Increase in Influenza-like illness

Published: December 18, 2008

During week 51 2008 (week ending December 21st), the general practitioner consultation rate for influenza-like illness (ILI) in Ireland increased to 61.6 per 100,000 population from a rate of 38.1 per 100,000 during week 50 (week ending December 14th). This rate continues to exceed the Irish baseline threshold of 17.8/100,000 (to assess influenza activity during the 2008/2009 influenza season in Ireland) above which the use of antiviral drugs is triggered.  The rate of increase was most pronounced in the 0-4 years and the 5-14 years age categories.  Genetic characterisation of  the two influenza A (H3) viruses identified this season confirms them to be A/Brisbane/10/2007 which is included as a component in the 2008/2009 influenza vaccine.   The flu report for week 51 is available here.

Due to the levels of influenza activity seen last week in Ireland, antiviral drugs for the prevention and/or treatment of influenza in at-risk patients continues to be recommended in line with the National Institute of Clinical Excellence (NICE) UK guidelines.

In line with the National Institute of Clinical Excellence (NICE) UK guidelines, the use of antiviral drugs for the treatment or prevention of influenza in at-risk patients is now recommended. 

A summary of the NICE guidelines for the use of antiviral drugs for the treatment or prevention of influenza in at-risk patients is available here.

The complete NICE guidance are outlined below:
Recommendations on the use of antiviral neuraminidase inhibitors for the treatment of influenza when influenza is known to be circulating in the community.
http://www.nice.org.uk/Guidance/TA58.

NICE have updated guidance on the use of antivirals for the prophylaxis of influenza. This was published in September 2008 and is available at:
http://www.nice.org.uk/Guidance/TA158/Guidance/pdf/English and http://www.nice.org.uk/Guidance/TA158/QuickRefGuide/pdf/English.

Influenza Vaccine
As influenza-like illness rates are increasing and influenza A is circulating, it is also important that persons in at-risk groups for influenza are vaccinated as these groups are at higher risk of developing complications from influenza.  
 
Risk groups for influenza vaccine are outlined below as per the Immunisation Guidelines for Ireland 2008 (Chapter 7). They are as follows:

Those older than 6 months of age who are at increased risk of influenza-related complications including the following groups:

1. Persons aged 50 years or older as recommended by WHO*
2. Those with chronic illness requiring regular medical follow-up (e.g. chronic respiratory disease, including cystic fibrosis, moderate or severe asthma, chronic heart disease, bronchopulmonary dysplasia, diabetes mellitus, haemoglobinopathies, chronic renal failure, etc.)
3. Immunosuppression due to disease or treatment, including asplenia or splenic dysfunction
4. Children on long-term aspirin therapy (because of the risk of Reyes Syndrome)
5. Children with any condition (e.g. cognitive dysfunction, spinal cord injury, seizure disorder, or other neuromuscular disorder) that can compromise respiratory function
6. Residents of nursing homes, old people’s homes, and other long-stay facilities where rapid spread is likely to follow introduction of infection
7. Those likely to transmit influenza to a person at high risk for influenza complications (including household contacts and out-of-home caregivers)
8. Healthcare workers, both for their own protection - as these are a group likely to come in contact with influenza during outbreaks - and for the protection of their patients
9. Poultry workers, veterinary inspectors, agricultural workers, park rangers and those with likely contact with water fowl (as this puts them at risk of co-infection with avian influenza)
10. Pregnant women in the risk groups 2 and 3 listed above should be vaccinated before the influenzas season, regardless of the stage of pregnancy. Studies indicate that pregnancy may increase the risk of complications from influenza because of the alterations in heart rate, lung capacity and immunological function. It is estimated that immunisation could prevent 1-2 hospitalisations per 1,000 pregnant women. Because influenza vaccine is not a live vaccine it is considered safe in pregnancy.

*Currently HSE are implementing this in those aged 65 years and over

The Immunisation Guidelines for Ireland 2008 are available at available at http://www.ndsc.ie/hpsc/A-Z/VaccinePreventable/Vaccination/Guidance/ .

Further Information
Details of Influenza Activity in Ireland are available on the HPSC website at:
http://www.ndsc.ie/hpsc/A-Z/Respiratory/Influenza/SeasonalInfluenza/InfluenzaSurveillanceReports/20082009Season/

Details of Influenza Activity in Europe are available on the EISS website at: http://www.eiss.org/

Details of Influenza Information for Health Professionals on the HPSC website at:
http://www.ndsc.ie/hpsc/A-Z/Respiratory/Influenza/Guidance

Details of international influenza websites are available at:
http://www.ndsc.ie/hpsc/A-Z/Respiratory/Influenza/SeasonalInfluenza/Links/