiveness of wearing masks at a mass level, however, properly fitted, special grade masks can be worn in situations such as healthcare settings
  • receive appropriate vaccines for your destination, including seasonal influenza vaccine if you come under the recommended risk groups (see NaTHNaC Health Information Sheet on Influenza)

Travellers who have visited affected areas should monitor their health for seven days after the visit. If you develop a febrile illness with cough, sore throat, headache and muscle aches, you should:

  • check your symptoms on NHS Direct (www.nhsdirect.nhs.uk) or NHS Choices (www.nhs.uk), and if you remain concerned,  contact your GP or NHS Direct (0845 4647) and inform them of your travel history
  • limit contact with other people
  • cover your nose and mouth with a tissue when you cough or sneeze and dispose of the tissue promptly
  • wash hands with soap and water
  • keep hard surfaces (e.g. door handles, countertops) clean using a normal cleaning solution

Further information is available at the following sources:

Health Protection Agency, Swine Influenza: http://www.hpa.org.uk/webw/HPAweb&Page&HPAwebAutoListN

ame/Page/1240732817665?p=1240732817665

WHO, Swine Influenza: http://www.who.int/csr/disease/swineflu/en/index.html

Centers for Disease Control and Prevention, Swine Influenza (flu): http://www.cdc.gov/swineflu/

NaTHNaC Country Information pages: http://www.nathnac.org/ds/map_world.aspx

References

1. World Health Organization. Swine influenza – update 4. 28 April 2009. [Accessed 29 April 2009]. Available at: http://www.who.int/csr/don/2009_04_28/en/index.html

2. World Health Organization. Swine influenza. 27 April 2009. [Accessed 28 April 2009]. Available at: http://www.who.int/mediacentre/news/statements/2009/h1n1_2

0090427/en/index.html

3. Bundesministerium Fur Gesundheit. Neue Grippe: BMG informiert über Testergebnisse. 29 April 2009. [Accessed 29 April 2009]. Available at: http://www.bmg.gv.at/cms/site/presse_detail.html?channel=CH

0616&doc=CMS1241003566249

4. Health Canada. Cases of Human Swine Influenza in Canada. 28 April 2009. [Accessed 29 April 2009]. Available at:  http://www.phac-aspc.gc.ca/alert-alerte/swine-porcine/surveillance-eng.php

5. Robert Koch Institut. Neue Grippe erstmals in Deutschland nachgewiesen. 29 April 2009. [Accessed 29 April 2009]. Available at: http://www.rki.de/cln_161/nn_200120/DE/Content/Service/Press

e/Pressemitteilungen/2009/08__2009.html

6. Ministry of Health, New Zealand. Mexican Swine Influenza, update 11. 29 April 2009. [Accessed 29 April 2009]. Available at: http://www.moh.govt.nz/moh.nsf/indexmh/mexican-swine-influenza-update-eleven-290409

7. Ministrerio de Sanidad y Política Social, Spain.  Comunicado sobre el brote humano de gripe de origen porcino. 29 April 2009. [Accessed 29 April 2009]. Available at:

http://www.msc.es/gabinetePrensa/notaPrensa/desarrolloNota

Prensa.jsp?id=1476

8. Health Protection Agency. Suspected cases in Scotland test positive for swine flu. 27 April 2009. [Accessed 29 April 2009]. Available at: http://www.hpa.org.uk/web/HPAweb&HPAwebStandard/HPAweb

_C/1240812259242

9. Health Protection Agency. Swine flu precautionary measures taken at college in Paignton, Devon. 29 April 2009. [Accessed 29 April 2009]. Available at: http://www.hpa.org.uk/webw/HPAweb&HPAwebStandard/HPAwe

b_C/1240986142422?p=1231252394302

10. Centers for Disease Control and Prevention. Swine influenza (flu). 29 April 2009. [Accessed 29 April 2009]. Available at: http://www.cdc.gov/swineflu/  

11. Centers for Disease Control and Prevention. Interim guidance for clinicians on identifying and caring for patients with swine-origin influenza A (H1N1) virus infection. 29 April 2009. [Accessed 29 April 2009]. Available at: http://www.cdc.gov/swineflu/identifyingpatients.htm    

12. Myers KP, Olsen CW, Gray GC. Cases of swine influenza in humans: a review of the literature. Clin Infect Dis 2007;44:1084-8.

13. Health Protection Agency. Algorithm for the management of returning travellers and visitors from countries affected by swine influenza A/H1N1. 28 April 2009. [Accessed 29 April 2009]. Available at: http://www.hpa.org.uk/webc/HPAwebFile/HPAweb_C/124073281

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