 |
Dr. Rungrueng Kitphati
17 December 2006
The rapid test or
screening test kit, that used to basically analyze Influenza
patients, uses the principle of analyzing the antigen of
Influenza A and B from the excretion of the respiratory
system of the suspected patients by immuno-chromatography
or Enzyme Immuno Assay (EIA). The test kit yields the result
rapidly with in 15 – 30 minutes. If the test results positive,
it is most likely to believe that the patient is infected
from an influenza virus. The data shows that the screening
test kit has an approximately 75 percent sensitivity and
approximately 90 percent specificity. By using this Influenza
screening test kit for Avian Influenza test is for helping
in primarily diagnosing only (not for diagnosing Avian Influenza
virus infected patients) and is for helping in deciding
whether the antiviral medication is needed. In the operational
level, however, misunderstandings have often been found
on that if the test result from the kit is negative, the
certain patient is not infected by the Avian Influenza virus.
Physicians or officers then mostly will not send the specimen
to the laboratories of Department of Medical Sciences for
testing as well as will not report the case according to
the surveillance system. The substantial usage of the screening
kit reveals that the kit has a very low sensitivity percentage
for Avian Influenza virus. Although the result from using
the screening test kit is negative, the surveillance report
must be taking place. Moreover, if the patient has any severe
symptom, attended physicians should prescribed an antiviral
medication as necessary.
The results from the
coordinating system for laboratory testing and surveillance,
Department of Medical Sciences, are illustrated in the following
table:
Table shows
numbers of suspected patients in Avian Influenza surveillance
system, numbers of Avian Influenza infected patients, numbers
of Avian Influenza infected patients that had been tested
using the screening test kit, and the sensitivity of the
screening test kit, comparing before and after taking “How
to have a quality in samples collecting and delivering”
training for medical and health officer.
Process duration |
Before the training
(1 Dec 03 – 31 Mar 04) |
After the training |
| No. of suspected patients |
610 |
4,417 |
| No. of samples to be tested per one patient (range)
|
1-3 |
1-6 |
| No. of Avian Influenza infected patient |
12 |
13 |
| No. of Avian Influenza infected patient that had been
tested using the screening test kit |
7 |
10 |
No. of Avian Influenza infected patient
with the positive test result |
2 |
3 |
| Sensitivity (in percentage) |
28.6 |
30.0 |
This shows that the quality of the samples are better (
p = 0.02)
Note:
- The screening test kits used in Thailand are SD Bioline
Influenza Antigen A/B, MT Promedt Consulting GmbH and Quickvue
Influenza A+B test, Quidel.
- “How to have a quality in samples collecting and delivering”
training for medical and health officer was held from 1
April – 31 August 2004.
- There was one Avian Influenza infected patient that had
been given an antivirus (Tamiflu) for longer than 48 hours
before the specimen was collected and the test result from
the screening test kit was negative.
|
|
