Pandemic (H1N1) influenza activity in Middlesex-London:
While Pandemic H1N1 influenza
continues to be present in the community, many indicators suggest the extent of
influenza activity is declining. No school reported absenteeism over 10% when
averaged over four days and the percentage of people reporting fever and
respiratory illness at health care providers’ offices has fallen to low levels.
The percentage of people attending an emergency room who reported fever and
respiratory illness has fallen to 11.3% during the week of November 15 to 20
compared to 18.4% in the previous report. The number of laboratory-confirmed
cases also fell to 18 from November 16 to 20 compared to 39 in the previous
week. However, the percentage of nose
samples taken from Middlesex-London residents with respiratory illness that
have come back positive for influenza A during the week of November 8 to 14 was
still quite high, based on partial data (it was 50% for Middlesex-London
compared to 36.7% for the province as a whole.)
The more serious consequences of
Pandemic H1N1 influenza continue to be noted in the community but have also
decreased, with 3 hospitalizations being reported among individuals with
influenza A or Pandemic H1N1 influenza, and one additional death being
reported. Since the arrival of Pandemic H1N1 influenza, 71 Middlesex-London
residents have been hospitalized and eight individuals have died.
Appendix A
Summary of Influenza Indicators
November 21, 2009
While Pandemic H1N1 influenza
continues to be present in the community, many indicators suggest the extent of
influenza activity is declining.
|
Indicator
|
Recent data /
trends
|
Comments
|
|
Hospital emergency room reports regarding the
percentage of patients with fever and respiratory illness
|
High, but decreased compared to previous three weeks
|
·
From November 15
to 20, 11.3% of patients presented with a fever and respiratory illness
across all emergency rooms and the urgent care centre. Values ranged from 3.7% to 29.4%, depending
on the site and day.
·
The average
continues to be highest at the paediatric emergency
room, where 23.9% of patients presented with a fever and respiratory
symptoms.
·
By comparison,
over the summer less than 3% of patients presenting to London emergency rooms
have had a fever and respiratory symptoms.
|
|
Sentinel physicians reports regarding the percentage
of patients with fever and respiratory illness
|
Low and decreased compared to previous three weeks
|
·
For the week of
November 16 to 20, the overall percentage of patients reporting fever and
respiratory illness on the surveillance day(s) was 2.2%. Values ranged from 0% to 5.9% depending on
the practice and the day.
·
Based on reports
from ten physicians screening at three medical practices.
|
|
Sentinel X-ray provider reports regarding newly
identified bronchopneumonia cases
|
Comparable to previous week
|
·
Between November
16 and 19, 7.6% of chest X-rays were diagnosed as bronchopneumonia. This compares to 6.9% from the previous
week.
·
The daily average
for this diagnosis is typically lower, between 1% and 2%.
|
|
Absence reports from child care centres
(i.e. absenteeism > 10%)
|
None reported
|
·
Between November
16 and 20, no child care centres in Middlesex-London reported absenteeism
> 10%.
|
|
Absence reports from schools
(i.e. absenteeism > 10%)
|
None reported
|
·
Between November
16 and 19, no elementary schools in the two English school boards in
Middlesex-London had a four-day all-cause absenteeism rate exceeding 10%.
·The four-day average percentage of students absent
ranged from 0.3% to 9.9%, depending on the school.
·
|
|
Laboratory-confirmed cases
|
Decreased compared to previous two weeks
|
·
From November 16
to 20, 18 laboratory-confirmed cases of influenza A were reported. This includes 7 cases of Pandemic (H1N1)
and 11 influenza A positive cases that are likely to be Pandemic (H1N1).
·
As of November
20, a total of 211 laboratory-confirmed cases of Pandemic (H1N1) and 154
influenza A positive cases that are quite likely to be the Pandemic (H1N1)
strain have been reported among Middlesex-London residents, the majority of
whom have acquired their infection this fall.
·
Appendix B shows
laboratory confirmed cases by week of illness onset / specimen collection
date.
Note:
Numbers may change slightly as additional information becomes available.
|
|
Percentage of all laboratory samples that are
positive
|
High
|
·
In
Middlesex-London from November 1 to 7, 50.0% of all samples taken to test for
influenza were positive for the influenza A.
This compares to 47.3% across the province for the same time period.
·
Based on partial
results for the week of November 8 to 14, 50.0% of samples from
Middlesex-London are positive for influenza A. This compares to 36.7% of samples from
across Ontario for the same time period.
·
These results
compare to approximately 1% at the beginning of September.
|
|
Antiviral prescriptions filled by major pharmacies
|
Low
|
·
From November 8
to 14 in Middlesex-London, the proportion of antiviral prescriptions filled
by major pharmacies, relative to other prescriptions, was low and comparable
to the previous week.
|
|
Calls to Telehealth Ontario
related to respiratory and influenza-like illness
|
Not reported
|
·
Between November
16 and 20, the Health Unit received no notifications about the number of
calls related to respiratory illness exceeding expected volumes.
|
|
Long-term care facility outbreaks
|
None declared
|
·
Between November
16 and 20, no new outbreaks were declared in institutional settings.
·
To date, 2
influenza A outbreaks have been declared in institutional settings.
|
|
Hospitalizations
|
Decreased compared to previous three weeks
|
·
Between November
16 and 20, 3 hospitalizations were reported among laboratory-confirmed cases.
·
To date, 71
people have been hospitalized who had laboratory confirmation of the Pandemic
(H1N1) strain or who had influenza A which is quite likely to be the Pandemic
(H1N1) strain.
Note:
Numbers may change slightly as additional information becomes available.
|
|
Deaths
|
Decreased compared to previous two weeks
|
·
Between November
16 and 20, the Health Unit was notified about 1 death among
laboratory-confirmed cases of influenza A.
·
In total, 8
deaths have been reported. One case
occurred in an infant, 4 occurred in adults and 3 occurred in people 65 years
of age or older, most of whom had underlying medical conditions.
|
Appendix B
Laboratory-confirmed influenza A
cases by week of illness onset / specimen collection date
This graph shows
laboratory-confirmed cases by week of onset of their illness, or, when onset
date is not available, by date the sample from the nose was taken (specimen
collection date). This graph excludes 10
cases for whom neither illness onset date nor specimen collection date is
available.